Efficient positioning reference signal detection for sidelink positioning in unlicensed bandwidth

Abstract

Exemplary embodiments of the present disclosure relate to an apparatus, method, device, and computer-readable medium for supporting efficient positioning reference signal detection for sidelink positioning in unlicensed spectrum. A first terminal device in a radio access network may be configured to initiate a first listen-before-talk procedure before transmitting a sidelink positioning reference signal in the unlicensed spectrum to a second terminal device in the radio access network during a sidelink positioning session, transmit positioning-related control information to the second terminal device in the licensed spectrum, and transmit a sidelink positioning reference signal in the unlicensed spectrum in response to successful completion of the first listen-before-talk procedure. The positioning-related control information includes instructions for the second terminal device to receive notification of whether the first listen-before-talk procedure was successful or to perform a second listen-before-talk procedure.

Description

[Technical Field]

[0001] The various exemplary embodiments described herein generally relate to communication technologies, and more particularly to devices, methods, apparatus, and computer-readable media that support efficient positioning reference signal (PRS) detection for sidelink positioning in unlicensed spectrum. [Background technology]

[0002] The abbreviations used in this specification and in the figures are defined below. 3GPP (Registered Trademark) Third Generation Partner Project CCA Clear Channel Assessment COT channel occupancy time CW Contention Window DMRS demodulation reference signal gNB Next Generation Node B LBT Listen Before Talk NR new radio PRS positioning reference signal PSCCH Physical Sidelink Control Channel PSFCH (Physical Sidelink Feedback Channel) PSSCH Physical Sidelink Shared Channel Rx receiver SL Sidelink SCI Sidelink Control Information Tx transmitter UE User Equipment

[0003] In recent years, 3GPP® has approved research projects aimed at enhancing positioning, with side-link positioning being a key component. Possible solutions for side-link positioning include relative positioning, ranging, and absolute positioning. This research project explores extending side-link positioning to license-free bandwidths. [Overview of the project]

[0004] In general, exemplary embodiments of this disclosure provide efficient positioning reference signal detection solutions for sidelink positioning in unlicensed bandwidth.

[0005] In a first embodiment, an exemplary embodiment of a first terminal device in a radio access network is provided. The first terminal device may include at least one processor and at least one memory for storing instructions. When executed by at least one processor, an instruction can cause the first terminal device to perform at least: initiate a first listen-before-talk procedure before transmitting a side-link positioning reference signal in the unlicensed band to a second terminal device in the radio access network during a side-link positioning session; transmit positioning-related control information to the second terminal device in the licensed spectrum; and transmit a side-link positioning reference signal in the unlicensed band in response to the successful completion of the first listen-before-talk procedure initiated by the first terminal device. The positioning-related control information may include instructions for the second terminal device to receive notification of whether the first listen-before-talk procedure initiated by the first terminal device was successful, or to perform a second listen-before-talk procedure.

[0006] In a second embodiment, an exemplary embodiment of a second terminal device in a radio access network is provided. The second terminal device may include at least one processor and at least one memory for storing instructions. When executed by the at least one processor, the instructions can cause the second terminal device to perform at least: receive positioning-related control information on a sidelink in the permitted band from a first terminal device in the radio access network; and perform sidelink positioning reference signal detection in the unlicensed band at a timing determined based on the positioning-related control information. The positioning-related control information may include instructions for the second terminal device to receive notification of whether a first listen-before-talk procedure initiated by the first terminal device was successful, or to perform a second listen-before-talk procedure.

[0007] Exemplary embodiments of methods, apparatus, and computer-readable media are also provided. Such exemplary embodiments generally correspond to the above-described exemplary embodiments of devices, and for convenience, a repeated description thereof is omitted here.

[0008] Other features of the exemplary embodiments of this disclosure, and preferably in conjunction with the accompanying drawings illustrating the principles of the exemplary embodiments of this disclosure, will also become apparent from the following description relating to specific embodiments. [Brief explanation of the drawing]

[0009] Next, some exemplary embodiments will be described, as non-limiting examples, with reference to the accompanying drawings. [Figure 1] Figure 1 is a schematic diagram showing a communication network in which exemplary embodiments of the present disclosure can be implemented. [Figure 2A] Figure 2A is a schematic diagram showing the channel occupancy period obtained by the listen-before-talk procedure. [Figure 2B] Figure 2B is a schematic flowchart illustrating the Type 1 Listen Before Talk procedure. [Figure 3] Figure 3 is a schematic message flowchart illustrating sidelink communication between multiple user devices. [Figure 4] Figure 4 is a schematic message flowchart illustrating the process according to an exemplary embodiment of the present disclosure. [Figure 5] Figure 5 is a schematic block diagram showing an apparatus according to an exemplary embodiment of the present disclosure. [Figure 6] Figure 6 is a schematic block diagram showing an apparatus according to an exemplary embodiment of the present disclosure. [Figure 7] Figure 7 is a schematic block diagram showing an apparatus according to an exemplary embodiment of the present disclosure. Throughout the drawings, the same or similar reference numerals indicate the same or similar elements. Repeated descriptions of the same elements are omitted. [Modes for carrying out the invention]

[0010] In the following, several exemplary embodiments will be described in detail with reference to the accompanying drawings. The following description includes specific details for the purpose of fully understanding various concepts. However, it will be apparent to those skilled in the art that these concepts can be implemented without these specific details. In some cases, well-known circuits, technologies, and components are shown in block diagram form to avoid obscuring the described concepts and features.

[0011] As used herein, the term "network device" refers to any suitable entity or device that can provide a cell or coverage through which a terminal device can access the network or receive services. A network device is sometimes generally referred to as a base station. The term "base station" as used herein can represent a Node B (NB), an evolved Node B (eNB), or a gNB. A base station can be embodied as a macro base station, a relay node, or a low-power node such as a pico base station or a femto base station. A base station may be composed of a plurality of distributed network units such as a central unit (CU), one or more distributed units (DUs), and one or more remote radio heads (RRHs) or remote radio units (RRUs). The number and functions of these distributed units depend on the selected split RAN architecture.

[0012] As used herein, the terms “Terminal Equipment” or “User Equipment” (UE) refer to any entity or device that can communicate wirelessly with or with network equipment. Examples of Terminal Equipment include mobile phones, mobile terminals (MTs), mobile stations (MSs), subscriber stations (SSs), mobile subscriber stations (PSSs), access terminals (ATs), computers, wearable devices, vehicle communication equipment, mechanical communication (MTC) equipment, device-to-device (D2D) equipment, vehicle-to-vehicle (V2X) equipment, sensors, and the like. The term “Terminal Equipment” may be used interchangeably with UE, user equipment, mobile terminal, mobile station, or wireless equipment.

