WO2024124588A1

WO2024124588A1 - Time-frequency synchronization for low power devices

Info

Publication number: WO2024124588A1
Application number: PCT/CN2022/139805
Authority: WO
Inventors: Zhikun WU; Yuchul Kim; Huilin Xu; Wei Yang; Ahmed Elshafie; Yu Zhang; Le LIU; Yiqing Cao
Original assignee: Qualcomm Incorporated
Priority date: 2022-12-17
Filing date: 2022-12-17
Publication date: 2024-06-20

Abstract

Methods, systems, and devices for wireless communications are described. A first wireless device (e.g., a user equipment (UE) or network entity) may generate a synchronization signal including an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both. In some examples, the amplitude modulated portion may indicate one or more calibration parameters for an oscillator calibration. The first wireless device may transmit the synchronization signal to a second wireless device (e.g., a radio frequency identification (RFID) tag). The second wireless device may tune an associated oscillator based on the one or more calibration parameters of the synchronization signal. The second wireless device may send to the first wireless device, a response message to the synchronization signal using the tuned oscillator.

Description

TIME-FREQUENCY SYNCHRONIZATION FOR LOW POWER DEVICES

FIELD OF TECHNOLOGY

The following relates to wireless communications, including time-frequency synchronization for low power devices.

BACKGROUND

Wireless communications systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power) . Examples of such multiple-access systems include fourth generation (4G) systems such as Long Term Evolution (LTE) systems, LTE-Advanced (LTE-A) systems, or LTE-A Pro systems, and fifth generation (5G) systems which may be referred to as New Radio (NR) systems. These systems may employ technologies such as code division multiple access (CDMA) , time division multiple access (TDMA) , frequency division multiple access (FDMA) , orthogonal FDMA (OFDMA) , or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-S-OFDM) . A wireless multiple-access communications system may include one or more base stations, each supporting wireless communication for communication devices, which may be known as user equipment (UE) .

SUMMARY

The described techniques relate to improved methods, systems, devices, and apparatuses that support time-frequency synchronization for low power devices. For example, the described techniques provide for a wireless device (e.g., a user equipment (UE) or a network entity) to communicate with a radio-frequency identification (RFID) tag via a forward link (from wireless device to RFID tag) , a backward link (from RFID tag to wireless device) , or both. The wireless device may transmit signaling to calibrate (e.g., tune) an oscillator at the RFID to improve the communication performance of the RFID tag with the wireless device. For example, the wireless device may generate a synchronization signal with a first duration of an amplitude modulated signal and a second (e.g., subsequent) duration of an unmodulated signal.

The wireless device may transmit the synchronization signal to the RFID tag, and the RFID tag may use the synchronization signal to calibrate the oscillator at the RFID tag. For example, the synchronization signal may include one or more calibration parameters that indicate a calibration frequency. As such, the RFID tag may tune the oscillator to the calibration frequency. In some examples, the amplitude modulated portion of the synchronization signal may tune the oscillator to a first level or degree of accuracy and the unmodulated portion of the synchronization signal may further tune (e.g., fine tune) the oscillator to a second level of degree accuracy that may be greater than the first level of accuracy.

A method for wireless communication at a first wireless device is described. The method may include generating a synchronization signal including an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration and transmitting, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based on the one or more calibration parameters.

An apparatus for wireless communication at a first wireless device is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to generate a synchronization signal including an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration and transmit, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based on the one or more calibration parameters.

Another apparatus for wireless communication at a first wireless device is described. The apparatus may include means for generating a synchronization signal including an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration and means for transmitting, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based on the one or more calibration parameters.

A non-transitory computer-readable medium storing code for wireless communication at a first wireless device is described. The code may include instructions executable by a processor to generate a synchronization signal including an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration and transmit, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based on the one or more calibration parameters.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for monitoring for a response message from the second wireless device based on the synchronization signal.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, monitoring for the response message may include operations, features, means, or instructions for monitoring a set of frequency resources for the response message, the set of frequency resources corresponding to the calibration frequency.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, monitoring for the response message may include operations, features, means, or instructions for monitoring a set of frequency resources for the response message, the set of frequency resources corresponding to a frequency of transmission of the unmodulated portion or a frequency shift relative to the frequency of transmission of the unmodulated portion.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the first wireless device may be a UE and the method, apparatuses, and non-transitory computer-readable medium may include further operations, features, means, or instructions for receiving, from a network entity, an indication that the network entity may be to communicate with the second wireless device via the UE, where the synchronization signal may be transmitted based on the indication that the network entity may be to communicate with the second wireless device via the UE.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, generating the synchronization signal may include operations, features, means, or instructions for generating the amplitude modulated portion spanning one or more frequency tones.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, generating the synchronization signal may include operations, features, means, or instructions for generating the amplitude modulated portion spanning the first duration according to a radio frequency activation pattern, where the radio frequency activation pattern includes a set of same amplitudes or different amplitudes.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, generating the synchronization signal may include operations, features, means, or instructions for generating the unmodulated portion spanning a single frequency tone.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, generating the synchronization signal may include operations, features, means, or instructions for generating the synchronization signal including only the amplitude modulated portion based on a classification of the second wireless device, where the classification may be a passive classification.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, generating the synchronization signal may include operations, features, means, or instructions for generating the synchronization signal including both the amplitude modulated portion and the unmodulated portion based on a classification of the second wireless device, where the classification may be an active classification, a semi-active classification, a semi-passive classification, or a passive classification.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, transmitting the synchronization signal may include operations, features, means, or instructions for transmitting the synchronization signal including only the amplitude modulated portion after a calibration duration that corresponds to a timing of a previous oscillator calibration for the second wireless device.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving an indication of the calibration duration via a dynamic signal.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving, from the second wireless device, a message indicating a classification of the second wireless device, a classification switch of the second wireless device, a timing accuracy target of the second wireless device, a temperature change of the second wireless device, or any combination thereof.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting a packet including the synchronization signal, a data portion, and a cyclic redundancy check (CRC) portion.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, transmitting the packet may include operations, features, means, or instructions for transmitting the amplitude modulated portion of the synchronization signal, the data portion, and the CRC portion via a first carrier frequency and transmitting the unmodulated portion of the synchronization signal via a second carrier frequency different from the first carrier frequency.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, transmitting the packet may include operations, features, means, or instructions for transmitting the packet according to a periodicity.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting an additional packet subsequent to the packet, where the additional packet includes a second synchronization signal having a second amplitude modulated portion, a second unmodulated portion, or both.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the additional packet includes the second synchronization signal based on threshold and the threshold corresponds to a quantity of packets, a time threshold, or both.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting a packet including the synchronization signal, a control portion, a data portion, and a CRC portion, where the control portion indicates a presence or absence of the unmodulated portion of the synchronization signal.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, a format of the amplitude modulated portion of the synchronization signal indicates a presence or absence of the unmodulated portion of the synchronization signal.

A method for wireless communication at a second wireless device is described. The method may include receiving, from a first wireless device, a synchronization signal based on a classification of the second wireless device, where the synchronization signal includes an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration, tuning an oscillator of the second wireless device based on the one or more calibration parameters of the synchronization signal, and sending, to the first wireless device, a response message to the synchronization signal using the tuned oscillator.

An apparatus for wireless communication at a second wireless device is described. The apparatus may include a processor, memory coupled with the processor, and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to receive, from a first wireless device, a synchronization signal based on a classification of the second wireless device, where the synchronization signal includes an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration, tune an oscillator of the second wireless device based on the one or more calibration parameters of the synchronization signal, and send, to the first wireless device, a response message to the synchronization signal using the tuned oscillator.

Another apparatus for wireless communication at a second wireless device is described. The apparatus may include means for receiving, from a first wireless device, a synchronization signal based on a classification of the second wireless device, where the synchronization signal includes an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration, means for tuning an oscillator of the second wireless device based on the one or more calibration parameters of the synchronization signal, and means for sending, to the first wireless device, a response message to the synchronization signal using the tuned oscillator.

A non-transitory computer-readable medium storing code for wireless communication at a second wireless device is described. The code may include instructions executable by a processor to receive, from a first wireless device, a synchronization signal based on a classification of the second wireless device, where the synchronization signal includes an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration, tune an oscillator of the second wireless device based on the one or more calibration parameters of the synchronization signal, and send, to the first wireless device, a response message to the synchronization signal using the tuned oscillator.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, tuning the oscillator may include operations, features, means, or instructions for tuning the oscillator to the calibration frequency.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the synchronization signal may include operations, features, means, or instructions for receiving the amplitude modulated portion spanning one or more frequency tones.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the synchronization signal may include operations, features, means, or instructions for receiving the amplitude modulated portion spanning the first duration according to a radio frequency activation pattern, where the radio frequency activation pattern includes a set of a set of same amplitudes or different amplitudes.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the synchronization signal may include operations, features, means, or instructions for receiving the unmodulated portion spanning a single frequency tone.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the synchronization signal may include operations, features, means, or instructions for receiving the synchronization signal including only the amplitude modulated portion based on the classification of the second wireless device, where the classification may be a passive classification.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the synchronization signal may include operations, features, means, or instructions for receiving the synchronization signal including both the amplitude modulated portion and the unmodulated portion based on the classification of the second wireless device, where the classification may be an active classification, a semi-active classification, a semi-passive classification, or a passive classification.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the synchronization signal may include operations, features, means, or instructions for receiving the synchronization signal including only the amplitude modulated portion after a calibration duration that corresponds to a timing of a previous oscillator calibration for the second wireless device.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting an indication of the calibration duration via a dynamic signal.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for transmitting, to the first wireless device, a message indicating the classification of the second wireless device, a classification switch of the second wireless device, a timing accuracy target of the second wireless device, a temperature change of the second wireless device, or any combination thereof.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving a packet including the synchronization signal, a data portion, and a CRC portion.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the packet may include operations, features, means, or instructions for receiving the amplitude modulated portion of the synchronization signal, the data portion, and the CRC portion via a first carrier frequency and receiving the unmodulated portion of the synchronization signal via a second carrier frequency different from the first carrier frequency.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, receiving the packet may include operations, features, means, or instructions for receiving the packet according to a periodicity.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving an additional packet subsequent to the packet, where the additional packet includes a second synchronization signal having a second amplitude modulated portion, a second unmodulated portion, or both.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, the additional packet includes the second synchronization signal based on a threshold and the threshold corresponds to a quantity of packets, a time threshold, or both.

In some examples of the method, apparatuses, and non-transitory computer-readable medium described herein, sending the response message may include operations, features, means, or instructions for sending the response message via a set of frequency resources, the set of frequency resources corresponding to a frequency of transmission of the unmodulated portion or a frequency shift relative to the frequency of transmission of the unmodulated portion.

Some examples of the method, apparatuses, and non-transitory computer-readable medium described herein may further include operations, features, means, or instructions for receiving a packet including the synchronization signal, a control portion, a data portion, and a CRC portion, where the control portion indicates a presence or absence of the unmodulated portion of the synchronization signal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a wireless communications system that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure.

FIG. 2 illustrates an example of a wireless communications system that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure.

FIG. 3A and 3B illustrate examples of packet configurations that support time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure.

FIG. 4A and 4B illustrate examples of packet configurations that support time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure.

FIG. 5A through 5C illustrate examples of packet configurations that support time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure.

FIG. 6 illustrates an example of a process flow that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure.

FIGs. 7 and 8 illustrate block diagrams of devices that support time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure.

FIG. 9 illustrates a block diagram of a communications manager that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure.

FIG. 10 illustrates a diagram of a system including a device that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure.

FIGs. 11 through 14 illustrate flowcharts showing methods that support time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure.

DETAILED DESCRIPTION

In some examples of wireless communications, a wireless device (e.g., a user equipment (UE) or a network entity) may communicate with a radio-frequency identification (RFID) tag via a forward link and a backward link. The wireless device may transmit signaling to calibrate (e.g., tune) an oscillator at the RFID to improve the communication performance of the RFID tag with the wireless device. For example, the wireless device may transmit signaling to the RFID tag indicating for the RFID to send a message (e.g., reflect a message using radio frequency energy) at a calibrated frequency to the wireless device. However, the signaling may be amplitude shift keying (ASK) based for communication with the RFID tag, and the signaling may not accurately meet the target frequency (e.g., be within a range of the target frequency) to communicate with the wireless device. For example, the signaling may tune the RFID to a first level of accuracy that is associated with a time or frequency error. As such, if the wireless device is monitoring for a response message via a carrier wave at a first frequency, and the error associated with the oscillator results in a carrier wave at a second frequency, the wireless device may be unable to receive the response message. Failing to meet the target frequency may result in increased latency and inefficient communications.

To decrease latency and improve efficiency, the wireless device may generate a synchronization signal that includes a duration of a modulated part (e.g., an amplitude modulated portion, such as an ASK signal) and a duration of an unmodulated signal. In some examples, the wireless device may generate the synchronization signal based on a class of the RFID tag. For instance, if the class of the RFID tag is classified as a passive tag or semi-passive tag, the wireless device may refrain from including the unmodulated portion in the synchronization signal. If the RFID tag is classified a semi-active tag or an active tag the wireless device may include both the amplitude modulated portion and the unmodulated portion in the synchronization signal.

