TWI880633B - Methods and devices for timing advance - Google Patents

Abstract

Embodiments of the present disclosure relate to methods and apparatus for timing advance (TA) in a radio access network, in particular, through random access preamble transmission for TA maintenance. A terminal device receives, from a network device, a transmission mode configuration which indicates to the terminal device a transmission mode of a random access preamble. The transmission mode comprises a periodical mode or a one-shot mode. The terminal device transmits, to a target network device, the random access preamble based on the transmission mode. In this way, the terminal device can transmit the random access preamble based on the indicated transmission mode, thereby avoiding unnecessary transmissions of the random access preamble for TA maintenance.

Description

Method and device for timing advance

Various exemplary embodiments relate to the field of telecommunications, and more particularly to methods, devices, apparatuses, and computer-readable storage media for timing advance (TA) in a radio access network, particularly TA transmitted via random access preamble coding for TA maintenance.

With the development of communication technology, a multiple downlink control information (multi-DCI) for multiple transmission reception point (multi-TRP) operation has been proposed for wireless communication systems. Currently, multi-TRP operation supports two timing advance (TA) values in uplink (UL) multi-DCI. Timing advance management is required to maintain UL timing advance alignment.

A random access (RA) procedure may be triggered for various purposes, such as requesting resources for a radio resource control (RRC) connection, uplink synchronization, such as timing alignment, and the like. As is known, in the RA procedure, a random access preamble code may be sent to the network, and the network may send a random access response (RAR) containing a TA value within an configured time window. If the RAR is not received by the user equipment (UE), the UE may retransmit the random access preamble code until a RAR is received, resulting in a high additional load. Therefore, there is a need to further investigate the transmission of random access preamble codes for TA maintenance (e.g., TA acquisition and TA update).

In general, the exemplary embodiments of the present disclosure provide a solution for indicating a transmission mode of a random access preamble coding for TA maintenance to support multi-TRP transmission.

In a first aspect, a terminal device is provided. The terminal device includes one or more transceivers; and one or more processors coupled to the one or more transceivers, wherein the one or more transceivers are assembled with the one or more processors to cause the terminal device to perform the following actions: receiving a transmission mode configuration from a network device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode; and transmitting the random access preamble code to a target network device based on the transmission mode.

In a second aspect, a network device is provided. The network device includes one or more transceivers; and one or more processors coupled to the one or more transceivers, wherein the one or more transceivers are assembled with the one or more processors to cause the network device to perform the following actions: transmit a transmission mode configuration to a network terminal device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode; and transmit the random access preamble code to a target network device based on the transmission mode.

In a third aspect, a method is provided at a terminal device. The method includes receiving a transmission mode configuration from a network device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode; and transmitting the random access preamble code to a target network device based on the transmission mode.

In a fourth aspect, a method is provided at a network device, the method comprising: transmitting a transmission mode configuration to a terminal device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode.

In a fifth aspect, a device for a terminal device is provided. The device includes a component for receiving a transmission mode configuration from a network device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode; and a component for transmitting the random access preamble code to a target network device based on the transmission mode.

In a sixth aspect, an apparatus for a network device is provided, the apparatus comprising: a component for transmitting a transmission mode configuration to a terminal device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode comprises a periodic mode or a single-shot mode.

In a seventh aspect, a terminal device is provided. The terminal device includes at least one processor; and at least one memory including computer program codes, wherein the at least one memory and the computer program codes are configured to cooperate with the at least one processor, so that the terminal device performs the following actions: receiving a transmission mode configuration from a network device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode; and transmitting the random access preamble code to a target network device based on the transmission mode.

In an eighth aspect, a network device is provided. The network device includes at least one processor; and at least one memory including computer program codes, wherein the at least one memory and the computer program codes are configured to cooperate with the at least one processor to cause the network device to perform the following actions: transmit a transmission mode configuration to a terminal device, wherein the transmission mode configuration indicates a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode.

In a ninth aspect, a non-transitory computer-readable medium is provided, which contains program instructions for causing a device to perform at least a method according to any one of the third to fourth aspects above.

In a tenth aspect, a computer program comprising instructions is provided, which, when executed by a device, causes the device to perform at least the following actions: receiving a transmission mode configuration from a network device through a terminal device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode; and transmitting the random access preamble code to a target network device based on the transmission mode.

In an eleventh aspect, a computer program comprising instructions is provided, wherein when the instructions are executed by a device, the device performs at least the following actions: transmitting a transmission mode configuration through a network device and to a terminal device, wherein the transmission mode configuration indicates a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode comprises a periodic mode or a single-shot mode.

In a twelfth aspect, a terminal device is provided. The terminal device includes: a receiving circuit system configured to receive a transmission mode configuration from a network device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode; and a transmitting circuit system configured to transmit the random access preamble code to a target network device based on the transmission mode.

In a thirteenth aspect, a network device is provided, comprising: a transmission circuit system configured to transmit a transmission mode configuration to a terminal device, wherein the transmission mode configuration indicates a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode.

In a fourteenth aspect, a device is provided. The device includes components for performing the following actions: receiving a transmission mode configuration from a network device by a terminal device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode; and transmitting the random access preamble code to a target network device based on the transmission mode.

In a fifteenth aspect, a device is provided, which includes a component for performing the following actions: transmitting a transmission mode configuration to a terminal device through a network device, wherein the transmission mode configuration indicates a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode.

It should be understood that the content of the present invention is not intended to identify the key or essential features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easy to understand through the following description.

The principles of the present disclosure will now be described with reference to some exemplary embodiments. It is to be understood that these embodiments are described for illustrative purposes only and are intended to assist one of ordinary skill in the art in understanding and implementing the present disclosure, and do not suggest any limitation on the scope of the present disclosure. The disclosure described herein may be implemented in a variety of ways other than those described below.

In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which this disclosure belongs.

References to "an embodiment," "an embodiment," "an exemplary embodiment," and the like in this disclosure indicate that the embodiment may include a particular feature, structure, or characteristic, but not necessarily every embodiment includes the particular feature, structure, or characteristic. In addition, such words do not necessarily refer to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in conjunction with an embodiment, it is understood that it is within the knowledge of a person of ordinary skill in the art to affect the feature, structure, or characteristic in conjunction with other embodiments, whether or not explicitly stated.

It should be understood that although the terms "first" and "second" may be used herein to describe various components, these components should not be limited to these terms. These terms are only used to distinguish one component from another component. For example, a first component may be called a second component, and similarly, a second component may be called a first component without departing from the scope of the exemplary embodiments. The term "and/or" when used herein includes any term and all combinations of one or more of the listed terms.

The terminology used herein is intended only to illustrate specific embodiments and is not intended to limit the exemplary embodiments. When used herein, the singular forms "a", "an" and "the" are intended to include the plural forms at the same time, unless the context clearly indicates otherwise. It will be further understood that the words "comprising", "having" and/or "including" and/or their parts of speech when used herein specify the presence of the features, elements, and/or components, etc., but do not exclude the presence or addition of one or more other features, elements, components and/or combinations thereof. "At least one of the following: <a list of two or more elements>" and "at least one of <a list of two or more elements>" and similar words when used herein, where the list of two or more elements is linked by "and" or "or", means at least any one of the elements, or at least any two or more of the elements, or at least all of the elements.

"Circuitry" as used in this application may mean one, more or all of the following: (a) hardware-only circuit implementations (such as implementations in analog and/or digital circuit systems), and (b) combinations of hardware circuits and software, such as (as applicable): (i) combinations of analog and/or digital hardware circuits and software/firmware, and (ii) any portion of hardware processor(s) (including digital signal processor(s), software and memory(s) with software that operate together to enable a device such as a mobile phone or server to perform various functions, and (c) Hardware circuit(s) and/or processor(s) that require software (e.g., firmware) to operate, such as a microprocessor(s) or a portion of a microprocessor(s) but may not exist if the software is not required for operation.

