WO2025054057A1

WO2025054057A1 - User equipment dynamic switching of waveforms

Info

Publication number: WO2025054057A1
Application number: PCT/US2024/044205
Authority: WO
Inventors: Jibing Wang; Erik Stauffer
Original assignee: Google LLC
Current assignee: Google LLC
Priority date: 2023-09-07
Filing date: 2024-08-28
Publication date: 2025-03-13
Anticipated expiration: 2026-03-07

Abstract

This disclosure provides systems, devices, apparatus, and methods, including computer programs encoded on storage media, for switching of waveforms in wireless communication. A UE (102) receives (434), from a network entity (104) using a default waveform, a recovery control message indicating a recovery reference signal configuration and a RACH resource. The UE (102) sends (440), to the network entity (104) on the RACH resource using the default waveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery reference signal. The UE (102) receives (444), from the network entity (104) using the default waveform, a RACH response including an indication of a configuration of an updated waveform of at least one of an uplink signal or a downlink signal based on the first report message.

Description

USER EQUIPMENT DYNAMIC SWITCHING OF WAVEFORMS

CROSS REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of and priority to U.S. Provisional Application Serial No. 63/537,174, entitled “USER EQUIPMENT DYNAMIC SWITCHING OF WAVEFORMS” and filed on September 7, 2023, which is expressly incorporated by reference herein in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates generally to wireless communication, and more particularly, to dynamic switching of waveforms.

BACKGROUND

[0003] The Third Generation Partnership Project (3GPP) specifies a radio interface referred to as fifth generation (5G) new radio (NR) (5G NR). An architecture for a 5G NR wireless communication system (5GS) includes a 5G core (5GC) network, a 5G radio access network (5G-RAN), a 5G user equipment (5G UE), etc. The 5G NR architecture seeks to provide increased data rates, decreased latency, and/or increased capacity compared to prior generation cellular communication systems.

[0004] Wireless communication systems, in general, provide various telecommunication services (e.g., telephony, video, data, messaging, etc.) based on multiple-access technologies, such as orthogonal frequency division multiple access (OFDMA) technologies, that support communication with multiple UEs. Improvements in mobile broadband continue the progression of such wireless communication technologies. For example, wireless communications are challenging due to delay spread and Doppler spread created by wireless channels. Further, different types of waveforms communicated through the wireless channels might have different performance tradeoffs with respect to the delay spread and the Doppler spread.

BRIEF SUMMARY

[0005] The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects. This summary neither identifies key or critical elements of all aspects nor delineates the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

[0006] Wireless communications between a network entity, such as a base station or a unit of a base station, and a user equipment (UE) are challenging due to delay spread and Doppler spread created by the wireless channels. Different waveform receivers handle the delay spread and the Doppler spread differently and have different performance/complexity tradeoffs. For example, orthogonal frequency-division multiplexing (OFDM) waveforms work well to mitigate multipath delay spread with simple receivers, but performance of the OFDM waveforms suffers under high Doppler spread conditions. In high mobility scenarios, other waveforms, such as orthogonal time-frequency space (OTFS) waveforms, have better performance but at the cost of higher complexity.

[0007] High delay spread and/or high Doppler spread might result in a high block errorrate (BLER) when using a current waveform while the power signal quality (e.g.. reference signal received power (RSRP) or reference signal received quality (RSRQ)) remains high. The high BLER might trigger a failure, e.g., a beam failure or radio link failure (RLF), at the UE. If the beam failure or the RLF is not triggered at the UE, the BLER remains high due to the high delay spread and/or the high Doppler spread.

[0008] Aspects of the present disclosure address the above-noted and other deficiencies by dynamically switching the waveform for the downlink and/or uplink signal based on the delay spread and/or Doppler spread created by the wireless channels. For example, the UE estimates the delay spread and the Doppler spread of a reference signal. Continuing with the example, the UE feeds back the delay spread and the Doppler spread measurements to the network entity. The network entity might change the waveform (e.g., from OFDM to OTFS waveform or vice versa) for the downlink and/or uplink signal to adapt to the reported delay spread and Doppler spread in an efficient manner.

[0009] In case the channel changes abruptly, the network entity configures a recovery reference signal for a fast beam-failure recovery and further configures one or more random access channel (RACH) preamble/resources for the beam-failure recovery. The UE monitors the BLER while using the current waveform. The UE might detect the beam failure or RLF if the BLER of the current waveform is above a predetermined BLER threshold. Based on the recovery reference signal, the UE might estimate delay spread and Doppler spread and send the detected delay spread and Doppler spread estimate using the RACH preamble/resources. The network entity might send a configuration for a different waveform using a RACH response.

[0010] According to some aspects, a UE receives from a network entity (and the network entity transmits to the UE) using a default waveform, a recovery control message indicating a recovery reference signal configuration and a RACH resource. The UE sends to the network entity (and the network entity receives from the UE) on the RACH resource using the default waveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery reference signal. The UE receives from the network entity (and the network entity transmits to the UE) using the default waveform, a RACH response including an indication of a configuration of an updated waveform for at least one of an uplink signal or a downlink signal based on the first report message.

[0011] Advantageously, dynamically switching the waveform allows a radio access network (RAN) to adapt to a wider variety of quickly-changing channel conditions and also enables a fast beam-failure recovery after a beam failure or a fast radio resource control (RRC) connection reestablishment after a RLF. By dynamically switching the waveform for the downlink and/or uplink signal based on the delay spread and Doppler spread created by the wireless channels, the network entity and the UE compensate for changing delay/Doppler spreading conditions, such as in high mobility scenarios. In the meantime, the complexity of the system is optimized, thereby improving the overall system performance.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 illustrates a diagram of a w ireless communications system that includes a plurality⁷ of user equipments (UEs) and network entities in communication over one or more cells according to an embodiment.

[0013] FIG. 2 is a signaling diagram illustrating communications between a UE and a network entity for dynamically switching a waveform based on a reference signal according to an embodiment.

[0014] FIG. 3 is a signaling diagram illustrating communications between a UE and a network entity for dynamically switching a waveform based on a sounding reference signal (SRS) according to an embodiment.

[0015] FIG. 4 is a signaling diagram illustrating communications between a UE and a network entity⁷ for dynamically switching a waveform in a fast beam-failure recovery or a fast radio resource control (RRC) connection reestablishment according to an embodiment.

[0016] FIG. 5 is a flowchart of a method of wireless communication at a UE according to an embodiment.

[0017] FIG. 6 is a flowchart of a method of wireless communication at a network entity according to an embodiment.

[0018] FIG. 7 is a diagram illustrating a hardware implementation for an example UE apparatus according to some embodiments.

[0019] FIG. 8 is a diagram illustrating a hardware implementation for one or more example network entities according to some embodiments.

DETAILED DESCRIPTION

[0020] FIG. 1 illustrates a diagram 100 of a wireless communications system associated with a plurality of cells 190. The wireless communications system includes user equipments (UEs) 102 and base stations/network entities 104. Some base stations may include an aggregated base station architecture and other base stations may include a disaggregated base station architecture. The aggregated base station architecture utilizes a radio protocol stack that is physically or logically integrated within a single radio access network (RAN) node. A disaggregated base station architecture utilizes a protocol stack that is physically or logically distributed among two or more units (e.g., radio unit (RU) 106. distributed unit (DU) 108, central unit (CU) 110). For example, a CU 110 is implemented within a RAN node, and one or more DUs 108 may be co-located with the CU 110, or alternatively, may be geographically or virtually distributed throughout one or multiple other RAN nodes. The DUs 108 may be implemented to communicate with one or more RUs 106. Any of the RU 106, the DU 108 and the CU 110 can be implemented as virtual units, such as a virtual radio unit (VRU), a virtual distributed unit (VDU). or a virtual central unit (VCU). The base station/network entity 104 (e g., an aggregated base station or disaggregated units of the base station, such as the RU 106 or the DU 108), may be referred to as a transmission reception point (TRP).

[0021] Operations of the base station 104 and/or network designs may be based on aggregation characteristics of base station functionality. For example, disaggregated base station architectures are utilized in an integrated access backhaul (TAB) network, an open-radio access network (O-RAN) network, or a virtualized radio access network (vRAN), which may also be referred to a cloud radio access network (C- RAN). Disaggregation may include distributing functionality across the tw o or more units at various physical locations, as well as distributing functionality for at least one unit virtually, which can enable flexibility in network designs. The various units of the disaggregated base station architecture, or the disaggregated RAN architecture, can be configured for wired or wireless communication with at least one other unit. For example, the base stations 104d, 104e and/or the RUs 106a, 106b, 106c, 106d may communicate with the UEs 102a, 102b, 102c, 102d, and/or 102s via one or more radio frequency (RF) access links based on a Uu interface. In examples, multiple RUs 106 and/or base stations 104 may simultaneously serve the UEs 102, such as by intracell and/or inter-cell access links between the UEs 102 and the RUs 106/base stations 104.