The wireless device may transmit the synchronization signal to the RFID tag, and the RFID tag may use the synchronization signal to calibrate the oscillator. For example, the synchronization signal may include one or more calibration parameters that indicate a calibration frequency. As such, the RFID tag may tune the oscillator to the calibration frequency. In some examples, the amplitude modulated portion of the synchronization signal may tune the oscillator to a first level of accuracy and the unmodulated portion of the synchronization signal may further tune the oscillator to a second level of accuracy that may be greater than the first level of accuracy.

In some examples, the wireless device may transmit the synchronization signal aperiodically or periodically. For instance, in examples of aperiodic signaling, the wireless device may dynamically transmit the synchronization signal to the tag. In examples of periodic signaling, the wireless device may transmit the synchronization signal periodically and on demand to the tag for a configured duration of time or for a configure quantity of periodic transmissions. Additionally, or alternatively, the synchronization signal may be included in a packet, where the packet further includes a data portion and a cyclic redundancy check (CRC) portion. In some examples, the wireless device may transmit subsequent synchronization signals to the RFID tag.

Aspects of the disclosure are initially described in the context of wireless communications systems. Aspects of the disclosure are further illustrated by and described with reference to packet configurations and process flows. Aspects of the disclosure are further illustrated by and described with reference to apparatus diagrams, system diagrams, and flowcharts that relate to time-frequency synchronization for low power devices.

FIG. 1 illustrates an example of a wireless communications system 100 that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. The wireless communications system 100 may include one or more network entities 105, one or more UEs 115, and a core network 130. In some examples, the wireless communications system 100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-APro network, a New Radio (NR) network, or a network operating in accordance with other systems and radio technologies, including future systems and radio technologies not explicitly mentioned herein.

The network entities 105 may be dispersed throughout a geographic area to form the wireless communications system 100 and may include devices in different forms or having different capabilities. In various examples, a network entity 105 may be referred to as a network element, a mobility element, a radio access network (RAN) node, or network equipment, among other nomenclature. In some examples, network entities 105 and UEs 115 may wirelessly communicate via one or more communication links 125 (e.g., a radio frequency (RF) access link) . For example, a network entity 105 may support a coverage area 110 (e.g., a geographic coverage area) over which the UEs 115 and the network entity 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area over which a network entity 105 and a UE 115 may support the communication of signals according to one or more radio access technologies (RATs) .

The UEs 115 may be dispersed throughout a coverage area 110 of the wireless communications system 100, and each UE 115 may be stationary, or mobile, or both at different times. The UEs 115 may be devices in different forms or having different capabilities. Some example UEs 115 are illustrated in FIG. 1. The UEs 115 described herein may be capable of supporting communications with various types of devices, such as other UEs 115 or network entities 105, as shown in FIG. 1.

As described herein, a node of the wireless communications system 100, which may be referred to as a network node, or a wireless node, may be a network entity 105 (e.g., any network entity described herein) , a UE 115 (e.g., any UE described herein) , a network controller, an apparatus, a device, a computing system, one or more components, or another suitable processing entity configured to perform any of the techniques described herein. For example, a node may be a UE 115. As another example, a node may be a network entity 105. As another example, a first node may be configured to communicate with a second node or a third node. In one aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a UE 115. In another aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a network entity 105. In yet other aspects of this example, the first, second, and third nodes may be different relative to these examples. Similarly, reference to a UE 115, network entity 105, apparatus, device, computing system, or the like may include disclosure of the UE 115, network entity 105, apparatus, device, computing system, or the like being a node. For example, disclosure that a UE 115 is configured to receive information from a network entity 105 also discloses that a first node is configured to receive information from a second node.

In some examples, network entities 105 may communicate with the core network 130, or with one another, or both. For example, network entities 105 may communicate with the core network 130 via one or more backhaul communication links 120 (e.g., in accordance with an S1, N2, N3, or other interface protocol) . In some examples, network entities 105 may communicate with one another via a backhaul communication link 120 (e.g., in accordance with an X2, Xn, or other interface protocol) either directly (e.g., directly between network entities 105) or indirectly (e.g., via a core network 130) . In some examples, network entities 105 may communicate with one another via a midhaul communication link 162 (e.g., in accordance with a midhaul interface protocol) or a fronthaul communication link 168 (e.g., in accordance with a fronthaul interface protocol) , or any combination thereof. The backhaul communication links 120, midhaul communication links 162, or fronthaul communication links 168 may be or include one or more wired links (e.g., an electrical link, an optical fiber link) , one or more wireless links (e.g., a radio link, a wireless optical link) , among other examples or various combinations thereof. A UE 115 may communicate with the core network 130 via a communication link 155.

One or more of the network entities 105 described herein may include or may be referred to as a base station 140 (e.g., a base transceiver station, a radio base station, an NR base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB) , a next-generation NodeB or a giga-NodeB (either of which may be referred to as a gNB) , a 5G NB, a next-generation eNB (ng-eNB) , a Home NodeB, a Home eNodeB, or other suitable terminology) . In some examples, a network entity 105 (e.g., a base station 140) may be implemented in an aggregated (e.g., monolithic, standalone) base station architecture, which may be configured to utilize a protocol stack that is physically or logically integrated within a single network entity 105 (e.g., a single RAN node, such as a base station 140) .

In some examples, a network entity 105 may be implemented in a disaggregated architecture (e.g., a disaggregated base station architecture, a disaggregated RAN architecture) , which may be configured to utilize a protocol stack that is physically or logically distributed among two or more network entities 105, such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance) , or a virtualized RAN (vRAN) (e.g., a cloud RAN (C-RAN) ) . For example, a network entity 105 may include one or more of a central unit (CU) 160, a distributed unit (DU) 165, a radio unit (RU) 170, a RAN Intelligent Controller (RIC) 175 (e.g., a Near-Real Time RIC (Near-RT RIC) , a Non-Real Time RIC (Non-RT RIC) ) , a Service Management and Orchestration (SMO) 180 system, or any combination thereof. An RU 170 may also be referred to as a radio head, a smart radio head, a remote radio head (RRH) , a remote radio unit (RRU) , or a transmission reception point (TRP) . One or more components of the network entities 105 in a disaggregated RAN architecture may be co-located, or one or more components of the network entities 105 may be located in distributed locations (e.g., separate physical locations) . In some examples, one or more network entities 105 of a disaggregated RAN architecture may be implemented as virtual units (e.g., a virtual CU (VCU) , a virtual DU (VDU) , a virtual RU (VRU) ) .

The split of functionality between a CU 160, a DU 165, and an RU 170 is flexible and may support different functionalities depending on which functions (e.g., network layer functions, protocol layer functions, baseband functions, RF functions, and any combinations thereof) are performed at a CU 160, a DU 165, or an RU 170. For example, a functional split of a protocol stack may be employed between a CU 160 and a DU 165 such that the CU 160 may support one or more layers of the protocol stack and the DU 165 may support one or more different layers of the protocol stack. In some examples, the CU 160 may host upper protocol layer (e.g., layer 3 (L3) , layer 2 (L2) ) functionality and signaling (e.g., Radio Resource Control (RRC) , service data adaption protocol (SDAP) , Packet Data Convergence Protocol (PDCP) ) . The CU 160 may be connected to one or more DUs 165 or RUs 170, and the one or more DUs 165 or RUs 170 may host lower protocol layers, such as layer 1 (L1) (e.g., physical (PHY) layer) or L2 (e.g., radio link control (RLC) layer, medium access control (MAC) layer) functionality and signaling, and may each be at least partially controlled by the CU 160. Additionally, or alternatively, a functional split of the protocol stack may be employed between a DU 165 and an RU 170 such that the DU 165 may support one or more layers of the protocol stack and the RU 170 may support one or more different layers of the protocol stack. The DU 165 may support one or multiple different cells (e.g., via one or more RUs 170) . In some cases, a functional split between a CU 160 and a DU 165, or between a DU 165 and an RU 170 may be within a protocol layer (e.g., some functions for a protocol layer may be performed by one of a CU 160, a DU 165, or an RU 170, while other functions of the protocol layer are performed by a different one of the CU 160, the DU 165, or the RU 170) . A CU 160 may be functionally split further into CU control plane (CU-CP) and CU user plane (CU-UP) functions. A CU 160 may be connected to one or more DUs 165 via a midhaul communication link 162 (e.g., F1, F1-c, F1-u) , and a DU 165 may be connected to one or more RUs 170 via a fronthaul communication link 168 (e.g., open fronthaul (FH) interface) . In some examples, a midhaul communication link 162 or a fronthaul communication link 168 may be implemented in accordance with an interface (e.g., a channel) between layers of a protocol stack supported by respective network entities 105 that are in communication via such communication links.

In wireless communications systems (e.g., wireless communications system 100) , infrastructure and spectral resources for radio access may support wireless backhaul link capabilities to supplement wired backhaul connections, providing an IAB network architecture (e.g., to a core network 130) . In some cases, in an IAB network, one or more network entities 105 (e.g., IAB nodes 104) may be partially controlled by each other. One or more IAB nodes 104 may be referred to as a donor entity or an IAB donor. One or more DUs 165 or one or more RUs 170 may be partially controlled by one or more CUs 160 associated with a donor network entity 105 (e.g., a donor base station 140) . The one or more donor network entities 105 (e.g., IAB donors) may be in communication with one or more additional network entities 105 (e.g., IAB nodes 104) via supported access and backhaul links (e.g., backhaul communication links 120) . IAB nodes 104 may include an IAB mobile termination (IAB-MT) controlled (e.g., scheduled) by DUs 165 of a coupled IAB donor. An IAB-MT may include an independent set of antennas for relay of communications with UEs 115, or may share the same antennas (e.g., of an RU 170) of an IAB node 104 used for access via the DU 165 of the IAB node 104 (e.g., referred to as virtual IAB-MT (vIAB-MT) ) . In some examples, the IAB nodes 104 may include DUs 165 that support communication links with additional entities (e.g., IAB nodes 104, UEs 115) within the relay chain or configuration of the access network (e.g., downstream) . In such cases, one or more components of the disaggregated RAN architecture (e.g., one or more IAB nodes 104 or components of IAB nodes 104) may be configured to operate according to the techniques described herein.

In the case of the techniques described herein applied in the context of a disaggregated RAN architecture, one or more components of the disaggregated RAN architecture may be configured to support time-frequency synchronization for low power devices as described herein. For example, some operations described as being performed by a UE 115 or a network entity 105 (e.g., a base station 140) may additionally, or alternatively, be performed by one or more components of the disaggregated RAN architecture (e.g., IAB nodes 104, DUs 165, CUs 160, RUs 170, RIC 175, SMO 180) .

A UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the “device” may also be referred to as a unit, a station, a terminal, or a client, among other examples. A UE 115 may also include or may be referred to as a personal electronic device such as a cellular phone, a personal digital assistant (PDA) , a tablet computer, a laptop computer, or a personal computer. In some examples, a UE 115 may include or be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communications (MTC) device, among other examples, which may be implemented in various objects such as appliances, or vehicles, meters, among other examples.

The UEs 115 described herein may be able to communicate with various types of devices, such as other UEs 115 that may sometimes act as relays as well as the network entities 105 and the network equipment including macro eNBs or gNBs, small cell eNBs or gNBs, or relay base stations, among other examples, as shown in FIG. 1.

The UEs 115 and the network entities 105 may wirelessly communicate with one another via one or more communication links 125 (e.g., an access link) using resources associated with one or more carriers. The term “carrier” may refer to a set of RF spectrum resources having a defined physical layer structure for supporting the communication links 125. For example, a carrier used for a communication link 125 may include a portion of a RF spectrum band (e.g., a bandwidth part (BWP) ) that is operated according to one or more physical layer channels for a given radio access technology (e.g., LTE, LTE-A, LTE-A Pro, NR) . Each physical layer channel may carry acquisition signaling (e.g., synchronization signals, system information) , control signaling that coordinates operation for the carrier, user data, or other signaling. The wireless communications system 100 may support communication with a UE 115 using carrier aggregation or multi-carrier operation. A UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both frequency division duplexing (FDD) and time division duplexing (TDD) component carriers. Communication between a network entity 105 and other devices may refer to communication between the devices and any portion (e.g., entity, sub-entity) of a network entity 105. For example, the terms “transmitting, ” “receiving, ” or “communicating, ” when referring to a network entity 105, may refer to any portion of a network entity 105 (e.g., a base station 140, a CU 160, a DU 165, a RU 170) of a RAN communicating with another device (e.g., directly or via one or more other network entities 105) .

Signal waveforms transmitted via a carrier may be made up of multiple subcarriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM) ) . In a system employing MCM techniques, a resource element may refer to resources of one symbol period (e.g., a duration of one modulation symbol) and one subcarrier, in which case the symbol period and subcarrier spacing may be inversely related. The quantity of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme, the coding rate of the modulation scheme, or both) , such that a relatively higher quantity of resource elements (e.g., in a transmission duration) and a relatively higher order of a modulation scheme may correspond to a relatively higher rate of communication. A wireless communications resource may refer to a combination of an RF spectrum resource, a time resource, and a spatial resource (e.g., a spatial layer, a beam) , and the use of multiple spatial resources may increase the data rate or data integrity for communications with a UE 115.