The definition of "circuit system" applies to all uses of the term in this application, including all uses of the term in any claim of the application. By way of further example, the term "circuit system," when used in this application, also covers an implementation of only a hardware circuit or processor (or multiple processors), or a portion of a hardware circuit or processor, and accompanying software and/or firmware. The term "circuit system" also covers, by way of example and if applicable to the particular claimed component, a baseband integrated circuit or processor integrated circuit used in a mobile device, or a similar integrated circuit in a server, a cellular network device, or other computing or networking device.

The term "communication network" as used herein means a network that complies with any appropriate communication standard, such as Long Term Evolution (LTE), LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), High Speed Packet Access (HSPA), Narrowband Internet of Things (NB-IoT), etc. Furthermore, the communication between a terminal device and a network device in the communication network may be performed according to any appropriate generation communication protocol, including but not limited to the third generation (3G), fourth generation (4G), 4.5G, fifth generation (5G), or further sixth generation (6G) communication protocols, and/or any other protocols currently known or to be developed in the future. The embodiments of the present disclosure may be applied in various communication systems. In view of the rapid development of communications, there will certainly be future communications technologies and systems that can specifically implement this disclosure. The scope of this disclosure should not be considered limited to the aforementioned systems.

The term "network device" as used herein means a node in a communication network through which a terminal device accesses the network and receives services therefrom. A network device may be referred to as a base station (BS) or an access point (AP), such as a NodeB or NB, an evolved NodeB (eNodeB or eNB), a NR NB (also known as a gNB), a remote radio unit (RRU), a radio head (RH), a remote radio head (RRH), a repeater, a low power node such as a femto, a pico, etc., depending on the terminology and technology used.

The term "terminal device" means any terminal device capable of wireless communication. By way of example, but not limitation, a terminal device may also be referred to as a communication device, a user equipment (UE), a subscriber station (SS), a portable subscriber station, a mobile station (MS), or an access terminal (AT). The terminal device may include, but is not limited to, a mobile phone, a cellular phone, a smart phone, a voice over IP (VoIP) phone, a wireless local loop phone, a tablet computer, a wearable terminal device, a personal digital assistant (PDA), a portable computer, a desktop computer, an image capture terminal device such as a digital camera, a game terminal device, a music storage and playback device, a car wireless terminal device, a wireless terminal, a mobile radio, a laptop embedded equipment (LEE), a laptop docking equipment (LME ), a hardware lock, a smart device, a wireless customer premises equipment (CPE), an Internet of Things (IoT) device, a watch or other wearable device, a head mounted display (HMD), a vehicle, a drone, a medical device and application (e.g., telesurgery), an industrial device and application (e.g., a robot and/or other wireless device operating in an industrial and/or automated process chain environment), a consumer electronic device, a device operating on a commercial and/or industrial wireless network, and the like. In the following description, the terms "terminal device", "communication device", "terminal", "user equipment" and "UE" are used interchangeably.

The term "transmission reception point (TRP)" means a transmission reception point having an antenna array (with one or more antenna elements) on the network side located at a specific geographical location, which can be used to transmit and receive signals to/from terminal devices. In the embodiments of the present disclosure, a TRP may refer to a macro cell, a micro cellular base station, an RRH, a repeater, a femto node, a pico node, etc. Although some embodiments of the present disclosure are described, for example, with reference to two TRPs, these embodiments are still used for illustrative purposes only and to help those with ordinary knowledge in the relevant technical field understand and implement the present disclosure, and no limitation on the scope of the present disclosure is suggested.

It is to be understood that the present disclosure described herein can be implemented in a variety of ways other than those described below.

As mentioned above, retransmitting the random access preamble code until the RAR is received may cause high additional overhead. Regarding whether RAR is required for a candidate cell in Layer 1/Layer 2 (L1/L2) triggered inter-cell mobility (LTM) using a physical downlink control channel (PDCCH) ordered random access channel (RACH), the following alternatives are considered for further study: Alternative 1: RAR is required Alternative 2: RAR is not required - Note: If Alternative 2 is supported, a TA value of the candidate cell is indicated in the cell handover command Alternative 3: Whether RAR is required can be configured.

Therefore, in Rel-18, it is possible to configure whether RAR is required in at least some use cases. For example, for a candidate cell in LTM, a physical downlink control channel (PDCCH) ordered RACH may or may not require RAR.

In alternatives 2 and 3, regardless of whether RAR is needed or whether RAR reception can be configured, the TA value can be provided based on one of the random access procedures (such as non-contention random access (CFRA) based on a PDCCH command) after triggering a cell switching command. As is known, the reception of RAR is associated with the transmission of the preamble code, that is, if RAR is not provided by the network or the terminal device does not receive PAR, the terminal device can be configured to retransmit the RACH preamble code.

Since the RAR or the network response to the UE UL transmission (e.g., Physical Random Access Channel (PRACH) or Sounding Reference Signal (SRS)) or the information carried by the RAR (such as TA value) may be provided in the handover (or cell handover) command, it will be necessary to implement TA maintenance in an efficient way in the time between the (initial) CFRA (or in general, any UL transmission for TA acquisition) transmission and the cell handover command. In one option, the network may trigger the terminal device to transmit or retransmit a CFRA for TA maintenance, but a dedicated scheduling of DCI-triggered PDCCH commands will always be required, thereby causing an increased signaling overhead and reducing scheduling flexibility.

Therefore, there is currently no mechanism for a UE to understand whether it should expect a RAR, or if so, or if it expects and receives a RAR, whether it should retransmit the random access preamble.

According to an embodiment of the present disclosure, a solution is provided for indicating a transmission mode of a random access preamble code, especially for TA maintenance. In this solution, a terminal device receives a transmission mode configuration from a network device. The transmission mode configuration indicates a transmission mode of a random access preamble code to the terminal device. The transmission mode includes a periodic mode and a single-shot mode. With the received transmission mode configuration, the terminal device transmits the random access preamble code to a target network device based on the transmission mode indicated by the transmission mode configuration. The solution is used for TA maintenance, for example, in a scenario of multiple TRPs or in a scenario of lower layer triggered mobility (LTM).

In this way, an indication of the transmission mode of the random access preamble is provided so that the UE can transmit the random access preamble to a target network device based on the indicated transmission mode, thereby avoiding unnecessary transmission of the random access preamble. In addition, a periodic mode can be indicated by the transmission mode configuration, thereby reducing the signaling overhead for triggering a CFRA for TA maintenance.

The principles and embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. However, it should be noted that these embodiments are illustrated as examples and are not intended to limit the scope of the present application in any way.

First, please refer to FIG. 1, which illustrates an exemplary communication network 100 that can implement the embodiments of the present disclosure. As shown in FIG. 1, the communication network 100 includes a network device (e.g., a base station) 110 and a terminal device (e.g., a user device) 101 served by the network device 110. The terminal device 101 can communicate with the network device 110 via one or more physical communication channels or links.

In the communication network 100, a link from the terminal device 101 to the network device 110 is called a UL, and a link from the network device 110 to the terminal device 101 is called a downlink (DL). The UL and DL may be collectively referred to as beam pair links. In the UL, the terminal device 101 is a TX device (or a transmitter), and the network device 110 is a RX device (or a receiver). In the DL, the network device 110 is a transmitting (TX) device (or a transmitter), and the terminal device 101 is a receiving (RX) device (or a receiver).

It should be understood that the number of network devices and terminal devices is for illustrative purposes only and does not suggest any limitation to the present disclosure. The communication network 100 may include any suitable number of BSs, UEs and/or TRPs suitable for implementing the implementation aspects of the present disclosure.