[0013] Figure 1 shows an exemplary communication network 100 on which exemplary embodiments of the present disclosure may be implemented. The communication network 100 may be a radio access network (RAN), for example, a 5G New Radio (NR) RAN. As shown in Figure 1, the communication network 100 may include a plurality of user equipment (UEs) 110a to 110c (each individually also referred to as UE110, or collectively as UE110) and a base station 120 that communicates with one or more of the plurality of UE110a to 110c. The base station 120 is shown as a 5G base station gNB, but may also be implemented as other base stations such as a Long-Term Evolution (LTE) base station eNB, a Beyond 5G base station, or a future base station. The base station 120 may communicate with one or more UEs 110 via uplink (UL) channels and downlink (DL) channels via a Uu interface. In some exemplary embodiments, the base station 120 may implement other radio access technologies to communicate with one or more UEs 110.

[0014] UE110 may be a mobile phone, a vehicle-mounted terminal, a roadside unit, etc. In addition to communication with the base station 120, UE110 can also perform direct communication with each other, called sidelink (SL) communication, for example via the PC5 interface. Multiple UE110s can each function as an SL transmit (Tx) UE that transmits over the sidelink, or an SL receive (Rx) UE that receives over the sidelink. A Tx UE can perform sidelink transmission to one or more Rx UEs by unicast, groupcast, or broadcast, with or without network control. For example, a sidelink may be established between UE110s that are all within network coverage (in-coverage scenario), UE110s that are all outside network coverage (out-of-coverage scenario), or UE110s where one or more UEs are within network coverage and others are outside network coverage (partial coverage scenario).

[0015] The UE110 can use different bandwidths for different sidelink communications. For example, the UE110 can transmit the Physical Sidelink Control Channel (PSCCH) and Physical Sidelink Shared Channel (PSSCH) in an authorized bandwidth (e.g., LTE or NR bandwidth) and the Sidelink Reference Signal (e.g., Sidelink Positioning Reference Signal (SL-PRS)) in an unlicensed bandwidth. An unlicensed bandwidth may refer to any frequency band that does not require a license from the appropriate regulatory body, and the frequency band can be used by any device, not just devices that are licensed to use a specific frequency band. Examples of unlicensed bandwidths available worldwide include 2.4GHz, 5GHz, and 60GHz.

[0016] Unlicensed frequency bands may also be used by other communication systems. For example, the 2.4GHz and 5GHz frequency bands are used for WiFi® communications. Considering coexistence with other systems, before a Tx UE initiates sidelink transmission in an unlicensed frequency band, the Tx UE must perform a clear channel evaluation procedure to assess whether the channel is available in the unlicensed frequency band. To assess channel availability, a Listen Before Talk (LBT) channel access mechanism is introduced. When a Tx UE intends to initiate sidelink transmission, an "extended" LBT procedure is performed to assess whether the channel is available during the contention window (CW). The "extended" LBT procedure generally grants the Tx UE the "right" to access the channel for a certain period, referred to as Channel Occupancy Time (COT), immediately after the contention window, if the channel is available during the duration of a Type 1 LBT, or LBT Cat.4. Contention Window. Figure 2A is a schematic diagram of the Contention Window (CW) and Channel Occupancy Time (COT). The Tx UE can perform sidelink transmission once it obtains a COT (Center of Terror).

[0017] Figure 2B is a schematic flowchart showing the Type 1 LBT procedure 200. In the LBT procedure 200, the UE observes the channel as a series of consecutive Clear Channel Assessment (CCA) slots, also called sensing slots. In the sub-7 GHz range, the duration T of the CCA slots sl The time interval is 9 μs. The UE determines that a channel is idle / available in a CCA slot if the power measured (i.e., collected energy) in the CCA slot is below a predetermined threshold.

[0018] Referring to Figure 2B, at 210, UE has a waiting period T. dIf it is detected that the channel is idle during the period, at 212, the UE can initialize the backoff counter N for the type 1 LBT procedure with a random number uniformly distributed between 0 and CW. The waiting period T d is the period T f = 16 μs, immediately followed by a configuration where m p consecutive slot periods T sl follow.

[0019] At 214, the UE can determine whether the backoff counter N is equal to zero. If the backoff counter N is equal to zero, the UE acquires the right to access the channel during the channel occupancy time (COT) and can immediately transmit sidelink transmission in the unlicensed band.

[0020] At 214, if the backoff counter N is greater than zero, at 216, the UE decreases the backoff counter N by 1, and at 218, can detect the channel during an additional slot period T sl . If the channel is idle during the additional slot period T sl , the process 200 returns to step 214. If the channel is busy (the collected energy is above a predetermined energy threshold) during the additional slot period T sl , the UE detects the channel at 220 until it is detected that an additional waiting period T d is idle, and then the process 200 returns to step 214.

[0021] In a synchronous cellular communication system, transmission can only be initiated at the start of a slot (e.g., an NR slot) or a symbol within a slot (e.g., an OFDM symbol within an NR slot). In 214, if the backoff counter N is equal to zero (i.e., the type 1 LBT procedure has finished), the UE acquires the right to access the channel. In this embodiment, if the UE is attempting to initiate transmission at the start of a slot or symbol (the slot or symbol has finished the type 1 LBT procedure), the UE performs an additional shortening / reduction LBT procedure immediately before the slot or symbol (e.g., a waiting period T). d (For an additional period, check whether the channel is idle.) After the UE has confirmed that the channel is idle during the above period, it can start transmitting at the beginning of the slot or symbol. In other embodiments, the UE additionally senses the channel when the UE is ready to transmit. The UE senses the channel for at least the duration T of the CCA slot. sl If the channel is detected as idle, transmission can be made on the channel.