[0022] The RU 106, the DU 108, and the CU 110 may include (or may be coupled to) one or more interfaces configured to transmit or receive information/signals via a wired or wireless transmission medium. For example, a wired interface can be configured to transmit or receive the information/signals over a wired transmission medium, such as via the fronthaul link 160 between the RU 106d and the baseband unit (BBU) 112 of the base station 104d associated with the cell 190d. The BBU 112 includes a DU 108 and a CU 110, which may also have a wired interface (e.g., midhaul link) configured between the DU 108 and the CU 110 to transmit or receive the information/signals between the DU 108 and the CU 110. In further examples, a wireless interface, which may include a receiver, a transmitter, or a transceiver, such as an RF transceiver, configured to transmit and/or receive the information/signals via the wireless transmission medium, such as for information communicated between the RU 106a of the cell 190a and the base station 104e of the cell 190e via cross-cell communication beams 136-138 of the RU 106a and the base station 104e.

[0023] The RUs 106 may be configured to implement lower layer functionality. For example, the RU 106 is controlled by the DU 108 and may correspond to a logical node that hosts RF processing functions, or lower layer PHY functionality, such as execution of fast Fourier transform (FFT), inverse FFT (iFFT), digital beamforming, physical random access channel (PRACH) extraction and filtering, etc. The functionality of the RU 106 may be based on the functional split, such as a functional split of lower layers. [0024] The RUs 106 may transmit or receive over-the-air (OTA) communication with one or more UEs 102. For example, the RU 106b of the cell 190b communicates with the UE 102b of the cell 190b via a first set of communication beams 132 of the RU 106b and a second set of communication beams 134b of the UE 102b, which may correspond to inter-cell communication beams or, in some examples, cross-cell communication beams. For instance, the UE 102b of the cell 190b may communicate with the RU 106a of the cell 190a via a third set of communication beams 134a of the UE 102b and a fourth set of communication beams 136 of the RU 106a. DUs 108 can control both real-time and non-real-time features of control plane and user plane communications of the RUs 106.

[0025] Any combination of the RU 106, the DU 108, and the CU 110, or reference thereto individually, may correspond to a base station 104. Thus, the base station 104 may include at least one of the RU 106, the DU 108, or the CU 110. The base stations 104 provide the UEs 102 with access to a core network. The base stations 104 may relay communications between the UEs 102 and the core network (not shown). The base stations 104 may be associated with macrocells for higher-pow er cellular base stations and/or small cells for low er-power cellular base stations. For example, the cell 190e may correspond to a macrocell, whereas the cells 190a-190d may correspond to small cells. Small cells include femtocells, picocells, microcells, etc. A network that includes at least one macrocell and at least one small cell may be referred to as a “heterogeneous network.”

[0026] Transmissions from a UE 102 to a base station 104/RU 106 are referred to as uplink (UL) transmissions, whereas transmissions from the base station 104/RU 106 to the UE 102 are referred to as downlink (DL) transmissions. Uplink transmissions may also be referred to as reverse link transmissions and downlink transmissions may also be referred to as forward link transmissions. For example, the RU 106d utilizes antennas of the base station 104d of cell 190d to transmit a downlink/forward link communication to the UE 102d or receive an uplink/reverse link communication from the UE 102d based on the Uu interface associated with the access link between the UE 102d and the base station 104d/RU 106d.

[0027] Communication links between the UEs 102 and the base stations 104/RUs 106 may be based on multiple-input and multiple-output (MIMO) antenna technology, including spatial multiplexing, beamforming, and/or transmit diversity. The communication links may be associated with one or more carriers. The UEs 102 and the base stations 104/RUs 106 may utilize a spectrum bandwidth of F MHz (e.g., 5. 10, 15, 20, 100, 400, 800, 1600, 2000, etc. MHz) per carrier allocated in a carrier aggregation of up to a total of Yx MHz, where x component carriers (CCs) are used for communication in each of the uplink and downlink directions. The carriers may or may not be adjacent to each other along a frequency spectrum. In examples, uplink and downlink carriers may be allocated in an asymmetric manner, with more or fewer carriers allocated to either the uplink or the downlink. A primary' component carrier and one or more secondary' component carriers may be included in the component carriers. The primary component carrier may be associated with a primary cell (PCell) and a secondary component carrier may be associated with a secondary cell (SCell).

[0028] Some UEs 102, such as the UEs 102a and 102s, may perform device-to-device (D2D) communications over sidelink. For example, a sidelink communication/D2D link utilizes a spectrum for a wireless wide area network (WWAN) associated with uplink and downlink communications. Such sidelink/D2D communication may be performed through various wireless communications systems, such as wireless fidelity (Wi-Fi) systems. Bluetooth systems, Long Term Evolution (LTE) systems, New Radio (NR) systems, etc.

[0029] The UEs 102 and the base stations 104/RUs 106 may each include a plurality of antennas. The plurality of antennas may⁷ correspond to antenna elements, antenna panels, and/or antenna arrays that may facilitate beamforming operations. For example, the RU 106b transmits a downlink beamformed signal based on a first set of communication beams 132 to the UE 102b in one or more transmit directions of the RU 106b. The UE 102b may receive the downlink beamformed signal based on a second set of communication beams 134b from the RU 106b in one or more receive directions of the UE 102b. In a further example, the UE 102b may also transmit an uplink beamformed signal (e.g.. sounding reference signal (SRS)) to the RU 106b based on the second set of communication beams 134b in one or more transmit directions of the UE 102b. The RU 106b may receive the uplink beamformed signal from the UE 102b in one or more receive directions of the RU 106b. The UE 102b may perform beam training to determine the best receive and transmit directions for the beamformed signals. The transmit and receive directions for the UEs 102 and the base stations 104/RUs 106 may or may not be the same. [0030] In further examples, beamformed signals may be communicated between a first base station/RU 106a and a second base station 104e. For instance, the base station 104e of the cell 190e may transmit a beamformed signal to the RU 106a based on the communication beams 138 in one or more transmit directions of the base station 104e. The RU 106a may receive the beamformed signal from the base station 104e of the cell 190e based on the RU communication beams 136 in one or more receive directions of the RU 106a. In further examples, the base station 104e transmits a downlink beamformed signal to the UE 102e based on the communication beams 138 in one or more transmit directions of the base station 104e. The UE 102e receives the downlink beamformed signal from the base station 104e based on UE communication beams 130 in one or more receive directions of the UE 102e. The UE 102e may also transmit an uplink beamformed signal to the base station 104e based on the UE communication beams 130 in one or more transmit directions of the UE 102e, such that the base station 104e may receive the uplink beamformed signal from the UE 102e in one or more receive directions of the base station 104e.

[0031] The base station 104 may include and/or be referred to as a network entity. That is, “network entity'’ may refer to the base station 104 or at least one unit of the base station 104, such as the RU 106, the DU 108. and/or the CU 110. The base station 104 may also include and/or be referred to as a next generation evolved Node B (ng- eNB), a next generation NB (gNB), an evolved NB (eNB), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS). an extended service set (ESS), a TRP, a network node, network equipment, or other related terminology. The base station 104 or an entity at the base station 104 can be implemented as an IAB node, a relay node, a sidelink node, an aggregated (monolithic) base station, or a disaggregated base station including one or more RUs 106. DUs 108, and/or CUs 110. A set of aggregated or disaggregated base stations may be referred to as a next generation-radio access network (NG-RAN). In some examples, the UE 102a operates in dual connectivity (DC) with the base station 104e and the base station/RU 106a. In such cases, the base station 104e can be a master node and the base station/RU 160a can be a secondary node.

[0032] Uplink/downlink signaling may also be communicated via a satellite positioning system (SPS) 114. In an example, the SPS 114 associated with the cell 190c may be in communication with one or more UEs 102, such as the UE 102c, and one or more base stations 104/RUs 106, such as the RU 106c. The SPS 114 may correspond to one or more of a Global Navigation Satellite System (GNSS), a global position system (GPS), a non-terrestrial network (NTN), or other satellite position/location system. The SPS 114 may be associated with LTE signals, NR signals (e.g., based on round trip time (RTT) and/or multi-RTT), wireless local area network (WLAN) signals, a terrestrial beacon system (TBS), sensor-based information, NR enhanced cell ID (NR E-CID) techniques, downlink angle-of-departure (DL-AoD), downlink time difference of arrival (DL-TDOA), uplink time difference of arrival (UL-TDOA), uplink angle-of-arrival (UL-AoA). and/or other systems, signals, or sensors.

[0033] Still referring to FIG. 1, in certain aspects, any of the UEs 102 may include a detection component 140 configured to receive, from a network entity using a default waveform, a recovery control message indicating a recovery reference signal configuration and a random access channel (RACH) resource. The detection component 140 is configured to send, to the network entity on the RACH resource using the default waveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery reference signal. The detection component 140 is configured to receive, from the network entity using the default waveform, a RACH response including an indication of a configuration of an updated waveform of at least one of an uplink signal or a downlink signal based on the first report message.