It should be noted that the network device 110 in the present disclosure may be a control unit (CU) of a gNB, or it may be a distributed unit (DU) of the gNB, or it may be a gNB. The network device 110 may also be a TRP part of a gNB. The present disclosure has no limitation on the implementation of the network device.

In the communication device 100, the terminal device 101 receives a transmission mode configuration from the network device 110, and the transmission mode configuration indicates a transmission mode of a random access preamble code to the terminal device 101. The transmission mode includes a periodic mode or a single-shot mode. The terminal device 101 further transmits the random access preamble code to a target network device (a target cell) based on the transmission mode.

Communications in the communication system 100 may be implemented according to any appropriate communication protocol, including but not limited to third generation (3G), fourth generation (4G) and fifth generation (5G) or higher generation wireless local area network communication protocols such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocol currently known or to be developed in the future. In addition, communications may utilize any appropriate wireless communication technology, including but not limited to: code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), frequency division duplex (FDD), time division duplex (TDD), multiple input multiple output (MIMO), orthogonal frequency division multiplexing (OFDM), discrete Fourier spread OFDM (DFT-s-OFDM) and/or any other technology currently known or to be developed in the future.

In the communication system 100, the network device 110 transmits a transmission mode configuration to the terminal device 101. The transmission mode configuration indicates a transmission mode of a random access preamble code to the terminal device 101, and the transmission mode includes a periodic mode or a single-shot mode. The terminal device 101 receives the transmission mode configuration and transmits the random access preamble code to a target network device based on the transmission mode.

Referring now to FIG. 2 , an example of a process 200 is shown for indicating a transmission mode of a random access preamble coding according to an embodiment of the present disclosure. For discussion purposes, the process 200 will be described with reference to FIG. 1 . The process 200 may involve the terminal device 101 , a serving cell 202 and a target cell 202 .

In some embodiments of the present disclosure, the serving cell 201 and the target cell 202 are two different cells, but may be provided by the same base station. For example, the network device 110. The serving cell 201 and the target cell 202 may be provided by different base stations. For example, the serving cell 201 may be provided by the network device 110, and the target cell 202 may be provided by another network device.

In a multi-TRP scenario, the serving cell 201 may be provided by a first TRP or a first set of TRPs, and the target cell 202 may be provided by a second TRP or a second set of TRPs. The first TRP (or first set of TRPs) and the second TRP (or second set of TRPs) may be located in the same base station, or alternatively, in different base stations.

As described above, in a multi-TRP scenario or an LTM scenario, the terminal device 101 may be switched or handed over from the serving cell 201 to the target cell for, for example, better transmission quality.

In process 200, the serving cell 201 transmits 205 a transmission mode configuration 210 to the terminal device 101. The terminal device 101 receives 215 the transmission mode configuration 210.

The transmission mode configuration 210 indicates a transmission mode of a random access preamble code to the terminal device 101, and the transmission mode includes a periodic mode or a single-shot mode. The random access preamble code may include a contention-based random access (CBRA) preamble code. Alternatively, the random access preamble code may include a non-contention random access (CFRA) preamble code. In a four-step CFRA procedure, the random access preamble code may be assigned to the terminal device 101 by the serving cell 201. In a two-step CFRA procedure, the terminal device 101 may be assigned a CFRA preamble code and a physical uplink shared channel (PUSCH) for a payload.

In any of the embodiments herein, a (sounding reference signal) SRS transmission or any uplink transmission may be used interchangeably with the CFRA/random access preamble coded transmission herein. The uplink transmission may be used to obtain a TA value for a target cell (or a serving cell), or to maintain a TA for a target cell (or a serving cell).

In some embodiments, the one-shot mode may indicate a transmission of the random access preamble code that supports a retransmission until a response to the random access preamble code is received. In other words, in the one-shot mode, the terminal device 101 may initially transmit the random access preamble code, and if a response to the random access preamble code is not received, retransmit the random access preamble code.

In some embodiments, the response to the random access preamble coding may be a RAR. For example, in a CFRA procedure, the response to the CFRA preamble coding may be a RAR indicating that the random access procedure was successful. For example, the response to the random access preamble coding may be a response indicating that the random access preamble coding was successfully received (by the network). For example, by containing a response associated with the transmission of the preamble coding. Alternatively, an indication that the random access procedure was not successfully completed by the UE is that no response was received.

In some embodiments, the single-shot mode may indicate that the UE is to perform a single transmission of a random access preamble code (e.g., via a PDCCH order), regardless of whether a response to the random access preamble code is received. In this case, the terminal device 101 may perform a single transmission of the random access preamble code without expecting a response to the random access preamble code. Furthermore, in this case, the UE may determine that the random access procedure is complete after transmitting the preamble code (without expecting or monitoring a response). In another example, the single-shot mode may indicate that the terminal device 101 may perform a single transmission of the random access preamble code without expecting a response to the random access preamble code.

In some embodiments, the periodic mode may indicate a periodic transmission of a random access preamble code. In the periodic mode, the terminal device 101 may periodically transmit the random access preamble code to the target cell 202. For each periodic transmission of the random access preamble code, the terminal device 101 may monitor a response to the random access preamble code during a time window. The terminal device 101 may receive a response to the random access preamble code for a first (first transmission of the assembled periodic transmission) transmission during the time window. The terminal device 101 may not receive a response to the random access preamble code for another periodic transmission. In a case where no response is received, the terminal device 101 may retransmit the random access preamble code (e.g., until a response is received). In a case where no response is received, the terminal device 101 may retransmit the random access preamble code (e.g., until a response is received) and take periodic transmissions after receiving the response. Alternatively, for a single transmission, the terminal device 101 may only perform a single random access preamble code transmission without any retransmissions. In a further exemplary embodiment, the terminal device 101 may expect to receive a response to the random access preamble code for each periodic transmission. In one example, if the terminal device 101 does not receive a (network) response to the random access preamble for a transmission (which may be periodic), it may stop (or pause or cancel) the (periodic) transmission of the random access preamble.

In some embodiments, the periodicity pattern may further indicate periodicity information used for the periodicity pattern. The periodicity information may be a periodic transmission encoded by the random access preamble including a periodicity value and/or a repetition number. In one example, the periodicity information indicated by the downlink control information (DCI) may refer to a configured periodicity value (e.g., indicated by RRC). In one example, the repetition number information indicated by the downlink control information (DCI) may refer to a pre-configured repetition number (e.g., indicated by RRC). In one example, the periodicity and repetition number may be indicated together with a single value (e.g., a code point indicating a specific pre-configured value, such as an RRC value).

The periodicity value may be explicitly assigned in milliseconds (ms) or seconds, for example, every 100 ms (200 ms, 400 ms, etc.). Alternatively, the periodicity value may be assigned based on a random access opportunity (RO) periodicity value. The periodicity value may be assigned based on the RO periodicity value associated with a downlink resource indicated by a PDCCH command. For example, if an RO periodicity value is 20 ms, the periodicity value for the periodic transmission of the random access preamble code may be assigned, for example, every N RO opportunities (N=1, 2, 3, 4, 5...). If N=5, the periodicity value used for the periodic mode would be 100 ms, i.e., every five ROs.

In any example herein, the periodicity and/or repetition value for an uplink transmission (such as a random access preamble, SRS, or any other UL transmission) may be configured by RRC. In any example herein, the periodicity and/or repetition value for an uplink transmission (such as a random access preamble, SRS, or any other UL transmission) may be specific to a RACH configuration for the cell (or group of cells) for which the uplink transmission is performed. In any example herein, the periodicity and/or repetition value for an uplink transmission (such as a random access preamble, SRS, or any other UL transmission) may be a predefined/fixed value applicable for performing any uplink transmission (e.g., for TA acquisition or maintenance).