The time intervals for the network entities 105 or the UEs 115 may be expressed in multiples of a basic time unit which may, for example, refer to a sampling period of T _s=1/ (Δf _max·N _f) seconds, for which Δf _max may represent a supported subcarrier spacing, and N _f may represent a supported discrete Fourier transform (DFT) size. Time intervals of a communications resource may be organized according to radio frames each having a specified duration (e.g., 10 milliseconds (ms) ) . Each radio frame may be identified by a system frame number (SFN) (e.g., ranging from 0 to 1023) .

Each frame may include multiple consecutively-numbered subframes or slots, and each subframe or slot may have the same duration. In some examples, a frame may be divided (e.g., in the time domain) into subframes, and each subframe may be further divided into a quantity of slots. Alternatively, each frame may include a variable quantity of slots, and the quantity of slots may depend on subcarrier spacing. Each slot may include a quantity of symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period) . In some wireless communications systems 100, a slot may further be divided into multiple mini-slots associated with one or more symbols. Excluding the cyclic prefix, each symbol period may be associated with one or more (e.g., N _f) sampling periods. The duration of a symbol period may depend on the subcarrier spacing or frequency band of operation.

A subframe, a slot, a mini-slot, or a symbol may be the smallest scheduling unit (e.g., in the time domain) of the wireless communications system 100 and may be referred to as a transmission time interval (TTI) . In some examples, the TTI duration (e.g., a quantity of symbol periods in a TTI) may be variable. Additionally, or alternatively, the smallest scheduling unit of the wireless communications system 100 may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs) ) .

Physical channels may be multiplexed for communication using a carrier according to various techniques. A physical control channel and a physical data channel may be multiplexed for signaling via a downlink carrier, for example, using one or more of time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. A control region (e.g., a control resource set (CORESET) ) for a physical control channel may be defined by a set of symbol periods and may extend across the system bandwidth or a subset of the system bandwidth of the carrier. One or more control regions (e.g., CORESETs) may be configured for a set of the UEs 115. For example, one or more of the UEs 115 may monitor or search control regions for control information according to one or more search space sets, and each search space set may include one or multiple control channel candidates in one or more aggregation levels arranged in a cascaded manner. An aggregation level for a control channel candidate may refer to an amount of control channel resources (e.g., control channel elements (CCEs) ) associated with encoded information for a control information format having a given payload size. Search space sets may include common search space sets configured for sending control information to multiple UEs 115 and UE-specific search space sets for sending control information to a specific UE 115.

In some examples, a network entity 105 (e.g., a base station 140, an RU 170) may be movable and therefore provide communication coverage for a moving coverage area 110. In some examples, different coverage areas 110 associated with different technologies may overlap, but the different coverage areas 110 may be supported by the same network entity 105. In some other examples, the overlapping coverage areas 110 associated with different technologies may be supported by different network entities 105. The wireless communications system 100 may include, for example, a heterogeneous network in which different types of the network entities 105 provide coverage for various coverage areas 110 using the same or different radio access technologies.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices and may provide for automated communication between machines (e.g., via Machine-to-Machine (M2M) communication) . M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a network entity 105 (e.g., a base station 140) without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay such information to a central server or application program that uses the information or presents the information to humans interacting with the application program. Some UEs 115 may be designed to collect information or enable automated behavior of machines or other devices. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business charging.

The wireless communications system 100 may be configured to support ultra-reliable communications or low-latency communications, or various combinations thereof. For example, the wireless communications system 100 may be configured to support ultra-reliable low-latency communications (URLLC) . The UEs 115 may be designed to support ultra-reliable, low-latency, or critical functions. Ultra-reliable communications may include private communication or group communication and may be supported by one or more services such as push-to-talk, video, or data. Support for ultra-reliable, low-latency functions may include prioritization of services, and such services may be used for public safety or general commercial applications. The terms ultra-reliable, low-latency, and ultra-reliable low-latency may be used interchangeably herein.

In some examples, a UE 115 may be configured to support communicating directly with other UEs 115 via a device-to-device (D2D) communication link 135 (e.g., in accordance with a peer-to-peer (P2P) , D2D, or sidelink protocol) . In some examples, one or more UEs 115 of a group that are performing D2D communications may be within the coverage area 110 of a network entity 105 (e.g., a base station 140, an RU 170) , which may support aspects of such D2D communications being configured by (e.g., scheduled by) the network entity 105. In some examples, one or more UEs 115 of such a group may be outside the coverage area 110 of a network entity 105 or may be otherwise unable to or not configured to receive transmissions from a network entity 105. In some examples, groups of the UEs 115 communicating via D2D communications may support a one-to-many (1: M) system in which each UE 115 transmits to each of the other UEs 115 in the group. In some examples, a network entity 105 may facilitate the scheduling of resources for D2D communications. In some other examples, D2D communications may be carried out between the UEs 115 without an involvement of a network entity 105.

The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or 5G core (5GC) , which may include at least one control plane entity that manages access and mobility (e.g., a mobility management entity (MME) , an access and mobility management function (AMF) ) and at least one user plane entity that routes packets or interconnects to external networks (e.g., a serving gateway (S-GW) , a Packet Data Network (PDN) gateway (P-GW) , or a user plane function (UPF) ) . The control plane entity may manage non-access stratum (NAS) functions such as mobility, authentication, and bearer management for the UEs 115 served by the network entities 105 (e.g., base stations 140) associated with the core network 130. User IP packets may be transferred through the user plane entity, which may provide IP address allocation as well as other functions. The user plane entity may be connected to IP services 150 for one or more network operators. The IP services 150 may include access to the Internet, Intranet (s) , an IP Multimedia Subsystem (IMS) , or a Packet-Switched Streaming Service.

The wireless communications system 100 may operate using one or more frequency bands, which may be in the range of 300 megahertz (MHz) to 300 gigahertz (GHz) . Generally, the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band because the wavelengths range from approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features, which may be referred to as clusters, but the waves may penetrate structures sufficiently for a macro cell to provide service to the UEs 115 located indoors. Communications using UHF waves may be associated with smaller antennas and shorter ranges (e.g., less than 100 kilometers) compared to communications using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.

The wireless communications system 100 may utilize both licensed and unlicensed RF spectrum bands. For example, the wireless communications system 100 may employ License Assisted Access (LAA) , LTE-Unlicensed (LTE-U) radio access technology, or NR technology using an unlicensed band such as the 5 GHz industrial, scientific, and medical (ISM) band. While operating using unlicensed RF spectrum bands, devices such as the network entities 105 and the UEs 115 may employ carrier sensing for collision detection and avoidance. In some examples, operations using unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating using a licensed band (e.g., LAA) . Operations using unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, among other examples.

A network entity 105 (e.g., a base station 140, an RU 170) or a UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. The antennas of a network entity 105 or a UE 115 may be located within one or more antenna arrays or antenna panels, which may support MIMO operations or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some examples, antennas or antenna arrays associated with a network entity 105 may be located at diverse geographic locations. A network entity 105 may include an antenna array with a set of rows and columns of antenna ports that the network entity 105 may use to support beamforming of communications with a UE 115. Likewise, a UE 115 may include one or more antenna arrays that may support various MIMO or beamforming operations. Additionally, or alternatively, an antenna panel may support RF beamforming for a signal transmitted via an antenna port.

Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a network entity 105, a UE 115) to shape or steer an antenna beam (e.g., a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining the signals communicated via antenna elements of an antenna array such that some signals propagating along particular orientations with respect to an antenna array experience constructive interference while others experience destructive interference. The adjustment of signals communicated via the antenna elements may include a transmitting device or a receiving device applying amplitude offsets, phase offsets, or both to signals carried via the antenna elements associated with the device. The adjustments associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., with respect to the antenna array of the transmitting device or receiving device, or with respect to some other orientation) .

In some examples of wireless communications, a wireless device (e.g., a UE 115 or a network entity 105) may communicate with a second wireless device (e.g., an IoT device such as an RFID tag, which may be a UE 115) via a forward link and a backward link. The wireless device may transmit signaling to calibrate (e.g., tune) an oscillator at the RFID to improve the communication performance of the RFID tag with the wireless device. For example, the wireless may transmit signaling to the RFID tag indicating for the RFID to send a message (e.g., reflect a message using radio frequency energy) at a calibrated frequency to the wireless device.

To decrease latency and improve efficiency, the wireless device may generate a synchronization signal with a duration of a amplitude modulate signal (e.g., an ASK based signal) and a duration of an unmodulated signal. In some examples, the wireless device may generate the synchronization signal based on a class of the RFID tag. For instance, if the class of the RFID tag is classified as a passive tag, the wireless device may refrain from including the unmodulated portion in the synchronization signal. If the RFID tag is classified as semi-passive, semi-active, or active, the wireless device may include both the amplitude modulated portion and the unmodulated portion in the synchronization signal

The wireless device may transmit the synchronization signal to the RFID tag, and the RFID tag may use the synchronization signal to calibrate the oscillator. For example, the synchronization signal may include one or more calibration parameters that indicate a calibration frequency. As such, the RFID tag may tune the oscillator to the calibration frequency. In some examples, the amplitude modulated portion of the synchronization signal may tune the oscillator to a first level of accuracy and the unmodulated portion of the synchronization signal may further tune the oscillator to a second level of accuracy that may be greater than the first level of accuracy. In some examples, the wireless device may transmit the synchronization signal aperiodically or periodically. Additionally, or alternatively, the synchronization signal may be included in a packet, where the packet further includes a data portion and a CRC portion. In some examples, the wireless device may transmit subsequent synchronization signals to the RFID tag.

FIG. 2 illustrates an example of a wireless communications system 200 that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. In some examples, the wireless communications system 200 may support aspects of a wireless communications system 100. For example, the wireless communications system 200 may include a wireless device 205-a which may be an example of a UE 115 or a network entity 105 with reference to FIG. 2. Further, the wireless communications system 200 may include a wireless device 205-b, which may be an example of a UE 115 with reference to FIG. 1.

In some examples, the wireless device 205-a may be a UE 115 that communicates with the wireless device 205-b while operating in a half-duplex mode. Additionally, or alternatively, the wireless device 205-a may be a UE 115 that communicates with the wireless device 205-b while operating in a full-duplex mode. In some examples, the wireless device 205-a may be a network entity 105 that communicates with the wireless device 205-b using a UE 115 as a relay to communicate with the wireless device 205-b.

The wireless device 205-b may be an example of an RFID tag which may communicate with the wireless device 205-a via a forward link and a backward link. As such, the wireless device 205-b may be one or more types of an RFID tag. Systems that support communications between wireless device 205-a and 205-b may be referred to as RFID systems and may operate in ISM bands, licensed bands, or both.

In some examples, the wireless device 205-b may be a passive tag which may be a light weight IoT device with no battery. As such, the passive tag may capture power from a radio wave and use radio frequency backscatter communications to communicate with the wireless device 205-a. For example, the wireless device 205-b may include a modulated retro reflector (MRR) 215, which may allow the wireless device 205-b to reflect and modulate received optical beams 210 (e.g., at a high bandwidth) . The MRR 215 may include a modulator 225 and a reflector 220. There may be many different types of modulators 225 such as deformable micro-electro-mechanical systems (MEMs) , liquid crystals, electro-optic phase modulators, and multiple quantum wells (MQW) . Further, there may be many different types of reflectors 220 such as corner cube or cat’s eye. The wireless device 205-b may receive an optical beam 210 from the wireless device 205-a and change the direction of the optical beam 210 using the reflector 220 (e.g., reflect the optical beam 210 in a same or similar direction in which it was received) . The reflected optical beam 210 (e.g., an optical beam 210-a) may pass through the modulator 225 and the modulated optical beam 210 (e.g., the modulated optical beam 210-b) may continue in the direction dictated by the reflector 220.

In some examples, the wireless device 205-b may be a semi-passive tag, which may be a light weight IoT device that uses radio frequency backscatter communications to communicate with the wireless device 205-a. In some cases, the semi-passive tag may include a battery that may be rechargeable. Additionally, or alternately, the semi-passive tag may perform energy harvesting (e.g., harvest energy from received wireless transmissions) and store the harvested energy in energy storage circuits. Additionally, or alternatively, the semi-passive tag may include a power amplifier that may be embedded in a reception component of the tag or a transmission component of the tag.

In some examples, the wireless device 205-b may be a semi-active tag, which may be light weight IoT device, that uses radio frequency backscatter communications to communicate with the wireless device 205-a. Additionally, or alternatively, the semi-active tag may perform active communications. For example, the wireless device 205-b may receive wireless transmissions at an antenna 230 and transmit a response to the wireless transmissions using the antenna 230. As such, the semi-active tag may include a battery that may be rechargeable or may perform energy harvesting and store the harvested energy in energy storage circuits.