[0022] In this disclosure, when the backoff counter for a Type 1 LBT procedure decreases to 0, the Type 1 LBT procedure is considered to have terminated or to have succeeded. The UE performs the Type 1 LBT based on the Channel Access Priority Class (CAPC) associated with the sidelink transmission transmitted in the unlicensed band. The aforementioned parameters for the Type 1 LBT procedure are CW, m p , T d The COT may be determined based on CAPC. The UE obtains the COT when a Type 1 LBT procedure is successfully completed, and the obtained COT remains valid even if the UE pauses transmission. If the UE wants to start a new transmission within the COT, it must also perform a “reduced” (or shortened) LBT procedure. The “reduced” LBT procedure, generally known as LBT Type 2, has the following variations: • Type 2A (also known as 25μs LBT or LBT Cat.2) For sidelink transmissions within the starting device that has obtained COT (when the gap between two sidelink transmissions is 25 μs or more, and for sidelink transmissions following other sidelink transmissions) • Type 2B (also known as 16μs LBT or LBT Cat.2) For sidelink transmissions within the starting device that has obtained COT (used only for sidelink transmissions following other sidelink transmissions with a gap equal to 16μs). • Type 2C (without LBT, also known as LBT Cat.1) For sidelink transmissions following other sidelink transmissions with a transmit gap of less than 16 μs, the allowable duration of the sidelink transmission is 584 μs or less.

[0023] The initiating UE (i.e., the UE initiating a sidelink transmission) can share the acquired COT with the intended receiver (the responding UE). For this purpose, the initiating UE can notify the responding UE of the COT duration, for example, via control signaling. The responding UE can then use this information to determine which type of LBT to apply when performing a transmission where the intended receiver is the initiating UE. If the responding UE's transmission goes outside the COT range, or if the responding UE wants to make a new transmission to another UE, the responding UE must acquire a new COT using LBT type 1 with the appropriate CAPC.

[0024] Figure 3 shows an example of sidelink communication 300 between multiple UEs. Referring to Figure 3, the first UE 110a can perform a Type 1 LBT procedure at 310 to acquire the first COT, and then at 312 send a sidelink transmission via PSCCH / PSSCH to the second UE 110b in the first COT. The first UE 110a can also share the first COT with the second UE 110b via control signaling. Within the first COT, the second UE 110b can perform a "reduced" LBT (LBT Type 2) at 314 to check channel availability, and at 316 send a Hybrid Automatic Retransmission Request (HARQ) feedback to the first UE 110a via the Physical Sidelink Feedback Channel (PSFCH) in response to the PSCCH / PSSCH transmission received from the first UE 110a. The PSFCH is introduced to enable HARQ feedback over the sidelink from the UE that is the intended recipient of the sidelink transmission (i.e., the Rx UE) to the UE that performed the sidelink transmission (i.e., the Tx UE). If the Rx UE successfully receives and decodes the sidelink transmission, the Rx UE generates a positive HARQ acknowledgment (ACK) and sends the HARQ ACK on the PSFCH to the Tx UE to confirm successful reception of the sidelink transmission. If the Rx UE fails to receive or decode the sidelink transmission, the Rx UE generates a negative HARQ acknowledgment (NACK) and sends the HARQ NACK on the PSFCH to the Tx UE to request retransmission of the sidelink transmission.

[0025] If the second UE110b wants to send a sidelink transmission to the third UE110c, the second UE110b can perform a Type 1 LBT procedure to obtain the second COT at 318 and send the sidelink transmission to the third UE110c at 320, for example, on the PSCCH / PSSCH. The second UE110b can also share the second COT with the third UE110c via control signaling. Within the second COT, the third UE110c can perform a Type 2 LBT procedure at 322 to check channel availability and send HARQ feedback on the PSFCH to the second UE110b at 324 in response to the sidelink transmission received from the second UE110b.

[0026] When operating in unlicensed bandwidth, the listen-before-talk requirement creates uncertainty about whether a particular transmission can be performed when intended. For example, in sidelink positioning procedures, the Tx UE is uncertain about when it can transmit a positioning reference signal (PRS), and therefore the time at which the corresponding Rx UE needs to detect the PRS is also uncertain. To overcome the uncertainty of the timing of PRS detection, the Rx UE can apply continuous PRS sequence detection. However, this requires high power consumption. Another option for the Rx UE is to perform PRS sequence detection only in the slot / symbol indicated by the Tx UE. However, in this case, the Tx UE may not be able to capture the channel before the indicated slot / symbol, resulting in long latency.

[0027] According to one aspect of this disclosure, an efficient PRS detection mechanism for sidelink positioning in unlicensed bands is provided. In some exemplary embodiments, the Tx UE can dynamically determine an efficient method for the Rx UE to detect a sidelink PRS transmitted in an unlicensed band. For example, if the delay between the PSSCH and the associated PSFCH is longer than the remaining time of the LBT procedure performed by the Tx UE for PRS transmission, the Tx UE can use a modified PSFCH to notify the Rx UE whether the LBT procedure performed by the Tx UE was successful. In another example, if the Tx UE and the Rx UE are observing the same radio environment, the Tx UE can request the Rx UE to perform the same LBT procedure performed by the Tx UE in order to predict the timing of a PRS transmission. The Tx UE can transmit positioning-related control information to the Rx UE before the Tx UE acquires the right to transmit a PRS in an unlicensed band by transmitting a PRS to the Rx UE in an authorized band and transmitting positioning-related control information to the Rx UE in an authorized band. The proposed mechanism allows the Rx UE to rapidly detect PRS in the unlicensed band while keeping complexity and power consumption low.

[0028] Figure 4 shows a process 400 for sidelink PRS transmission and detection in an unlicensed band in an exemplary embodiment of the present disclosure. Process 400 may be performed by a Tx UE transmitting sidelink PRS and one or more Rx UEs receiving sidelink PRS. The Tx UE and Rx UE may include a plurality of means, modules, components, or elements for performing the operations in process 400, and the means, modules, components, or elements may be implemented in various forms including, but not limited to, software, hardware, firmware, or any combination thereof.

[0029] Referring to Figure 4, at 410, Tx UE110a can perform a sidelink positioning establishment procedure with Rx UE110b in response to a sidelink positioning request from a higher layer. The sidelink positioning establishment request may be associated with a procedure for positioning Tx UE110a or Rx UE110b. In the sidelink positioning establishment procedure, Tx UE110a can determine whether Tx UE110a and Rx UE110b are observing the same radio environment.

