WO2025059940A1

WO2025059940A1 - Sidelink positioning in unlicensed band

Info

Publication number: WO2025059940A1
Application number: PCT/CN2023/120180
Authority: WO
Inventors: Qi Yang; Chuangxin JIANG; Mengzhen LI; Focai Peng; Junpeng LOU; Cong Wang
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2023-09-20
Filing date: 2023-09-20
Publication date: 2025-03-27
Anticipated expiration: 2026-03-20

Abstract

A wireless communication method includes determining parameters of accessing channel (s) for transmission of a sidelink (SL) positioning signal and configurations of the SL positioning signal on an unlicensed band. The sidelink positioning signal is transmitted by a first wireless communication entity to a second wireless communication entity.

Description

SIDELINK POSITIONING IN UNLICENSED BAND

TECHNICAL FIELD

The disclosure relates generally to wireless communications, including but not limited to systems and methods for positioning.

BACKGROUND

The standardization organization Third Generation Partnership Project (3GPP) is currently in the process of specifying a new Radio Interface called 5G New Radio (5G NR) as well as a Next Generation Packet Core Network (NG-CN or NGC) . The 5G NR will have three main components: a 5G Access Network (5G-AN) , a 5G Core Network (5GC) , and a User Equipment (UE) . In order to facilitate the enablement of different data services and requirements, the elements of the 5GC, also called Network Functions, have been simplified with some of them being software based, and some being hardware based, so that they could be adapted according to need. In current sidelink communication technology in unlicensed band, there are two types of channel access procedures: Type 1 channel access procedure and Type 2 channel access procedure. In Type 1 channel access procedure, the LBT duration is random, which is based on CAPC (Channel access priority class) value. Each CAPC value is associated with a CW (Contention Window) size related information and the maximum COT (Channel Occupancy Time) . In Type 2 channel access procedure, the LBT duration is fixed. Type 2 channel access procedure is further subdivided into three kinds of channel access procedures, these are Type 2A, Type 2B and Type 2C. Type 2 channel access procedure can be used by a UE to share a COT initiated by another UE using Type 1 channel access procedure. If time gap between the current SL transmission and the previous SL transmission is 25μs, a UE can share the COT and transmit the current SL transmission by sensing the channel to be idle for at least a sensing interval of 25μs, this is Type 2A channel access procedure. If time gap between the current SL transmission and the previous SL transmission is 16μs, a UE can share the COT and transmit the current SL transmission by sensing the channel to be idle for a sensing duration of 16μs, this is Type 2B channel access procedure. If time gap between the current SL transmission and the previous SL transmission is up to 16μs, a UE can directly share the COT and transmit the current SL transmission without sensing, this is Type 2C channel access procedure. Especially, Type 2A channel access procedure can be used to initiate a COT when some conditions are satisfied. However, positioning service in unlicensed band is under studying now. How to configure the parameters of channel access procedure and SL-PRS configurations to improve the probability of LBT success is a problem. In this disclosure, solutions for parameter design of channel access procedure and SL-PRS configuration in sidelink unlicensed band are provided.

SUMMARY

The example embodiments disclosed herein are directed to solving the issues relating to one or more of the problems presented in the prior art, as well as providing additional features that will become readily apparent by reference to the following detailed description when taken in conjunction with the accompany drawings. In accordance with various embodiments, example systems, methods, devices and computer program products are disclosed herein. It is understood, however, that these embodiments are presented by way of example and are not limiting, and it will be apparent to those of ordinary skill in the art who read the present disclosure that various modifications to the disclosed embodiments can be made while remaining within the scope of this disclosure.

At least one aspect is directed to a system, method, apparatus, or a computer-readable medium of the following. A wireless communication entity (e.g., a UE, a radio device) may determine parameters of accessing channel (s) for transmission of a sidelink (SL) positioning signal and configurations of the SL positioning signal on an unlicensed band wherein the sidelink positioning signal is transmitted by a first wireless communication entity to a second wireless communication entity.

In some embodiments the parameters of accessing channel (s) include at least a Contention Window (CW) and a transmission time of the SL positioning signal transmission in a shared Channel Occupancy Time (COT) . The configurations of the SL positioning signal include at least a transmission time for Automatic Gain Control (AGC) of the second wireless communication entity, a candidate starting time of the SL positioning signal, a gap before the SL positioning signal and idle duration before the SL positioning signal. The SL positioning signal includes at least one of: a Sidelink Control Information (SCI) , or a Sidelink Positioning Reference Signal (SL-PRS) . The transmission time configured for the AGC the second wireless communication entity is configured prior to sending the SL positioning signal, and wherein the transmission time for the AGC occupies a time resource less than one symbol.

In some embodiments, a length of the transmission time is configured by a wireless communication node, preconfigured, configured per SL BWP/resource pool, configured based on a capability of the second wireless communication entity. In some embodiments, the second wireless communication entity reports an expected length of the transmission time based on the capability of the second wireless communication entity to the first wireless communication entity, a network node, or a third communication entity. In some embodiments, the network node or the third wireless communication entity recommends the length of the transmission time to the first wireless communication entity based on the expected length of the transmission time, where recommend lengths of the transmission time for a plurality of the first wireless communication entities are identical to one another.

In some embodiments, the first wireless communication entity can prioritize the recommended length of the transmission time. In some embodiments, the network node or the third wireless communication entity determines the length of the transmission time based on the expected length of the transmission time and send the determined length of the transmission time to the first wireless communication entity, where determined lengths of the transmission time for a plurality of the first wireless communication entities are identical to one another.

The wireless communication entity further receives an AGC-related capability of the second wireless communication entity and determines, the length of the AGC time based on the AGC-related capability. In some embodiments, the second wireless communication entity reports its AGC-related capability to a network node or a third wireless communication entity. In some embodiments, the network node or the third wireless communication entity determines/recommends the length of the transmission time for the first wireless communication entity based on the AGC-related capability, where determined/recommended lengths of the transmission time for a plurality of the first wireless communication entities are identical to one another. In some embodiments, a plurality of candidate lengths of the transmission time is configured by a wireless communication node or preconfigured. In some embodiments, one of the candidate lengths is selected by the wireless communication node or the first wireless communication entity, prior to the first wireless communication entity sending the SL positioning signal.

In some embodiments, the wireless communication node indicates the selected candidate length via Downlink Control Information (DCI) , if one of the candidate lengths is selected by the wireless communication node. In some embodiments, the contention window (CW) is adjusted based on measurement feedback received by the first wireless communication entity. In some embodiments, the measurement feedback includes at least one of: a Reference Signal Received Power (RSRP) , a Channel Occupancy Ratio (CR) , or a Channel Busy Ratio (CBR) , a Reference Signal Received Quality (RSRQ) , a Reference Signal Strength Indicator (RSSI) , or a Signal-to-Noise and Interference Ratio (SNIR) , or a Signal-to-Noise Ratio (SNR) .

In some embodiments, the measurement feedback is measured based on at least one of the SL-PRS, or a Demodulation Reference Signal (DMRS) of a Physical Sidelink Shared Channel (PSCCH) associated with the SL-PRS. In some embodiments, if the measurement feedback is available and satisfies one or more conditions, a minimum CW size is set as a current CW for every CAPC value. In some embodiments, the one or more conditions include: a measurement measured in a reference duration for a latest sidelink positioning related channel occupancy is equal to or larger than a threshold. In some embodiments, the threshold is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity. In some embodiments, the threshold is configured per resource pool or SL BWP. In some embodiments, the threshold is an RSRP threshold, a CR threshold, a CBR threshold, a RSRQ threshold, a RSSI threshold, a SNIR threshold, or a SNR threshold. In some embodiments, a reference duration is defined as a duration corresponding to a channel occupancy initiated by a UE including transmission of PSCCH carrying SCI and/or the SL-PRS, and wherein the duration starts from a beginning of the channel occupancy to an end of a first slot where at least one of the SCI or the SL-PRS is transmitted.

In some embodiments, if the measurement feedback is available but the measurement feedback does not satisfy the one or more conditions, the CW is increased by the first wireless communication entity for every CAPC value to a next higher allowed value. In some embodiments, if the measurement feedback is not available, the CW is maintained by the first wireless communication entity for every CAPC value. In some embodiments, the adjustment on the CW is not based on a feedback mechanism. In some embodiments, a latest CW used for any SL transmissions on a channel using Type 1 channel access procedures associated with a CAPC value is reused as a size for the CW for accessing channel (s) for SL positioning signal transmission associated with that CAPC value. In some embodiments, two or more first candidate starting symbols are configured for sending the SL positioning signal, which includes Sidelink Control Information (SCI) , in a slot. In some embodiments, a number of the first candidate starting symbols is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity. In some embodiments, a number of the first candidate starting symbols is configured per SL BWP/resource pool.

In some embodiments, a location of each of the first candidate starting symbols is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity. In some embodiments, second candidate starting symbols are configured for sending the SL signal, which includes an SL-PRS, are related with the first candidate starting symbols.