In some examples, the wireless device 205-b may be an active tag which may be a light weight IoT device, that uses active communications to communicate with the wireless device 205-a. As such, the semi-active tag may include a battery that may be rechargeable or may perform energy harvesting and store the harvested energy in energy storage circuits.

As illustrated in FIG. 2, the wireless device 205-b may include an oscillator 235 which may be used to generate transmissions (e.g., backscattering, or active transmissions) from the wireless device 205-b to the wireless device 205-a. For instance, the oscillator 235 may be tuned, such that the transmissions are generated in a given frequency range. In some cases, however, the oscillator 235 may have an associated time or frequency error. For instance, if an active tag generates a carrier wave of 3.5 GHz and the oscillator 235 of the active tag has a time or frequency error of 4%, then the resulting carrier wave may have an error of 140 MHz. As such, if the wireless device 205-a is expecting a carrier wave at a first frequency and the wireless device 205-b transmits the carrier wave at a second frequency, then the wireless device 205-amay be unable to receive the transmission. In some cases, the oscillator 235 may be an example of crystal oscillator, which may decrease time and frequency errors, but may result in increased price and power consumption at the wireless device 205-b. In some cases, the wireless device 205-b may be an example of a wiliot tag, where the wireless device 205-a may calibrate the oscillator 235 of the wiliot tag using a Bluetooth low energy (BLE) packet (e.g., a frequency-shift keying (FSK) packet) . However, wiliot tags may be implemented for low energy Bluetooth communications and may be unable to communicate via ISM or licensed bands.

According to the techniques described herein, the wireless device 205-a may calibrate the oscillator 235 of the wireless device 205-b using a synchronization signal 245 For example, the wireless device 205-b may receive synchronization signal 245 via the antenna 230, which may be connected to a frequency lock loop (FLL) 240 component. In some examples, the FLL 240 component may be a circuit that compares the frequency of the oscillator 235 to a reference frequency and may automatically raise or lower the frequency of the oscillator 235 until the frequency of the oscillator 235 matches that of the reference frequency. As such, the synchronization signal 245 may indicate the reference frequency, such that the FLL 240 component may adjust the frequency of the oscillator 235 in accordance with the synchronization signal 245.

In some examples, the synchronization signal 245 may include an amplitude modulated portion 250 and an unmodulated portion 255. In some cases, the amplitude modulated portion 250 may be an example of ASK. In some examples, ASK may be a form of amplitude modulation that represents digital data as variations in the amplitude of a carrier wave. In an ASK system, a symbol, representing one or more bits, may be sent by transmitting a fixed-amplitude carrier wave at a fixed frequency for a specific time duration. The ASK based signal may be a multi-tone signal (e.g., span multiple frequency tones) or be a single tone signal. Additionally, or alternatively, the ASK based signal may have a set of off durations (e.g., radio frequency off durations) and a set of on durations (e.g., radio frequency on durations) , or both. In some examples, the amplitude modulated portion 250 may include a delimiter that indicates to the wireless device 205-b the start point of a packet. In some examples, the amplitude modulated portion 250 may include one or more calibration parameters that may be used at the wireless device 205-b to tune the oscillator 235 to a first threshold of accuracy (e.g., calibrate the oscillator 235 within 4%of the baseband frequency) .

In some cases, the unmodulated portion 255 may be a single frequency tone. In some examples, the unmodulated portion 255 may further calibrate the oscillator 235 to a second threshold of accuracy, where the second threshold of accuracy may be greater than the first threshold of accuracy. Additionally, or alternatively, the unmodulated portion 255 may calibrate an accuracy of a time domain clock associated with the oscillator 235.

In some examples, the unmodulated portion 255 of the synchronization signal 245 may be optional based on one or more capabilities of the wireless device 205-b. For example, the wireless device 205-b may transmit to the wireless device 205-a a capability message 260 that may indicate a classification of the wireless device 205-b (e.g., passive, semi-passive, semi-active, or active) , a timing accuracy target of the wireless device 205-b, a temperature change of the wireless device 205-b, or a combination thereof.

The wireless device 205-a may refrain from including the unmodulated portion 255 in the synchronization signal 245 if the capability message 260 indicates that the wireless device 205-b is a passive tag, based on the passive tag not including a battery or energy storage components. Additionally, or alternatively, the wireless device 205-a may refrain from including the modulated portion based on a duration since a previous oscillator calibration (e.g., a calibration duration) . For example, the wireless device 205-a may transmit the synchronization signal 245 including only the amplitude modulated portion 250 within the calibration duration that corresponds to a timing of a previous oscillator calibration for the wireless device 205-b. In some examples, the calibration duration may be preconfigured at the wireless device 205-a. In some examples, the wireless device 205-a may receive from the wireless device 205-b a dynamic signal indicating the calibration duration (e.g., as part of the capability message 260 or in a separate signal) .

In some examples, the wireless device 205-a may include the unmodulated portion 255 if the capability message 260 indicates that the wireless device 205-b is an active tag, a semi-active tag, or a semi-passive tag. In some examples, the wireless device 205-a may determine to include the unmodulated portion 255 based on the mode of the wireless device 205-b. For instance, if the wireless device 205-b is a semi-active tag, the wireless device 205-b may perform communications via a passive mode (e.g., via backscattering) or via an active mode (e.g., via active communications) . As such, if the wireless device 205-b indicates to the wireless device 205-a that the wireless device 205-b is operating in an active mode, then the wireless device 205-a may generate the synchronization signal 245 including both the amplitude modulated portion 250 and the unmodulated portion 255. If the wireless device 205-b indicates to the wireless device 205-a that the wireless device 205-b is operating in an passive mode, then the wireless device 205-a may generate the synchronization signal 245 including only the amplitude modulated portion 250. Additionally, or alternatively, the wireless device 205-b may be operating in a passive mode but may indicate to the wireless device 205-a a capability (e.g., enough power) to switch to the active mode. As such, the wireless device 205-amay generate the synchronization signal 245 including both the amplitude modulated portion 250 and the unmodulated portion 255.

In some examples, the wireless device 205-a may include the unmodulated portion 255 if the wireless device 205-b requests a high timing accuracy target. For example, if the capability message 260 indicates a timing accuracy target above a configured threshold, then the wireless device 205-a may include the unmodulated portion 255 in the synchronization signal 245 to further tune the oscillator 235, such that the time accuracy target is satisfied.

In some examples, the wireless device 205-a may include the unmodulated portion 255 if the wireless device 205-b experiences a change on temperature. For example, if the capability message 260 indicates a temperature change at the wireless device 205-b above a configured threshold, then the oscillator 235 may experience an increase in inaccuracy. As such, the wireless device 205-a may include the unmodulated portion 255 in the synchronization signal 245 to further tune the oscillator 235 such that the change in temperature may not decrease the accuracy of the oscillator 235.

In some examples, the wireless device 205-a may monitor for a response message 265 from the wireless device 205-b via a set of resources corresponding to a frequency of transmission of the unmodulated portion 255 or a frequency shift relative to the frequency of transmission of the unmodulated portion 255. As such, the wireless device 205-b may transmit the response message 265 to the wireless device 205-a using the set of resources.

In some examples, the synchronization signal 245 may be part of a packet that includes a data portion and/or a CRC portion. Further discussion of configuration of the packet including the synchronization signal 245 is described herein, including with reference to FIGs. 3 through 5.

FIG. 3A and 3B illustrate respective examples of a packet configuration 300-a and 300-b that support time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. In some examples, the packet configurations 300 may support aspects of a

wireless communications systems

100 and 200. For example, a packet 305 may include an amplitude modulated portion 310 and an unmodulated portion 315 which may be respective examples of an amplitude modulated portion 250 and an unmodulated portion 255 of a synchronization signal 245, as described with reference to FIG. 2. Further, the packets 305 may be an example of a transmission from the wireless device 205-a to the wireless device 205-b, and may be used to calibrate an oscillator 235 of the wireless device 205-b.

As illustrated in FIG. 3A, a packet 305-a may be configured in accordance with the packet configuration 300-a. For example, the packet 305-a may include the synchronization signal, a data 320 portion, a CRC 325 portion, or a combination thereof. In some examples of packet 305-a, the amplitude modulated portion 310 and the unmodulated portion 315 may both be at the head (e.g., beginning) of the packet 305-a, which may be followed by the data 320 portion and/or the CRC 325 portion. In some examples, the amplitude modulated portion 310 may be associated with a frequency 330-a and the unmodulated portion 315 may be associated with a frequency 330-b. In some instances, the frequency 330-a and the frequency 330-b may be the same frequency or different frequencies.

In some examples, the wireless device 205-a may transmit the unmodulated portion 315 according to a periodicity. For example, the packet 305-a may be an aperiodic transmission such that the unmodulated portion 315 is included based on on-demand signaling. For example, the wireless device 205-a may receive signaling from the wireless device 205-b indicating to include the unmodulated portion 315 in packet 305-a. As such, the packet 305-a may include the unmodulated portion and subsequent packets 305 may only include the amplitude modulated portion 310.

Additionally or alternately, the wireless device 205-a may include the unmodulated portion 315 in accordance with a periodicity. For example, the wireless device 205-a may include the unmodulated portion 315 in every N-th packet 305. For instance, packet 305-a may include the unmodulated portion 315 and every N-th packet 305 after packet 305-a may also include the unmodulated portion 315. In such examples, the wireless device 205-a may be preconfigured with the periodicity, or the wireless device 205-b may transmit to the wireless device 205-a an indication of the periodicity (e.g., a value of N) .

As illustrated in FIG. 3B, a packet 305-b may be configured in accordance with the packet configuration 300-b. For example, the packet 305-b may include the synchronization signal, a data 320 portion, a CRC 325 portion, or a combination thereof. In some examples of packet 305-b, the amplitude modulated portion 310 at the head (e.g., beginning) of the packet 305-a, followed by the data 320 portion, the CRC 325 portion, and ending with the unmodulated portion 315. In some examples, the amplitude modulated portion 310 may be associated with a frequency 330-a and the unmodulated portion 315 may be associated with a frequency 330-b. In some instances, the frequency 330-a and the frequency 330-b may be the same frequency or different frequencies.

In some examples, the wireless device 205-a may transmit the unmodulated portion 315 according to a periodicity. For example, the packet 305-b may be an aperiodic transmission such that the unmodulated portion 315 is included based on on-demand signaling. For example, the wireless device 205-a may receive signaling from the wireless device 205-b indicating to include the unmodulated portion 315 in packet 305-b. As such, the packet 305-a may include the unmodulated portion 315 and subsequent packets 305 may only include the amplitude modulated portion 310.

FIG. 4A and 4B illustrate respective examples of a packet configuration 400-a and 400-b that support time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. In some examples, the packet configurations 400 may support aspects of a

wireless communications systems

100 and 200. For example, a packet 405 may include an amplitude modulated portion 410 which may be an example of an amplitude modulated portion 250 of a synchronization signal 245, as described with reference to FIG. 2. In some examples, the packet 405 may also include an unmodulated portion indication 415, which may indicate whether an unmodulated portion (such as an unmodulated portion 255) is included in the packet 405. Further, the packets 405 may be an example of a transmission from the wireless device 205-a to the wireless device 205-b, and may be used to calibrate an oscillator 235 of the wireless device 205-b.

As illustrated in FIG. 4A, the packet 405-a may include the amplitude modulated portion 410, a data 420 portion and/or a CRC 425 portion. In some examples, the amplitude modulated portion 410 may denote the presence or absence of the unmodulated portion of the synchronization signal. For example, the amplitude modulated portion 410 may include the unmodulated portion indication 415 which may indicate whether the packet 405-a may include the unmodulated portion. If the unmodulated portion indication 415 indicates that the packet 405-a includes the unmodulated portion, then the unmodulated portion may not be adjacent to (e.g., subsequent to or consecutive in time with) the amplitude modulated portion 410. For instance, the unmodulated portion may be included at the end of the packet 405-a (e.g., subsequent to the CRC 425 portion if included) . In some examples, the wireless device 205-b may use a same frequency carrier to receive the unmodulated portion that the wireless device 205-b uses to receive the amplitude modulated portion 410. Additionally, or alternatively, the wireless device 205-b may receive the unmodulated portion using a frequency shift relative to the frequency carrier used to receive the amplitude modulated portion 410.

As illustrated in FIG. 4B, the packet 405-b may include the amplitude modulated portion 410, a set of control bits 430, a data 420 portion, a CRC 425 portion, or a combination thereof. In some examples, the set of control bits 430 may denote the presence or absence of the unmodulated portion of the synchronization signal. For example, set of control bits 430 may include the unmodulated portion indication 415 which may indicate whether the packet 405-b may include the unmodulated portion. If the unmodulated portion indication 415 indicates that the packet 405-b includes the unmodulated portion, then the unmodulated portion may not be adjacent to (e.g., subsequent to or consecutive in time with) the amplitude modulated portion 410. For instance, the unmodulated portion may be included at the end of the packet 405-b (e.g., subsequent to the CRC 425 portion, if included) . In some examples, the wireless device 205-b may use a same frequency carrier to receive the unmodulated portion that the wireless device 205-b uses to receive the amplitude modulated portion 410. Additionally, or alternatively, the wireless device 205-b may receive the unmodulated portion using a frequency shift relative to the frequency carrier used to receive the amplitude modulated portion 410.