[0034] In certain aspects, any of the base stations 104 or a network entity⁷ of the base stations 104 may include a configuration component 150 configured to transmit, to a UE using a default waveform. UE. a recovery control message indicating a recovery reference signal configuration and a RACH resource. The configuration component 150 is configured to receive, from the UE on the RACH resource and using the default waveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery reference signal. The configuration component 150 is configured to transmit, to the UE using the default waveform, a RACH response including an indication of a configuration of an updated waveform of at least one of an uplink signal or a downlink signal based on the first report message.

[0035] Accordingly, FIG. 1 describes a wireless communication system that may be implemented in connection with aspects of one or more other figures described herein. Further, although the following description may be focused on 5G NR, the concepts described herein may be applicable to other similar areas, such as 5G- Advanced and future versions, LTE, LTE-advanced (LTE-A), and other wireless technologies, such as 6G.

[0036] FIG. 2 illustrates a diagram 200 of communications between a UE 102 and a network entity 104 for dynamically switching a waveform based on a reference signal according to an embodiment. The network entity 104 might correspond to a base station or a unit of a base station, such as the RU 106, the DU 108, the CU 110, etc. The UE 102 and the network entity 104 might communicate with each other using a first waveform on a wireless channel at the beginning. However, a changed condition of the wireless channel might create a high delay spread and/or a high Doppler spread, which might result in a high BLER. Different waveform receivers handle the delay spread and the Doppler spread differently. The signal processing of an OTFS waveform is more complex than an OFDM waveform, but the OTFS waveform exhibits higher performance in high delay spread/Doppler spread scenarios.

[0037] Based on the delay spread and/or Doppler spread, the network entity 104 and the UE 102 might dynamically switch to a different waveform (e.g., a second waveform) from the first waveform for DL/UL communication (e.g., for a DL/UL signal). For example, the network entity 104 and the UE 102 dynamically switch from OFDM to OTFS waveform, or vice versa. By dynamically switching to the different waveform for the DL/UL communication, the RAN can adapt to a wider variety of quickly- changing channel conditions (e.g., when a UE enters a high speed train). Therefore, the performance of the wireless communication system is improved, while decreasing the complexity of the system. Dynamically switching the waveform also enables a fast beam-failure recovery after a beam failure or a fast RRC connection reestablishment after an RLF.

[0038] Referring to FIG. 2, the UE 102 may report, to the network entity 104, a capability of the UE 102 for dynamic changing of waveforms. That is, the UE 102 may transmit 203, to the network entity 104, a UE capability message indicating at least two waveforms (e.g., OFDM and OTFS waveforms) that the UE 102 supports for an uplink signal, at least two waveforms (e.g., OFDM and OTFS waveforms) that the UE 102 supports for a downlink signal, at least one time interval for the UE 102 to change a waveform of the downlink signal, or at least one time interval for the UE to change the waveform of an uplink signal. The time interval for the UE 102 to change the w aveform may be a same time interval or a different time interval for the uplink signal and downlink signal. The network entity- 104 receives 203 the UE capability message from the UE 102.

[0039] The time interval might refer to a waveform transition time, such as for transitioning the waveform from OFDM to OTFS or vice versa for downlink and/or uplink communications. In some implementations, the UE capability message indicates two time intervals for the UE 102 to change the waveform of the downlink signal, including a first time interval for the UE 102 to change from the OFDM waveform to the OTFS waveform and a second time interval for the UE 102 to change from the OTFS waveform to the OFDM waveform. The first time interval and the second time interval may be the same time interval or different time intervals.

[0040] The UE 102 might have different capabilities for UL and DL communication. The UE capability message may indicate the delay interval on how fast the UE 102 can change the waveform after receiving a command from the network entity 104, including (1) the delay (e.g., time interval) in the DL communication; and (2) the delay (e.g., time interval) in UL communication. In DL communication (such as for the physical downlink shared channel (PDSCH)Zphysical downlink control channel (PDCCH)), the capability message may indicate the delay between when the UE 102 received the command from the network entity 104 on changing the DL waveform and when the UE 102 can start to detect a DL communication using the second waveform. In UL communication (such as for the physical uplink shared channel (PUSCH)Zphysical uplink control channel (PUCCH)Zsounding reference signal (SRS)). the capability message may indicate the delay between when the UE 102 received the command from the network entity 104 on changing the UL waveform and when the UE 102 can start sending the UL communication with the updated waveform.

[0041] Thus, the UE capability message might indicate four time intervals for the UE to change between two waveforms: (1) from a first waveform to a second waveform for a downlink. (2) from the second waveform to the first waveform for the downlink, (3) from the first waveform to the second wav eform for an uplink, and (4) from the second waveform to the first waveform for the uplink. The UE 102 might send, to the network entity 104, the capability on adapting the waveform to the changed channel condition while in an RRC connected mode.

[0042] The UE 102 receives 204, from the netw ork entity- 104 using a default waveform (e.g., an OFDM waveform), a first control message indicating a reference signal configuration for a reference signal. The reference signal configuration might indicate a reference signal waveform and time-frequency resources for the reference signal. The network entity 104 transmits 204, to the UE 102 using the default waveform, the first control message indicating the reference signal configuration. The first control message might be an RRC message. The network entity 104 sends 204 the reference signal configuration, using the first control message (e.g., RRC messages), indicating sequences and resources (such as time-frequency resources) allocated for the reference signal, to assist the UE 102 with estimating the delay spread and the Doppler spread created by the wireless channel. For example, the delay spread refers to the difference between the time of arrival of the earliest component (e.g., the line-of-sight wave if there exists) and the time of arrival of the latest multipath component of a wireless communications channel. For example, Doppler spread refers to the widening of the spectrum of a narrow-band signal transmitted through a multipath propagation channel, due to the different Doppler shift frequencies associated with the multiple propagation paths when there is relative motion between the transmitter and the receiver. Pilot tones can be used for the reference signal too, although perfomiance depends on the delay spread/Doppler spread. For example, more reference signals (e.g.. pilots) in the time domain may be needed for high Doppler spread estimation. The network entity 104 transmits 206 (and the UE might receive 206) the reference signal.

[0043] The UE 102 measures 208 the delay spread and the Doppler spread from the reference signal. The UE 102 can detect the delay spread and Doppler spread locally. The UE 102 can refine the estimate of the Doppler spread based on a mobility/ speed estimate, e g., using a global positioning system (GPS)Zglobal navigation satellite system (GNSS).

[0044] The UE 102 transmits 210 to the network entity 104 (and the network entity 104 receives 210 from the UE 102). using the default waveform, a second control message indicating the measured delay spread and Doppler spread. For example, the second control message is an RRC message. The UE 102 sends/updates 210 a UE measurement report indicating the estimated delay spread (e.g., in units of Lisec) and Doppler spread (e.g.. in units of kHz) to the network, by the second control message (e.g., RRC message). The UE measurement report might be periodic or triggered. As an example, the update/report of the estimated delay spread and Doppler spread might be triggered when the delay spread and/or the Doppler spread has changed by more than a respective predetermined threshold. The HE 102 might transmit 210 the second control message in response to determining that at least one of: a difference between a first measurement of the delay spread and a second measurement of the delay spread is larger than a first predetermined threshold, or a difference between a first measurement of the Doppler spread and a second measurement of the Doppler spread is larger than a second predetermined threshold. The UE 102 might propose a different waveform along with the measurement report.

[0045] After receiving the estimate of the delay spread and Doppler spread from the UE 102, the network enti ty 104 might determine a second waveform for the UE 102 to use based on the estimate of the delay spread and Doppler spread. The network entity 104 might select 212 the second waveform configuration based on the delay spread and the Doppler spread. For example, the network entity⁷ 104 uses time hysteresis to avoid ping-pong switching, e.g., switching back and forth between waveforms too frequently. For example, when the delay spread or Doppler spread measurement fulfills a threshold criterion, the netw ork entity determines the second waveform (e g., different waveform).

[0046] The UE 102 receives 214, from the network entity 104 using the default waveform, a third control message indicating a configuration for the second waveform. The network entity⁷ 104 transmits 214, to the UE 102 using the default waveform, the third control message indicating the configuration for the second waveform. For example, the third control message is an RRC message or medium access control (MAC) control element (CE). The network entity 104 can use the RRC message or MAC CE to indicate to the UE 102 the second waveform and associated numerologies to use for DL (e.g., PDSCH) and UL (e.g., PUSCH), respectively .