[0030] In an exemplary embodiment, Tx UE110 can determine whether Tx UE110a and Rx UE110b are in the same radio environment based on the distance between them. Tx UE110a can estimate the approximate distance between Tx UE110a and Rx UE110b by utilizing a reference signal received from Rx UE110b, for example, a demodulated reference signal (DMRS) received from Rx UE110b on the PSSCH. If the distance is below a set threshold, Tx UE110a determines that Tx UE110a and Rx UE110b are observing the same radio environment. In the sidelink positioning establishment procedure, Tx UE110a and Rx UE110b can exchange information via the PSSCH transmitted in the permitted band. Because the carrier wave is within the permitted bandwidth, the distance estimation is approximate and not accurate enough for positioning, but it is acceptable for estimating the wireless environment.

[0031] In another exemplary embodiment, Tx UE110 can determine whether Tx UE110a and Rx UE110b are in the same radio environment based on channel measurements performed by Tx UE110a and Rx UE110b. In the sidelink positioning establishment procedure, Tx UE110a and Rx UE110b can negotiate the timing and method of measuring channels in the unlicensed band and then measure channels in the unlicensed band as agreed. Rx UE110b can transmit its measurement results to Tx UE110a, for example, via the PSSCH of the permitted band. If the measurement results of Rx UE110b are the same as those of Tx UE110a, Tx UE110a can determine that Tx UE110a and Rx UE110b are in the same radio environment. Other solutions may be used to determine whether Tx UE110a and Rx UE110b are in the same wireless environment, and it should be noted that the exemplary embodiments are not limited to the examples in this embodiment.

[0032] In 412, Tx UE110a can initiate a Type 1 LBT procedure. Before initiating a Type 1 LBT procedure, Tx UE110a can determine the parameters of the Type 1 LBT procedure. For example, Tx UE110a can determine the contention window (CW) value and waiting period T for the Type 1 LBT procedure based on the channel access priority class (CAPC) associated with the sidelink positioning reference signal (PRS). d This allows us to determine the channel occupancy time (COT) value. The Type 1 LBT procedure can be performed as described above with reference to Figure 2B, and for convenience, a detailed explanation of its repetition is omitted here.

[0033] In 414, Tx UE110a can select a sidelink resource for transmitting positioning-related control information in the permitted bandwidth. In an exemplary embodiment, positioning-related control information may be transmitted as part of sidelink control information (SCI). The SCI may have a two-stage SCI structure, including a first-stage SCI carried on the PSCCH and a second-stage SCI carried on the PSSCH, to support size differences between SCIs for various NR sidelink service types. Tx UE110a can select a PSCCH and / or PSSCH resource for transmitting the SCI containing positioning-related control information.

[0034] Two radio resource allocation modes can be configured for the Tx UE110a. In the first mode, the network is responsible for allocating sidelink resources to the Tx UE110a. The Tx UE110a can send a sidelink scheduling request (SL-SR) to the base station 120, and the base station 120 can respond to the received SL-SR by sending a resource allocation to the Tx UE110a. In the second mode, the Tx UE110a can autonomously select a sidelink resource from the configured sidelink resource pool(s). For example, the Tx UE110a can first perform a sensing procedure on the configured sidelink resource pool to obtain information on reserved resources, and then select a sidelink resource based on the sensing results.

[0035] In an exemplary embodiment, Tx UE110a may perform operation 412 before operation 414, or operations 412 and 414 may be performed in parallel. If a sidelink resource is selected for transmitting positioning-related control information, the Type 1 LBT procedure may still be in progress. In another exemplary embodiment, Tx UE110a may perform operation 412 after operation 418. Tx UE110a can initiate the Type 1 LBT procedure after transmitting positioning-related control information to Rx UE110b using the selected sidelink resource in the permitted bandwidth.

[0036] In 416, Tx UE110a can determine an efficient method for sidelink PRS detection for Rx UE110b. As mentioned above, due to the LBT procedure, there is uncertainty when Tx UE110a transmits sidelink PRS. Tx UE110a can dynamically determine an efficient PRS detection for Rx UE110b based on, for example, the progress of a Type 1 LBT procedure initiated by Tx UE110a, the delay between the sidelink resource selected for transmitting positioning-related control information and the physical sidelink feedback channel (PSFCH) resource associated with the selected sidelink resource, the radio environment of Tx UE110a and Rx UE110b, or at least one of additional factors.

[0037] In an exemplary embodiment, if the delay between the sidelink resource selected for transmitting positioning-related control information and the PSFCH resource associated with the selected sidelink resource is longer than the estimated remaining time of a Type 1 LBT procedure initiated by Tx UE110a, Tx UE110a can estimate that the Type 1 LBT procedure will be completed before HARQ feedback is sent on the PSFCH. Tx UE110a can then decide to reuse the PSFCH resource to notify Rx UE110 whether the Type 1 LBT procedure was successful or not. The estimated remaining time of the Type 1 LBT procedure is the CCA sensing slot period T.sl at least n times (n × T) sl ) can be determined as n is the current value of the backoff counter N. The delay between the selected sidelink resource and the associated PSFCH resource can be determined from the PSFCH-to-PSFCH time gap parameter K, which is set via the information elements sl-MinTimeGapPSFCH in Tx UE110a and Rx UE110b. For example, for a selected sidelink resource with the last symbol in slot s, the associated PSFCH resource is expected to be in slot s+a (where a is the smallest integer greater than or equal to K).

[0038] External interference in this embodiment may also be considered when Tx UE110a decides whether to reuse the PSFCH to notify Rx UE110 whether the Type 1 LBT procedure was successful. If external interference is little or sporadic, Rx UE110b has a high probability of successfully receiving the sidelink transmission from Tx UE110a. Therefore, Rx UE110b does not need to use the PSFCH to confirm successful reception of the sidelink transmission, and Tx UE110a can reuse the PSFCH to notify Rx UE110b whether the LBT procedure initiated by Tx UE110a was successful. Also, if external interference is little or sporadic, the channel will be idle for most of the time within the delay.

[0039] In an exemplary embodiment, if Tx UE110a and Rx UE110b are in the same radio environment, Tx UE110a may decide in 416 to instruct Rx UE110b to perform a Type 1 LBT procedure to predict the timing of PRS transmissions from Tx UE110a. Rx UE110b may perform a Type 1 LBT procedure in synchronization with the Type 1 LBT procedure performed by Tx UE110a, which will be described in detail below. For convenience of explanation, the LBT procedure performed by Tx UE110a will be referred to as the first LBT procedure, and the LBT procedure performed by Rx UE110b will be referred to as the second LBT procedure.