In some embodiments, the terminal device 101 may receive 215 a transmission mode configuration 210 in a downlink control information (DCI) containing a PDCCH command for a random access transmission. The transmission mode configuration 210 may include a bit field in the DCI. The bit field may include one or more bits. A value or a code point of the bit field may indicate a transmission mode for random access preamble coding. In addition, different values or code points of the bit field may indicate different periodicity values for the periodicity mode and/or a repetition number for the random access preamble coding.

For example, a first (or one) value or code point of a bit field may indicate a single transmission of a random access preamble code without an expected RAR (e.g., within a RAR response window). In one example, the RAR or response may be provided in a further downlink message. This message may be, for example, a cell switch command (handover) or other message. In one example, a first (or one) value or code point of a bit field may indicate a single transmission of a random access preamble code with an expected RAR. A second (or one) value or code point of the bit field may indicate that a transmission of a random access preamble code supports a retransmission until a response to the random access preamble code is received. A third value (or one) or code point of the bit field may indicate a periodic transmission of a random access preamble code with a first periodicity value. A fourth value or code point of the bit field may indicate a periodic transmission of a random access preamble code with a second periodicity value. In one example, the UE may be configured to perform a periodic transmission of a random access preamble code after receiving a response (e.g., RAR).

Alternatively or additionally, the terminal device 101 may receive 215 the transmission mode configuration 210 in a random access channel (RACH) configuration. In other words, the transmission mode configuration 210 may be included in the RACH configuration. For the terminal device 101, the RACH configuration may be provided for the target cell 202 to be transmitted using a RACH. Alternatively or additionally, for the terminal device 101, the RACH configuration may be provided for one or more candidate cells to be transmitted using a RACH.

In some embodiments, the periodicity information for the periodicity mode may be indicated by both the RACH configuration and the DCI. A portion of the periodicity information may be included in the RACH configuration, and another portion of the periodicity information may be included in the DCI. Specifically, the RACH configuration may configure the terminal device 101 with one or more candidate periodicity values, and the DCI may indicate a periodicity value selected/indicated by the terminal device 101 from the one or more candidate periodicity values.

With the received transmission mode configuration 210, the terminal device 101 further transmits 220 a random access preamble 225 to the target cell 202 based on the transmission mode. Depending on the transmission mode indicated by the transmission mode configuration 210, the terminal device 101 may transmit 220 the random access preamble 225 in a one-shot mode with an expectation of a response. Alternatively, the terminal device 101 may transmit 220 the random access preamble 225 in a single transmission without expecting any response to the random access preamble 225. Alternatively, the terminal device 101 may periodically transmit 220 the random access preamble 225 in a periodic mode.

In some embodiments, in the periodic mode, the terminal device 101 may stop a periodic transmission of the random access preamble 225 under certain circumstances. For example, the terminal device 101 may stop the periodic transmission after receiving a PDCCH command indicating to stop the periodic transmission. For example, the terminal device 101 may receive a DCI containing the PDCCH command and determine that one or more bits in the DCI indicate the stopping of the periodic transmission. For another example, the terminal device 101 may receive a DCI containing the PDCCH command and determine that one or more bits in the DCI indicate the stopping of all periodic transmissions. For another example, the terminal device 101 may receive a DCI containing a PDCCH command and determine that one or more bits in the DCI indicate that all periodic transmissions are stopped for a set of candidate cells. For another example, the terminal device 101 may receive a DCI containing a PDCCH command and determine that one or more bits in the DCI indicate that periodic transmissions are stopped for a specific cell.

In some embodiments, a timer T may be configured to monitor the periodic transmission of a random access preamble code. When the timer T is running, the UE may perform (periodic) transmission of a random access preamble code to a target cell. The target cell may be indicated by a PDCCH command. In another example, the timer T may be activated when the UE transmits the preamble code. In another example, the timer T may be activated when the UE receives a response to the transmitted preamble code (e.g., random access).

In one example, the timer T may be pre-configured with a specific value. In one example, the timer T may be configured in a random access configuration of the target cell. In one example, the timer T is RRC configured with a value specific to the random access transmission used by the TA. In one example, the timer T may have one or more candidate values configured (e.g., by RRC) and indicated in the downlink control message that triggers the PDCCH command. The candidate values may be expressed in milliseconds, seconds, etc. The timer may be cell specific.

In one example, the terminal device 101 may stop a (periodic) transmission of the random access preamble 225 after a transmission timer expires. The transmission timer may be configured to trigger the terminal device 101 to stop the periodic transmission after the transmission timer expires. The transmission timer may be started after an initial transmission of the random access preamble 225 or after receiving a response. While the transmission timer is running, the terminal device 101 may periodically transmit the random access preamble 225.

In any of the embodiments herein, the response to an uplink transmission (RAN or SRS or other UL transmission) may be provided by the target cell (of the PDCCH command) or the serving cell.

In any embodiment herein, RAR may refer to a random access response or any response provided by the network for UL transmission provided by the UE (for timing advance acquisition and/or maintenance). In any embodiment, RAR (or any response provided by the network) may refer to a response in which the UE is provided with a TA value for at least one target cell.

The terminal device 101 may receive a timer configuration included in an RRC message or in a RACH configuration for transmitting a value of the timer. For the terminal device 101, the RACH configuration may be provided for a RACH transmission for the serving cell 201. Alternatively or additionally, for the terminal device 101, the RACH configuration may be provided for a RACH transmission for one or more candidate cells.

Alternatively, the terminal device 101 may stop periodic transmission after reaching a predetermined number of transmissions of the random access preamble code 225. When the predetermined number of transmissions is reached, the terminal device 101 may consider the random access procedure to be successful.

Alternatively, the terminal device 101 may stop periodic transmission after receiving a cell switching command. For example, the serving cell 201 may send a cell switching command to the terminal device 101 to indicate a cell switching or handover from the serving cell 201 to the target cell 202. In this case, the terminal device 101 may obtain the TA value from the cell switching command and may therefore stop periodic transmission for TA maintenance.

In some other cases, a cell switch or handover originating from the serving cell 201 may indicate a switch or handover to a candidate cell instead of the target cell 202. In this case, there is no need to send a random access preamble code to the target cell 202, and therefore the terminal device 101 may stop periodic transmission to the target cell 202 to avoid unnecessary transmission.

In some embodiments, the transmission mode configuration 210 may be cell-specific, cell group-specific, base station-specific, terminal device-specific, or RACH configuration-specific. For example, the transmission mode configuration 210 may be provided for a random access transmission for a cell or a cell group.

Therefore, with the exemplary process 200, an indication of a transmission mode of a random access preamble 225 can be provided so that the terminal device 101 can transmit the random access preamble 225 based on the indicated transmission mode, thereby reducing the overhead. For example, if the transmission mode configuration 210 indicates a single-shot mode without an expected RAR, the terminal device 101 may not retransmit the random access preamble 225 even if a RAR is not received.

As described above, the RA procedure may be used for timing alignment, i.e., timing advance (TA) maintenance, for the terminal device 101. Specifically, for TA maintenance, in a one-step, two-step, or four-step CFRA procedure, the network device may assign a dedicated CFRA preamble code to the terminal device 101. The terminal device 101 may transmit the dedicated CFRA preamble code to the target cell 202 or a candidate cell (or the serving cell 201) for TA acquisition or update. The terminal device 101 may receive a RAR indicating a TA value from the corresponding cell for TA acquisition or TA update.

FIG. 3 illustrates an example of a process 300 for TA maintenance according to some embodiments of the present disclosure, wherein a single-shot mode is configured. For discussion purposes, the process 300 will be described with reference to FIG. 1 . The process 300 may involve the terminal device 101, a serving cell 301, and a target cell 302. Similarly, the serving cell 301 and the target cell 302 may be provided by the same network device or different network devices.

In process 300, servo cell 301 may transmit 305 a transmission mode configuration 310 indicating a single-shot mode to terminal device 101. Terminal device 101 may receive 315 the transmission mode configuration 310 and determine to transmit a CFRA preamble code based on the indicated single-shot mode.