[0047] The UL and DL communication might have different waveforms. For example, when signal -to-interference plus noise ratio (SINR) requirements are different (e.g., DL communication has a higher modulation and coding scheme (MCS) while UL communication has a lower MCS), the peak-to-average power ratio (PAPR) requirements are also different (e.g., UL communication has a lower PAPR than DL communication). Such differences in the UL and DL waveforms (e.g., DL may be CP-OFDM while UL may be DFT-s-OFDM), are for managing UL PAPR at the UE side. The network entity 104 might inform the UE 102 when the second waveform will be implemented. As an example, the third control message indicates a start time of the second w aveform for the UL and/or DL communication, e.g., based on the UE capability. The network entity 104 might account for the delay, e.g., delay-gap or time interval, based on the UE capability, between the next grant of PDSCH/PUSCH with the second waveform.

[0048] The network entity 104 might transmit 216 to the UE 102 (and the UE 102 might receive 216 from the network entity 104), a PDCCH downlink control information (DCI) indicating a start time of the new waveform (e g., second waveform) for the UL and/or DL communication (e.g., PDSCH, PUSCH, and/or PUCCEI). The network entity 104 can use the PDCCH DCI to indicate the start of the second waveform (and associated numerologies) for the PDSCH and/or PUSCH/PUCCH. For example, if the default waveform is the OFDM waveform, the PDCCH implements the OFDM waveform (e.g., default waveform). The PDCCH has a low SNR, and hence, can tolerate ahigher Doppler spread. Control (e.g., control signal/message) and data (e.g., data signal/message) can use different waveforms. The control (e.g., control signal/message) can use the OFDM waveform, whereas the data (e.g.. data signal/message) can use adjacent OFDM and OTFS waveform resource configurations, e.g., with guard resources between different waveforms. In examples, the start time of the second waveform is based on a guard period between the PDCCH DCI and at least one of a PDSCH, a PUSCH, or a PUCCH. There is a time gap (e.g.. guard period) between the PDCCH/DCI/grant of the PDSCH/PUSCH/PUCCH with the second waveform and when the second waveform of PDSCH and PUSCH/PUCCH starts.

[0049] The UE 102 detects 218 the non-default waveform (e.g., second waveform) of the PDSCH as indicated in the PDCCH DCI sent using the default waveform. The UE 102 communicates 220, 222, with the network entity 104 using the second waveform for the UL signal and/or the DL signal. The network entity’ 104 might transmit 220 (and the UE 102 might receive 220) a DCI configuring updated PUSCH on which the UE 102 can send the uplink data using the second waveform. The UE 102 transmits 222 (and the network entity 104 receives 222) the uplink data on the updated PUSCH using the second waveform.

[0050] FIG. 2 illustrates dynamically switching the waveform based on the downlink reference signal, as an example. Although only uplink data transfer is shown in the diagram 200, the principles described in FIG. 2 also apply to downlink data transfer. In another example, FIG. 3 illustrates dynamically switching a waveform based on the uplink reference signal (e.g., a sounding reference signal (SRS)). [0051] FIG. 3 is a signaling diagram 300 illustrating communications between a UE 102 and a network entity 104 for dynamically switching a waveform based on an SRS according to an embodiment. The difference between FIG. 2 and FIG. 3 is that the UE 102 might send 306 the SRS for the estimation of the delay spread and Doppler spread at the network entity side, instead of the network entity 104 sending 206 the reference signal for the estimation of the delay spread and Doppler spread at the UE side. Elements 203, 214, 216, 218, 220, and 222 have already been described with respect to FIG. 2.

[0052] Referring to FIG. 3, the network entity 104 transmits 304 to the UE 102 (and the UE 102 receives 304 from the network entity 104) using a default waveform, a first control message indicating an SRS configuration for the SRS. The SRS configuration might indicate an SRS waveform (e.g., OFDM waveform or OFTS waveform) and time-frequency resources. The default waveform might be an OFDM waveform. For example, the first control message is an RRC message. The network entity 104 can configure 304 the UE 102 to send 306 a specific UL pilot (e.g., SRS) for the delay spread and Doppler spread estimation at the network entity side instead of the network entity 104 sending 206 a DL signal for delay spread and Doppler spread estimation at the UE side (as shown in FIG. 2). The network entity 104 sends 304 the SRS configuration to the UE 102 using the first control message (e.g., RRC messages), indicating sequences and resources (such as time-frequency) allocated for the SRS.

[0053] The UE 102 transmits 306 to the network entity 104 (and the network entity 104 receives 306 from the UE 102), the SRS in conformance with the SRS configuration. The network entity 104 can use the SRS with frequency division duplex (FDD) bands where UL and DL communications are at different frequencies. The SRS may be specific for delay spread and Doppler spread estimation. For example, the network entity 104 configures 304 the SRS for the estimation of the delay spread and Doppler spread. For the estimation of high delay spread and/or high Doppler spread, the network entity 104 might adjust the time and frequency density of the SRS.

[0054] The network entity 104 measures 308 the delay spread and the Doppler spread of the SRS received 306 from the UE 102. The network entity 104 might select 312 a second waveform configuration based on the delay spread and the Doppler spread. For example, the network entity 104 transitions from instructing the UE 102 to transmit uplink data using an OFDM waveform to instructing the UE 102 to transmit uplink data using an OFTS waveform. The network entity 104 can use a time hysteresis to avoid ping-pong switching, as described above with respect to FIG. 2. For example, when the delay spread or Doppler spread measurement fulfills a threshold criterion, the network entity 104 determines the different waveform (e.g., second waveform). Although only uplink data transfer is shown, the principles described in FIG. 3 also apply to downlink data transfer. FIG. 2 and FIG. 3 illustrate dynamically switching the waveform based on reference signals. FIG. 4 illustrates dynamically switching a waveform in a fast beam-failure recovery after a beam failure, or a fast RRC connection reestablishment after RLF.

[0055] FIG. 4 is a signaling diagram 400 illustrating communications between a UE 102 and a network entity 104 for dynamically switching a waveform in a fast beam-failure recovery or a fast RRC connection reestablishment according to an embodiment. The network entity⁷ 104 might correspond to a base station or a unit of a base station, such as the RU 106, the DU 108, the CU 110. etc. The UE 102 and the network entity 104 communicate with each other using a current waveform on a wireless channel for a DL and/or UL signal (e.g., DL and/or UL communication). The current waveform might be OFDM waveform. The wireless channel might create high delay spread and/or high Doppler spread, which might result in high BLER when using the current waveform. For example, if the UE 102 suddenly moves to a different environment, or suddenly its speed changes, then high BLER might occur. The high BLER might trigger a failure, e.g., a beam failure or RLF, at the UE, for example, in the case the channel changes abruptly. Dynamically switching the waveform (e.g., from OFDM to OTFS waveform) enables a fast beam-failure recovery after the beam failure, or a fast RRC connection reestablishment after the RLF. For example, the network entity 104 and the UE 102 perform the fast beam-failure recovery using a predetermined recovery⁷ reference signal (e.g., pilot) and predetermined RACH preamble/resources.

[0056] Referring to FIG. 4, the network entity 104 configures 434 the recovery reference signal for the fast beam-failure recovery (or fast RRC connection reestablishment) and further configures one or more RACH preamble/resources. For example, the network entity 104 indicates 434 a failure recovery⁷ process with an RRC message to the UE 102, after the beam failure or RLF possibly due to the high delay spread/Doppler spread at the UE 102. The failure recovery⁷ process might be a fast beam-failure recovery at Layer 1 or a fast RRC connection reestablishment at Layer 3. The network entity 104 transmits 434 to the UE 102 (and the UE 102 receives 434 from the network entity 104) using a default waveform, a recovery control message indicating a recovery reference signal configuration and a RACH resource. The default waveform might be the OFDM waveform. The recovery' reference signal configuration might indicate a recovery' reference signal waveform and timefrequency resources for the recovery reference signal. For example, the recovery control message is an RRC message. The network entity 104 can send 434 the recovery reference signal configuration, using the recovery control message, indicating sequences and resources (such as time-frequency) allocated for the recovery reference signal, to assist the UE 102 with estimating the delay spread and the Doppler spread created by the wireless channel. The recovery reference signal (for recovery from the failure due to delay/Doppler spread) can have a specific recovery reference signal configuration for the estimation of delay/Doppler spread. The recovery reference signal can have specific RACH signature/resources. For example, the recovery reference signal is a new reference signal, such as a low duty-cycle reference signal configured for estimation of the delay/Doppler spread. The recovery reference signal might be referred as a delay/Doppler spread failure recovery signal (or pilot). The network entity 104 transmits 436 the recovery reference signal periodically for detection by a UE 102 experiencing a failure.

[0057] The UE 102 monitors the BLER while using the current waveform. The UE 102 might detect the beam failure or RLF when the BLER of the current waveform is above a predetermined BLER threshold. For the failure detection, the UE 102 can monitor the current BLER and detect the failure when the BLER is above a predetermined threshold. For example, the BLER may be referred to as a waveform error-rate. The UE 102 might detect the BLER of the DL and/or UL signal (e g., DL and/or UL communication) using the current waveform.