[0040] In 418, Tx UE110a may transmit positioning-related control information to Rx UE110b using a selected sidelink resource within the permitted bandwidth. As described above, positioning-related control information may be included in the sidelink control information (SCI), and may be transmitted to Rx UE110b before the first LBT procedure initiated by Tx UE110a is completed.

[0041] Depending on the decision in operation 416, the positioning-related control information may include instructions for Rx UE110b to receive notification of whether the first LBT procedure was successful, or instructions for Rx UE110b to perform a second LBT procedure. Instructions for Rx UE110b to perform a second LBT procedure may include one or more parameters related to the first LBT procedure performed by Tx UE110a. In one example, one or more parameters related to the first LBT procedure may include, for example, at least one of the start time or duration of the first LBT procedure, the current value of the backoff counter for the first LBT procedure, the waiting period for the first LBT, the energy threshold for the first LBT procedure, or the channel access priority class for the first LBT procedure.

[0042] If the positioning-related control information transmitted at 418 includes instructions for Rx UE110b to perform the second LBT procedure, Rx UE110b may perform the second LBT procedure at 420. UE110b may perform the second LBT procedure using one or more parameters of the first LBT procedure so that the first and second LBT procedures are performed synchronously with each other. For example, Rx UE110b may use the current backoff counter value of the first LBT procedure to start the backoff counter N of the second LBT procedure.

[0043] At 422a, the first LBT procedure performed by Tx UE110a completes successfully. At 418, Rx UE110b is instructed to perform the second LBT procedure. Since Tx UE110a and Rx UE110b are in the same wireless environment and the second LBT procedure is performed synchronously with the first LBT procedure, the second LBT procedure performed by Rx UE110b also completes successfully at 422b.

[0044] Once the second LBT procedure performed by Rx UE110b has successfully completed, Rx UE110b can determine the timing of sidelink positioning reference signal (PRS) detection in 423. In one embodiment, Rx UE110b may decide to perform sidelink PRS detection in the unlicensed band immediately after the successful completion of the second LBT procedure. In another example, Rx UE110b may decide to start performing sidelink PRS detection in the unlicensed band at the beginning of a slot (e.g., an NR slot) or a symbol within a slot (e.g., an OFDM symbol within an NR slot), where the slot or symbol is after the successful completion of the second LBT procedure. Furthermore, since Tx UE110a and Rx UE110b are in the same radio environment, Rx UE110b may perform an additional shortened / reduced LBT procedure (e.g., when the channel has a waiting period T) immediately before the slot or symbol. d The Rx UE110b can perform an additional check to see if the channel is idle during the above period. After confirming that the channel is idle during the above period, the Rx UE110b can start performing sidelink PRS detection in the unlicensed band at the start of the slot or symbol.

[0045] In 418, if Tx UE110a instructs Rx UE110b to receive notification of whether the first LBT procedure was successful, Rx UE110b recognizes that the PSFCH resource associated with the transmission of positioning-related control information will be used to propagate the notification, and in that case, Rx UE110b may not send HARQ feedback to Tx UE110a on the PSFCH resource associated with the positioning-related control information. Instead, in 424, Rx UE110b receives the notification sent from Tx UE110a on the PSFCH resource.

[0046] The delay between the transmission of positioning-related control information and the associated PSFCH resource is longer than the estimated remaining time of the first LBT procedure initiated by Tx UE110a. Therefore, when Tx UE110a sends a notification on the PSFCH resource to Rx UE110b, the first LBT procedure may have already completed successfully. Subsequently, Tx UE110a sends a HARQ ACK on the PSFCH resource to Rx UE110b, and Rx UE110b can determine from the HARQ ACK that the first LBT procedure was successful.

[0047] For example, if the channel is busy in the sensing slot and Tx UE110a must sense that the channel is idle during an additional waiting period, and the first LBT procedure has not yet completed at the timing of the PSFCH resource, Tx UE110a can send a HARQ NACK on the PSFCH resource to Rx UE110b. From the HARQ NACK, Rx UE110b can determine that the first LBT procedure has not completed successfully.

[0048] When a notification represented by HARQ feedback is received on the PSFCH, Rx UE110b can determine the timing of sidelink positioning reference signal (PRS) detection at 425 based on the received notification. In one example, if the received notification indicates that the first LBT procedure initiated by Tx UE110a has completed successfully, Rx UE110b can decide to immediately perform sidelink PRS detection in the unlicensed band. In another embodiment, if the received notification indicates that the first LBT procedure initiated by Tx UE110a has completed successfully, Rx UE110b can decide to start performing sidelink PRS detection in the unlicensed band at the beginning of a slot (e.g., an NR slot) or a symbol within a slot (e.g., an OFDM symbol within an NR slot). The slot or symbol is one that occurs after the notification has been received by Rx UE110b. If the received notification indicates that the first LBT procedure initiated by Tx UE110a has not yet completed, Rx UE110b may decide not to detect the sidelink PRS transmitted from Tx UE110a in the unlicensed band. In this case, operations 418, 424, and 425 may be repeated until the first LBT procedure completes successfully.

[0049] In the exemplary embodiments described above, a PSFCH resource associated with positioning-related control information is used to send an LBT termination notice, but this disclosure is not limited thereto. In the exemplary embodiments, the positioning-related control information may further include a resource allocation for sending an LBT termination notice. Rx UE110b can use the PSFCH resource to confirm receipt of the positioning-related control information as usual, and Tx UE110a can send an LBT termination notice to Rx UE110b based on the resource allocation.

[0050] In response to notification that the first LBT procedure has completed successfully, or in response to notification that the second LBT procedure has completed successfully, Rx UE110b may initiate detection of sidelink PRS in the unlicensed band at 426.

[0051] In response to the successful completion of the first LBT procedure, Tx UE110a may transmit a sidelink PRS to Rx UE110b in the unlicensed band at 428. In an exemplary embodiment, Tx UE110a may periodically transmit a sidelink PRS during the channel occupancy time (COT) obtained through the first LBT procedure.

[0052] In 430, Rx UE110b can send measurement reports related to the sidelink PRS to Tx UE110a. Rx UE110b can send measurement reports in authorized or unlicensed bands. Before sending a measurement report in an unlicensed band, Rx UE110b may perform a Type 2 LBT procedure to verify channel availability if the measurement report transmission is within a COT shared by Tx UE110a, or a new Type 1 LBT procedure to obtain a new COT if the measurement report transmission is after a COT shared by Tx UE110a.