The end device 101 may transmit 320 a dedicated CFRA preamble code 325 to the target cell 302. The target cell 302 may receive 330 the CFRA preamble code 325. After the (initial) transmission of the CFRA preamble code 325, the end device 101 may monitor 335 for a response to the CFRA preamble code 325 during a time window. If a response is not received during the time window, the end device 101 may determine 335 to retransmit the CFRA preamble code 325 until a response indicating a TA value is received.

As shown in FIG3 , the terminal device 101 may retransmit 340 the CFRA preamble code 325 to the target cell 302. The target cell 302 may receive 350 the CFRA preamble code 325. In response to the transmission of the CFRA preamble code 325, the target cell 302 may measure the TA based on the CFRA preamble code 325 and transmit the measured TA to the serving cell 301 in a backload. The serving cell 301 may transmit 355 a response 360 indicating a TA value to the terminal device 101. The terminal device 101 may receive 365 the response 360 indicating the TA value. Alternatively or additionally, the target cell 302 may transmit the response 360 indicating the TA value directly to the terminal device 101.

Therefore, in process 300, based on the transmission mode configuration 310 indicating the single-shot mode, the terminal device 101 can retransmit the CFRA preamble code 325 to the target cell 302 until a TA value is received, without additionally scheduling a DCI containing a PDCCH command for triggering the terminal device 101 to transmit a random access preamble code for TA maintenance.

FIG. 4 illustrates another example of a process 400 for TA maintenance, wherein a periodic pattern is configured, according to some embodiments of the present disclosure. For discussion purposes, the process 400 will be described with reference to FIG. 1 . The process 400 may involve the terminal device 101, a serving cell 401, and a target cell 402. Similarly, the serving cell 401 and the target cell 402 may be provided by the same network device or different network devices.

In process 400, a serving cell 401 may transmit 405 a transmission mode configuration 410 indicating a periodic pattern to a terminal device 101. The terminal device 101 may receive 415 the transmission mode configuration 410 and determine to transmit a CFRA preamble code based on the indicated periodic pattern.

As shown in FIG4 , the terminal device 101 may transmit 420 a dedicated CFRA preamble code 425 to the target cell 402. The target cell 402 receives 430 the CFRA preamble code 425. For the transmission of the CFRA preamble code 425, the target cell 402 may measure a TA based on the CFRA preamble code 425 and transmit the measured TA to the serving cell 401 in a backload. The serving cell 401 may transmit 435 a first TA value 440 (the measured TA above) to the terminal device 101. The terminal device 101 may receive 445 the first TA value 440. Alternatively or additionally, the target cell 402 may transmit the first TA value 440 directly to the terminal device 101.

The transmission mode configuration 410 may further indicate periodic information for the periodic mode. Based on the periodic information, the terminal device 101 may periodically perform CFRA. For example, the terminal device 101 may transmit 450 a CFRA preamble code 425 to the target cell 402 at a time point consistent with the periodicity, for example by using a timer. The target cell 402 may receive 455 the CFRA preamble code 425 and measure the TA based on the received CFRA preamble code 425. The target cell 402 may transmit the measured TA (in 455) to the serving cell 401 in a backload. The serving cell 401 may transmit 460 a second TA value (e.g., another/second/further message providing a (updated) TA value) 465 (the measured TA in 455) to the terminal device 101. The terminal device 101 may receive 470 the second TA value 465. Alternatively or additionally, the target cell 402 may transmit the second TA value 465 directly to the terminal device 101.

In this way, in processes 300 and 400, the signaling overhead can be reduced and scheduling flexibility can be improved.

In some embodiments, as shown in FIG4 , the terminal device 101 may continue a periodic transmission of the random access preamble code after receiving a response to the random access preamble code containing a TA value. Alternatively, the terminal device 101 may stop a periodic transmission of the random access preamble code after receiving a response to the random access preamble code containing a TA value. In other words, the terminal device 101 may periodically transmit the CFRA preamble code until a response containing a TA value is received.

By virtue of the process 400, the terminal device 101 may receive a first TA value 440 and a second TA value (e.g., another/second/further message providing a (updated) TA value) 465 for TA updating. In this way, TA maintenance may be performed for the terminal device 101 during a period between the initial transmission of the CFRA preamble code 425 and the receipt of the RAR or cell handover command indicating the TA value, particularly when the period is relatively long due to the need for signaling between cells to coordinate a target cell for the terminal device 101 via the core network. The terminal device 101 can periodically send the CFRA preamble code to the target cell 402 to update the TA value, without scheduling a DCI containing a PDCCH command to trigger the random access preamble code transmission for TA maintenance, thereby reducing the additional load and improving the scheduling flexibility.

As shown in FIG4 , in some cases, the terminal device 101 may stop 475 the periodic transmission of the CFRA preamble code 425. In some embodiments, the terminal device 101 may stop 475 the periodic transmission upon receiving a cell switching command. The terminal device 101 may switch to a different cell than the target cell 402, and therefore does not need to perform TA maintenance for the target cell 402. Therefore, by stopping the periodic transmission, unnecessary TA maintenance between the target cell 402 and the terminal device 101 may be avoided.

Alternatively, the terminal device 101 may receive the transmission mode configuration 410 from the serving cell 401, and the transmission mode configuration 410 indicates a transmission mode for the terminal device 101 to use for CFRA transmission for the target cell 402 or a candidate cell. The terminal device 101 may transmit the CFRA preamble code for TA maintenance along with the target cell 402 or one or more candidate cells. In this way, the terminal device 101 may perform TA maintenance for the target cell 402 or the candidate cells without separately scheduling a DCI containing a PDCCH command to trigger RA transmission by the serving cell 401.

In addition, in a multi-TRP transmission, the terminal device 101 can perform TA maintenance for intra-cell and inter-cell conditions based on a first TRP and a second TRP according to some embodiments of the present disclosure. If necessary, the terminal device 101 can receive a first TA value for a first TRP and a second TA value for a second TRP.

Now please refer to Figure 5, which shows an exemplary flow chart of a method 500 implemented at a terminal device. For discussion purposes, method 500 will be described from the perspective of terminal device 101 with reference to Figure 1.

At block 510, the terminal device 101 receives a transmission mode configuration from the network device 110, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device. The transmission mode includes a periodic mode or a single-shot mode. At block 520, the terminal device 101 transmits the random access preamble code to a target network device based on the transmission mode. The target network device may be the same as the network device 110. Alternatively, the target network device may be different from the network device 110.

In some embodiments, the single-shot mode may indicate any one of the following: a transmission of the random access preamble code supporting a retransmission until a response to the random access preamble code is received, or a single transmission of the random access preamble code regardless of whether a response to the random access preamble code is received.

In some embodiments, the transmission mode configuration may include a bit field in downlink control information DCI, and wherein the DCI contains a physical downlink control channel PDCCH order for a random access transmission.

In some embodiments, different code points in the bit field may indicate different periodicity values in the periodicity pattern.

In some embodiments, the transmission mode configuration may be applied to at least one of a target cell or one or more candidate cells.

In some embodiments, the transmission mode configuration may be included in a random access channel (RACH) configuration.

In some embodiments, the transmission mode may further indicate periodicity information for the periodicity mode, wherein a portion of the periodicity information is included in a RACH configuration and another portion of the periodicity information is included in a DCI, and wherein the RACH configuration configures the terminal device with one or more candidate periodicity values and the DCI indicates a periodicity value selected for the terminal device from the one or more candidate periodicity values.

In some embodiments, the periodicity mode may indicate a periodic transmission of the random access preamble, and the periodic transmission of the random access preamble is assembled based on a random access opportunity (RO) periodicity value.

In some embodiments, the RO periodicity value may be associated with a downlink resource indicated by a PDCCH command.

In some embodiments, the terminal device may further stop a periodic transmission of the random access preamble code after receiving a cell switching command.