[0058] The UE 102 might detect 437 the failure, e.g., the beam failure or RLF, in response to detecting the BLER of the current waveform being above the predetermined threshold. In the presence of high delay spread and/or high Doppler spread, the RSRP might be above a threshold level, but the SINR might drop suddenly. A sudden drop in the SINR might be used for determining that the failure, based on the BLER being above the predetermined threshold, is caused by the high delay spread and/or high Doppler spread. For example, when the SINR is below a SINR threshold, the UE detects 437 the beam failure or RLF in response to detecting the BLER being above the predetermined threshold. The SINR threshold might be predetermined and stored in the UE 102 or configured by the network entity 104. The S1NR threshold could be related to time and/or value. In another example, when a rate of change of the SINR is above a SINR rate change threshold, the UE detects 437 the beam failure or RLF in response to detecting the BLER being above the predetermined threshold. The SINR rate change threshold might be based on a decrease or an increase of the SINR over a time period. The SINR rate change threshold might be predetermined and stored in the UE 102 or configured by the network entity 104.

[0059] Based on the recovery reference signal, the UE 102 measures/estimates 438 the delay spread and Doppler spread. The UE 102 can use the configured recovery reference signal (e.g., delay /Doppler failure recovery pilot) to measure/estimate 438 the delay and Doppler spread. For the failure that results from the high delay spread and/or high Doppler spread, the signal level from the network entity 104 is at a reasonable level, but the SINR drops and/or the BLER is high.

[0060] The UE 102 sends 440 the detected delay spread and Doppler spread estimate using the RACH preamble/resources. The UE 102 sends 440 to the network entity 104 (and the network entity 104 receives 440 from the UE 102) on the RACH resource using the default waveform, a first report message (e.g., a message A (MSGA)) indicating the delay spread and the Doppler spread measured from the recovery reference signal. The UE 102 uses the MSGA to indicate the detected delay spread and Doppler spread at the UE side, while the UE 102 is performing the failure recovery⁷, e.g., the recovery⁷ from the beam failure or the RLF failure. The UE 102 sends 440 the measurement report of the delay spread and Doppler spread in the MSGA payload.

[0061] After receiving 440 the estimate of the delay spread and Doppler spread from the UE 102, the network entity 104 determines an updated waveform for the UE 102 to use based on the estimate of the delay spread and Doppler spread. The network entity 104 selects 442 the updated waveform (e.g., a different waveform) configuration based on the indicated delay spread and the Doppler spread. For example, the network uses an OFDM control signal to indicate to the UE 102 that a subsequent downlink data signal (e.g., a next downlink data signal) sent on a PDSCH will use an OTFS signal. The network entity 104 can use a time hysteresis to avoid ping-pong switching, e.g., switching back and forth between OFDM and OTFS waveforms within a given time span. For example, when the delay spread or Doppler spread measurement fulfills a threshold criterion, the network entity 104 determines the different waveform (e.g., updated waveform) for the UE 102.

[0062] The network entity 104 sends 444, to the UE 102, a configuration for the updated waveform (e.g., the different waveform) using a RACH response. The network entity 104 transmits 444 (and the UE 102 receives 444) using the default waveform, the RACH response (e.g., using a message B (MSGB)) including an indication of the configuration of the updated waveform of the UL and/or DL signal based on the first report message. For example, the updated waveform is an OTFS waveform. The network entity 104 uses the MSGB to indicate, to the UE 102. the updated waveform selected by the network entity’ 104. Then, the UE 102 and the network entity 104 might communicate 446 with each other using the updated waveform for the UL and/or DL signal for UL and/or DL communication.

[0063] FIGs. 2-4 illustrate dynamically switching the waveform based on a reference signal and a fast beam-failure recovery after a beam failure, or a fast RRC connection reestablishment after an RLF. FIGs. 5-6 show methods for implementing one or more aspects of FIGs. 2-4. In particular, FIG. 5 shows an implementation by the UE 102 of the one or more aspects of FIGs. 2-4. FIG. 6 shows an implementation by the network entity 104 of the one or more aspects of FIGs. 2-4.

[0064] FIG. 5 illustrates a flowchart 500 of a method of wireless communication at a UE. With reference to FIGs. 1-4, the method may be performed by the UE 102. The UE 102 might transmit 503, to a network entity, a UE capability message that indicates UE capability, e.g.. at least two waveforms that the UE supports for an uplink signal, at least two waveforms that the UE supports for a downlink signal, at least one time interval for the UE to change a waveform of a downlink signal, or at least one time interval for the UE to change a waveform of an uplink signal. For example, referring to FIG. 2, the UE 102 transmits 203, to the network entity, a UE capability message that indicates: at least two waveforms (e.g.. OFDM and OTFS waveforms) that the UE supports for an uplink signal, at least two waveforms (e g., OFDM and OTFS waveforms) that the UE supports for a downlink signal, at least one time interval for the UE to change a waveform of a downlink signal, or at least one time interval for the UE to change a waveform of an uplink signal.

[0065] The UE 102 might receive 504, from the network entity using the default waveform, a first control message indicating a reference signal configuration. For example, referring to FIG. 2, the UE 102 might receive 204, from the network entity 104 using a default waveform, a first control message indicating a reference signal configuration for the reference signal.

[0066] The UE 102 might receive 506, from the network entity, the reference signal. For example, referring to FIG. 2, the UE 102 might receive 206. from the network entity, the reference signal. The UE 102 might measure 508 the first delay spread and the first Doppler spread from the reference signal. For example, referring to FIG. 2, the UE 102 might measure 208 the delay spread and the Doppler spread from the reference signal. The UE 102might transmit 510, to the network entity using the default waveform, a second control message indicating the first delay spread and the first Doppler spread. For example, referring to FIG. 2, the UE 102 might transmit 210, to the network entity using the default waveform, a second control message indicating the delay spread and the Doppler spread. The UE 102 might perform the operations 506, 508 and 510 repeatedly.

[0067] The UE 102 might receive 514. from the network entity using the default waveform, a third control message indicating a configuration for a second waveform. For example, referring to FIG. 2, the UE 102 might receive 214, from the network entity using the default waveform, a third control message indicating a configuration for the second waveform.

[0068] The UE 102 receives 534, from the network entity' 104 using the default waveform, a recovery control message indicating a recovery reference signal configuration and a RACH resource. For example, referring to FIG. 4, the UE 102 receives 434, from a network entity 104 using a default waveform, a recovery control message indicating a recovery reference signal configuration and a RACH resource.

[0069] The UE 102 might detect 537 a beam failure in response to detecting a BLER being above a predetermined threshold. For example, referring to FIG. 4, the UE 102 might detect 437 the beam failure (or RLF) in response to detecting the BLER being above the predetermined threshold.

[0070] The UE 102 sends 540, to the network entity on the RACH resource using the default waveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery reference signal. For example, referring to FIG. 4. the UE 102 sends 440 the detected delay spread and Doppler spread estimate using the RACH preamble/resources. The UE 102 sends 440, to the network entity 104 on the RACH resource using the default waveform, a first report message (e.g., MSGA) indicating the delay spread and the Doppler spread measured from the recovery reference signal.

[0071] The UE 102 receives 544, from the network entity using the default waveform, a RACH response including an indication of a configuration of an updated waveform of at least one of an uplink signal or a downlink signal based on the first report message. For example, referring to FIG. 4, the UE 102 receives 444, from the network entity' 104 using the default waveform, the RACE! response (e.g., MSGB) including an indication of the configuration of the updated waveform of the UL and/or DL signal based on the first report message. FIG. 5 describes a method from a UE-side of a wireless communication link, whereas FIG. 6 describes a method from a network-side of the wireless communication link.

[0072] FIG. 6 is a flow chart 600 of a method of w ireless communication at a netw ork entity. With reference to FIGs. 1-4, the method may be performed by one or more network entities 104, which may correspond to a base station or a unit of the base station, such as the RU 106, the DU 108, and/or the CU 110. The network entity 104 might receive 603, from the UE, a UE capability message that indicates: at least tw o waveforms that the UE supports for an uplink signal, at least two waveforms that the UE supports for a downlink signal, at least one time interval for the UE to change a waveform of a downlink signal, or at least one time interval for the UE to change a w aveform of an uplink signal. For example, referring to FIG. 2, The netw ork entity 104 might receive 203, from the UE, a UE capability message that indicates: at least two waveforms (e.g., OFDM and OTFS waveforms) that the UE supports for an uplink signal, at least two waveforms (e.g., OFDM and OTFS waveforms) that the UE supports for a dow ilink signal, at least one time interval for the UE to change a waveform of a downlink signal, or at least one time interval for the UE to change a waveform of an uplink signal.