[0053] In the exemplary embodiment described above, Tx UE110a can dynamically determine efficient sidelink PRS detection for Rx UE110b, and thus Rx UE can rapidly detect sidelink PRS in the unlicensed band with reduced complexity and power consumption. Since the PSFCH may be reused to notify Rx UE that the LBT procedure has been completed at Tx UE, the signaling overhead between Tx UE and Rx UE does not increase significantly.

[0054] In other exemplary embodiments, the first LBT procedure (e.g., a Type 1 LBT procedure) may terminate before the preparation of positioning-related control information. In 418, Tx UE110a may transmit positioning-related control information to Rx UE110b using a selected sidelink resource in the permitted band indicating that the first LBT procedure has terminated. Based on the positioning-related control information, Rx UE110b may determine the timing of sidelink positioning reference signal (PRS) detection. In one embodiment, Rx UE110b may decide to perform sidelink PRS detection in the unlicensed band immediately after receiving the positioning-related control information. In other examples, Rx UE110b may decide to start performing sidelink PRS detection in the unlicensed band at the beginning of a slot (e.g., an NR slot) or a symbol within a slot (e.g., an OFDM symbol within an NR slot). The slot or symbol occurs after Rx UE110b has received the positioning-related control information. Furthermore, if Tx UE110a and Rx UE110b are in the same wireless environment, Rx UE110b will perform an additional shortening / reduction LBT procedure immediately before the slot or symbol (for example, if the channel has a waiting period T d The Rx UE110b can perform an additional check to see if the channel is idle during the above period. After confirming that the channel is idle during the above period, the Rx UE110b can start performing sidelink PRS detection in the unlicensed band at the beginning of the slot or symbol.

[0055] In other exemplary embodiments, the first LBT procedure is a Type 2 LBT procedure, and the first LBT procedure is initiated after operation 418. In 418, Tx UE110a may transmit positioning-related control information to Rx UE110b using a sidelink resource selected in the permitted band, indicating that the first LBT procedure is a Type 2 LBT procedure. Based on the positioning-related control information, Rx UE110b can determine the timing of sidelink positioning reference signal (PRS) detection. In one example, Rx UE110b may decide to perform sidelink PRS detection in the unlicensed band immediately after receiving the positioning-related control information. In another example, Rx UE110b may decide to initiate sidelink PRS detection in the unlicensed band at the beginning of a slot (e.g., an NR slot) or a symbol within a slot (e.g., an OFDM symbol within a slot), which occurs after Rx UE110b has received the positioning-related control information. Furthermore, if the Tx UE110a and Rx UE110b are in the same radio environment, the Rx UE110b can perform an additional shortening / reduction LBT procedure (e.g., a Type 2 LBT) immediately before a slot or symbol. After confirming that the channel is idle, the Rx UE110b can initiate sidelink PRS detection in the unlicensed band at the start of a slot or symbol.

[0056] Figure 5 is a schematic block diagram showing an apparatus 500 according to an exemplary embodiment of the present disclosure. The apparatus 500 may be implemented in terminal equipment such as a Tx UE110a to perform operations related to the Tx UE110a, as described above. The operations related to the Tx UE110a have been described in detail with reference to Figures 1 to 5, so here we will briefly describe the blocks of the apparatus 500, and refer to the above description for further details.

[0057] As shown in Figure 5, the device 500 may comprise a first means 510, a second means 520, and a third means 530. The first means 510 can initiate a first listen-before-talk (LBT) procedure before Tx UE 110a transmits a sidelink positioning reference signal (PRS) to Rx UE 110b in the unlicensed band during a sidelink positioning session. The second means 520 can transmit positioning-related control information to Rx UE 110b in the permitted band. The positioning-related control information may include notification to Rx UE 110b whether the first LBT procedure initiated by Tx UE 110a was successful, or instructions to perform a second LBT procedure. The third means 530 can transmit a sidelink PRS in the unlicensed band in response to the successful completion of the first LBT procedure initiated by Tx UE 110a.

[0058] In an exemplary embodiment, the instruction for Rx UE110b to perform a second LBT procedure may include one or more parameters related to the first LBT initiated by Tx UE110a, so that Rx UE110b can perform the second LBT procedure synchronously with respect to the first LBT procedure performed by Tx UE110a. The one or more parameters related to the first LBT procedure may include at least one of the following: the start time or duration of the first LBT procedure, the backoff counter value of the first LBT procedure, the wait period of the first LBT procedure, the energy threshold of the first LBT procedure, or the channel access priority class of the first LBT procedure.

[0059] In an exemplary embodiment, positioning-related control information is transmitted before the first LBT procedure is completed.

[0060] In exemplary embodiments, the device 500 may further comprise a fourth means 540 and a fifth means 550. The fourth means 540 can select a sidelink resource for transmitting positioning-related control information to the Rx UE 110b. The fifth means 550 can determine whether to notify the Rx UE 110b whether the first LBT procedure was successful or to instruct the Rx UE 110b to perform a second LBT procedure, based on at least one of the progress of the first LBT procedure, the delay between the selected sidelink resource and the sidelink feedback channel resource associated with the selected sidelink resource, or the radio environments of Tx UE 110a and Rx UE 110b.

[0061] In an exemplary embodiment, the fifth means 550 may decide to notify the Rx UE 110b whether the first LBT procedure was successful if the delay between the selected sidelink resource and the sidelink feedback channel resource associated with the selected sidelink resource is longer than the estimated remaining time of the first LBT procedure.

[0062] In an exemplary embodiment, the fifth means 550 may decide to instruct Rx UE110b to perform a second LBT procedure if Tx UE110a and Rx UE110b are in the same radio environment.

[0063] In an exemplary embodiment, the device 500 may further include a sixth means 560 for sending a notification to the Rx UE 110b on the sidelink feedback channel resource associated with the positioning-related control information whether the first LBT procedure was successful, when the positioning-related control information includes an instruction for the Rx UE 110b to receive a notification.

[0064] In an exemplary embodiment, the device 500 may further include a seventh means 570 for determining whether Tx UE110a and Rx UE110b are in the same radio environment before transmitting positioning-related control information. In one example, the seventh means 570 determines that Tx UE110a and Rx UE110b are in the same radio environment if the distance between Tx UE110a and Rx UE110b is less than or equal to a threshold, or if Tx UE110a and Rx UE110b obtain the same measurement result by unlicensed band measurement.