In some embodiments, each of the first candidate starting symbols corresponds to one or more of the second candidate starting symbols. In some embodiments, a number of the second candidate starting symbols corresponding to each of the first candidate starting symbols is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity. In some embodiments, the number of the second candidate starting symbols corresponding to each of the first starting symbols is configured per SL BWP, or resource pool, or SL-PRS resource. In some embodiments, a location of each of the second candidate starting symbols is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity. In some embodiments, the location corresponds to a plurality of values, one of which is selected by the wireless communication node, the network node, or the third wireless communication entity, or preconfigured or determined by the first wireless communication entity.

In some embodiments, the location of each of the second candidate starting symbols is configured per SL BWP, or resource pool, or SL-PRS resource. In some embodiments, each of the first candidate starting symbols is associated with a different number of the second candidate starting symbols. In some embodiments, a number of the second candidate starting symbols and their respective locations are related to associated ones of the first candidate starting symbols. In some embodiments, in the shared COT, SCI transmission from a sharing wireless communication entity can follow transmission of the SL signal, which includes SCI or SL-PRS from an initiated wireless communication entity. In some embodiments, if the SCI transmission from the sharing wireless communication entity follows the transmission of the SCI from the initiated wireless communication entity in the shared COT, the initiated wireless communication entity transmits a Cyclic Prefix Extension (CPE) immediately following the transmission of the SCI and before the SCI transmission from the sharing wireless communication entity.

In some embodiments, if the SCI transmission from the sharing wireless communication entity follows the transmission of the SL-PRS in the shared COT from the initiated wireless communication entity and if the sharing wireless communication entity is a target of the transmission of the SL-PRS from the initiated wireless communication entity, the sharing wireless communication entity does not receive last N symbols of the transmission of the SL-PRS from the initiated wireless communication entity. In some embodiments, the shared COT initiated by a wireless communication node is forwarded to one or more wireless communication entities in out-of-coverage of a wireless communication node. In some embodiments, a gap symbol immediately follows each SL-PRS resource. In some embodiments, the idle duration immediately preceding to an AGC symbol before a SL-PRS resource is configured if multiple SCI transmissions are multiplexed in a FDM manner and multiple SL-PRS resources are multiplexed in a TDM manner.

In some embodiments, the idle duration immediately preceding to an AGC symbol before an SCI transmission is configured in a sub-slot structure where multiple SCI transmissions are multiplexed in a TDM manner and there is no time gap between the SCI transmission and its associated SL-PRS resource. In some embodiments, information about the idle duration can be configured explicitly. In some embodiments, information about the idle duration can be associated with a configuration of the SL-PRS resource. In some embodiments, the information about the idle duration includes at least a length of the idle duration.

In some embodiments, the length of the idle duration is zero, one symbol, or multiple symbols. In some embodiments, the information about the idle duration is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity. In some embodiments, the information about the idle duration is configured per SL BWP, or resource pool, or SL-PRS resource. In some embodiments, the configuration of the SL-PRS resource includes at least one of: a CAPC, a priority, a time resource allocation, or a starting symbol.

In some embodiments, if the SL-PRS resource is adjacent to an associated SCI transmission, a length of the idle duration is zero. In some embodiments, a mapping between the idle duration and the SL-PRS resource is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity. In some embodiments, information about the idle duration is indicated in SCI. In some embodiments, a time-frequency resource occupied by any idle duration is avoided when the time-frequency resource is configured by a wireless communication node for an SL-PRS transmission.

In some embodiments, in Scheme 2 resource allocation, a time-frequency resource occupied by the idle duration indicated in the SCI should be excluded in a selection window. In some embodiments, a resource occupied by the idle duration can be excluded in the selection window by the first wireless communication entity in a physical layer. In some embodiments, a resource occupied by the idle duration can be excluded by a higher layer. In some embodiments, a wireless communications apparatus includes a processor and a memory, wherein the processor is configured to read code from the memory and implement a method recited in an earlier embodiment. In some embodiments, a computer program product includes a computer-readable program medium code stored thereupon, the code, when executed by a processor, causing the processor to implement a method recited in an earlier embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

Various example embodiments of the present solution are described in detail below with reference to the following figures or drawings. The drawings are provided for purposes of illustration only and merely depict example embodiments of the present solution to facilitate the reader's understanding of the present solution. Therefore, the drawings should not be considered limiting of the breadth, scope, or applicability of the present solution. It should be noted that for clarity and ease of illustration, these drawings are not necessarily drawn to scale.

FIG. 1 illustrates an example cellular communication network in which techniques disclosed herein may be implemented, in accordance with an embodiment of the present disclosure;

FIG. 2 illustrates a block diagram of an example base station and a user equipment device, in accordance with some embodiments of the present disclosure;

FIG. 3 illustrates an example parameter design of channel access procedure for sidelink positioning, in accordance with some embodiments of the present disclosure;

FIG. 4 illustrates a flowchart of the example parameter design of channel access procedure for sidelink positioning, in accordance with some embodiments of the present disclosure;

FIG. 5 illustrates the example parameter design of channel access procedure for sidelink positioning, in accordance with some embodiments of the present disclosure;

FIG. 6 illustrates the example parameter design of channel access procedure for sidelink positioning, in accordance with some embodiments of the present disclosure;

FIG. 7 illustrates the example parameter design of channel access procedure for sidelink positioning, in accordance with some embodiments of the present disclosure;

FIG. 8 illustrates the example parameter design of channel access procedure for sidelink positioning, in accordance with some embodiments of the present disclosure;

FIG. 9 illustrates the example parameter design of channel access procedure for sidelink positioning, in accordance with some embodiments of the present disclosure;

FIG. 10 illustrates the example parameter design of channel access procedure for sidelink positioning, in accordance with some embodiments of the present disclosure;

FIG. 11 illustrates the example parameter design of channel access procedure for sidelink positioning, in accordance with some embodiments of the present disclosure;

FIG. 12 illustrates a flowchart of the example parameter design of channel access procedure for sidelink positioning, in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

Mobile Communication Technology and Environment

FIG. 1 illustrates an example wireless communication network, and/or system, 100 in which techniques disclosed herein may be implemented, in accordance with an embodiment of the present disclosure. In the following discussion, the wireless communication network 100 may be any wireless network, such as a cellular network or a narrowband Internet of things (NB-IoT) network and is herein referred to as “network 100. ” Such an example network 100 includes a base station 102 (hereinafter “BS 102” ; also referred to as wireless communication node) and a user equipment device 104 (hereinafter “UE 104” ; also referred to as wireless communication device) that can communicate with each other via a communication link 110 (e.g., a wireless communication channel) , and a cluster of cells 126, 130, 132, 134, 136, 138 and 140 overlaying a geographical area 101. In FIG. 1, the BS 102 and UE 104 are contained within a respective geographic boundary of cell 126. Each of the other cells 130, 132, 134, 136, 138 and 140 may include at least one base station operating at its allocated bandwidth to provide adequate radio coverage to its intended users.

For example, the BS 102 may operate at an allocated channel transmission bandwidth to provide adequate coverage to the UE 104. The BS 102 and the UE 104 may communicate via a downlink radio frame 118, and an uplink radio frame 124 respectively. Each radio frame 118/124 may be further divided into sub-frames 120/127 which may include data symbols 122/128. In the present disclosure, the BS 102 and UE 104 are described herein as non-limiting examples of “communication nodes, ” generally, which can practice the methods disclosed herein. Such communication nodes may be capable of wireless and/or wired communications, in accordance with various embodiments of the present solution.

FIG. 2 illustrates a block diagram of an example wireless communication system 200 for transmitting and receiving wireless communication signals (e.g., OFDM/OFDMA signals) in accordance with some embodiments of the present solution. The system 200 may include components and elements configured to support known or conventional operating features that need not be described in detail herein. In one illustrative embodiment, system 200 can be used to communicate (e.g., transmit and receive) data symbols in a wireless communication environment such as the wireless communication environment 100 of FIG. 1, as described above.

System 200 generally includes a base station 202 (hereinafter “BS 202” ) and a user equipment device 204 (hereinafter “UE 204” ) . The BS 202 includes a BS (base station) transceiver module 210, a BS antenna 212, a BS processor module 214, a BS memory module 216, and a network communication module 218, each module being coupled and interconnected with one another as necessary via a data communication bus 220. The UE 204 includes a UE (user equipment) transceiver module 230, a UE antenna 232, a UE memory module 234, and a UE processor module 236, each module being coupled and interconnected with one another as necessary via a data communication bus 240. The BS 202 communicates with the UE 204 via a communication channel 250, which can be any wireless channel or other medium suitable for transmission of data as described herein.

As would be understood by persons of ordinary skill in the art, system 200 may further include any number of modules other than the modules shown in FIG. 2. Those skilled in the art will understand that the various illustrative blocks, modules, circuits, and processing logic described in connection with the embodiments disclosed herein may be implemented in hardware, computer-readable software, firmware, or any practical combination thereof. To clearly illustrate this interchangeability and compatibility of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps are described generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software can depend upon the particular application and design constraints imposed on the overall system. Those familiar with the concepts described herein may implement such functionality in a suitable manner for each particular application, but such implementation decisions should not be interpreted as limiting the scope of the present disclosure.