[0073] The network entity 104 might transmit 604, to the UE using the default waveform, a first control message indicating a reference signal configuration. For example, referring to FIG. 2, the network entity' 104 might transmit 204, to the UE using the default waveform, the first control message indicating the reference signal configuration.

[0074] The network entity 104 might transmit 606, to the UE, the reference signal. For example, referring to FIG. 2, the network entity' 104 might transmit 206, to the UE, the reference signal. The network entity 104 might receive 610, from the UE using the default waveform, a second control message indicating a first delay spread and a first Doppler spread measured from the reference signal. For example, referring to FIG. 2, the network entity 104 might receive 210, from the UE using the default waveform, the second control message indicating the delay spread and the Doppler spread. For example, the second control message is an RRC message. The network entity 104 might perform the operations 606, and 610 repeatedly.

[0075] The network entity 104 might transmit 614, to the UE using the default waveform, a third control message indicating a configuration for a second waveform. For example, referring to FIG. 2, the network entity 104 might transmit 214, to the UE using the default waveform, the third control message indicating the configuration for the second waveform.

[0076] The network entity 104 transmits 634, to the UE 102, using the default waveform, a recovery control message indicating a recovery reference signal configuration and a RACH resource. For example, referring to FIG. 4. the network entity 104 transmits 434, to the UE 102 using the default waveform, the recovery control message indicating the recovery' reference signal configuration and the RACH resource.

[0077] The network entity 104 receives 640, from the UE on the RACH resource and using the default waveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery reference signal. For example, referring to FIG. 4, the network entity 104 receives 440, from the UE 102 on the RACH resource using the default waveform, the first report message (e.g., MSGA) indicating the delay spread and the Doppler spread measured from the recovery reference signal. [0078] The network entity 104 transmits 644, to the UE using the default waveform, a RACH response including an indication of a configuration of an updated waveform of at least one of an uplink signal or a downlink signal based on the first report message. For example, referring to FIG. 4, the network entity 104 transmits 444, to the UE 120 using the default waveform, the RACH response (e.g., MSGB) including the indication of the configuration of the updated waveform of the UL and/or DL signal based on the first report message. A UE apparatus 702, as described in FIG. 7, may perform the method of flowchart 500. The one or more network entities 104, as described in FIG. 8, may perform the method of flowchart 600.

[0079] FIG. 7 is a diagram 700 illustrating an example of a hardware implementation for a UE apparatus 702. The UE apparatus 702 may be the UE 102, a component of the UE 102, or may implement UE functionality . The UE apparatus 702 may include an application processor 706. which may have on-chip memory 706^?. In examples, the application processor 706 may be coupled to a secure digital (SD) card 708 and/or a display 710. The application processor 706 may also be coupled to asensor(s) module 712, a power supply 714. an additional module of memory 716, a camera 718, and/or other related components.

[0080] The UE apparatus 702 may further include a wireless baseband processor 726, which may be referred to as a modem. The wireless baseband processor 726 may have on-chip memory 726'. Along with, and similar to, the application processor 706, the wireless baseband processor 726 may also be coupled to the sensor(s) module 712. the power supply 714, the additional module of memory 716, the camera 718, and/or other related components. The wireless baseband processor 726 may be additionally coupled to one or more subscriber identity' module (SIM) card(s) 720 and/or one or more transceivers 730 (e.g., wireless RF transceivers).

[0081] Within the one or more transceivers 730. the UE apparatus 702 may include a Bluetooth module 732, a WLAN module 734, an SPS module 736 (e g., GNSS module), and/or a cellular module 738. The Bluetooth module 732, the WLAN module 734, the SPS module 736, and the cellular module 738 may each include an on-chip transceiver (TRX). or in some cases, just a transmitter (TX) or just a receiver (RX). The Bluetooth module 732, the WLAN module 734, the SPS module 736, and the cellular module 738 may⁷ each include dedicated antennas and/or utilize antennas 740 for communication with one or more other nodes. For example, the UE apparatus 702 can communicate through the transceiver(s) 730 via the antennas 740 with another UE (e.g., sidelink communication) and/or with a network entity 104 (e.g.. uplink/downlink communication), where the network entity 104 may correspond to a base station or a unit of the base station, such as the RU 106, the DU 108, or the CU 110.

[0082] The wireless baseband processor 726 and the application processor 706 may each include a computer-readable medium / memory 726', 706', respectively. The additional module of memory 716 may also be considered a computer-readable medium / memory. Each computer-readable medium / memory' 726', 706', 716 may be non-transitory. The wireless baseband processor 726 and the application processor 706 may each be responsible for general processing, including execution of software stored on the computer-readable medium / memory 726', 706', 716. The software, when executed by the wireless baseband processor 726 / application processor 706, causes the wireless baseband processor 726 / application processor 706 to perform the various functions described herein. The computer-readable medium / memory may also be used for storing data that is manipulated by the wireless baseband processor 726 / application processor 706 when executing the software. The wireless baseband processor 726 I application processor 706 may be a component of the UE 102. The UE apparatus 702 may be a processor chip (e.g., modem and/or application) and include just the wireless baseband processor 726 and/or the application processor 706. In other examples, the UE apparatus 702 may be the entire UE 102 and include the additional modules of the apparatus 702.

[0083] As discussed in FIG. 1 and implemented with respect to FIG. 5, the detection component 140 is configured to receive, from a network entity using a default waveform, a recovery control message indicating a recovery⁷ reference signal configuration and a RACH resource. The detection component 140 is configured to send, to the network entity on the RACH resource using the default waveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery reference signal. The detection component 140 is configured to receive, from the network entity using the default waveform, a RACH response including an indication of a configuration of an updated waveform of at least one of an uplink signal or a downlink signal based on the first report message. The detection component 140 may be within the application processor 706 (e.g., at 140a), the wireless baseband processor 726 (e.g., at 140b), or both the application processor 706 and the wireless baseband processor 726. The detection component 140a- 140b may be one or more hardware components specifically configured to carry out the stated processes/algorithm, implemented by one or more processors configured to perform the stated processes/algorithm, stored within a computer-readable medium for implementation by the one or more processors, or a combination thereof.

[0084] FIG. 8 is a diagram 800 illustrating an example of a hardware implementation for one or more network entities 104. The one or more network entities 104 may be a base station, a component of a base station, or may implement base station functionality. The one or more network entities 104 may include, or may correspond to, at least one of the RU 106, the DU, 108, or the CU 110. The CU 110 may include a CU processor 846, which may have on-chip memory 846'. In some aspects, the CU 110 may further include an additional module of memory’ 856 and/or a communications interface 848, both of which may be coupled to the CU processor 846. The CU 110 can communicate with the DU 108 through a midhaul link 162. such as an Fl interface between the communications interface 848 of the CU 110 and a communications interface 828 of the DU 108.

[0085] The DU 108 may include a DU processor 826, which may have on-chip memory 826'. In some aspects, the DU 108 may further include an additional module of memory 836 and/or the communications interface 828, both of which may be coupled to the DU processor 826. The DU 108 can communicate with the RU 106 through a fronthaul link 160 between the communications interface 828 of the DU 108 and a communications interface 808 of the RU 106.

[0086] The RU 106 may include an RU processor 806, which may have on-chip memory 806'. In some aspects, the RU 106 may further include an additional module of memory' 816, the communications interface 808, and one or more transceivers 830, all of which may be coupled to the RU processor 806. The RU 106 may further include antennas 840, which may be coupled to the one or more transceivers 830, such that the RU 106 can communicate through the one or more transceivers 830 via the antennas 840 with the UE 102.

[0087] The on-chip memory 806', 826', 846' and the additional modules of memory' 816, 836, 856 may each be considered a computer-readable medium / memory. Each computer-readable medium / memory may be non-transitory. Each of the processors 806, 826, 846 is responsible for general processing, including execution of software stored on the computer-readable medium / memory'. The software, when executed by the corresponding processor(s) 806, 826, 846 causes the processor(s) 806, 826, 846 to perform the various functions described herein. The computer-readable medium / memory may also be used for storing data that is manipulated by the processor(s) 806, 826, 846 yvhen executing the software. In examples, the configuration component 150 may sit at any of the one or more network entities 104, such as at the CU 110; both the CU 110 and the DU 108; each of the CU 110, the DU 108. and the RU 106; the DU 108; both the DU 108 and the RU 106; or the RU 106.

[0088] As discussed in FIG. 1 and implemented yvith respect to FIG. 6, the configuration component 150 is configured to transmit, to a UE using a default waveform, a recovery control message indicating a recovery reference signal configuration and a RACH resource. The configuration component 150 is configured to receive, from the UE on the RACH resource and using the default yvaveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery reference signal. The configuration component 150 is configured to transmit, to the UE using the default waveform, a RACH response including an indication of a configuration of an updated waveform of at least one of an uplink signal or a downlink signal based on the first report message. The configuration component 150 may be within one or more processors of the one or more network entities 104, such as the RU processor 806 (e g., at 150a), the DU processor 826 (e g., at 150b), and/or the CU processor 846 (e.g., at 150c). The configuration component 150a-150c may be one or more hardware components specifically configured to cany out the stated processes/algorithm, implemented by one or more processors 806. 826, 846 configured to perform the stated processes/algorithm, stored within a computer- readable medium for implementation by the one or more processors 806, 826, 846, or a combination thereof.