[0065] In an exemplary embodiment, the first LBT procedure performed on Tx UE110a is a type 1 LBT procedure, and the second LBT procedure performed on Rx UE110b is a type 1 LBT procedure.

[0066] Figure 6 is a schematic block diagram showing an apparatus 600 according to an exemplary embodiment of the present disclosure. The apparatus 600 may be implemented with terminal equipment such as an Rx UE110b to perform operations related to the Rx UE110b, as described above. The operations related to the Rx UE110b have been described in detail with reference to Figures 1 to 5, so here we will briefly describe the blocks of the apparatus 600, and refer to the above description for further details.

[0067] As shown in Figure 6, the device 600 may include a first means 610 for receiving positioning-related control information from Tx UE 110a via sidelink in the permitted band, and a second means 620 for performing sidelink positioning reference signal (PRS) detection in the unlicensed band at a timing determined based on the positioning-related control information. The positioning-related control information may include notification to Rx UE 110b whether the first LBT procedure initiated by Tx UE 110a was successful, or instructions to perform a second LBT procedure.

[0068] In an exemplary embodiment, the device 600 may further include a third means 630 for receiving notification on a sidelink feedback channel resource associated with positioning-related control information whether a first LBT procedure initiated by Tx UE 110a was successful, when the positioning-related control information includes instructions for Rx UE 110b to receive notification; and a fourth means 640 for determining the timing of sidelink PRS detection when the received notification indicates that the first LBT procedure initiated by Tx UE 110a was successful.

[0069] In an exemplary embodiment, the device 600 may further include a fifth means 650 for executing a second LBT procedure if the positioning-related control information includes an instruction for Rx UE 110b to execute a second LBT procedure, and a sixth means 660 for determining the timing of sidelink PRS detection if the second LBT procedure executed in Rx UE 110b is successful. The instruction for Rx UE 110b to execute a second LBT procedure may include one or more parameters related to a first LBT procedure initiated by Tx UE 110a. In an exemplary embodiment, one or more parameters related to the first LBT procedure may include at least one of the following: start time or duration of the first LBT procedure, backoff counter value of the first LBT procedure, waiting period of the first LBT procedure, energy threshold of the first LBT procedure, or channel access priority class of the first LBT procedure.

[0070] In an exemplary embodiment, the first LBT procedure initiated by Tx UE110a is a type 1 LBT procedure, and the second LBT procedure executed by Rx UE110b is a type 1 LBT procedure.

[0071] Figure 7 is a schematic block diagram of device 700 according to an exemplary embodiment of the present disclosure. Device 700 may be implemented as the Tx UE110a and / or Rx UE110b described above.

[0072] Referring to Figure 7, the device 700 may comprise one or more processors 711, one or more memories 712, and one or more transceivers 713 interconnected via one or more buses 714. The one or more buses 714 may be an address bus, a data bus, or a control bus, and may include any interconnection mechanism such as a series of wires on a motherboard or integrated circuit, fiber, optical or other optical communication equipment. Each of the one or more transceivers 713 may comprise a receiver and a transmitter connected to one or more antennas 716. The device 700 can wirelessly communicate with network equipment or terminal equipment via one or more antennas 716. The one or more memories 712 may contain instructions 715 that, when executed by one or more processors 711, cause the device 700 to perform operations related to Tx UE110a and / or operations related to Rx UE110b, as described above.

[0073] One or more processors 711 may be of any suitable type appropriate for the local technology network and may include one or more general-purpose processors, special-purpose processors, microprocessors, digital signal processors (DSPs), one or more processors of a processor-based multicore processor architecture, and dedicated processors such as those developed based on field-programmable gate arrays (FPGAs) and special-purpose integrated circuits (ASICs). One or more processors 711 may be configured to control and cooperate with other elements of the device 700 to perform the procedures described above.

[0074] One or more memories 712 may include at least one storage medium of various forms, such as volatile and / or non-volatile media. Volatile memories may include, but are not limited to, random access memory (RAM) or cache. Non-volatile memories may include, but are not limited to, read-only memory (ROM), hard disks, flash memory, etc. Furthermore, one or more memories 712 may include, but are not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any combination thereof.

[0075] Some exemplary embodiments further provide computer program code or instructions that, when executed by one or more processors, can cause a device or apparatus to perform the steps described above. The computer program code or instructions for performing the steps of the exemplary embodiments can be written in any combination of one or more programming languages. The computer program code or instructions can be provided to one or more processors or controllers of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the program code or instructions are executed by the processor or controller, a particular function / operation is performed in a flowchart and / or block diagram. The program code or instructions may run entirely on a machine, partially on a machine as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0076] Some exemplary embodiments further provide non-temporary computer program products, or non-temporary computer-readable media having computer program code or instructions stored therein. As used herein, the term “non-temporary” refers to the limitations of the medium itself (i.e., tangible, not signaling) as opposed to the permanent limitations of data storage (e.g., RAM vs. ROM). A non-temporary computer-readable medium may be any tangible medium that can contain or store a program for use by, or in connection with, an instruction execution system, apparatus, or device. A computer-readable medium may be a computer-readable signaling medium or a computer-readable storage medium. Computer-readable media include, but are not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. More specific examples of computer-readable storage media include electrical connections with one or more wires, portable computer diskettes, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash® memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0077] It will be understood that the blocks in the drawing may be implemented in various ways, including software, hardware, firmware, or any combination thereof. In some embodiments, one or more blocks may be implemented using software and / or firmware, for example, machine-executable instructions stored on a storage medium. In addition to, or instead of, machine-executable instructions, some or all of the blocks in the drawing may be implemented at least partially by one or more hardware logic components. For example, but not limited to, exemplary types of hardware logic components that can be used include FPGAs (Field-Programmable Gate Arrays), ASICs (Application-Specific Integrated Circuits), ASSPs (Application-Specific Standard Products), SOCs (System-on-Chip Systems), and CPLDs (Composite Programmable Logic Devices).

[0078] Furthermore, although the operations are described in a specific order, this should not be understood as requiring that such operations be performed in a specific illustrated order or sequentially, or that all illustrated operations be performed, in order to achieve the desired result. In certain circumstances, multitasking and parallel processing may be preferable. Similarly, although some specific implementation details are included in the above description, these should not be interpreted as limiting the scope of this disclosure, but rather as descriptions of features that may be specific to a particular embodiment. Certain features described in the context of a separate embodiment may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately or in any suitable subcombination in multiple embodiments.