In accordance with some embodiments, the UE transceiver 230 may be referred to herein as an "uplink" transceiver 230 that includes a radio frequency (RF) transmitter and a RF receiver each comprising circuitry that is coupled to the antenna 232. A duplex switch (not shown) may alternatively couple the uplink transmitter or receiver to the uplink antenna in time duplex fashion. Similarly, in accordance with some embodiments, the BS transceiver 210 may be referred to herein as a "downlink" transceiver 210 that includes a RF transmitter and a RF receiver each comprising circuity that is coupled to the antenna 212. A downlink duplex switch may alternatively couple the downlink transmitter or receiver to the downlink antenna 212 in time duplex fashion. The operations of the two transceiver modules 210 and 230 may be coordinated in time such that the uplink receiver circuitry is coupled to the uplink antenna 232 for reception of transmissions over the wireless transmission link 250 at the same time that the downlink transmitter is coupled to the downlink antenna 212. Conversely, the operations of the two transceivers 210 and 230 may be coordinated in time such that the downlink receiver is coupled to the downlink antenna 212 for reception of transmissions over the wireless transmission link 250 at the same time that the uplink transmitter is coupled to the uplink antenna 232. In some embodiments, there is close time synchronization with a minimal guard time between changes in duplex direction.

The UE transceiver 230 and the base station transceiver 210 are configured to communicate via the wireless data communication link 250 and cooperate with a suitably configured RF antenna arrangement 212/232 that can support a particular wireless communication protocol and modulation scheme. In some illustrative embodiments, the UE transceiver 210 and the base station transceiver 210 are configured to support industry standards such as the Long Term Evolution (LTE) and emerging 5G standards, and the like. It is understood, however, that the present disclosure is not necessarily limited in application to a particular standard and associated protocols. Rather, the UE transceiver 230 and the base station transceiver 210 may be configured to support alternate, or additional, wireless data communication protocols, including future standards or variations thereof.

In accordance with various embodiments, the BS 202 may be an evolved node B (eNB) , a serving eNB, a target eNB, a femto station, or a pico station, for example. In some embodiments, the UE 204 may be embodied in various types of user devices such as a mobile phone, a smart phone, a personal digital assistant (PDA) , tablet, laptop computer, wearable computing device, etc. The processor modules 214 and 236 may be implemented, or realized, with a general-purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. In this manner, a processor may be realized as a microprocessor, a controller, a microcontroller, a state machine, or the like. A processor may also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration.

Furthermore, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in firmware, in a software module executed by processor modules 214 and 236, respectively, or in any practical combination thereof. The memory modules 216 and 234 may be realized as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In this regard, memory modules 216 and 234 may be coupled to the processor modules 210 and 230, respectively, such that the processors modules 210 and 230 can read information from, and write information to, memory modules 216 and 234, respectively. The memory modules 216 and 234 may also be integrated into their respective processor modules 210 and 230. In some embodiments, the memory modules 216 and 234 may each include a cache memory for storing temporary variables or other intermediate information during execution of instructions to be executed by processor modules 210 and 230, respectively. Memory modules 216 and 234 may also each include non-volatile memory for storing instructions to be executed by the processor modules 210 and 230, respectively.

The network communication module 218 generally represents the hardware, software, firmware, processing logic, and/or other components of the base station 202 that enable bi-directional communication between base station transceiver 210 and other network components and communication nodes configured to communication with the base station 202. For example, network communication module 218 may be configured to support internet or WiMAX traffic. In a typical deployment, without limitation, network communication module 218 provides an 802.3 Ethernet interface such that base station transceiver 210 can communicate with a conventional Ethernet based computer network. In this manner, the network communication module 218 may include a physical interface for connection to the computer network (e.g., Mobile Switching Center (MSC) ) . The terms “configured for, ” “configured to” and conjugations thereof, as used herein with respect to a specified operation or function, refer to a device, component, circuit, structure, machine, signal, etc., that is physically constructed, programmed, formatted and/or arranged to perform the specified operation or function.

The Open Systems Interconnection (OSI) Model (referred to herein as, “open system interconnection model” ) is a conceptual and logical layout that defines network communication used by systems (e.g., wireless communication device, wireless communication node) open to interconnection and communication with other systems. The model is broken into seven subcomponents, or layers, each of which represents a conceptual collection of services provided to the layers above and below it. The OSI Model also defines a logical network and effectively describes computer packet transfer by using different layer protocols. The OSI Model may also be referred to as the seven-layer OSI Model or the seven-layer model. In some embodiments, a first layer may be a physical layer. In some embodiments, a second layer may be a Medium Access Control (MAC) layer. In some embodiments, a third layer may be a Radio Link Control (RLC) layer. In some embodiments, a fourth layer may be a Packet Data Convergence Protocol (PDCP) layer. In some embodiments, a fifth layer may be a Radio Resource Control (RRC) layer. In some embodiments, a sixth layer may be a Non-Access Stratum (NAS) layer or an Internet Protocol (IP) layer, and the seventh layer being the other layer.

Various example embodiments of the present solution are described below with reference to the accompanying figures to enable a person of ordinary skill in the art to make and use the present solution. As would be apparent to those of ordinary skill in the art, after reading the present disclosure, various changes or modifications to the examples described herein can be made without departing from the scope of the present solution. Thus, the present solution is not limited to the example embodiments and applications described and illustrated herein. Additionally, the specific order or hierarchy of steps in the methods disclosed herein are merely example approaches. Based upon design preferences, the specific order or hierarchy of steps of the disclosed methods or processes can be re-arranged while remaining within the scope of the present solution. Thus, those of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or acts in a sample order, and the present solution is not limited to the specific order or hierarchy presented unless expressly stated otherwise.

Sidelink Positioning in Unlicensed Band

In sidelink unlicensed band, a UE (User Equipment) 104 needs to perform channel access procedure before signals/data transmission. The channel access procedure is also named as LBT (Listen Before Talk) , which intends to evaluate the availability of the channel (s) . If the channel is sensed to be idle in LBT procedure, the UE will transmit signals/data after the LBT duration. Otherwise, LBT fails and the UE will not transmit signals/data after the LBT duration. For sidelink positioning service, sidelink positioning reference signal (SL-PRS) is transmitted by a UE to another UE. The mechanism of transmission and reception for SL-PRS is different from that for sidelink communication. In sidelink unlicensed band, the LBT procedure and parameters of LBT procedure for sidelink communication cannot directly be used for sidelink positioning. Therefore, for sidelink positioning in unlicensed band, how to configure the parameters of channel access procedure and SL-PRS configurations to improve the probability of LBT success is a problem. This disclosure is related to parameter design of channel access procedure for sidelink positioning and SL-PRS configuration in sidelink unlicensed band.

Solution 1: Sub-Symbol AGC

AGC (Automatic Gain Control) is an operation of the receiving UE to adjust the received signal level. From the perspective of a transmission UE, there should be a transmission time used for AGC of a receiving UE immediately before the transmission signal. In current technology, the transmission time used for AGC of a receiving UE may be one symbol, which is abbreviated as AGC symbol. The transmission time used for AGC of the receiving UE is abbreviated as AGC time where the AGC symbol refers to one symbol used for AGC of the receiving UE. A default AGC time may be proceeded by a SL-PRS resource and SCI (Sidelink Control Information) unless otherwise specified.

In a dedicated resource pool, SL-PRS with its associated are included. PSCCH (Physical Sidelink Control Channel) carrying SCI may be proceeded by the AGC symbol. Furthermore, a SL-PRS resource may be proceeded by an AGC symbol. Each AGC may occupy one symbol in time domain. In unlicensed band, LBT procedure may be performed, and a COT is initiated for SCI and SL-PRS transmission purpose. Therefore, LBT sensing may be performed before the AGC time. To extend the candidate time for LBT sensing and improve LBT success probability, AGC time with sub-symbol granularity is configured in this embodiment. The AGC time can occupy time resources off less than one symbol therefore the time resource allocation granularity of an AGC time is sub-symbol.

AGC time with sub-symbol granularity as shown in FIG. 3, is least applied on the dedicated resource pool. It also can be applied on the shared resource pool with PSSCH/PSCCH (Physical Sidelink Shared Channel/Physical Sidelink Control Channel) transmission and SL-PRS transmission.

Option 1: Length of AGC time is configured per resource pool/SL BWP

A length of AGC time in time domain can be configured by higher layer of BS (Base station) , e.g., RRC, MAC, preconfigured, configured per resource pool, or configured per SL BWP (Bandwidth Part) .