FIG. 5A–5C illustrate respective examples of a packet configuration 500-a, 500-b, and 500-c that support time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. In some examples, the packet configurations 500 may support aspects of a

wireless communications systems

100 and 200. For example, a packet 505 may have a synchronization signal 510 that may include an amplitude modulated portion 525 and an unmodulated portion 530, which may be an example of a synchronization signal 245 that includes an amplitude modulated portion 250 and an unmodulated portion 255, as described with reference to FIG. 2. Further, the packets 505 may be an example of a transmission from the wireless device 205-a to the wireless device 205-b, and may be used to calibrate an oscillator 235 of the wireless device 205-b.

As illustrated in FIG. 5A, the wireless device 205-a may transmit to the wireless device 205-b a set of packets 505 (e.g., packet 505-a, packet 505-b, and packet 505-c) . Each packet 505 of packet configuration 500-a may include a synchronization signal 510 (e.g., synchronization signal 510-a, 510-b, and 510-c) , a data 515 portion (e.g., data 515-a, 515-b, and 515-c) , and an optional CRC 520 portion (e.g., CRC 520-a, 520-b, and 520-c) . In some examples, the configuration of the synchronization signal 510 may be different per packet 505. For example, synchronization signal 510-a of packet 505-a may include both the amplitude modulated portion 525 and the unmodulated portion 530 and subsequent packets 505 may include respective synchronization signals 510 that only include the unmodulated portion 530. For example, the synchronization signal 510-b of packet 505-b may include only the unmodulated portion 530 and the synchronization signal 510-c of packet 505-c may include only the unmodulated portion 530.

As illustrated in FIG. 5B, the wireless device 205-a may transmit to the wireless device 205-b a set of packets 505 (e.g., packet 505-a, packet 505-b, and packet 505-c) . Each packet 505 of packet configuration 500-b may include a synchronization signal 510 (e.g., synchronization signal 510-a, 510-b, and 510-c) , a data 515 portion (e.g., data 515-a, 515-b, and 515-c) , and an optional CRC 520 portion (e.g., CRC 520-a, 520-b, and 520-c) . In some examples, the configuration of the synchronization signal 510 may be different per packet 505. For example, synchronization signal 510-a of packet 505-a may include both the amplitude modulated portion 525 and the unmodulated portion 530 and subsequent packets 505 may include respective synchronization signals 510 that only include the amplitude modulated portion 525. For example, the synchronization signal 510-b of packet 505-b may include only the amplitude modulated portion 525 and the synchronization signal 510-c of packet 505-c may include only the amplitude modulated portion 525.

As illustrated in FIG. 5C, the wireless device 205-a may transmit to the wireless device 205-b a set of packets 505 (e.g., packet 505-a, packet 505-b, and packet 505-c) . Each packet 505 of packet configuration 500-b may include a synchronization signal 510, a data 515 portion (e.g., data 515-a, 515-b, and 515-c) , and an optional CRC 520 portion (e.g., CRC 520-a, 520-b, and 520-c) . In some examples, the configuration of the synchronization signal 510 may be different per packet 505. For example, synchronization signal 510-a of packet 505-a may include both the amplitude modulated portion 525 and the unmodulated portion 530 and subsequent packets 505 may not include synchronization signals. For example, packets 505-b and 505-c may not include respective synchronization signals 510. In some examples, the wireless device 205-amay be configured with one or more parameters that indicate when to include a synchronization signal 510 in a packet 505. For example, a first parameter may indicate for the wireless device 205-a to include a synchronization signal 510 in every N-th packet 505. Additionally, or alternatively, a second parameter may indicate for the wireless device 205-a to include a synchronization signal 510 after a duration of time (e.g., every N seconds) . In some examples, the wireless device 205-a may be preconfigured with the one or more parameters, or the wireless device 205-b may transmit an indication of the one or more parameters to the wireless device 205-a.

FIG. 6 illustrates an example of a process flow 600 that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. In some examples, the process flow 600 may be implemented by aspects of a wireless communications system 100, wireless communications system 200, and packet configurations 300 through 500. For example, the process flow 600 may be implemented by a wireless device 605-a and a wireless device 605-b which may be respective examples of a wireless device 205-a and a wireless device 205-b, with reference to FIG. 2. Alternative examples of the following be implemented, where some steps are performed in a different order than described or are not performed at all. In some cases, steps may include additional features not mentioned below, or further steps may be added.

In some examples, the wireless device 605-a may be an example of a UE. In some examples, the UE may receive, from a network entity, an indication that the network entity is to communicate with the wireless device 605-b via the UE. In such examples, a synchronization signal may be transmitted (e.g., at 625) based on the indication that the network entity is to communicate with the wireless device 605-b via the wireless device 605-a.

At 610, the wireless device 605-a may receive a capability message indicating a classification of the wireless device 605-b, a classification switch of the wireless device 605-b, a timing accuracy target of the wireless device 605-b, a temperature change of the wireless device 605-b, or any combination thereof.

At 615, the wireless device 605-a may receive an indication of a calibration duration that corresponds to a timing of a previous oscillator calibration for the wireless device 605-b. In some examples, the wireless device 605-a may receive the indication via a dynamic signal. In some examples, the wireless device 605-a may receive the indication as part of the capability message, at 610.

At 620, the wireless device 605-a may generate a synchronization signal that includes an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both. In some examples, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration of the wireless device 605-b.

In some examples, the wireless device 605-a may generate the amplitude modulated portion spanning one or more frequency tones. Additionally or alterability, the wireless device 605-a may generate the amplitude modulated portion spanning the first duration according to a radio frequency activation pattern. In some examples, the radio frequency activation pattern may include a set of same amplitudes or different amplitudes. In some examples, the wireless device 605-a may generate the unmodulated portion spanning a single frequency tone.

In some examples, the wireless device 605-a may generate the synchronization signal that includes only the amplitude modulated portion based on a classification of the wireless device 605-b, where the classification is a passive classification. Additionally, or alternatively, the wireless device 605-a may generate the synchronization signal that includes both the amplitude modulated portion and the unmodulated portion based on a classification of the wireless device 605-b, where the classification is an active classification, a semi-active classification, a semi-passive classification, or a passive classification.

At 625, the wireless device 605-a may transmit to the wireless device 605-b, the synchronization signal to calibrate an oscillator of the wireless device 605-b based on the one or more calibration parameters. In some examples, the wireless device 605-amay transmit the synchronization signal that includes only the amplitude modulated portion after the calibration duration indicated, at 615.

In some examples, the wireless device 605-a may transmit the synchronization signal as part of a packet. For example, the packet may include the synchronization signal, a data portion, and a CRC portion. In some examples, the wireless device 605-a may transmit the amplitude modulated portion of the synchronization signal, the data portion, and the CRC portion via a first carrier frequency and transmit the unmodulated portion of the synchronization signal via a second carrier frequency different from the first carrier frequency. In some examples, the wireless device 605-a may transmit the packet according to a periodicity.

In some examples, the wireless device 605-a may transmit an additional packet subsequent to the packet, where the additional packet may include a second synchronization signal having a second amplitude modulated portion, a second unmodulated portion, or both. In some examples, the additional packet may include the second synchronization signal based on threshold, where the threshold corresponds to a quantity of packets, a time threshold, or both.

In some examples, the wireless device 605-a may transmit a packet that includes the synchronization signal, a control portion, a data portion, and a CRC portion, where the control portion indicates a presence or absence of the unmodulated portion of the synchronization signal. Additionally, or alternatively, a format of the amplitude modulated portion of the synchronization signal may indicate a presence or absence of the unmodulated portion of the synchronization signal.

At 630, the wireless device 605-b may tune the oscillator based on the one or more calibration parameters of the synchronization signal. In some examples, the one or more calibration parameters may include a calibration frequency, such that the wireless device 605-b tunes the oscillator to the calibration frequency.

At 635, the wireless device 605-a may monitor for a response message from the wireless device 605-b based on the synchronization signal. For example, the one or more calibration parameters may indicate a calibration frequency, and the wireless device 605-a may monitor a set of frequency resources corresponding to the calibration frequency. Additionally, or alternatively, the set of frequency resources may correspond to a frequency of transmission of the unmodulated portion or a frequency shift relative to the frequency of transmission of the unmodulated portion.

At 640, the wireless device 605-b may send, to the wireless device 605-a, a response message to the synchronization signal using the tuned oscillator.

FIG. 7 illustrates a block diagram 700 of a device 705 that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. The device 705 may be an example of aspects of a UE 115 as described herein. The device 705 may include a receiver 710, a transmitter 715, and a communications manager 720. The device 705 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 710 may provide a means for receiving information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to time-frequency synchronization for low power devices) . Information may be passed on to other components of the device 705. The receiver 710 may utilize a single antenna or a set of multiple antennas.

The transmitter 715 may provide a means for transmitting signals generated by other components of the device 705. For example, the transmitter 715 may transmit information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to time-frequency synchronization for low power devices) . In some examples, the transmitter 715 may be co-located with a receiver 710 in a transceiver module. The transmitter 715 may utilize a single antenna or a set of multiple antennas.

The communications manager 720, the receiver 710, the transmitter 715, or various combinations thereof or various components thereof may be examples of means for performing various aspects of time-frequency synchronization for low power devices as described herein. For example, the communications manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may support a method for performing one or more of the functions described herein.

In some examples, the communications manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be implemented in hardware (e.g., in communications management circuitry) . The hardware may include a processor, a digital signal processor (DSP) , a central processing unit (CPU) , an application-specific integrated circuit (ASIC) , a field-programmable gate array (FPGA) or other programmable logic device, a microcontroller, discrete gate or transistor logic, discrete hardware components, or any combination thereof configured as or otherwise supporting a means for performing the functions described in the present disclosure. In some examples, a processor and memory coupled with the processor may be configured to perform one or more of the functions described herein (e.g., by executing, by the processor, instructions stored in the memory) .

Additionally, or alternatively, in some examples, the communications manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be implemented in code (e.g., as communications management software or firmware) executed by a processor. If implemented in code executed by a processor, the functions of the communications manager 720, the receiver 710, the transmitter 715, or various combinations or components thereof may be performed by a general-purpose processor, a DSP, a CPU, an ASIC, an FPGA, a microcontroller, or any combination of these or other programmable logic devices (e.g., configured as or otherwise supporting a means for performing the functions described in the present disclosure) .

In some examples, the communications manager 720 may be configured to perform various operations (e.g., receiving, obtaining, monitoring, outputting, transmitting) using or otherwise in cooperation with the receiver 710, the transmitter 715, or both. For example, the communications manager 720 may receive information from the receiver 710, send information to the transmitter 715, or be integrated in combination with the receiver 710, the transmitter 715, or both to obtain information, output information, or perform various other operations as described herein.

The communications manager 720 may support wireless communication at a first wireless device in accordance with examples as disclosed herein. For example, the communications manager 720 may be configured as or otherwise support a means for generating a synchronization signal including an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The communications manager 720 may be configured as or otherwise support a means for transmitting, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based on the one or more calibration parameters.

Additionally, or alternatively, the communications manager 720 may support wireless communication at a second wireless device in accordance with examples as disclosed herein. For example, the communications manager 720 may be configured as or otherwise support a means for receiving, from a first wireless device, a synchronization signal based on a classification of the second wireless device, where the synchronization signal includes an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The communications manager 720 may be configured as or otherwise support a means for tuning an oscillator of the second wireless device based on the one or more calibration parameters of the synchronization signal. The communications manager 720 may be configured as or otherwise support a means for sending, to the first wireless device, a response message to the synchronization signal using the tuned oscillator.

By including or configuring the communications manager 720 in accordance with examples as described herein, the device 705 (e.g., a processor controlling or otherwise coupled with the receiver 710, the transmitter 715, the communications manager 720, or a combination thereof) may support techniques for increasing frequency accuracy for transmission of a carrier wave resulting in reduced processing, reduced power consumption, and a more efficient utilization of communication resources.

FIG. 8 illustrates a block diagram 800 of a device 805 that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. The device 805 may be an example of aspects of a device 705 or a UE 115 as described herein. The device 805 may include a receiver 810, a transmitter 815, and a communications manager 820. The device 805 may also include a processor. Each of these components may be in communication with one another (e.g., via one or more buses) .

The receiver 810 may provide a means for receiving information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to time-frequency synchronization for low power devices) . Information may be passed on to other components of the device 805. The receiver 810 may utilize a single antenna or a set of multiple antennas.

The transmitter 815 may provide a means for transmitting signals generated by other components of the device 805. For example, the transmitter 815 may transmit information such as packets, user data, control information, or any combination thereof associated with various information channels (e.g., control channels, data channels, information channels related to time-frequency synchronization for low power devices) . In some examples, the transmitter 815 may be co-located with a receiver 810 in a transceiver module. The transmitter 815 may utilize a single antenna or a set of multiple antennas.