[0079] While this subject matter is described in a language specific to structural features and / or methodological actions, it should be understood that the subject matter defined in the attached claims is not limited to the specific features or actions described above. Rather, the specific features and actions described above are disclosed as examples of implementing the claims.

Claims

1. A first terminal device in a wireless access network, At least one processor, When executed by the at least one processor, the first terminal device receives at least, During a sidelink positioning session, before transmitting a sidelink positioning reference signal to a second terminal device within the radio access network in the unlicensed band, the first listen-before-talk procedure is initiated. Transmitting positioning-related control information to the second terminal device within the permitted bandwidth, wherein the positioning-related control information includes instructions for the second terminal device to receive notification of whether the first listen-before-talk procedure initiated by the first terminal device was successful, or to perform a second listen-before-talk procedure. In response to the successful completion of the first listen-before-talk procedure initiated by the first terminal device, the side-link positioning reference signal is transmitted in the unlicensed band. At least one memory that stores instructions to execute, The first terminal device, including the above.

2. The first terminal device according to claim 1, wherein the positioning-related control information is transmitted before the first listen-before-talk procedure initiated by the first terminal device is completed.

3. When executed by the at least one processor, the first terminal device receives at least, If the positioning-related control information includes the instruction for the second terminal device to receive the notification of whether the first listen-before-talk procedure initiated by the first terminal device was successful, then the notification of whether the first listen-before-talk procedure initiated by the first terminal device was successful is transmitted to the second terminal device on the side-link feedback channel resource associated with the positioning-related control information. The first terminal device according to claim 1, further storing a command to execute the following.

4. The first terminal device according to claim 1, wherein the instruction for the second terminal device to perform the second listen-before-talk procedure includes one or more parameters related to the first listen-before-talk procedure initiated by the first terminal device.

5. The one or more parameters relating to the first listen-before-talk procedure initiated by the first terminal device are: The start time or duration of the first listen-before-talk procedure, The backoff counter value of the first listen-before-talk procedure, Waiting period of the first Listen Before Talk procedure, The energy threshold of the first listen-before-talk procedure, or The channel access priority class of the first listen-before-talk procedure, The first terminal device according to claim 4, comprising at least one of the following.

6. When executed by the at least one processor, the first terminal device receives at least, Selecting a side link resource for transmitting the positioning-related control information to the second terminal device, Based on at least one of the following: the progress of the first listen-before-talk procedure initiated by the first terminal device, the delay between the selected sidelink resource and the sidelink feedback channel resource associated with the selected sidelink resource, or the wireless environment between the first terminal device and the second terminal device, it is determined whether to notify the second terminal device whether the first listen-before-talk procedure initiated by the first terminal device was successful, or to instruct the second terminal device to perform the second listen-before-talk procedure. The first terminal device according to claim 1, further storing a command to execute the following.

7. The first terminal device according to claim 6, wherein the first terminal device decides to notify the second terminal device whether the first listen-before-talk procedure initiated by the first terminal device was successful if the delay between the selected side-link resource and the side-link feedback channel resource associated with the selected side-link resource is longer than the estimated remaining time of the first listen-before-talk procedure initiated by the first terminal device.

8. The first terminal device according to claim 6, wherein the first terminal device decides to instruct the second terminal device to perform the second listen-before-talk procedure when the first terminal device and the second terminal device are in the same wireless environment.

9. When executed by the at least one processor, the first terminal device receives at least, Before transmitting the positioning-related control information, determine whether the first terminal device and the second terminal device are in the same wireless environment. The first terminal device according to claim 8, further storing a command to execute the above.

10. The first terminal device is, If the distance between the first terminal device and the second terminal device is less than or equal to a threshold, If the first terminal device and the second terminal device obtain the same measurement result by measuring the unlicensed bandwidth, The first terminal device according to claim 9, wherein it is determined that the first terminal device and the second terminal device are in the same wireless environment.

11. The first terminal device according to claim 1, wherein the first listen-before-talk procedure initiated by the first terminal device is a type 1 listen-before-talk procedure, and the second listen-before-talk procedure performed by the second terminal device is a type 1 listen-before-talk procedure.

12. A second terminal device in a wireless access network, At least one processor, When executed by the at least one processor, the second terminal device receives at least, Receiving positioning-related control information from a first terminal device within the wireless access network via a sidelink in the permitted band, wherein the positioning-related control information includes receiving notification that the second terminal device has received whether a first listen-before-talk procedure initiated by the first terminal device was successful, or instructions to perform a second listen-before-talk procedure. Based on the positioning-related control information, the system performs side-link positioning reference signal detection in the unlicensed band at a timing determined accordingly. At least one memory that stores instructions to execute, A second terminal device equipped with the following features.

13. When the at least one memory is executed by the at least one processor, it provides at least the second terminal device with If the positioning-related control information includes an instruction for the second terminal device to receive the notification, the first terminal device receives a notification on the side-link feedback channel resource associated with the positioning-related control information indicating whether the first listen-before-talk procedure initiated by the first terminal device was successful. When the received notification indicates that the first listen-before-talk procedure initiated by the first terminal device was successful, the timing of the side-link positioning reference signal detection is determined. The second terminal device according to claim 12, further storing a command to execute the command.

14. When the at least one memory is executed by the at least one processor, it provides at least the second terminal device with The positioning-related control information includes the instruction for the second terminal device to execute the second listen-before-talk procedure, and the instruction for the second terminal device to execute the second listen-before-talk procedure includes one or more parameters related to the first listen-before-talk procedure initiated by the first terminal device, in which case the second listen-before-talk procedure is executed. If the second listen-before-talk procedure performed on the second terminal device is successful, the timing of the detection of the side-link positioning reference signal is determined, The second terminal device according to claim 12, further storing a command to execute the command.

15. The one or more parameters related to the first listen-before-talk procedure are: The start time or duration of the first listen-before-talk procedure, The backoff counter value of the first listen-before-talk procedure, Waiting period of the first Listen Before Talk procedure, The energy threshold of the first listen-before-talk procedure, or The channel access priority class of the first listen-before-talk procedure, The second terminal device according to claim 14, comprising at least one of the above.

16. The second terminal device according to claim 12, wherein the first listen-before-talk procedure initiated by the first terminal device is a type 1 listen-before-talk procedure, and the second listen-before-talk procedure performed by the second terminal device is a type 1 listen-before-talk procedure.

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