Option 2: Length of AGC time based on capability of the receiving UE

The length of AGC time in time domain can be based on capability of the receiving UE. A receiving UE can report an expected length of AGC time based on its capability to the transmission UE. When the transmission UE receives the expected length of AGC time from the receiving UE, the transmission UE can determine the length of AGC time. The length of AGC time transmitted by the transmission UE is not less than the expected length of AGC time. Furthermore, the receiving UE can report the expected length of AGC time based on its capability to LMF (Location Management Function) /server UE. LMF/server UE recommends the length of AGC time to the transmission UE based on the expected length of AGC time of the receiving UE. The transmission UE can prioritize the recommended length of AGC time as the actual length of AGC time transmitted by the transmission UE. When the LMF/server UE receives the expected length of AGC time of the receiving UE, the LMF/server UE can align the lengths of recommended AGC times for multiple transmissions UE’s, allowing the AGC times transmitted by multiple UE’s to be the same. The aligned AGC times may be in a same resource pool, SL BWP but in different resource pool, or different SL BWP. The recommended length of AGC time may not be less than any expected length of AGC time from receiving UE’s.

The receiving UE can report the expected length of AGC time based on its capability to LMF/server UE.LMF/server UE determines the length of AGC time based on the expected length of AGC time of the receiving UE and sends the determined length of AGC time to the transmission UE. When LMF/server UE receives the expected length of AGC time of the receiving UE, the LMF/serve UE can align the lengths of AGC times for multiple transmission UEs, allowing the AGC times transmitted by multiple UEs to be same. The aligned AGC times shall be in a same resource pool, SL BWP but in different resource pool, or different SL BWP. The determined length of AGC time may not be less than any expected lengths of AGC times from receiving UE’s.

The receiving UE can report its AGC related capability to the transmission UE. The transmission UE determines the length of AGC time in time domain based on the receiving UE’s AGC related capability. The length of AGC time may not be less than the AGC processing time of the receiving UE.

The receiving UE can report its AGC related capability to LMF/server UE. LMF/server UE recommends the length of AGC time to the transmission UE based on the receiving UE’s AGC related capability. Furthermore, LMF/server UE also delivers the receiving UE’s AGC related capability to the transmission UE. The transmission UE can prioritize the recommended length of AGC time as the actual length of AGC time transmitted by the transmission UE. The transmission UE may adjust the length of AGC time based on the recommended length of AGC time and the receiving UE’s AGC related capability. When LMF/server UE receives the receiving UE’s AGC related capability, the LMF/server can determine and align the lengths of recommended AGC times for multiple transmission UEs, allowing the lengths of AGC times transmitted by multiple UEs to be same. The aligned AGC times shall be in a same resource pool, SL BWP but in different resource pool, or different SL BWP. The recommended length of AGC time may not be less than the AGC processing time.

The receiving UE can report its AGC related capability to LMF/server UE. LMF/server UE determines the length of AGC time to the transmission UE based on the receiving UE’s AGC related capability and sends the determined length of AGC time to the transmission UE. When LMF/server UE receives the receiving UE’s AGC related capability, the LMF/server UE can align the lengths of determined AGC times for multiple transmission UEs, allowing the length of AGC times transmitted by multiple UEs to be same. The aligned AGC times shall be in a same resource pool, or in a same SL BWP but in different resource pool, or in different SL BWP. The recommended length of AGC time may not be less than the AGC processing time.

Option 3: Configure multiple candidate lengths of AGC time

Multiple candidate lengths of AGC time can be configured by higher layer of a BS (e.g., RRC, MAC) . A transmission UE may transmit one or more signals triggered by one length of AGC time selected by BS from multiple candidate lengths of AGC time and may be indicated by DCI (Downlink Control Information) . Multiple lengths of AGC time may be the same if multiple transmission times for AGC are in the same resource pool or are in the same SL BWP. Multiple candidate lengths of AGC time can be preconfigured/predefined. Before the transmission UE transmit (s) signal (s) , the length of AGC time is determined by the transmission UE and selected from the configured multiple candidate lengths of AGC time. If AGC time is immediately preceding SCI, the AGC time may be a duplicate of the first length of SCI transmission with the length same as the length of AGC time. If AGC time is preceding SL-PRS, the AGC time may be a duplicate of the first AGC length of SL-PRS transmission. Alternatively, if AGC is preceding SL-PRS, the AGC may be a duplicate of the last length of SL-PRS transmission with the length same as the length of AGC time. Alternatively, the RE offset in the AGC time is the same as that in the last length of the SL-PRS resource with the length same as the length of AGC time. The RS sequence in AGC time may generate based on the symbol index of the AGC time within the slot.

FIG. 3 depicts the relation of AGC time with sub-symbol granularity on LBT sensing time. The candidate LBT sensing time can be extended by introducing sub-symbol AGC time. For a transmission UE, LBT can be performed from the starting of the candidate LBT sensing time. If LBT fails at the beginning of the candidate LBT sensing time, a transmission UE may perform another LBT in the candidate LBT sensing time. If LBT succeeds and there is a time gap between the ending of LBT and AGC time, a CPE (Cyclic Prefix Extension) can be transmitted before the AGC time. Therefore, compare to legacy AGC time occupying one symbol, the design of AGC time with sub-symbol granularity can extend the candidate LBT sensing time and increase the candidate LBT number, further improving the LBT success probability. The solution described can be applied on the shared resource pool with PSSCH/PSCCH (Physical Sidelink Shared Channel/Physical Sidelink Control Channel) transmission and SL-PRS transmission.

Solution 2: CW adjustment for SL-PRS transmission

In Type 1 channel access procedure, LBT sensing time is associated with CW (Contention Window) size. Before a transmission UE performs Type 1 channel access procedure, it adjusts CW first. In legacy sidelink communication technology, CW is adjusted based on HARQ (Hybrid Automatic Repeat Request) feedback. However, in sidelink positioning, there may be no HARQ feedback mechanism. In current positioning, some measurements are reported to the transmission UE by a receiving UE, such as RSRP (Reference Signal Received Power) , CR (Channel Occupancy Ratio) , CBR (Channel Busy Ratio) and so on. The RSRP measurement is delivered to the transmission UE to facilitate transmission power control. The CR and CBR measurements are delivered to the transmission UE to facilitate congestion control. The CR and CBR measurements represent the channel resource status. The less the CR and CBR, the better the channel resource status. Therefore, CW for SL-PRS transmission can be adjusted based on the measurement delivered to a transmission UE. The measurement delivered to the transmission UE may be at least one of: RSRP, CR, CBR, reference signal received quality (RSRQ) , reference signal strength indicator (RSSI) , signal-to-noise and interference ratio (SNIR) , and signal-to-noise ratio (SNR) .

FIG. 4 illustrates a flowchart for CW adjustment for SL-PRS transmission. The method 400 begins at step 402, where for every CAPC value p ε {1, 2, 3, 4} , set its associated minimum CW size as the current CW, that is CW_p =CW_min, p. The method 400 proceeds to step 404 to determine if the measurement delivered to the transmission UE is available. If the measurement is available, the method 400 proceeds to step 406, otherwise the method 400 proceeds to step 410. The measurement delivered to the transmission UE can be at least one of: RSRP, CR, CBR, RSRQ, RSSI, SINR and SNR. The measurement and reference signal may be measured based on SL-PRS, DMRS of PSCCH associated with SL-PRS, or both of SL-PRS and DMRS of PSCCH associated with SL-PRS.

At step 406 a determination is made to observe if the measured delivered to the transmission UE satisfies one or more conditions. If the measurement satisfies the one or more conditions, the method 400 proceeds again to step 402. If none of the conditions are satisfied, the method 400 proceeds to step 408. One condition may be that the measurement is greater than or equal to a threshold where the threshold can be configured by a BS via RRC/MAC CE/DCI, LMF/aserver UE, determined by the transmission UE, or the threshold can be preconfigured/predefined. Furthermore, the threshold can be configured per resource pool/SL BWP. The threshold can be a RSRP threshold, CR threshold, a CBR threshold, RSRQ threshold, RSSI threshold, SNIR threshold, or SNR threshold. One condition may be that the measurement measured in a reference duration for the latest sidelink positioning related channel occupancy is greater than or equal to the threshold where the threshold can be configured by the BS via RRC/MAC CE/DCI, LMF/aserver UE, determined by the transmission UE, or the threshold can be preconfigured/predefined. Furthermore, the threshold can be configured per resource pool/SL BWP. The threshold can be a RSRP threshold, CR threshold, a CBR threshold, RSRQ threshold, RSSI threshold, SNIR threshold, or SNR threshold. For ease of description, the reference duration may be defined as a duration corresponding to a channel occupancy initiated by a UE including transmission of PSCCH carrying SCI or (and) SL-PRS, starting from the beginning of the channel occupancy initiated by the UE including transmission of PSCCH carrying SCI or (and) SL-PRS, until at least one of: the end of the first slot, first transmission burst, first slot, or the end of the first transmission burst where at least one SCI or one SL-PRS resource or both of one SCI and one SL-PRS resource are transmitted. Depending on whichever occurs earlier between channel occupancy, or slot where at least one SCI or one SL-PRS resource or both of one SCI and one SL-PRS resource transmitted, otherwise until the end of the channel occupancy.