In some embodiments, the terminal device may further stop the periodic transmission of the random access preamble code after receiving a PDCCH command indicating to stop the periodic transmission of the random access preamble code.

In some embodiments, the terminal device may further stop a periodic transmission of the random access preamble code after a transmission timer expires, wherein a value of the transmission timer is configured via a radio resource control RRC message or in a RACH configuration.

In some embodiments, the terminal device may further stop a periodic transmission of the random access preamble code after reaching a predetermined number of transmissions of the random access preamble code.

In some embodiments, the terminal device may further receive a response to the random access preamble code including a timing advance TA value from the network device; and stop a periodic transmission of the random access preamble code after receiving the response to the random access preamble code.

In some embodiments, the terminal device may further receive a response to the random access preamble code including a timing advance TA value from the network device; and continue a periodic transmission of the random access preamble code.

In some embodiments, the transmission mode configuration may be cell-specific, cell group-specific, base station-specific, or terminal device-specific.

In some embodiments, the random access preamble code may include a non-contention random access CFRA preamble code.

FIG. 6 shows an exemplary flow chart of a method 600 implemented at a network device according to some embodiments of the present disclosure. For discussion purposes, the method 600 will be described from the perspective of the network device 110 with reference to FIG. 1 .

As shown in FIG6 , in block 610 , the network device 110 transmits a transmission mode configuration to the terminal device 101 , and the transmission mode configuration indicates a transmission mode of a random access preamble code to the terminal device. The transmission mode includes a periodic mode or a single-shot mode.

In some embodiments, the single-shot mode may indicate any one of the following: a transmission of the random access preamble code supporting a retransmission until a response to the random access preamble code is received, or a single transmission of the random access preamble code regardless of whether a response to the random access preamble code is received.

In some embodiments, the transmission mode configuration may include a bit field in downlink control information DCI, and wherein the DCI contains a physical downlink control channel PDCCH order for a random access transmission.

In some embodiments, different code points in the bit field may indicate different periodicity values in the periodicity pattern.

In some embodiments, the transmission mode configuration may be applied to at least one of a target cell or one or more candidate cells.

In some embodiments, the transmission mode configuration may be included in a random access channel (RACH) configuration.

In some embodiments, the transmission mode may further indicate periodicity information for the periodicity mode, wherein a portion of the periodicity information is included in a RACH configuration and another portion of the periodicity information is included in a DCI, and wherein the RACH configuration configures the terminal device with one or more candidate periodicity values and the DCI indicates a periodicity value selected for the terminal device from the one or more candidate periodicity values.

In some embodiments, the periodicity mode may indicate a periodic transmission of the random access preamble, and the periodic transmission of the random access preamble is assembled based on a random access opportunity (RO) periodicity value.

In some embodiments, the RO periodicity value may be associated with a downlink resource indicated by a PDCCH command.

In some embodiments, the network device may further transmit a timer configuration to the terminal device, the timer configuration including a value for a transmission timer in a radio resource control RRC message or in a RACH configuration, wherein the transmission timer is configured to trigger the terminal device to stop a periodic transmission of the random access preamble code after the transmission timer expires.

In some embodiments, the transmission mode configuration may be cell-specific, cell group-specific, base station-specific, or terminal device-specific.

In some embodiments, the random access preamble code may include a non-contention random access CFRA preamble code.

In some embodiments, a device (e.g., terminal device 101) capable of performing any of the steps in method 500 may include components for performing the corresponding steps of method 500. The components may be implemented in any suitable form. For example, the components may be implemented in a circuit system or a software module.

In some embodiments, the apparatus includes a component for receiving a transmission mode configuration from a network device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode; and a component for transmitting the random access preamble code to a target network device based on the transmission mode.

In some embodiments, the single-shot mode may indicate any one of the following: a transmission of the random access preamble code supporting a retransmission until a response to the random access preamble code is received, or a single transmission of the random access preamble code regardless of whether a response to the random access preamble code is received.

In some embodiments, the transmission mode configuration may include a bit field in downlink control information DCI, and wherein the DCI contains a physical downlink control channel PDCCH order for a random access transmission.

In some embodiments, different code points in the bit field may indicate different periodicity values in the periodicity pattern.

In some embodiments, the transmission mode configuration may be applied to at least one of a target cell or one or more candidate cells.

In some embodiments, the transmission mode configuration may be included in a random access channel (RACH) configuration.

In some embodiments, the transmission mode may further indicate periodicity information for the periodicity mode, wherein a portion of the periodicity information is included in a RACH configuration and another portion of the periodicity information is included in a DCI, and wherein the RACH configuration configures the terminal device with one or more candidate periodicity values and the DCI indicates a periodicity value selected for the terminal device from the one or more candidate periodicity values.

In some embodiments, the periodicity mode may indicate a periodic transmission of the random access preamble, and the periodic transmission of the random access preamble is assembled based on a random access opportunity (RO) periodicity value.

In some embodiments, the RO periodicity value may be associated with a downlink resource indicated by a PDCCH command.

In some embodiments, the apparatus may further include means for stopping a periodic transmission of the random access preamble code upon receiving a cell switching command.

In some embodiments, the apparatus may further include means for stopping the periodic transmission of the random access preamble code upon receiving a PDCCH command indicating to stop the periodic transmission of the random access preamble code.

In some embodiments, the apparatus may further include means for stopping a periodic transmission of the random access preamble code after a transmission timer expires, wherein a value of the transmission timer is configured via a radio resource control (RRC) message or in a RACH configuration.

In some embodiments, the apparatus may further include a component for stopping a periodic transmission of the random access preamble code after a predetermined number of transmissions of the random access preamble code is reached.

In some embodiments, the apparatus may further include a component for receiving a response to the random access preamble code including a timing advance TA value from the network device; and a component for stopping a periodic transmission of the random access preamble code after receiving the response to the random access preamble code.

In some embodiments, the apparatus may further include means for receiving a response to the random access preamble code including a timing advance TA value from the network device; and means for continuing a periodic transmission of the random access preamble code.

In some embodiments, the transmission mode configuration may be cell-specific, cell group-specific, base station-specific, or terminal device-specific.

In some embodiments, the random access preamble code may include a non-contention random access CFRA preamble code.

In some embodiments, the device further includes components for performing other steps in some embodiments of method 500. In some embodiments, the components include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code are combined to cooperate with the at least one processor to cause the device to perform.

In some embodiments, a device (e.g., network device 110) capable of performing any of the steps in method 600 may include components for performing the corresponding steps of method 600. The components may be implemented in any suitable form. For example, the components may be implemented in a circuit system or a software module.

In some embodiments, the apparatus includes: means for transmitting a transmission mode configuration to a terminal device, the transmission mode configuration indicating a transmission mode of a random access preamble code to the terminal device, wherein the transmission mode includes a periodic mode or a single-shot mode.

In some embodiments, the single-shot mode may indicate any one of the following: a transmission of the random access preamble code supporting a retransmission until a response to the random access preamble code is received, or a single transmission of the random access preamble code regardless of whether a response to the random access preamble code is received.

In some embodiments, the transmission mode configuration may include a bit field in downlink control information DCI, and wherein the DCI contains a physical downlink control channel PDCCH order for a random access transmission.

In some embodiments, different code points in the bit field may indicate different periodicity values in the periodicity pattern.

In some embodiments, the transmission mode configuration may be applied to at least one of a target cell or one or more candidate cells.

In some embodiments, the transmission mode configuration may be included in a random access channel (RACH) configuration.

In some embodiments, the transmission mode may further indicate periodicity information for the periodicity mode, wherein a portion of the periodicity information is included in a RACH configuration and another portion of the periodicity information is included in a DCI, and wherein the RACH configuration configures the terminal device with one or more candidate periodicity values and the DCI indicates a periodicity value selected for the terminal device from the one or more candidate periodicity values.