[0089] The specific order or hierarchy of blocks in the processes and flowcharts disclosed herein is an illustration of example approaches. Hence, the specific order or hierarchy of blocks in the processes and flowcharts may be rearranged. Some blocks may also be combined or deleted. Dashed lines may indicate optional elements of the diagrams. The accompanying method claims present elements of the various blocks in an example order, and are not limited to the specific order or hierarchy presented in the claims, processes, and flowcharts.

[0090] The detailed description set forth herein describes various configurations in connection with the drawings and does not represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough explanation of various concepts. However, these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

[0091] Aspects of wireless communication systems, such as telecommunication systems, are presented wdth reference to various apparatuses and methods. These apparatuses and methods are described in the following detailed description and are illustrated in the accompanying drawings by various blocks, components, circuits, processes, call flows, systems, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or combinations thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

[0092] An element, or any portion of an element, or any combination of elements may be implemented as a ‘‘processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, graphics processing units (GPUs), central processing units (CPUs), application processors, digital signal processors (DSPs), reduced instruction set computing (RISC) processors, systems-on-chip (SoC), baseband processors, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other similar hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software, which may be referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software components, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, or any combination thereof.

[0093] If the functionality described herein is implemented in software, the functions may be stored on, or encoded as, one or more instructions or code on a computer-readable medium, such as a non-transitory computer-readable storage medium. Computer- readable media includes computer storage media and can include a random-access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of these types of computer-readable media, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer. Storage media may be any available media that can be accessed by a computer.

[0094] Aspects, implementations, and/or use cases described herein may be implemented across many differing platform types, devices, systems, shapes, sizes, and packaging arrangements. For example, the aspects, implementations, and/or use cases may come about via integrated chip implementations and other non-module-component based devices, such as end-user devices, vehicles, communication devices, computing devices, industrial equipment, retail/purchasing devices, medical devices, artificial intelligence (Al)-enabled devices, machine learning (ML)-enabled devices, etc. The aspects, implementations, and/or use cases may range from chip-level or modular components to non-modular or non-chip-level implementations, and further to aggregate, distributed, or original equipment manufacturer (OEM) devices or systems incorporating one or more techniques described herein.

[0095] Devices incorporating the aspects and features described herein may also include additional components and features for the implementation and practice of the claimed and described aspects and features. For example, transmission and reception of wireless signals necessarily includes a number of components for analog and digital purposes, such as hardware components, antennas, RF-chains. power amplifiers, modulators, buffers, processor(s), interleavers, adders/summers, etc. Techniques described herein may be practiced in a wide variety of devices, chip-level components, systems, distributed arrangements, aggregated or disaggregated components, end-user devices, etc., of varying configurations.

[0096] The description herein is provided to enable a person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not limited to the aspects described herein, but are to be interpreted in view of the full scope of the present disclosure consistent with the language of the claims.

[0097] Reference to an element in the singular does not mean “one and only one” unless specifically stated, but rather “one or more.” Terms such as “if,” “when,” and “while” do not imply an immediate temporal relationship or reaction. That is, these phrases, e.g., “when,” do not imply an immediate action in response to or during the occurrence of an action, but simply imply that if a condition is met then an action will occur, but without requiring a specific or immediate time constraint for the action to occur. The terms “may”, “might”, and “can”, as used in this disclosure, often carry certain connotations. For example, “may” refers to a permissible feature that may or may not occur, “might” refers to a feature that probably occurs, and “can” refers to a capability (e.g., capable of). The phrase “For example” often carries a similar connotation to “may” and, therefore, “may” is sometimes excluded from sentences that include “for example” or other similar phrases.

[0098] Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C” or “one or more of A, B, or C” include any combination of A, B, and/or C, such as A and B, A and C, B and C, or A and B and C. and may include multiples of A. multiples of B. and/or multiples of C, or may include A only, B only, or C only. Sets should be interpreted as a set of elements where the elements number one or more. Terms or articles such as “a”, “an”, and/or “the” may refer to one of an item, feature, element, etc., that the term or article precedes, or may refer to more than one of said item, feature, element, etc. that the term or article precedes. For example, the recitation “a widget” does not preclude reference to multiples of said widget, as “multiple widgets” necessarily includes “a widget”. Hence, the recitation “a widget" may be interpreted as “at least one widget” or, similarly, interpreted as “one or more widgets”.

[0099] Unless otherwise specifically indicated, ordinal terms such as “first” and “second” do not necessarily imply an order in time, sequence, numerical value, etc., but are used to distinguish between different instances of a term or phrase that follows each ordinal term.

[00100] Reference numbers, as used in the specification and figures, are sometimes cross- referenced among drawings to denote same or similar features. A feature that is exactly the same in multiple drawings may be labeled with the same reference number in the multiple drawings. A feature that is similar among the multiple drawings, but not exactly the same, may be labeled with reference numbers that have different leading numbers but have one or more of the same trailing numbers (e.g., 206, 306, 406, etc., may refer to similar features in the drawings). Hence, like numbers may refer to like actions.

[00101] Structural and functional equivalents to elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are encompassed by the claims. The words “module,” “mechanism,” “element,” “device,” and the like may not be a substitute for the word “means.” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.” As used herein, the phrase “based on” shall not be construed as a reference to a closed set of information, one or more conditions, one or more factors, or the like. In other words, the phrase “based on A”, where “A” may be information, a condition, a factor, or the like, shall be construed as “based at least on A” unless specifically recited differently.

[00102] The following examples are illustrative only and may be combined with other examples or teachings described herein, without limitation. [00103] Example 1 is a method of wireless communication at a UE. including: receiving, from a network entity using a default waveform, a recovery control message indicating a recovery' reference signal configuration and a random access channel, RACE!, resource; sending, to the network entity on the RACH resource using the default waveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery reference signal; and receiving, from the network entity using the default waveform, a RACH response including an indication of a configuration, based on the first report message, of an updated waveform of at least one of an uplink signal or a downlink signal.

[00104] Example 2 may be combined with Example 1 and includes that the default waveform is an orthogonal frequency-division multiplexing (OFDM) waveform.

[00105] Example 3 may be combined with any of Examples 1-2 and further includes the updated waveform is not an OFDM waveform.

[00106] Example 4 may be combined with Example 3 and further includes the updated waveform is an orthogonal time frequency space (OTFS) w aveform.

[00107] Example 5 may be combined with any of Examples 1-4 and further includes detecting a block error-rate (BLER) of the at least one of the uplink signal or the downlink signal using a current waveform, wherein the current waveform is an OFDM w aveform.

[00108] Example 6 may be combined with Example 5 and further includes detecting a beam failure in response to detecting the BLER being above a predetermined threshold.

[00109] Example 7 may be combined with Example 6 and further includes detecting a signal-to-interference plus noise ratio (SINR) using the current waveform, wherein the SINR is below a SINR threshold.

[00110] Example 8 may be combined with any of Examples 1-7 and further includes communicating (446), with the network entity, using the updated waveform for the at least one of the uplink signal or the downlink signal.

[00111] Example 9 may be combined with any of Examples 1-8 and further includes transmitting, to the network entity, a UE capability message that indicates at least one of at least two waveforms that the UE supports for an uplink signal, at least two waveforms that the UE supports for a downlink signal, at least one time interval for the UE to change a waveform of a downlink signal, or at least one time interval for the UE to change a waveform of an uplink signal.

[00112] Example 10 may be combined with any of Examples 1-9 and further includes: receiving, from the network entity using the default waveform, a first control message indicating a reference signal configuration; receiving, from the network entity, the reference signal; measuring the first delay spread and the first Doppler spread from the reference signal; transmitting, to the network entity using the default waveform, a second control message indicating the first delay spread and the first Doppler spread; receiving, from the network entity using the default waveform, a third control message indicating a configuration for a second waveform; and communicating, with the network entity using the second waveform, at least one of the uplink signal or the downlink signal.

[00113] Example 11 may be combined with Example 10 and further includes the transmitting the second control message comprises: transmitting the second control message in response to determining that at least one of: a difference between a first measurement of the first delay spread and a second measurement of the first delay spread being larger than a first predetermined threshold, or a difference between a first measurement of the first Doppler spread and a second measurement of the first Doppler spread being larger than a second predetermined threshold.