At step 408, the CW increases for every CAPC value p ε {1, 2, 3, 4} , to the next higher allowed value. If the latest CW corresponding to a CAPC value p is the allowed maximum value, and if the measurement does not satisfy the conditions described in step 406, maintain the maximum CW size as the current CW for that CAPC value p. If the maximum CW size corresponding to a CAPC value p is consecutively used K times, reset the minimum CW size as the current CW for that CAPC value p, where K can be configured by a BS via RRC/MAC CE/DCI. Or K can be configured by LMF/aserver UE, can be determined by the transmission UE. Or K can be preconfigured/predefined, multiple candidate values for K can be preconfigured/predefined and the transmission UE can select one value from the multiple candidate values for K corresponding to CAPC value p, or multiple candidate values for K can be configured by BS/LMF/server UE and the transmission UE can select one value from the multiple candidate values for K corresponding to CAPC value p. Furthermore, K can be configured per resource pool/SL BWP.

At step 410, for every CAPC value p ε {1, 2, 3, 4} , the values are maintained. If a same CW size is consecutively used K times, increase CW for every CAPC value to the next higher allowed value. Alternatively, if a CW size corresponding to a CAPC value p is consecutively used K times, increase CW only for that CAPC value p to the next higher allowed value. If the maximum CW size corresponding to a CAPC value p is consecutively used K times, reset the minimum CW size as the current CW for that CAPC value p, where K can be configured by a BS via RRC/MAC CE/DCI. Or K can be configured by LMF/aserver UE, can be determined by the transmission UE, K can be preconfigured/predefined, multiple candidate values for K can be preconfigured/predefined and the transmission UE can select one value from the multiple candidate values for K corresponding to CAPC value p, or multiple candidate values for K can be configured by BS/LMF/server UE and the transmission UE can select one value from the multiple candidate values for K corresponding to CAPC value p. Furthermore, K can be configured per resource pool/SL BWP.

If the CW size is the allowed maximum value corresponding to a CAPC value p, the next higher allowed value for adjusting CW is still the maximum size corresponding to that CAPC value p. If the maximum CW size corresponding to that CAPC value p is consecutively used K times, reset the minimum CW size as the current CW only for that CAPC value p, where K can be configured by a BS via RRC/MAC CE/DCI. Or K can be configured by LMF/aserver UE, can be determined by the transmission UE, K can be preconfigured/predefined, multiple candidate values for K can be preconfigured/predefined and the transmission UE can select one value from the multiple candidate values for K corresponding to CAPC value p, or multiple candidate values for K can be configured by BS/LMF/server UE and the transmission UE can select one value from the multiple candidate values for K corresponding to CAPC value p. Furthermore, K can be configured per resource pool/SL BWP.

CW adjustment for SL-PRS transmission may not be based on feedback mechanism. For every CAPC value p ε {1, 2, 3, 4} , the exemplary method uses the latest CW used for any SL transmissions on the channel using Type 1 channel access procedures associated with the channel access priority class p as the current CW size. If a same CW size is consecutively used K times, increase CW for every CAPC value p ε {1, 2, 3, 4} , to the next higher allowed value. The CW adjustment for SL positioning can be applied in dedicated resource pool or a shared resource pool including PSCCH/PSSCH transmission and SL-PRS transmission.

Solution 3: Candidate starting symbol for SCI/SL-PRS transmission

In a dedicated resource pool for sidelink positioning, SL-PRS resource is transmitted with its associated SCI in a same slot. SCI is carried in a PSCCH. The PSCCH and its associated SL-PRS are transmitted in the same slot in a TDMed multiplexing manner. In legacy sidelink communication in unlicensed band, two candidate starting symbols are configured for PSCCH/PSSCH transmission in a slot to improve LBT success probability.

Option 1: Two candidate starting symbol are configured for SCI transmission in a slot

The location of each candidate starting symbol for SCI transmission in a slot can be configured by BS via RRC/MAC CE/DCI, LMF/server UE, can be preconfigured/predefined, or can be determined by the transmission UE. Alternatively, a set of multiple values for location of each candidate starting symbol for SCI transmission in a slot can be configured by BS/LMF/server UE or preconfigured/predefined. One value can be selected from the configured or preconfigured set of multiple values by BS/LMF/server UE/transmission UE as the location of associated starting symbol for SCI transmission. The location of each candidate starting symbol for SCI transmission in the slot can be configured per SL BWP/resource pool. In the slot, the first starting symbol for SCI transmission may be no later than the second starting symbol. The candidate starting symbol (s) for SCI transmission are intended for AGC symbols prior to SCI.

Option 2: More than two candidates starting symbol are configured for SCI transmission in the slot

The number of candidate starting symbols for SCI transmission in a slot can be configured by BS via RRC/MAC CE/DCI, LMF/server UE, can be preconfigured/predefined, can be determined by the transmission UE. The number of respective starting symbols for SCI transmission in a slot can be (pre) configured per SL BWP/resource pool.

The location of each candidate starting symbol for SCI transmission in a slot can be configured by BS via RRC/MAC CE/DCI, LMF/server UE, can be preconfigured/predefined, can be determined by the transmission UE. Alternatively, a set of multiple values for location of each candidate starting symbol for SCI transmission in a slot can be configured by BS/LMF/server UE or preconfigured/predefined. One value can be selected from the configured or preconfigured set of multiple values by BS/LMF/server UE/transmission UE as the location of associated starting symbol for SCI transmission.

The location of each candidate starting symbol for SCI transmission in the slot can be configured per BWP/resource pool. In the slot, the starting symbol with less index for SCI transmission is no later than the starting symbol with larger index. The number of respective starting symbols for SCI transmission in a slot can be configured or preconfigured per SL BWP/resource pool.

Option 3: Each candidate starting symbol for SCI transmission is associated with one candidate starting symbol for SL-PRS transmission

In a slot, candidate starting symbols for SL-PRS transmission may correspond with candidate starting symbols for SCI transmission. Each candidate starting symbol for SCI transmission is corresponding to one candidate starting symbol for SL-PRS transmission. In the slot, the total number of candidate starting symbols for SL-PRS transmission is same as the number of candidate starting symbols for SCI transmission. The candidate starting symbol (s) for SL-PRS transmission are intended for AGC symbol immediately before SL-PRS. In some applications, the location of each candidate starting symbol for SL-PRS transmission in the slot can be configured by BS via RRC/MAC CE/DCI, can be configured by LMF/server UE, can be preconfigured/predefined, can be determined by the transmission UE. Furthermore, the location of each starting symbol for SL-PRS transmission may be later than the location of associated starting symbol for SCI transmission.

Alternatively, a set of multiple values for location of each candidate starting symbol for SL-PRS transmission in the slot can be configured by BS/LMF/server UE or preconfigured/predefined. One value can be selected from the configured or preconfigured set of multiple values by BS/LMF/server UE/transmission UE as the location of associated starting symbol for SL-PRS transmission.

Alternatively, the mapping relationship between one or more locations of one or more candidate starting symbols for SCI transmission and the one or more locations of one or more candidate starting symbols for SL-PRS transmission can be configured by BS via RRC/MAC CE/DCI, can be configured by LMF/server UE, can be preconfigured/predefined. Once the location of candidate starting symbol for SCI transmission is determined, the location of candidate starting symbol for SL-PRS transmission can be determined. Both of the one or more locations of each candidate starting symbol for SCI transmission and the location of each candidate starting symbol for SL-PRS transmission can be corresponding to a set of multiple values. One value can be selected from the set of multiple values as the location of associated starting symbol. The starting symbol for SL-PRS transmission is later than the starting symbol for SCI transmission. Furthermore, the location of candidate start symbols for SL-PRS transmission can be configured per SL BWP/resource pool.

For a SL-PRS resource transmission, the starting symbol for transmission of the SL-PRS resource may be dependent on the one or more locations of the one or more candidate starting symbols for SL-PRS transmission and configuration of SL-PRS resource. FIG. 5 shows an example on each candidate starting symbol for SCI associated with one candidate starting symbol for SL-PRS. For example, three candidate starting symbols are configured for SCI transmission, where the location of each candidate starting symbol for SCI transmission may correspond to a set of multiple values and one value can be selected as the starting symbol for SCI transmission. Furthermore, each candidate starting symbol for SCI transmission may associate with one candidate starting symbol for SL-PRS transmission, where the location of candidate starting symbol for SL-PRS transmission may correspond to he set of multiple values and one value later than the starting symbol of SCI transmission can be selected as the starting symbol of SL-PRS transmission.

In the slot, each candidate starting symbol for SCI transmission may corresponding to multiple candidate starting symbols for SL-PRS transmission. The number of candidate starting symbols for SL-PRS transmission may associate with one starting symbol for SCI transmission can be configured by BS via RRC/MAC CE/DCI, can be configured by LMF/server UE, or determined by the transmission UE or preconfigured/predefined. The number of candidate starting symbols for SL-PRS transmission may associate with one starting symbol for SCI transmission can be configured per SL BWP/resource pool. The locations of multiple candidate starting symbols for SL-PRS transmission may relate to the location of associated candidate starting symbol for SCI transmission. For starting symbol for SCI transmission, the candidate starting symbols for SL-PRS transmission may occur later than the candidate starting symbols for SL-PRS transmission associated starting symbol for SCI transmission. The candidate starting symbol (s) for SL-PRS transmission may be intended for AGC symbol before SL-PRS.