The device 805, or various components thereof, may be an example of means for performing various aspects of time-frequency synchronization for low power devices as described herein. For example, the communications manager 820 may include a signal generation component 825, a signal transmission component 830, a signal reception component 835, an oscillator tuning component 840, or any combination thereof. The communications manager 820 may be an example of aspects of a communications manager 720 as described herein. In some examples, the communications manager 820, or various components thereof, may be configured to perform various operations (e.g., receiving, obtaining, monitoring, outputting, transmitting) using or otherwise in cooperation with the receiver 810, the transmitter 815, or both. For example, the communications manager 820 may receive information from the receiver 810, send information to the transmitter 815, or be integrated in combination with the receiver 810, the transmitter 815, or both to obtain information, output information, or perform various other operations as described herein.

The communications manager 820 may support wireless communication at a first wireless device in accordance with examples as disclosed herein. The signal generation component 825 may be configured as or otherwise support a means for generating a synchronization signal including an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The signal transmission component 830 may be configured as or otherwise support a means for transmitting, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based on the one or more calibration parameters.

Additionally, or alternatively, the communications manager 820 may support wireless communication at a second wireless device in accordance with examples as disclosed herein. The signal reception component 835 may be configured as or otherwise support a means for receiving, from a first wireless device, a synchronization signal based on a classification of the second wireless device, where the synchronization signal includes an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The oscillator tuning component 840 may be configured as or otherwise support a means for tuning an oscillator of the second wireless device based on the one or more calibration parameters of the synchronization signal. The signal transmission component 830 may be configured as or otherwise support a means for sending, to the first wireless device, a response message to the synchronization signal using the tuned oscillator.

FIG. 9 illustrates a block diagram 900 of a communications manager 920 that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. The communications manager 920 may be an example of aspects of a communications manager 720, a communications manager 820, or both, as described herein. The communications manager 920, or various components thereof, may be an example of means for performing various aspects of time-frequency synchronization for low power devices as described herein. For example, the communications manager 920 may include a signal generation component 925, a signal transmission component 930, a signal reception component 935, an oscillator tuning component 940, a resource monitoring component 945, a modulated signal generation component 950, an unmodulated signal generation component 955, a modulated signal reception component 960, an unmodulated signal reception component 965, or any combination thereof. Each of these components may communicate, directly or indirectly, with one another (e.g., via one or more buses) .

The communications manager 920 may support wireless communication at a first wireless device in accordance with examples as disclosed herein. The signal generation component 925 may be configured as or otherwise support a means for generating a synchronization signal including an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The signal transmission component 930 may be configured as or otherwise support a means for transmitting, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based on the one or more calibration parameters.

In some examples, the resource monitoring component 945 may be configured as or otherwise support a means for monitoring for a response message from the second wireless device based on the synchronization signal.

In some examples, to support monitoring for the response message, the resource monitoring component 945 may be configured as or otherwise support a means for monitoring a set of frequency resources for the response message, the set of frequency resources corresponding to the calibration frequency.

In some examples, to support monitoring for the response message, the resource monitoring component 945 may be configured as or otherwise support a means for monitoring a set of frequency resources for the response message, the set of frequency resources corresponding to a frequency of transmission of the unmodulated portion or a frequency shift relative to the frequency of transmission of the unmodulated portion.

In some examples, the first wireless device is a UE, and the signal reception component 935 may be configured as or otherwise support a means for receiving, from a network entity, an indication that the network entity is to communicate with the second wireless device via the UE, where the synchronization signal is transmitted based on the indication that the network entity is to communicate with the second wireless device via the UE.

In some examples, to support generating the synchronization signal, the modulated signal generation component 950 may be configured as or otherwise support a means for generating the amplitude modulated portion spanning one or more frequency tones.

In some examples, to support generating the synchronization signal, the modulated signal generation component 950 may be configured as or otherwise support a means for generating the amplitude modulated portion spanning the first duration according to a radio frequency activation pattern, where the radio frequency activation pattern includes a set of same amplitudes or different amplitudes.

In some examples, to support generating the synchronization signal, the unmodulated signal generation component 955 may be configured as or otherwise support a means for generating the unmodulated portion spanning a single frequency tone.

In some examples, to support generating the synchronization signal, the signal generation component 925 may be configured as or otherwise support a means for generating the synchronization signal including only the amplitude modulated portion based on a classification of the second wireless device, where the classification is a passive classification.

In some examples, to support generating the synchronization signal, the signal generation component 925 may be configured as or otherwise support a means for generating the synchronization signal including both the amplitude modulated portion and the unmodulated portion based on a classification of the second wireless device, where the classification is an active classification, a semi-active classification, a semi-passive classification, or a passive classification.

In some examples, to support transmitting the synchronization signal, the signal generation component 925 may be configured as or otherwise support a means for transmitting the synchronization signal including only the amplitude modulated portion after a calibration duration that corresponds to a timing of a previous oscillator calibration for the second wireless device.

In some examples, the signal reception component 935 may be configured as or otherwise support a means for receiving an indication of the calibration duration via a dynamic signal.

In some examples, the signal reception component 935 may be configured as or otherwise support a means for receiving, from the second wireless device, a message indicating a classification of the second wireless device, a classification switch of the second wireless device, a timing accuracy target of the second wireless device, a temperature change of the second wireless device, or any combination thereof.

In some examples, the signal transmission component 930 may be configured as or otherwise support a means for transmitting a packet including the synchronization signal, a data portion, and a CRC portion.

In some examples, to support transmitting the packet, the signal transmission component 930 may be configured as or otherwise support a means for transmitting the amplitude modulated portion of the synchronization signal, the data portion, and the CRC portion via a first carrier frequency. In some examples, to support transmitting the packet, the signal transmission component 930 may be configured as or otherwise support a means for transmitting the unmodulated portion of the synchronization signal via a second carrier frequency different from the first carrier frequency.

In some examples, to support transmitting the packet, the signal transmission component 930 may be configured as or otherwise support a means for transmitting the packet according to a periodicity.

In some examples, the signal transmission component 930 may be configured as or otherwise support a means for transmitting an additional packet subsequent to the packet, where the additional packet includes a second synchronization signal having a second amplitude modulated portion, a second unmodulated portion, or both.

In some examples, the additional packet includes the second synchronization signal based on threshold. In some examples, the threshold corresponds to a quantity of packets, a time threshold, or both.

In some examples, the signal transmission component 930 may be configured as or otherwise support a means for transmitting a packet including the synchronization signal, a control portion, a data portion, and a CRC portion, where the control portion indicates a presence or absence of the unmodulated portion of the synchronization signal.

In some examples, a format of the amplitude modulated portion of the synchronization signal indicates a presence or absence of the unmodulated portion of the synchronization signal.

Additionally, or alternatively, the communications manager 920 may support wireless communication at a second wireless device in accordance with examples as disclosed herein. The signal reception component 935 may be configured as or otherwise support a means for receiving, from a first wireless device, a synchronization signal based on a classification of the second wireless device, where the synchronization signal includes an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The oscillator tuning component 940 may be configured as or otherwise support a means for tuning an oscillator of the second wireless device based on the one or more calibration parameters of the synchronization signal. In some examples, the signal transmission component 930 may be configured as or otherwise support a means for sending, to the first wireless device, a response message to the synchronization signal using the tuned oscillator.

In some examples, to support tuning the oscillator, the oscillator tuning component 940 may be configured as or otherwise support a means for tuning the oscillator to the calibration frequency.

In some examples, to support receiving the synchronization signal, the modulated signal reception component 960 may be configured as or otherwise support a means for receiving the amplitude modulated portion spanning one or more frequency tones.

In some examples, to support receiving the synchronization signal, the modulated signal reception component 960 may be configured as or otherwise support a means for receiving the amplitude modulated portion spanning the first duration according to a radio frequency activation pattern, where the radio frequency activation pattern includes a set of a set of same amplitudes or different amplitudes.

In some examples, to support receiving the synchronization signal, the unmodulated signal reception component 965 may be configured as or otherwise support a means for receiving the unmodulated portion spanning a single frequency tone.

In some examples, to support receiving the synchronization signal, the signal reception component 935 may be configured as or otherwise support a means for receiving the synchronization signal including only the amplitude modulated portion based on the classification of the second wireless device, where the classification is a passive classification.

In some examples, to support receiving the synchronization signal, the signal reception component 935 may be configured as or otherwise support a means for receiving the synchronization signal including both the amplitude modulated portion and the unmodulated portion based on the classification of the second wireless device, where the classification is an active classification, a semi-active classification, a semi-passive classification, or a passive classification.

In some examples, to support receiving the synchronization signal, the signal reception component 935 may be configured as or otherwise support a means for receiving the synchronization signal including only the amplitude modulated portion after a calibration duration that corresponds to a timing of a previous oscillator calibration for the second wireless device.

In some examples, the signal transmission component 930 may be configured as or otherwise support a means for transmitting an indication of the calibration duration via a dynamic signal.

In some examples, the signal transmission component 930 may be configured as or otherwise support a means for transmitting, to the first wireless device, a message indicating the classification of the second wireless device, a classification switch of the second wireless device, a timing accuracy target of the second wireless device, a temperature change of the second wireless device, or any combination thereof.

In some examples, the signal reception component 935 may be configured as or otherwise support a means for receiving a packet including the synchronization signal, a data portion, and a CRC portion.

In some examples, to support receiving the packet, the signal reception component 935 may be configured as or otherwise support a means for receiving the amplitude modulated portion of the synchronization signal, the data portion, and the CRC portion via a first carrier frequency. In some examples, to support receiving the packet, the signal reception component 935 may be configured as or otherwise support a means for receiving the unmodulated portion of the synchronization signal via a second carrier frequency different from the first carrier frequency.

In some examples, to support receiving the packet, the signal reception component 935 may be configured as or otherwise support a means for receiving the packet according to a periodicity.

In some examples, the signal reception component 935 may be configured as or otherwise support a means for receiving an additional packet subsequent to the packet, where the additional packet includes a second synchronization signal having a second amplitude modulated portion, a second unmodulated portion, or both.

In some examples, the additional packet includes the second synchronization signal based on a threshold. In some examples, the threshold corresponds to a quantity of packets, a time threshold, or both.

In some examples, to support sending the response message, the signal transmission component 930 may be configured as or otherwise support a means for sending the response message via a set of frequency resources, the set of frequency resources corresponding to a frequency of transmission of the unmodulated portion or a frequency shift relative to the frequency of transmission of the unmodulated portion.

In some examples, the signal reception component 935 may be configured as or otherwise support a means for receiving a packet including the synchronization signal, a control portion, a data portion, and a CRC portion, where the control portion indicates a presence or absence of the unmodulated portion of the synchronization signal.

FIG. 10 illustrates a diagram of a system 1000 including a device 1005 that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. The device 1005 may be an example of or include the components of a device 705, a device 805, or a UE 115 as described herein. The device 1005 may communicate (e.g., wirelessly) with one or more network entities 105, one or more UEs 115, or any combination thereof. The device 1005 may include components for bi-directional voice and data communications including components for transmitting and receiving communications, such as a communications manager 1020, an input/output (I/O) controller 1010, a transceiver 1015, an antenna 1025, a memory 1030, code 1035, and a processor 1040. These components may be in electronic communication or otherwise coupled (e.g., operatively, communicatively, functionally, electronically, electrically) via one or more buses (e.g., a bus 1045) .

The I/O controller 1010 may manage input and output signals for the device 1005. The I/O controller 1010 may also manage peripherals not integrated into the device 1005. In some cases, the I/O controller 1010 may represent a physical connection or port to an external peripheral. In some cases, the I/O controller 1010 may utilize an operating system such as

or another known operating system. Additionally, or alternatively, the I/O controller 1010 may represent or interact with a modem, a keyboard, a mouse, a touchscreen, or a similar device. In some cases, the I/O controller 1010 may be implemented as part of a processor, such as the processor 1040. In some cases, a user may interact with the device 1005 via the I/O controller 1010 or via hardware components controlled by the I/O controller 1010.

In some cases, the device 1005 may include a single antenna 1025. However, in some other cases, the device 1005 may have more than one antenna 1025, which may be capable of concurrently transmitting or receiving multiple wireless transmissions. The transceiver 1015 may communicate bi-directionally, via the one or more antennas 1025, wired, or wireless links as described herein. For example, the transceiver 1015 may represent a wireless transceiver and may communicate bi-directionally with another wireless transceiver. The transceiver 1015 may also include a modem to modulate the packets, to provide the modulated packets to one or more antennas 1025 for transmission, and to demodulate packets received from the one or more antennas 1025. The transceiver 1015, or the transceiver 1015 and one or more antennas 1025, may be an example of a transmitter 715, a transmitter 815, a receiver 710, a receiver 810, or any combination thereof or component thereof, as described herein.

The memory 1030 may include random access memory (RAM) and read-only memory (ROM) . The memory 1030 may store computer-readable, computer-executable code 1035 including instructions that, when executed by the processor 1040, cause the device 1005 to perform various functions described herein. The code 1035 may be stored in a non-transitory computer-readable medium such as system memory or another type of memory. In some cases, the code 1035 may not be directly executable by the processor 1040 but may cause a computer (e.g., when compiled and executed) to perform functions described herein. In some cases, the memory 1030 may contain, among other things, a basic I/O system (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices.