[00114] Example 12 may be combined with any of Examples 1-9 and further includes: receiving, from the network entity using the default waveform, a first control message indicating a sounding reference signal, SRS, configuration; transmitting, to the network entity, the SRS in accordance with the SRS configuration; receiving, from the netw ork entity using the default waveform, a third control message indicating a configuration for a second waveform; and communicating, with the network entity using the second waveform, at least one of the uplink signal or the dow nlink signal. [00115] Example 13 may be combined with any of Examples 10-12 and further includes the third control message indicates a start time of the second waveform of the at least one of the uplink signal or the downlink signal based on UE capability.

[00116] Example 14 may be combined with Examples 10-13 and further includes receiving, from the network entity, a physical downlink control channel. PDCCH. downlink control information, DC I, indicating a start time of the second waveform for the at least one of the uplink signal or the downlink signal, wherein the at least one of the uplink signal or the downlink signal includes at least one of a physical downlink shared channel, PDSCH, a physical uplink shared channel, PUSCH, or a physical uplink control channel, PUCCH.

[00117] Example 15 may be combined with Example 14 and further includes the start time of the second w aveform is based on a guard period between the PDCCH DCI and the at least one of the PDSCH. the PUSCH, or the PUCCH.

[00118] Example 16 is a method of wireless communication at a network entity and includes: transmitting, to a user equipment (102), UE, using a default waveform, a recovery⁷ control message indicating a recovery reference signal configuration and a random access channel. RACH, resource; receiving, from the UE on the RACH resource and using the default waveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery⁷ reference signal; and transmitting, to the UE using the default waveform, a RACH response including an indication of a configuration, based on the first report message, of an updated w aveform of at least one of an uplink signal or a downlink signal.

[00119] Example 17 may be combined with Example 16 and further includes the recovery⁷ reference signal has a low duty-cycle.

[00120] Example 18 may be combined with any of Examples 16-17 and further includes communicating, with the UE, using the updated waveform for the at least one of the uplink signal or the downlink signal.

[00121] Example 19 may be combined w ith any of Examples 16-18 and further includes the receiving (203), from the UE, a UE capability message that indicates at least one of: at least two waveforms that the UE supports for an uplink signal, at least two waveforms that the UE supports for a downlink signal, at least one time interval for the UE to change a waveform of a downlink signal, or at least one time interval for the UE to change a waveform of an uplink signal.

[00122] Example 20 may be combined with any of Examples 16-19 and further includes: transmitting, to the UE using the default waveform, a first control message indicating a reference signal configuration; transmitting, to the UE, the reference signal; receiving, from the UE using the default waveform, a second control message indicating a first delay spread and a first Doppler spread measured from the reference signal; transmitting, to the UE using the default waveform, a third control message indicating a configuration for a second waveform; and communicating, with the UE using the second waveform, at least one of the uplink signal or the downlink signal.

[00123] Example 21 may be combined with any of Examples 16-19 and further includes: transmitting, to the UE using the default waveform, a first control message indicating a sounding reference signal, SRS, configuration; receiving, from the UE, the SRS; transmitting, to the UE using the default waveform, a third control message indicating a configuration for a second waveform; and communicating, with the UE using the second waveform, at least one of the uplink signal or the downlink signal.

[00124] Example 22 may be combined with any of Examples 20-21 and further includes the third control message indicates a start time of the second waveform of the at least one of the uplink signal or the downlink signal based on UE capability.

[00125] Example 23 may be combined with any of Examples 20-22 and further transmitting (216), to the UE. a physical downlink control channel, PDCCH, downlink control information. DC I. indicating a start time of the second waveform for the at least one of the uplink signal or the downlink signal, wherein the at least one of the uplink signal or the downlink signal includes at least one of a physical downlink shared channel, PDSCEI, a physical uplink shared channel, PUSCH, or physical uplink control channel, PUCCH.

[00126] Example 24 may be combined with Example 23 and further includes the start time of the second w aveform is based on a guard period betw een the PDCCH DCI and the at least one of the PDSCH, the PUSCH, or the PUCCH. [00127] Example 25 is an apparatus for wireless communication comprising a transceiver, a memory, and a processor coupled to the memory and the transceiver, the apparatus being configured to implement a method as in any of claims 1-24.

[00128] Example 26 is an apparatus for wireless communication including means for implementing a method as in any of examples 1-24.

[00129] Example 27 is a non-transitory computer-readable medium storing computer executable code, the code when executed by a processor causes the processor to implement a method as in any of examples 1-24.

Claims

CLAIMS WHAT IS CLAIMED IS:

1. A method of wireless communication at a user equipment (102). UE, comprising: receiving (434), from a network entity (104) using a default waveform, a recovery control message indicating a recovery reference signal configuration and a random access channel, RACH, resource; sending (440), to the network entity on the RACH resource using the default waveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery reference signal; and receiving (444), from the network entity using the default waveform, a RACH response including an indication of a configuration, based on the first report message, of an updated waveform of at least one of an uplink signal or a downlink signal.

2. The method of claim 1 , wherein the default waveform is an orthogonal frequencydivision multiplexing (OFDM) waveform, and wherein the updated waveform is an orthogonal time frequency space (OTFS) waveform.

3. The method of any of the claims 1-2, further comprising: detecting a block error-rate (BLER) of the at least one of the uplink signal or the downlink signal using a current waveform, wherein the current waveform is an OFDM waveform; and detecting (437) a beam failure in response to detecting the BLER being above a predetermined threshold.

4. The method of claim 3, further comprising: detecting a signal-to-interference plus noise ratio (SINR) using the current waveform, wherein the SINR is below a SINR threshold.

5. The method of any of the claims 1-4, further comprising: communicating (446), with the network entity, using the updated waveform for the at least one of the uplink signal or the downlink signal.

6. The method of any of the claims 1-5, further comprising: transmitting (203), to the network entity, a UE capability message that indicates at least one of: at least two waveforms that the UE supports for an uplink signal, at least two waveforms that the UE supports for a downlink signal, at least one time interval for the UE to change a waveform of a downlink signal, or at least one time interval for the UE to change a waveform of an uplink signal.

7. The method of any of claims 1-6, further comprising: receiving (204), from the network entity using the default waveform, a first control message indicating a reference signal configuration; receiving (206), from the network entity, the reference signal; measuring (208) the first delay spread and the first Doppler spread from the reference signal; transmitting (210). to the network entity using the default waveform, a second control message indicating the first delay spread and the first Doppler spread; receiving (214), from the network entity' using the default waveform, a third control message indicating a configuration for a second waveform; and communicating (220, 222), with the network entity using the second waveform, at least one of the uplink signal or the dow nlink signal.

8. The method of claim 7, wherein the transmitting the second control message comprises: transmitting (210) the second control message in response to determining that at least one of: a difference between a first measurement of the first delay spread and a second measurement of the first delay spread being larger than a first predetermined threshold, or a difference between a first measurement of the first Doppler spread and a second measurement of the first Doppler spread being larger than a second predetermined threshold.

9. The method of any of claims 1-8, further comprising: receiving (304) , from the network entity using the default waveform, a first control message indicating a sounding reference signal, SRS, configuration; transmitting (306). to the network entity, the SRS in accordance with the SRS configuration; receiving (214), from the network entity using the default waveform, a third control message indicating a configuration for a second waveform; and communicating (220, 222), with the network entity using the second waveform, at least one of the uplink signal or the dow nlink signal.

10. The method of any of claims 7-9, wherein the third control message indicates a start time of the second waveform of the at least one of the uplink signal or the downlink signal based on UE capability.

11. The method of any of the claims 7-10, further comprising: receiving (216), from the network entity, a physical downlink control channel, PDCCH. downlink control information, DCI. indicating a start time of the second w aveform for the at least one of the uplink signal or the downlink signal, wherein the at least one of the uplink signal or the downlink signal includes at least one of a physical downlink shared channel, PDSCH, a physical uplink shared channel, PUSCH, or a physical uplink control channel, PUCCH.

12. The method of claim 11, wherein the start time of the second waveform is based on a guard period between the PDCCH DCI and the at least one of the PDSCH, the PUSCH, or the PUCCH.

13. A method of wireless communication at a network entity (104), comprising: transmitting (434), to a user equipment (102), UE, using a default w aveform, a recovery control message indicating a recovery reference signal configuration and a random access channel, RACH, resource; receiving (440), from the UE on the RACH resource and using the default w aveform, a first report message indicating a delay spread and a Doppler spread measured from the recovery reference signal; and transmitting (444). to the UE using the default waveform, a RACH response including an indication of a configuration, based on the first report message, of an updated w aveform of at least one of an uplink signal or a downlink signal.

14. The method of claim 13. the method further comprising: communicating (446), with the UE, using the updated waveform for the at least one of the uplink signal or the dow nlink signal.

15. An apparatus for wireless communication comprising a transceiver, a memory, and a processor coupled to the memory and the transceiver, the apparatus being configured to implement a method as in any of claims 1-14.