For the location of candidate starting symbol for SL-PRS transmission, the configuration described in an earlier embodiment may be compatible with the solution described herein. FIG. 6 shows an example on each candidate starting symbol for SCI associated with multiple candidate starting symbol for SL-PRS. For example, two candidate starting symbols are configured for SCI transmission, where the location of each candidate starting symbol for SCI transmission is corresponding to a set of multiple values and one value can be selected as the starting symbol for SCI transmission. Furthermore, each candidate starting symbol for SCI transmission is associated with two candidate starting symbol for SL-PRS transmission, where the location of candidate starting symbol for SL-PRS transmission is corresponding to the set of multiple values and one value later than the starting symbol of SCI transmission can be selected as the starting symbol of SL-PRS transmission.

In the slot, each candidate starting symbol for SCI transmission may associate with different number of candidate starting symbols for SL-PRS transmission. The starting of a slot for the candidate starting symbol for SCI transmission, the larger the number of associated candidate starting symbols for SL-PRS transmission. For a different candidate starting symbols for SCI transmission, the numbers of their associated candidate starting symbols for SL-PRS transmission may be different. The number of candidate starting symbols for SL-PRS transmission and the location of these candidate starting symbols for SL-PRS transmission may be related to the associated candidate starting symbol for SCI transmission. The number of candidate starting symbols for SL-PRS transmission associated with each candidate starting symbol for SCI transmission can be configured or preconfigured per SL BWP/resource pool. The candidate starting symbols for SL-PRS transmission is later than associated starting symbol for SCI transmission. The candidate starting symbol (s) for SL-PRS transmission may be intended for AGC symbol immediately before SL-PRS. The location of candidate starting symbols for SL-PRS transmission is related to the location of associated starting symbol of SCI transmission.

In some applications, the locations of candidate starting symbols for SL-PRS can be configured by BS via RRC/MAC CE/DCI, configured by LMF/server UE, or preconfigured/predefined, determined by the transmission UE. Furthermore, the location of each candidate starting symbol for SL-PRS transmission can be corresponding to a set of multiple values, and one value can be selected by gNB/LMF/server UE/transmission UE from the configured or preconfigured set of multiple values as the location of starting symbol for SL-PRS transmission.

In some applications, the configuration for the location of candidate starting symbols for SL-PRS transmission described in an earlier embodiment can be applied or configured per SL BWP/resource pool. The mapping relationship may be established between candidate starting symbol for SCI transmission and configuration of candidate starting symbol for SL-PRS transmission. The configuration of candidate starting symbol for SL-PRS transmission includes at least one or more of: number of candidate starting symbol for SL-PRS transmission and location of candidate starting symbol for SL-PRS transmission. FIG. 7 shows an example on different candidate starting symbol for SCI associated with different number of candidate starting symbol for SL-PRS. For example, three candidate starting symbols are configured for SCI transmission, where the location of each candidate starting symbol for SCI transmission is corresponding to a set of multiple values and one value can be selected as the starting symbol for SCI transmission. Furthermore, the first candidate starting symbol for SCI transmission is associated with three candidate starting symbols for SL-PRS transmission, the second candidate starting symbol for SCI transmission may associate with two candidate starting symbols for SL-PRS transmission, and the third candidate starting symbol for SCI transmission is associated with one candidate starting symbols for SL-PRS transmission. Moreover, the location of each candidate starting symbol for SL-PRS transmission may correspond to a set of multiple values and one value later than the associated starting symbol of SCI transmission can be selected as the starting symbol of SL-PRS transmission.

Solution 4: SL-PRS transmission in shared channel (s)

In legacy sidelink communication technology, a UE can use Type 2 channel access procedure to share a COT initiated by another UE. For sidelink positioning, SL-PRS transmission in shared channel (s) can be supported. When a UE initiates a COT for SL-PRS transmission, it can send the COT sharing information to multiple other UEs. The COT sharing information may include at least one of: time information of the COT (such as the COT length, the available COT length for sharing and so on) , frequency information of the COT (such as the available RB sets of the COT, an available RB set of the COT for sharing, bandwidth of the COT and so on) , a starting location information for other UEs sharing, or duration for other UEs sharing. The starting location information for other UEs sharing can be a time offset from the end of the SL transmission from the initiated UE to the beginning of SL transmission from the sharing UEs. The COT sharing information can be carried in SCI.

SL-PRS is transmitted with associated SCI in a same slot, and SCI transmission precedes SL-PRS transmission. In a shared COT, SCI transmission from a sharing UE can follow SCI transmission of the initiated UE, or SL-PRS transmission of the initiated UE. If SCI transmission of the sharing UE follows SCI transmission of the initiated UE in the shared COT, the time duration from the end of SCI of the initiated UE to the beginning of SCI of the sharing UE, namely, time offset, can be used by the sharing UE to receive and decode the SCI from the initiated UE and achieve receiving-transmitting switching. The time offset may be less than the SCI processing time of the sharing UE, where the SCI process time refers to the total time for receiving and decoding SCI and achieving receiving-transmitting switching. To maintain the COT from being preempted by other devices in the time duration from the end of SCI of the initiated UE to the beginning of SCI of the sharing UE, the initiated UE can transmit CPE immediately following its SCI transmission and before SCI of the sharing UE. Moreover, the legacy CCPE length for sidelink communication can be reused for sidelink positioning. Alternatively, specific CPE length can be configured or preconfigured for sidelink positioning. The specific CPE length can be configured by BS via RRC/MAC CE/DCI or by LMF/server UE/preconfigured/predefined or determined by transmission UE. Specific CPE length for sidelink positioning can be configured or preconfigured per BWP/resource pool.

FIG. 8 shows an example on SCI of sharing UEs following SCI of the initiated UE. For example, there may be a gap without any transmission in time offset from the end of SCI of the initiated UE to the beginning of SCI of the sharing UE. For example, the initiated UE may transmit a CPE following its SCI in time offset to maintain the COT. When SCI transmission of a sharing UE follows SL-PRS transmission of the initiated UE in a shared COT, if the sharing UE is the target UE of the SL-PRS transmission from the initiated UE, the sharing UE may not receive the last N symbols of SL-PRS from the initiated UE. In the time of last N symbols of SL-PRS of the initiated UE, the sharing UE need to achieve receiving-transmitting switching. For ease of description, N can be configured by BS via RRC/MAC CE/DCI, by LMF/server UE/preconfigured/predefined, determined by the sharing UE, or configured per SL BWP/resource pool/UE.

A UE may share a COT initiated by a gNB to transmit SL-PRS. The sharing UE is in coverage of the gNB and may forward the sharing COT to other UEs in out-of-coverage of the gNB. Therefore, if a gNB initiates the COT for DL (Downlink) transmission, the UE in coverage of the gNB can share the COT using Type 2 channel access procedure to transmit SL-PRS related transmission. Moreover the sharing UE can send the COT sharing information to other UEs in out-of-coverage of the gNB to share the COT initiated by the gNB. Solution 5: Type 1 LBT blocking for SL-PRS transmission

In a dedicated resource pool, multiple SL-PRS resource can be transmitted in TDMed multiplexing manner. However, there may occur Type 1 LBT block problem, where one UE performing a Type 1 LBT procedure for SCI/SL-PRS transmission may be blocked by another UE’s SL transmission at least in a slot preceding to the SCI/SL-PRS and causes the LBT to fail. FIG. 9 shows an example on Type 1 LBT blocking problem. For example, UE2 intends to initiate a COT for SL-PRS2 transmission using Type 1 channel access procedure while SL-PRS1 is transmitted by UE1 preceding to SL-PRS2, which causes LBT failure of UE2.

Option 1: A SL-PRS resource is immediately followed by a gap symbol.

A SL PRS resource may be followed by a gap symbol, if the gap symbol corresponds to the last SL symbol of a slot in a dedicated resource pool has been supported. To solve Type 1 LBT blocking problem, one gap symbol may follow each SL-PRS resource in SL unlicensed band. Moreover, LBT for SL-PRS transmission can be performed in gap symbol.

Option 2: Configure an idle duration immediately before AGC symbol preceding to a SL-PRS resource.

For a SL-PRS resource, an idle duration preceding to AGC symbol before a SL-PRS resource is configured for slot structure where multiple SL-PRS resources are multiplexed in TDM manner and multiple SCIs associated with SL-PRS resources are multiplexed in FDM manner. The default AGC symbol may further precede to a SL-PRS resource unless otherwise specified, and the default AGC symbol preceding to SCI unless otherwise specified. For ease of description, AGC symbol is omitted. Therefore, the idle duration preceding to AGC symbol before a SL-PRS resource can be described as the idle duration preceding to a SL-PRS resource. The idle duration preceding to AGC symbol before SCI can be described as the idle duration preceding to SCI. The idle duration related information can be configured explicitly and includes the length of the idle duration where the idle duration can be zero or more symbols. The idle duration related information can be configured by BS via RRC/MAC CE/DCI, configured by LMF/server UE, preconfigured/predefined, or determined by the transmission UE. The idle duration related information can be configured or preconfigured per SL BWP/resource pool. Furthermore, the idle duration related information can be configured or preconfigured per SL-PRS resource. The idle duration related information can be included in SL BWP configuration, in resource pool configuration, or in SL-PRS resource configuration.