The processor 1040 may include an intelligent hardware device (e.g., a general-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof) . In some cases, the processor 1040 may be configured to operate a memory array using a memory controller. In some other cases, a memory controller may be integrated into the processor 1040. The processor 1040 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 1030) to cause the device 1005 to perform various functions (e.g., functions or tasks supporting time-frequency synchronization for low power devices) . For example, the device 1005 or a component of the device 1005 may include a processor 1040 and memory 1030 coupled with or to the processor 1040, the processor 1040 and memory 1030 configured to perform various functions described herein.

The communications manager 1020 may support wireless communication at a first wireless device in accordance with examples as disclosed herein. For example, the communications manager 1020 may be configured as or otherwise support a means for generating a synchronization signal including an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The communications manager 1020 may be configured as or otherwise support a means for transmitting, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based on the one or more calibration parameters.

Additionally, or alternatively, the communications manager 1020 may support wireless communication at a second wireless device in accordance with examples as disclosed herein. For example, the communications manager 1020 may be configured as or otherwise support a means for receiving, from a first wireless device, a synchronization signal based on a classification of the second wireless device, where the synchronization signal includes an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The communications manager 1020 may be configured as or otherwise support a means for tuning an oscillator of the second wireless device based on the one or more calibration parameters of the synchronization signal. The communications manager 1020 may be configured as or otherwise support a means for sending, to the first wireless device, a response message to the synchronization signal using the tuned oscillator.

By including or configuring the communications manager 1020 in accordance with examples as described herein, the device 1005 may support techniques for increasing frequency accuracy for transmission of a carrier wave resulting in improved communication reliability, reduced latency, improved user experience related to reduced processing, reduced power consumption, more efficient utilization of communication resources, improved coordination between devices, longer battery life, and improved utilization of processing capability.

In some examples, the communications manager 1020 may be configured to perform various operations (e.g., receiving, monitoring, transmitting) using or otherwise in cooperation with the transceiver 1015, the one or more antennas 1025, or any combination thereof. Although the communications manager 1020 is illustrated as a separate component, in some examples, one or more functions described with reference to the communications manager 1020 may be supported by or performed by the processor 1040, the memory 1030, the code 1035, or any combination thereof. For example, the code 1035 may include instructions executable by the processor 1040 to cause the device 1005 to perform various aspects of time-frequency synchronization for low power devices as described herein, or the processor 1040 and the memory 1030 may be otherwise configured to perform or support such operations.

FIG. 11 illustrates a flowchart illustrating a method 1100 that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. The operations of the method 1100 may be implemented by a UE or its components as described herein. For example, the operations of the method 1100 may be performed by a UE 115 as described with reference to FIGs. 1 through 10. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the described functions. Additionally, or alternatively, the UE may perform aspects of the described functions using special-purpose hardware.

At 1105, the method may include generating a synchronization signal including an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The operations of 1105 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1105 may be performed by a signal generation component 925 as described with reference to FIG. 9.

At 1110, the method may include transmitting, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based on the one or more calibration parameters. The operations of 1110 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1110 may be performed by a signal transmission component 930 as described with reference to FIG. 9.

FIG. 12 illustrates a flowchart illustrating a method 1200 that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. The operations of the method 1200 may be implemented by a UE or its components as described herein. For example, the operations of the method 1200 may be performed by a UE 115 as described with reference to FIGs. 1 through 10. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the described functions. Additionally, or alternatively, the UE may perform aspects of the described functions using special-purpose hardware.

At 1205, the method may include generating a synchronization signal including an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The operations of 1205 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1205 may be performed by a signal generation component 925 as described with reference to FIG. 9.

At 1210, the method may include transmitting, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based on the one or more calibration parameters. The operations of 1210 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1210 may be performed by a signal transmission component 930 as described with reference to FIG. 9.

At 1215, the method may include monitoring for a response message from the second wireless device based on the synchronization signal. The operations of 1215 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1215 may be performed by a resource monitoring component 945 as described with reference to FIG. 9.

FIG. 13 illustrates a flowchart illustrating a method 1300 that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. The operations of the method 1300 may be implemented by a UE or its components as described herein. For example, the operations of the method 1300 may be performed by a UE 115 as described with reference to FIGs. 1 through 10. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the described functions. Additionally, or alternatively, the UE may perform aspects of the described functions using special-purpose hardware.

At 1305, the method may include receiving, from a first wireless device, a synchronization signal based on a classification of the second wireless device, where the synchronization signal includes an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The operations of 1305 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1305 may be performed by a signal reception component 935 as described with reference to FIG. 9.

At 1310, the method may include tuning an oscillator of the second wireless device based on the one or more calibration parameters of the synchronization signal. The operations of 1310 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1310 may be performed by an oscillator tuning component 940 as described with reference to FIG. 9.

At 1315, the method may include sending, to the first wireless device, a response message to the synchronization signal using the tuned oscillator. The operations of 1315 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1315 may be performed by a signal transmission component 930 as described with reference to FIG. 9.

FIG. 14 illustrates a flowchart illustrating a method 1400 that supports time-frequency synchronization for low power devices in accordance with one or more aspects of the present disclosure. The operations of the method 1400 may be implemented by a UE or its components as described herein. For example, the operations of the method 1400 may be performed by a UE 115 as described with reference to FIGs. 1 through 10. In some examples, a UE may execute a set of instructions to control the functional elements of the UE to perform the described functions. Additionally, or alternatively, the UE may perform aspects of the described functions using special-purpose hardware.

At 1405, the method may include transmitting, to the first wireless device, a message indicating the classification of the second wireless device, a classification switch of the second wireless device, a timing accuracy target of the second wireless device, a temperature change of the second wireless device, or any combination thereof. The operations of 1405 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1405 may be performed by a signal transmission component 930 as described with reference to FIG. 9.

At 1410, the method may include receiving, from a first wireless device, a synchronization signal based on a classification of the second wireless device, where the synchronization signal includes an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration. The operations of 1410 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1410 may be performed by a signal reception component 935 as described with reference to FIG. 9.

At 1415, the method may include tuning an oscillator of the second wireless device based on the one or more calibration parameters of the synchronization signal. The operations of 1415 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1415 may be performed by an oscillator tuning component 940 as described with reference to FIG. 9.

At 1420, the method may include sending, to the first wireless device, a response message to the synchronization signal using the tuned oscillator. The operations of 1420 may be performed in accordance with examples as disclosed herein. In some examples, aspects of the operations of 1420 may be performed by a signal transmission component 930 as described with reference to FIG. 9.

The following provides an overview of aspects of the present disclosure:

Aspect 1: A method for wireless communication at a first wireless device, comprising: generating a synchronization signal comprising an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration; and transmitting, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based at least in part on the one or more calibration parameters.

Aspect 2: The method of aspect 1, further comprising: monitoring for a response message from the second wireless device based at least in part on the synchronization signal.

Aspect 3: The method of aspect 2, wherein the one or more calibration parameters comprise a calibration frequency, wherein monitoring for the response message comprises: monitoring a set of frequency resources for the response message, the set of frequency resources corresponding to the calibration frequency.

Aspect 4: The method of any of aspects 2 through 3, wherein monitoring for the response message comprises: monitoring a set of frequency resources for the response message, the set of frequency resources corresponding to a frequency of transmission of the unmodulated portion or a frequency shift relative to the frequency of transmission of the unmodulated portion.

Aspect 5: The method of any of aspects 1 through 4, wherein the first wireless device is a UE, the method further comprising: receiving, from a network entity, an indication that the network entity is to communicate with the second wireless device via the UE, wherein the synchronization signal is transmitted based at least in part on the indication that the network entity is to communicate with the second wireless device via the UE.

Aspect 6: The method of any of aspects 1 through 5, wherein generating the synchronization signal comprises: generating the amplitude modulated portion spanning one or more frequency tones.

Aspect 7: The method of any of aspects 1 through 6, wherein generating the synchronization signal comprises: generating the amplitude modulated portion spanning the first duration according to a radio frequency activation pattern, wherein the radio frequency activation pattern comprises a set of same amplitudes or different amplitudes.

Aspect 8: The method of any of aspects 1 through 7, wherein generating the synchronization signal comprises: generating the unmodulated portion spanning a single frequency tone.

Aspect 9: The method of any of aspects 1 through 8, wherein generating the synchronization signal comprises: generating the synchronization signal comprising only the amplitude modulated portion based at least in part on a classification of the second wireless device, wherein the classification is a passive classification.

Aspect 10: The method of any of aspects 1 through 9, wherein generating the synchronization signal comprises: generating the synchronization signal comprising both the amplitude modulated portion and the unmodulated portion based at least in part on a classification of the second wireless device, wherein the classification is an active classification, a semi-active classification, a semi-passive classification, or a passive classification.

Aspect 11: The method of any of aspects 1 through 10, wherein transmitting the synchronization signal comprises: transmitting the synchronization signal comprising only the amplitude modulated portion after a calibration duration that corresponds to a timing of a previous oscillator calibration for the second wireless device.

Aspect 12: The method of aspect 11, further comprising: receiving an indication of the calibration duration via a dynamic signal.

Aspect 13: The method of any of aspects 1 through 12, further comprising: receiving, from the second wireless device, a message indicating a classification of the second wireless device, a classification switch of the second wireless device, a timing accuracy target of the second wireless device, a temperature change of the second wireless device, or any combination thereof.

Aspect 14: The method of any of aspects 1 through 13, further comprising: transmitting a packet comprising the synchronization signal, a data portion, and a CRC portion.

Aspect 15: The method of aspect 14, wherein transmitting the packet comprises: transmitting the amplitude modulated portion of the synchronization signal, the data portion, and the CRC portion via a first carrier frequency; and transmitting the unmodulated portion of the synchronization signal via a second carrier frequency different from the first carrier frequency.

Aspect 16: The method of any of aspects 14 through 15, wherein transmitting the packet comprises: transmitting the packet according to a periodicity.

Aspect 17: The method of any of aspects 14 through 16, further comprising: transmitting an additional packet subsequent to the packet, wherein the additional packet comprises a second synchronization signal having a second amplitude modulated portion, a second unmodulated portion, or both.

Aspect 18: The method of aspect 17, wherein the additional packet comprises the second synchronization signal based at least in part on threshold, the threshold corresponds to a quantity of packets, a time threshold, or both.

Aspect 19: The method of any of aspects 1 through 18, further comprising: transmitting a packet comprising the synchronization signal, a control portion, a data portion, and a CRC portion, wherein the control portion indicates a presence or absence of the unmodulated portion of the synchronization signal.

Aspect 20: The method of any of aspects 1 through 19, wherein a format of the amplitude modulated portion of the synchronization signal indicates a presence or absence of the unmodulated portion of the synchronization signal.

Aspect 21: A method for wireless communication at a second wireless device, comprising: receiving, from a first wireless device, a synchronization signal based at least in part on a classification of the second wireless device, wherein the synchronization signal comprises an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration; tuning an oscillator of the second wireless device based at least in part on the one or more calibration parameters of the synchronization signal; and sending, to the first wireless device, a response message to the synchronization signal using the tuned oscillator.

Aspect 22: The method of aspect 21, wherein the one or more calibration parameters comprise a calibration frequency, wherein tuning the oscillator comprises: tuning the oscillator to the calibration frequency.

Aspect 23: The method of any of aspects 21 through 22, wherein receiving the synchronization signal comprises: receiving the amplitude modulated portion spanning one or more frequency tones.

Aspect 24: The method of any of aspects 21 through 23, wherein receiving the synchronization signal comprises: receiving the amplitude modulated portion spanning the first duration according to a radio frequency activation pattern, wherein the radio frequency activation pattern comprises a set of a set of same amplitudes or different amplitudes .

Aspect 25: The method of any of aspects 21 through 24, wherein receiving the synchronization signal comprises: receiving the unmodulated portion spanning a single frequency tone.

Aspect 26: The method of any of aspects 21 through 25, wherein receiving the synchronization signal comprises: receiving the synchronization signal comprising only the amplitude modulated portion based at least in part on the classification of the second wireless device, wherein the classification is a passive classification.

Aspect 27: The method of any of aspects 21 through 26, wherein receiving the synchronization signal comprises: receiving the synchronization signal comprising both the amplitude modulated portion and the unmodulated portion based at least in part on the classification of the second wireless device, wherein the classification is an active classification, a semi-active classification, a semi-passive classification, or a passive classification.

Aspect 28: The method of any of aspects 21 through 27, wherein receiving the synchronization signal comprises: receiving the synchronization signal comprising only the amplitude modulated portion after a calibration duration that corresponds to a timing of a previous oscillator calibration for the second wireless device.

Aspect 29: The method of aspect 28, further comprising: transmitting an indication of the calibration duration via a dynamic signal.

Aspect 30: The method of any of aspects 21 through 29, further comprising: transmitting, to the first wireless device, a message indicating the classification of the second wireless device, a classification switch of the second wireless device, a timing accuracy target of the second wireless device, a temperature change of the second wireless device, or any combination thereof.