In some embodiments, the periodicity mode may indicate a periodic transmission of the random access preamble, and the periodic transmission of the random access preamble is assembled based on a random access opportunity (RO) periodicity value.

In some embodiments, the RO periodicity value may be associated with a downlink resource indicated by a PDCCH command.

In some embodiments, the apparatus may further include a component for transmitting a timer configuration to the terminal device, the timer configuration including a value for a transmission timer in a radio resource control RRC message or in a RACH configuration, wherein the transmission timer is configured to trigger the terminal device to stop a periodic transmission of the random access preamble code after the transmission timer expires.

In some embodiments, the transmission mode configuration may be cell-specific, cell group-specific, base station-specific, or terminal device-specific.

In some embodiments, the random access preamble code may include a non-contention random access CFRA preamble code.

In some embodiments, the device further includes components for performing other steps in some embodiments of method 600. In some embodiments, the components include at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code are configured to cooperate with the at least one processor to cause the device to perform the steps.

FIG7 is a simplified block diagram of a device 700 suitable for implementing an embodiment of the present disclosure. The device 700 can be provided as an example communication device, for example, the terminal device 101, the network device 110 shown in FIG1. As shown, the device 700 includes one or more processors 710, optionally one or more memories 720 coupled to the processor 710, and one or more communication modules 740 coupled to the processor 710.

The communication module 740 is used for two-way communication. The communication module 740 may have at least one antenna to facilitate communication. The communication interface may represent any interface necessary for communicating with other network elements.

The communication module 740 may include, for example, one or more transceivers. One or more transceivers may be coupled to one or more antennas to transmit and receive communication signals wirelessly. One or more transceivers allow the communication device to communicate with other devices that may be wired and/or wireless. The transceiver may support one or more radio technologies. For example, one or more transceivers may include a cellular subsystem, a WLAN subsystem, and/or a Bluetooth ^TM subsystem. In some examples, one or more transceivers may include a processor, a controller, a radio, a communication port, a plug, a buffer, and similar circuits/devices for connecting to a network and communicating on the network.

Processor 710 may be of any type suitable for a local technology network, and may include, by way of non-limiting example, one or more of: a general purpose computer, a special purpose computer, a microprocessor, a digital signal processor (DSP), and a processor based on a multi-core processor architecture. Device 700 may have multiple processors, such as an application specific integrated circuit chip that is time slaved to a clock synchronized with a main processor.

The memory 720 may include one or more non-volatile memories and one or more volatile memories. Examples of non-volatile memories include, but are not limited to, a read-only memory (ROM) 724, an electrically programmable read-only memory (EPROM), a flash memory, a hard drive, a compact disk (CD), a digital video disk (DVD), and other magnetic storage and/or optical storage. Examples of volatile memories include, but are not limited to, a random access memory (RAM) 722 and other volatile memories that do not persist for the duration of a power outage.

The computer program 730 includes computer executable instructions that can be executed by the associated processor 710. The program 730 can be stored in the ROM 724. The processor 710 can perform any appropriate actions and processes by loading the program 730 into the RAM 722.

The embodiments of the present disclosure may be implemented by means of program 730 so that the device 700 can perform any process of the present disclosure as discussed with reference to Figures 5 to 6. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some embodiments, program 730 may be contained in a tangible form in a computer-readable medium that may be included in device 700, such as memory 720, or in other storage devices accessible by device 700. Device 700 may load program 730 from the computer-readable medium into RAM 722 for execution. The computer-readable medium may include any type of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. FIG. 8 shows an example of a computer-readable medium 800 in the form of a CD or DVD. The computer-readable medium has program 730 stored thereon.

In general, the various embodiments of the present disclosure may be implemented as hardware or special purpose circuits, software, logic, or any combination thereof. Some aspects may be implemented using hardware, while other aspects may be implemented using firmware or software that may be executed by a controller, microprocessor, or other computing device. Although the various aspects of the embodiments of the present disclosure are depicted and described as block diagrams, flow charts, or using some other graphical representation, it is understood that the blocks, apparatus, systems, techniques, or methods described herein may be implemented as non-limiting examples using hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controllers or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product stored in a tangible manner on a non-transitory computer-readable storage medium. The computer program product includes computer executable instructions, such as those included in a program module, which are executed in a device on a target real or virtual processor to implement the method 500 or 600 described above with reference to Figures 5-6. In general, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform specific tasks or implement specific abstract data types. As desired in various embodiments, the functions of the program modules can be combined or split between the program modules. The machine executable instructions for the program module can be executed in a local machine or a distributed device. In a distributed device, the program module can be located in both the local machine and the remote storage medium.

Program codes for implementing the methods disclosed herein may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing device so that when executed by the processor or controller, the functions/operations specified in the flow chart and/or block diagram are implemented. The program codes may be executed entirely on a machine, partially on a machine, as a stand-alone package, partially on a machine, and partially on a remote computer, or entirely on a remote machine or server.

In the context of the present disclosure, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus or processor to perform various processes and operations as described above. Examples of carriers include a signal, a computer-readable medium, and the like.

The computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. A computer-readable medium may be, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More specific examples of computer readable storage media would include an electrical connector having one or more conductors, a portable computer disk, a hard drive, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. The term "non-transitory" as used herein refers to a limitation of the medium itself (i.e., tangible, not a signal), as distinct from a limitation on the persistence of data storage (e.g., RAM versus ROM).

Furthermore, although the operations are shown in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in a sequential manner, or that all of the operations shown be performed to achieve the desired result. In some cases, multitasking and parallel processing can be helpful. Similarly, although the above discussion contains several specific implementation details, these details should not be regarded as limitations on the scope of the present disclosure, but rather as descriptions of features that are specific to a particular embodiment. Certain features described in the context of a single embodiment may also be implemented in a single embodiment in combination. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable subcombination.

Although the present disclosure has been described using words specific to structural features and/or methodological actions, it should be understood that the present disclosure defined in the appended claims is not necessarily limited to the above-mentioned specific features or actions. Instead, the above-mentioned specific features and actions disclosed are exemplary forms of implementing the claims.

100: Communication network; Communication system

101: Terminal device

110: Network device

201: Server Cell

202: Target Community

205:Send

210:Transfer mode configuration

215: Receive

220:Send

225: Random access preamble code

300: Process

301: Server Cell

302: Target Community

305:Send

310:Transfer mode configuration

315: Receive

320:Send

325:CFRA preamble encoding

330: Receive

335: Monitoring; Determination

340:Retransmission

350: Receive

355:Transmit

360: Response

365: Receive

400:Process

401: Server Cell

402: Target community

405:Send

410:Transfer Mode Configuration

415: Receive

420:Send

425:CFRA preamble encoding

430: Receive

435:Transmit

440: first TA value

445: Receive

450:Send

455: Receive

460:Send

465: Second TA value

470: Receive

475: Stop

500:Method

510: Program block

520: Program block

600: Method

610: Program block

700: Device

710: Processor

720:Memory

722: Random Access Memory; RAM

724: Read-only memory; ROM

730: Computer program; Program

740: Communication module

800: Computer-readable media

Some exemplary embodiments will now be described with reference to the accompanying drawings, in which:

FIG. 1 illustrates an exemplary communication network in which embodiments of the present disclosure may be implemented;

FIG. 2 illustrates an example of a process for indicating a transmission mode of a random access preamble coding according to an embodiment of the present disclosure;

FIG. 3 illustrates an example of a process for timing advance (TA) maintenance according to some embodiments of the present disclosure;

FIG. 4 illustrates another example of a process for TA maintenance according to some embodiments of the present disclosure;

FIG5 is an exemplary flow chart illustrating a method implemented at a terminal device according to some embodiments of the present disclosure;

FIG. 6 is an exemplary flow chart illustrating a method implemented at a network device according to some embodiments of the present disclosure;

FIG. 7 illustrates an exemplary simplified block diagram of an apparatus suitable for implementing an embodiment of the present disclosure; and

FIG. 8 illustrates a block diagram of an exemplary computer-readable medium according to some embodiments of the present disclosure.