The idle duration related information can be associated with the configuration of SL-PRS resource and includes the length of the idle duration where the idle duration can be zero or more symbols. There may be a mapping relationship between idle duration and associated SL-PRS resource. The configuration of SL-PRS resource at least includes one or more of: CAPC, priority, time resource allocation, starting symbol. The length of the idle duration may be associated with priority of SL-PRS, CAPC of SL-PRS, or time resources of SL-PRS. For ease of description, the less the priority value of SL-PRS resource, the less of the length of idle duration. For ease of description, the less the CAPC value of SL-PRS resource, the less of the length of idle duration. For ease of description, if SL-PRS resource is adjacent to associated SCI, the length of idle duration can be zero. Moreover, the mapping between idle duration and associated SL-PRS resource can be configured by BS via RRC/MAC CE/DCI or by LMF/server UE or preconfigured/predefined. FIG. 10 shows an example on the idle duration preceding to an associated SL-PRS resource.

The idle duration related information before a SL-PRS resource may be indicated in SCI. For example, resource allocation for SL-PRS transmission, network (e.g., BS/LMF) , avoids time-frequency resource occupied by any idle duration when it configures time-frequency resource for SL-PRS transmission. In another example, resource allocation for SL-PRS transmission, if the transmission UE receives a SCI in sensing window, the time-frequency resource occupied by idle duration indicated in SCI may be excluded in selection window except SL-PRS resource may be reserved in SCI. For resources occupied by idle duration indicated in SCI in selection window. For example, the resource occupied by idle duration can be excluded in selection window by the transmission UE in physical layer. Therefore, the candidate resource set reported to higher layers may not include resource occupied by idle duration. In another example, the resource occupied by idle duration can be excluded by higher layers (e.g., MAC layer) . Therefore, the candidate resource set reported to higher layers includes resource occupied by idle duration. Higher layer excludes resource occupied by idle duration when it selects resource for SL-PRS transmission. For ease of description, the MAC layer can exclude resource occupied by idle duration when the MAC layer selects resource from the candidate resource set for SL-PRS transmission.

For the sub-slot structure where multiple SCIs are multiplexed in TDM manner and there is no time gap between SCI and the SCI’s associated SL-PRS resource, the idle duration can precede to AGC symbol before associated SCI. FIG. 11 shows an example on idle duration preceding to SCI in sub-slot structure.

Solution 6: CW adjustment for DL-PRS/UL-SRS

In NR unlicensed band, the DL-PRS (Downlink Positioning Reference Signal) and UL-SRS (Uplink Sounding Reference Signal) are used to be reference signal for downlink positioning and uplink positioning. The CW adjustment for SL-PRS transmission can be used on Dl-PRS transmission and UL-SRS transmission. A CW adjustment for DL-PRS transmission and UL-SRS transmission can be based on measurement feedback, where the measurement represents the channel status. Alternatively, CW adjustment for DL-PRS transmission and UL-SRS transmission can be not based on feedback mechanism.

FIG. 12 illustrates a flowchart for CE adjustment for DL-PRS/UL-PRS transmission The method 1200 begins at step 1202, where for every CAPC value p ε {1, 2, 3, 4} , set its associated minimum CW size as the current CW, that is CW_p =CW_min, p. The method 1200 proceeds to step 1204 to determine if the measurement delivered to the transmission UE is available. If the measurement is available, the method 1200 proceeds to step 1206, otherwise the method 1200 proceeds to step 1210. At step 1206 a determination is made to observe if the measurement delivered to the transmitter satisfies one or more conditions. If the measurement satisfies the one or more conditions, the method 1200 proceeds again to step 1202. If none of the conditions are satisfied, the method 1200 proceeds to step 1208.

The conditions can be that the measurement is greater than or equal to a threshold. For DL, the threshold can be determined by BS or preconfigured. For the UL, the threshold can be configured by BS via RRC/MAC CE/DCI, determined by the transmission UE, configured by LMF, or preconfigured. The conditions can be that the measurement measured in a reference duration for the latest sidelink positioning related channel occupancy is greater than or equal to the threshold. For UL the threshold can be configured by BS via RRC/MAC CE/DCI, determined by the transmission UE, configured by LMF, or preconfigured. For DL, the threshold can be determined by BS or preconfigured where a reference duration for DL-PRS transmission can be defined as same as PDCCH/PDSCH. For UL, the reference duration for UL-SRS transmission can be defined as same as that for PUCCH/PUSCH. For ease of description, the reference duration for DL-PRS/UL-SRS transmission may be defined as a duration corresponding to a channel occupancy initiated by a transmitter including transmission of DL-PRS/UL-SRS, starting from the beginning of the channel occupancy initiated by the transmitter including transmission of DL-PRS/UL-SRS, until at least one of: the end of the first slot, first transmission burst, first slot, or the end of the first transmission burst where at least one SCI or one SL-PRS resource or both of one SCI and one SL-PRS resource are transmitted. Depending on whichever occurs earlier between channel occupancy, or slot where at least one SCI or one SL-PRS resource or both of one SCI and one SL-PRS resource transmitted, otherwise until the end of the channel occupancy. At step 1212, for every CAPC value p ε {1, 2, 3, 4} , the values are maintained.

For CW adjustment for DL-PRS transmission without feedback mechanism, the latest CW used for any DL (Downlink) transmissions on the channel using Type 1 channel access procedures associated with the channel access priority class p can be reused as the current CW size. If a same CW size is consecutively used K times, increase CW for every CAPC value to the next higher allowed value. For ease of description, K can be configured by LMF, determined by BS, preconfigured/predefined. Furthermore, multiple candidate values for K can be preconfigured/predefined and BS can select one value from the multiple candidate values for K corresponding to CAPC value p. If the maximum CW size corresponding to that CAPC value p is consecutively used K times, reset the minimum CW size as the current CW only for that CAPC value p. If CW not equal to the maximum CW size corresponding to other CAPC value, increase CW to the next higher allowed value.

CW adjustment for UL-SRS transmission may occur without a feedback mechanism. The latest CW used for any UL (Uplink) transmissions on the channel using Type 1 channel access procedures associated with the channel access priority class p can be reused as the current CW size. If a same CW size is consecutively used K times, increase CW for every CAPC value to the next higher allowed value. For ease of description K can be configured by LMF, configured by BS via RRC/MAC CE/DCI, determined by transmission UE, preconfigured/predefined. If the maximum CW size corresponding to that CAPC value p is consecutively used K times, reset the minimum CW size as the current CW only for that CAPC value p. For CW not equal to the maximum CW size corresponding to other CAPC value, increase CW to the next higher allowed value.

Claims

A wireless communication method, comprising:

determining, parameters of accessing channel (s) for transmission of a sidelink (SL) positioning signal and configurations of the SL positioning signal on an unlicensed band;

wherein the sidelink positioning signal is transmitted by a first wireless communication entity to a second wireless communication entity.
The wireless communication method of claim 1, wherein the parameters of accessing channel (s) include at least a Contention Window (CW) and a transmission time of the SL positioning signal transmission in a shared Channel Occupancy Time (COT) , and wherein the configurations of the SL positioning signal include at least a transmission time for Automatic Gain Control (AGC) of the second wireless communication entity, a candidate starting time of the SL positioning signal, a gap before the SL positioning signal and idle duration before the SL positioning signal.
The wireless communication method of claim 2, wherein the SL positioning signal includes at least one of:a Sidelink Control Information (SCI) , or a Sidelink Positioning Reference Signal (SL-PRS) .
The wireless communication method of claim 2, wherein the transmission time used for the AGC of the second wireless communication entity is configured prior to sending the SL positioning signal, and wherein the transmission time for the AGC occupies a time resource less than one symbol.
The wireless communication method of claim 4, wherein a length of the transmission time is configured by a wireless communication node or preconfigured.
The wireless communication method of claim 4, wherein a length of the transmission time is configured per SL BWP/resource pool.
The wireless communication method of claim 4, wherein a length of the transmission time is configured based on a capability of the second wireless communication entity.
The wireless communication method of claim 7, wherein the second wireless communication entity reports an expected length of the transmission time based on the capability of the second wireless communication entity to the first wireless communication entity, a network node, or a third communication entity.
The wireless communication method of claim 8, wherein the network node or the third wireless communication entity recommends the length of the transmission time to the first wireless communication entity based on the expected length of the transmission time, where recommend lengths of the transmission time for a plurality of the first wireless communication entities are identical to one another.
The wireless communication method of claim 9, wherein the first wireless communication entity can prioritize the recommended length of the transmission time.
The wireless communication method of claim 8, wherein the network node or the third wireless communication entity determines the length of the transmission time based on the expected length of the transmission time, and send the determined length of the transmission time to the first wireless communication entity, where determined lengths of the transmission time for a plurality of the first wireless communication entities are identical to one another.
The wireless communication method of claim 7, further comprising:

receiving, by the first wireless communication entity, an AGC-related capability of the second wireless communication entity; and

determining, by the first wireless communication entity, the length of the AGC time based on the AGC-related capability.
The wireless communication method of claim 7, wherein the second wireless communication entity reports its AGC-related capability to a network node or a third wireless communication entity.
The wireless communication method of claim 13, wherein the network node or the third wireless communication entity determines/recommends the length of the transmission time for the first wireless communication entity based on the AGC-related capability, where determined/recommended lengths of the transmission time for a plurality of the first wireless communication entities are identical to one another.
The wireless communication method of claim 4, wherein a plurality of candidate lengths of the transmission time is configured by a wireless communication node or preconfigured.
The wireless communication method of claim 15, wherein one of the candidate lengths is selected by the wireless communication node or the first wireless communication entity, prior to the first wireless communication entity sending the SL positioning signal.
The wireless communication method of claim 16, wherein the wireless communication node indicates the selected candidate length via Downlink Control Information (DCI) , if one of the candidate lengths is selected by the wireless communication node.
The wireless communication method of claim 2, wherein the contention window (CW) is adjusted based on a measurement feedback received by the first wireless communication entity.
The wireless communication method of claim 18, wherein the measurement feedback includes at least one of: a Reference Signal Received Power (RSRP) , a Channel Occupancy Ratio (CR) , or a Channel Busy Ratio (CBR) , a Reference Signal Received Quality (RSRQ) , a Reference Signal Strength Indicator (RSSI) , or a Signal-to-Noise and Interference Ratio (SNIR) , or a Signal-to-Noise Ratio (SNR) .
The wireless communication method of claim 19, wherein the measurement feedback is measured based on at least one of the SL-PRS, or a Demodulation Reference Signal (DMRS) of a Physical Sidelink Shared Channel (PSCCH) associated with the SL-PRS.
The wireless communication method of claim 20, wherein if the measurement feedback is available and satisfies one or more conditions, a minimum CW size is set as a current CW for every CAPC value.
The wireless communication method of claim 21, wherein the one or more conditions include: a measurement measured in a reference duration for a latest sidelink positioning related channel occupancy is equal to or larger than a threshold.
The wireless communication method of claim 22, wherein the threshold is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity.
The wireless communication method of claim 23, wherein the threshold is configured per resource pool or SL BWP.
The wireless communication method of claim 24, wherein the threshold is an RSRP threshold, a CR threshold, a CBR threshold, a RSRQ threshold, a RSSI threshold, a SNIR threshold, or a SNR threshold.
The wireless communication method of claim 22, wherein a reference duration is defined as a duration corresponding to a channel occupancy initiated by a UE including transmission of PSCCH carrying SCI and/or the SL-PRS, and wherein the duration starts from a beginning of the channel occupancy to an end of a first slot where at least one of the SCI or the SL-PRS is transmitted.
The wireless communication method of claim 21, wherein if the measurement feedback is available but the measurement feedback does not satisfy the one or more conditions, the CW is increased by the first wireless communication entity for every CAPC value to a next higher allowed value.
The wireless communication method of claim 21, wherein if the measurement feedback is not available, the CW is maintained by the first wireless communication entity for every CAPC value.
The wireless communication method of claim 18, wherein the adjustment on the CW is not based on a feedback mechanism.
The wireless communication method of claim 28, wherein a latest CW used for any SL transmissions on a channel using Type 1 channel access procedures associated with a CAPC value is reused as a size for the CW for accessing channel (s) for SL positioning signal transmission associated with that CAPC value.
The wireless communication method of claim 2, wherein two or more first candidate starting symbols are configured for sending the SL positioning signal, which includes Sidelink Control Information (SCI) , in a slot.
The wireless communication method of claim 31, wherein a number of the first candidate starting symbols is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity.
The wireless communication method of claim 32, wherein a number of the first candidate starting symbols is configured per SL BWP/resource pool.
The wireless communication method of claim 31, wherein a location of each of the first candidate starting symbols is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity.
The wireless communication method of claim 31, wherein second candidate starting symbols are configured for sending the SL positioning signal, which includes an SL-PRS, are related with the first candidate starting symbols.
The wireless communication method of claim 35, wherein each of the first candidate starting symbols corresponds to one or more of the second candidate starting symbols.
The wireless communication method of claim 36, wherein a number of the second candidate starting symbols corresponding to each of the first candidate starting symbols is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity.
The wireless communication method of claim 37, wherein the number of the second candidate starting symbols corresponding to each of the first starting symbols is configured per SL BWP, or resource pool, or SL-PRS resource.
The wireless communication method of claim 36, wherein a location of each of the second candidate starting symbols is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity.
The wireless communication method of claim 39, wherein the location corresponds to a plurality of values, one of which is selected by the wireless communication node, the network node, or the third wireless communication entity, or preconfigured or determined by the first wireless communication entity.
The wireless communication method of claim 39, wherein the location of each of the second candidate starting symbols is configured per SL BWP, or resource pool, or SL-PRS resource.
The wireless communication method of claim 36, wherein each of the first candidate starting symbols is associated with a different number of the second candidate starting symbols.
The wireless communication method of claim 42, wherein a number of the second candidate starting symbols and their respective locations are related to associated ones of the first candidate starting symbols.
The wireless communication method of claim 2, wherein, in the shared COT, SCI transmission from a sharing wireless communication entity can follow transmission of the SL signal, which includes SCI or SL-PRS from an initiated wireless communication entity.
The wireless communication method of claim 44, wherein if the SCI transmission from the sharing wireless communication entity follows the transmission of the SCI from the initiated wireless communication entity in the shared COT, the initiated wireless communication entity transmits a Cyclic Prefix Extension (CPE) immediately following the transmission of the SCI and before the SCI transmission from the sharing wireless communication entity.
The wireless communication method of claim 44, wherein if the SCI transmission from the sharing wireless communication entity follows the transmission of the SL-PRS in the shared COT from the initiated wireless communication entity and if the sharing wireless communication entity is a target of the transmission of the SL-PRS from the initiated wireless communication entity, the sharing wireless communication entity does not receive last N symbols of the transmission of the SL-PRS from the initiated wireless communication entity.
The wireless communication method of claim 44, wherein the shared COT initiated by a wireless communication node is forwarded to one or more wireless communication entities in out-of-coverage of a wireless communication node.
The wireless communication method of claim 2, wherein a gap symbol immediately follows each SL-PRS resource.
The wireless communication method of claim 2, wherein the idle duration immediately preceding to an AGC symbol before a SL-PRS resource is configured if multiple SCI transmissions are multiplexed in a FDM manner and multiple SL-PRS resources are multiplexed in a TDM manner.
The wireless communication method of claim 2, wherein the idle duration immediately preceding to an AGC symbol before an SCI transmission is configured in a sub-slot structure where multiple SCI transmissions are multiplexed in a TDM manner and there is no time gap between the SCI transmission and its associated SL-PRS resource.
The wireless communication method of claim 49 or 50, wherein information about the idle duration can be configured explicitly.
The wireless communication method of claim 49 or 50, wherein information about the idle duration can be associated with a configuration of the SL-PRS resource.
The wireless communication method of claims 50 to 51, wherein the information about the idle duration includes at least a length of the idle duration.
The wireless communication method of claim 53, wherein the length of the idle duration is zero, one symbol, or multiple symbols.
The wireless communication method of claim 51 or 52, wherein the information about the idle duration is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity.
The wireless communication method of claim 55, wherein the information about the idle duration is configured per SL BWP, or resource pool, or SL-PRS resource.
The wireless communication method of claim 52, wherein the configuration of the SL-PRS resource includes at least one of: a CAPC, a priority, a time resource allocation, or a starting symbol.
The wireless communication method of claim 52, wherein if the SL-PRS resource is adjacent to an associated SCI transmission, a length of the idle duration is zero.
The wireless communication method of claim 52, wherein a mapping between the idle duration and the SL-PRS resource is configured by a wireless communication node, a network node, or a third wireless communication entity, or preconfigured or determined by the first wireless communication entity.
The wireless communication method of claim 49 or 50, wherein information about the idle duration is indicated in SCI.
The wireless communication method of claim 60, wherein a time-frequency resource occupied by any idle duration is avoided when the time-frequency resource is configured by a wireless communication node for an SL-PRS transmission.
The wireless communication method of claim 61, wherein, in Scheme 2 resource allocation, a time-frequency resource occupied by the idle duration indicated in the SCI should be excluded in a selection window.
The wireless communication method of claim 62, wherein a resource occupied by the idle duration can be excluded in the selection window by the first wireless communication entity in a physical layer.
The wireless communication method of claim 62, wherein a resource occupied by the idle duration can be excluded by a higher layer.
A wireless communications apparatus comprising a processor and a memory, wherein the processor is configured to read code from the memory and implement a method recited in any of claims 1 to 64.
A computer program product comprising a computer-readable program medium code stored thereupon, the code, when executed by a processor, causing the processor to implement a method recited in any of claims 1 to 64.