Aspect 31: The method of any of aspects 21 through 30, further comprising: receiving a packet comprising the synchronization signal, a data portion, and a CRC portion.

Aspect 32: The method of aspect 31, wherein receiving the packet comprises: receiving the amplitude modulated portion of the synchronization signal, the data portion, and the CRC portion via a first carrier frequency; and receiving the unmodulated portion of the synchronization signal via a second carrier frequency different from the first carrier frequency.

Aspect 33: The method of any of aspects 31 through 32, wherein receiving the packet comprises: receiving the packet according to a periodicity.

Aspect 34: The method of any of aspects 31 through 33, further comprising: receiving an additional packet subsequent to the packet, wherein the additional packet comprises a second synchronization signal having a second amplitude modulated portion, a second unmodulated portion, or both.

Aspect 35: The method of aspect 34, wherein the additional packet comprises the second synchronization signal based at least in part on a threshold, the threshold corresponds to a quantity of packets, a time threshold, or both.

Aspect 36: The method of any of aspects 21 through 35, wherein sending the response message comprises: sending the response message via a set of frequency resources, the set of frequency resources corresponding to a frequency of transmission of the unmodulated portion or a frequency shift relative to the frequency of transmission of the unmodulated portion.

Aspect 37: The method of any of aspects 21 through 36, further comprising: receiving a packet comprising the synchronization signal, a control portion, a data portion, and a CRC portion, wherein the control portion indicates a presence or absence of the unmodulated portion of the synchronization signal.

Aspect 38: The method of any of aspects 21 through 37, wherein a format of the amplitude modulated portion of the synchronization signal indicates a presence or absence of the unmodulated portion of the synchronization signal.

Aspect 39: An apparatus for wireless communication at a first wireless device, comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method of any of aspects 1 through 20.

Aspect 40: An apparatus for wireless communication at a first wireless device, comprising at least one means for performing a method of any of aspects 1 through 20.

Aspect 41: A non-transitory computer-readable medium storing code for wireless communication at a first wireless device, the code comprising instructions executable by a processor to perform a method of any of aspects 1 through 20.

Aspect 42: An apparatus for wireless communication at a second wireless device, comprising a processor; memory coupled with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to perform a method of any of aspects 21 through 38.

Aspect 43: An apparatus for wireless communication at a second wireless device, comprising at least one means for performing a method of any of aspects 21 through 38.

Aspect 44: A non-transitory computer-readable medium storing code for wireless communication at a second wireless device, the code comprising instructions executable by a processor to perform a method of any of aspects 21 through 38.

It should be noted that the methods described herein describe possible implementations, and that the operations and the steps may be rearranged or otherwise modified and that other implementations are possible. Further, aspects from two or more of the methods may be combined.

Although aspects of an LTE, LTE-A, LTE-A Pro, or NR system may be described for purposes of example, and LTE, LTE-A, LTE-A Pro, or NR terminology may be used in much of the description, the techniques described herein are applicable beyond LTE, LTE-A, LTE-A Pro, or NR networks. For example, the described techniques may be applicable to various other wireless communications systems such as Ultra Mobile Broadband (UMB) , Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDM, as well as other systems and radio technologies not explicitly mentioned herein.

Information and signals described herein may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The various illustrative blocks and components described in connection with the disclosure herein may be implemented or performed using a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor but, in the alternative, the processor may be any processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration) .

The functions described herein may be implemented using hardware, software executed by a processor, firmware, or any combination thereof. If implemented using software executed by a processor, the functions may be stored as or transmitted using one or more instructions or code of a computer-readable medium. Other examples and implementations are within the scope of the disclosure and appended claims. For example, due to the nature of software, functions described herein may be implemented using software executed by a processor, hardware, firmware, hardwiring, or combinations of any of these. Features implementing functions may also be physically located at various positions, including being distributed such that portions of functions are implemented at different physical locations.

Computer-readable media includes both non-transitory computer storage media and communication media including any medium that facilitates transfer of a computer program from one location to another. A non-transitory storage medium may be any available medium that may be accessed by a general-purpose or special-purpose computer. By way of example, and not limitation, non-transitory computer-readable media may include RAM, ROM, electrically erasable programmable ROM (EEPROM) , flash memory, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other non-transitory medium that may be used to carry or store desired program code means in the form of instructions or data structures and that may be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of computer-readable medium. Disk and disc, as used herein, include CD, laser disc, optical disc, digital versatile disc (DVD) , floppy disk and Blu-ray disc. Disks may reproduce data magnetically, and discs may reproduce data optically using lasers. Combinations of the above are also included within the scope of computer-readable media.

As used herein, including in the claims, “or” as used in a list of items (e.g., a list of items prefaced by a phrase such as “at least one of” or “one or more of” ) indicates an inclusive list such that, for example, a list of at least one of A, B, or C means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) . Also, as used herein, the phrase “based on” shall not be construed as a reference to a closed set of conditions. For example, an example step that is described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of the present disclosure. In other words, as used herein, the phrase “based on” shall be construed in the same manner as the phrase “based at least in part on. ”

The term “determine” or “determining” encompasses a variety of actions and, therefore, “determining” can include calculating, computing, processing, deriving, investigating, looking up (such as via looking up in a table, a database or another data structure) , ascertaining and the like. Also, “determining” can include receiving (e.g., receiving information) , accessing (e.g., accessing data stored in memory) and the like. Also, “determining” can include resolving, obtaining, selecting, choosing, establishing, and other such similar actions.

In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label, or other subsequent reference label.

The description set forth herein, in connection with the appended drawings, describes example configurations and does not represent all the examples that may be implemented or that are within the scope of the claims. The term “example” used herein means “serving as an example, instance, or illustration, ” and not “preferred” or “advantageous over other examples. ” The detailed description includes specific details for the purpose of providing an understanding of the described techniques. These techniques, however, may be practiced without these specific details. In some instances, known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described examples.

The description herein is provided to enable a person having ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to a person having ordinary skill in the art, and the generic principles defined herein may be applied to other variations without departing from the scope of the disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

An apparatus for wireless communication at a first wireless device, comprising:

a processor;

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

generate a synchronization signal comprising an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration; and

transmit, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based at least in part on the one or more calibration parameters.
The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to:

monitor for a response message from the second wireless device based at least in part on the synchronization signal.
The apparatus of claim 2, wherein the one or more calibration parameters comprise a calibration frequency, wherein the instructions to monitor for the response message are executable by the processor to cause the apparatus to:

monitor a set of frequency resources for the response message, the set of frequency resources corresponding to the calibration frequency.
The apparatus of claim 2, wherein the instructions to monitor for the response message are executable by the processor to cause the apparatus to:

monitor a set of frequency resources for the response message, the set of frequency resources corresponding to a frequency of transmission of the unmodulated portion or a frequency shift relative to the frequency of transmission of the unmodulated portion.
The apparatus of claim 1, wherein the first wireless device is a user equipment (UE) , and the instructions are further executable by the processor to cause the apparatus to:

receive, from a network entity, an indication that the network entity is to communicate with the second wireless device via the UE, wherein the synchronization signal is transmitted based at least in part on the indication that the network entity is to communicate with the second wireless device via the UE.
The apparatus of claim 1, wherein the instructions to generate the synchronization signal are executable by the processor to cause the apparatus to:

generate the amplitude modulated portion spanning one or more frequency tones.
The apparatus of claim 1, wherein the instructions to generate the synchronization signal are executable by the processor to cause the apparatus to:

generate the amplitude modulated portion spanning the first duration according to a radio frequency activation pattern, wherein the radio frequency activation pattern comprises a set of same amplitudes or different amplitudes.
The apparatus of claim 1, wherein the instructions to generate the synchronization signal are executable by the processor to cause the apparatus to:

generate the unmodulated portion spanning a single frequency tone.
The apparatus of claim 1, wherein the instructions to generate the synchronization signal are executable by the processor to cause the apparatus to:

generate the synchronization signal comprising only the amplitude modulated portion based at least in part on a classification of the second wireless device, wherein the classification is a passive classification.
The apparatus of claim 1, wherein the instructions to generate the synchronization signal are executable by the processor to cause the apparatus to:

generate the synchronization signal comprising both the amplitude modulated portion and the unmodulated portion based at least in part on a classification of the second wireless device, wherein the classification is an active classification, a semi-active classification, a semi-passive classification, or a passive classification.
The apparatus of claim 1, wherein the instructions to transmit the synchronization signal are executable by the processor to cause the apparatus to:

transmit the synchronization signal comprising only the amplitude modulated portion after a calibration duration that corresponds to a timing of a previous oscillator calibration for the second wireless device.
The apparatus of claim 11, wherein the instructions are further executable by the processor to cause the apparatus to:

receive an indication of the calibration duration via a dynamic signal.
The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to:

receive, from the second wireless device, a message indicating a classification of the second wireless device, a classification switch of the second wireless device, a timing accuracy target of the second wireless device, a temperature change of the second wireless device, or any combination thereof.
The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit a packet comprising the synchronization signal, a data portion, and a cyclic redundancy check portion.
The apparatus of claim 14, wherein the instructions to transmit the packet are executable by the processor to cause the apparatus to:

transmit the amplitude modulated portion of the synchronization signal, the data portion, and the cyclic redundancy check portion via a first carrier frequency; and

transmit the unmodulated portion of the synchronization signal via a second carrier frequency different from the first carrier frequency.
The apparatus of claim 14, wherein the instructions to transmit the packet are executable by the processor to cause the apparatus to:

transmit the packet according to a periodicity.
The apparatus of claim 14, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit an additional packet subsequent to the packet, wherein the additional packet comprises a second synchronization signal having a second amplitude modulated portion, a second unmodulated portion, or both.
The apparatus of claim 17, wherein the additional packet comprises the second synchronization signal based at least in part on a threshold, and wherein the threshold corresponds to a quantity of packets, a time threshold, or both.
The apparatus of claim 1, wherein the instructions are further executable by the processor to cause the apparatus to:

transmit a packet comprising the synchronization signal, a control portion, a data portion, and a cyclic redundancy check portion, wherein the control portion indicates a presence or absence of the unmodulated portion of the synchronization signal.
The apparatus of claim 1, wherein a format of the amplitude modulated portion of the synchronization signal indicates a presence or absence of the unmodulated portion of the synchronization signal.
An apparatus for wireless communication at a second wireless device, comprising:

a processor;

memory coupled with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to:

receive, from a first wireless device, a synchronization signal based at least in part on a classification of the second wireless device, wherein the synchronization signal comprises an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration;

tune an oscillator of the second wireless device based at least in part on the one or more calibration parameters of the synchronization signal; and

send, to the first wireless device, a response message to the synchronization signal using the tuned oscillator.
The apparatus of claim 21, wherein the one or more calibration parameters comprise a calibration frequency, wherein the instructions to tune the oscillator are executable by the processor to cause the apparatus to:

tune the oscillator to the calibration frequency.
The apparatus of claim 21, wherein the instructions to receive the synchronization signal are executable by the processor to cause the apparatus to:

receive the amplitude modulated portion spanning one or more frequency tones.
The apparatus of claim 21, wherein the instructions to receive the synchronization signal are executable by the processor to cause the apparatus to:

receive the amplitude modulated portion spanning the first duration according to a radio frequency activation pattern, wherein the radio frequency activation pattern comprises a set of a set of same amplitudes or different amplitudes.
The apparatus of claim 21, wherein the instructions to receive the synchronization signal are executable by the processor to cause the apparatus to:

receive the unmodulated portion spanning a single frequency tone.
The apparatus of claim 21, wherein the instructions to receive the synchronization signal are executable by the processor to cause the apparatus to:

receive the synchronization signal comprising only the amplitude modulated portion based at least in part on the classification of the second wireless device, wherein the classification is a passive classification.
The apparatus of claim 21, wherein the instructions to receive the synchronization signal are executable by the processor to cause the apparatus to:

receive the synchronization signal comprising both the amplitude modulated portion and the unmodulated portion based at least in part on the classification of the second wireless device, wherein the classification is an active classification, a semi-active classification, a semi-passive classification, or a passive classification.
The apparatus of claim 21, wherein the instructions to receive the synchronization signal are executable by the processor to cause the apparatus to:

receive the synchronization signal comprising only the amplitude modulated portion after a calibration duration that corresponds to a timing of a previous oscillator calibration for the second wireless device.
A method for wireless communication at a first wireless device, comprising:

generating a synchronization signal comprising an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration; and

transmitting, to a second wireless device, the synchronization signal to calibrate an oscillator of the second wireless device based at least in part on the one or more calibration parameters.
A method for wireless communication at a second wireless device, comprising:

receiving, from a first wireless device, a synchronization signal based at least in part on a classification of the second wireless device, wherein the synchronization signal comprises an amplitude modulated portion that spans a first duration, an unmodulated portion that spans a second duration subsequent to the first duration, or both, the amplitude modulated portion indicating one or more calibration parameters for an oscillator calibration;

tuning an oscillator of the second wireless device based at least in part on the one or more calibration parameters of the synchronization signal; and

sending, to the first wireless device, a response message to the synchronization signal using the tuned oscillator.