In the various drawings, the same or similar reference numbers represent the same or similar elements.

101: Terminal device

201: Server Cell

202: Target community

205:Transmit

210:Transmission mode configuration

215: Receive

220:Transmit

225: Random access preamble code

230: Receive

Claims (34)

A terminal device, comprising: one or more transceivers; and one or more processors coupled to the one or more transceivers, wherein the one or more transceivers are configured to cause the terminal device to perform the following actions with the one or more processors: receiving a transmission mode configuration from a network device, the transmission mode configuration indicating one of the transmission modes of a random access preamble code to the terminal device, wherein the transmission modes include: a periodic mode and a single-shot mode; and transmitting the random access preamble code to a target network device based on the indicated transmission mode. A terminal device as claimed in claim 1, wherein the single-shot mode indicates any one of the following: a transmission of the random access preamble code that supports a retransmission until a response to the random access preamble code is received, or a single transmission of the random access preamble code regardless of whether a response to the random access preamble code is received. The terminal device of claim 1 or 2, wherein the transmission mode configuration comprises a bit field in downlink control information (DCI), and wherein the downlink control information includes a physical downlink control channel (PDCCH) command for a random access transmission. A terminal device as claimed in claim 3, wherein different code points in the bit field indicate different periodicity values in the periodicity mode. A terminal device as claimed in claim 1 or 2, wherein the transmission mode configuration is used for a target cell or at least one of one or more candidate cells. The terminal device of claim 1 or 2, wherein the transmission mode configuration is included in a random access channel (RACH) configuration. A terminal device as claimed in claim 1 or 2, wherein the transmission mode further indicates periodicity information for the periodicity mode, wherein a portion of the periodicity information is included in a random access channel configuration, and another portion of the periodicity information is included in a downlink control information, and wherein the random access channel configuration configures the terminal device with one or more candidate periodicity values, and the downlink control information indicates a periodicity value selected for the terminal device from the one or more candidate periodicity values. A terminal device as claimed in claim 1 or 2, wherein the periodicity mode indicates a periodic transmission of the random access preamble code, and the periodic transmission of the random access preamble code is assembled based on a random access opportunity (RO) periodicity value. A terminal device as claimed in claim 8, wherein the random access timing periodicity value is associated with a downlink resource indicated by a physical downlink control channel command. A terminal device as in claim 1 or 2, wherein the terminal device is further caused to perform the following actions: After receiving a cell switching command, the periodic transmission of the random access preamble code is stopped. A terminal device as in claim 1 or 2, wherein the terminal device is further caused to perform the following actions: After receiving a physical downlink control channel command indicating that the periodic transmission of the random access preamble code is stopped, the periodic transmission of the random access preamble code is stopped. A terminal device as claimed in claim 1 or 2, wherein the terminal device is further caused to perform the following actions: Ceasing a periodic transmission of the random access preamble code after a transmission timer expires, wherein a value of the transmission timer is configured via a radio resource control (RRC) message or in a random access channel configuration. A terminal device as in claim 1 or 2, wherein the terminal device is further caused to perform the following actions: After reaching a predetermined number of transmissions of the random access preamble code, the periodic transmission of the random access preamble code is stopped. A terminal device as in claim 1 or 2, wherein the terminal device is further caused to perform the following actions: receiving a response to the random access preamble code containing a timing advance (TA) value from the network device; and stopping a periodic transmission of the random access preamble code after receiving the response to the random access preamble code. A terminal device as in claim 1 or 2, wherein the terminal device is further caused to perform the following actions: receive a response to the random access preamble code containing a timing advance (TA) value from the network device; and continue a periodic transmission of the random access preamble code. A terminal device as claimed in claim 1 or 2, wherein the transmission mode configuration is cell-specific, cell group-specific, base station-specific or terminal device-specific. A terminal device as claimed in claim 1 or 2, wherein the random access preamble code comprises a contention-free random access (CFRA) preamble code. A network device, comprising: one or more transceivers; and one or more processors coupled to the one or more transceivers, wherein the one or more transceivers are configured to cause the network device to perform the following actions with the one or more processors: transmit a transmission mode configuration to a terminal device, wherein the transmission mode configuration indicates to the terminal device one of the transmission modes of a random access preamble coding, wherein the transmission modes include: a periodic mode and a single-shot mode. A network device as claimed in claim 18, wherein the single-shot mode indicates any one of the following: a transmission of the random access preamble code that supports a retransmission until a response to the random access preamble code is received, or a single transmission of the random access preamble code regardless of whether a response to the random access preamble code is received. The network device of claim 18 or 19, wherein the transmission mode configuration comprises a bit field in downlink control information (DCI), and wherein the downlink control information includes a physical downlink control channel (PDCCH) command for a random access transmission. A network device as claimed in claim 20, wherein different code points in the bit field indicate different periodicity values in the periodicity mode. A network device as claimed in claim 18 or 19, wherein the transmission mode configuration is used for a target cell or at least one of one or more candidate cells. The network device of claim 18 or 19, wherein the transmission mode configuration is included in a random access channel (RACH) configuration. A network device as claimed in claim 18 or 19, wherein the transmission mode further indicates periodicity information for the periodicity mode, wherein a portion of the periodicity information is included in a random access channel configuration, and another portion of the periodicity information is included in a downlink control information, and wherein the random access channel configuration configures the terminal device with one or more candidate periodicity values, and the downlink control information indicates a periodicity value selected for the terminal device from the one or more candidate periodicity values. The network device of claim 18 or 19, wherein the periodicity pattern indicates a periodic transmission of the random access preamble code, and the periodic transmission of the random access preamble code is assembled based on a random access opportunity (RO) periodicity value. A network device as claimed in claim 25, wherein the random access opportunity periodicity value is associated with a downlink resource indicated by a physical downlink control channel command. A network device as claimed in claim 18 or 19, wherein the network device is further caused to perform the following actions: Sending a timer configuration to the terminal device, the timer configuration comprising a value for a transmit timer in a radio resource control (RRC) message or in a random access channel configuration, wherein the transmit timer is configured to trigger the terminal device to stop a periodic transmission of the random access preamble code after the transmit timer expires. A network device as claimed in claim 18 or 19, wherein the transmission mode configuration is cell-specific, cell group-specific, base station-specific or terminal device-specific. The network device of claim 18 or 19, wherein the random access preamble code comprises a contention-free random access (CFRA) preamble code. A method implemented at a terminal device, comprising: receiving a transmission mode configuration from a network device, the transmission mode configuration indicating one of a transmission mode of a random access preamble code to the terminal device, wherein the transmission modes include: a periodic mode and a single-shot mode; and transmitting the random access preamble code to a target network device based on the indicated transmission mode. A method implemented at a network device, comprising: Sending a transmission mode configuration to a terminal device, the transmission mode configuration indicating one of a transmission mode of a random access preamble coding to the terminal device, wherein the transmission mode comprises: a periodic mode and a single-shot mode. A device for a terminal device, comprising: receiving a transmission mode configuration component from a network device, the transmission mode configuration indicating one of a transmission mode of a random access preamble coding to the terminal device, wherein the transmission mode includes: a periodic mode and a single-shot mode; and transmitting the random access preamble coding component to a target network device based on the indicated transmission mode. An apparatus for a network device, comprising: A component for transmitting a transmission mode configuration to a terminal device, wherein the transmission mode configuration indicates to the terminal device one of the transmission modes of a random access preamble coding, wherein the transmission mode includes: a periodic mode and a single-shot mode. A computer-readable medium comprising program instructions for causing a device to perform at least the method of claim 30 or 31.

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