Sidelink positioning initialization in 5G networks

Abstract

A mechanism is disclosed for performing sidelink positioning between a target user equipment (UE) and an anchor UE with or without interaction with a fifth generation radio access network (5G) base station (gNB). The mechanism includes transmitting a positioning request from the target UE to one or more anchor UEs via sidelink communication. Positioning signals are received from the one or more anchor UEs via the sidelink communication. Positioning measurements are performed based on the positioning signals.

Description

[Technical Field]

[0001] The present disclosure relates generally to fifth generation radio access network (5G) network technologies, and particularly to initiating sidelink communications between an anchor user equipment (UE) and a target UE to support sidelink positioning with or without reliance on a 5G network for resource communication allocation. [Background technology]

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 336,046, filed April 28, 2022, entitled "Method and Apparatus of Sidelink Positioning," which is incorporated herein by reference.

[0003] Several features related to fifth-generation (5G) new radio access technology are being developed and standardized by the Third Generation Partnership Project (3GPP). For example, one work item includes requirements for 5G New Radio (NR) Vehicle-to-Everything (V2X) wireless communication mechanisms, which aim to provide 5G-compatible, high-speed, and reliable connectivity for mobile communications. Summary of the Invention

[0004] In an embodiment, the present disclosure includes a method implemented by a target user equipment (UE). The method includes transmitting a positioning request to one or more anchor UEs via sidelink communication. The method further includes receiving positioning signals from the one or more anchor UEs via sidelink communication. The method further includes performing positioning measurements based on the positioning signals. A UE, such as a vehicle, phone, computer, tablet, industrial device, or other wireless network-based computing device, may desire to determine its current location / position. Furthermore, such a device may travel outside of network coverage, and thus the network may not be able to provide the UE with a location / position using a positioning system. This aspect includes a mechanism for initiating sidelink positioning between an anchor UE and a target UE. Sidelink positioning is a mechanism that allows either the anchor UE or the target UE to determine the target UE's location relative to the anchor UE via sidelink communication between the target UE and anchor UE without direct interaction, e.g., through a corresponding 5G network. The anchor UE can indicate its respective willingness and capability to serve as anchor UE via signaling. The target UE can then select one or more anchor UEs. The target UE and anchor UE can reserve time and frequency communication resources for signaling via an opportunistic mechanism or via allocation by the 5G network. A positioning request is then sent. The request can be sent by the target UE to one or more anchor UEs. In another example, the request can be sent by the anchor UE to the target UE. In another example, the anchor UE can act as a serving anchor UE and send the request to the target UE and coordinating anchor UEs, or to the target UE for further communication to the coordinating anchor UE. Upon receiving the request, the anchor UE responds with location information. In an example, the request is triggered by a condition. In another example, the location information is sent based on a condition without a request.Once the location information is sent, the target UE can either measure the target UE's location or send the location information back to an anchor UE, such as a serving anchor UE, allowing the anchor UE to measure the target UE's location. Location information from cooperating UEs can also be sent to the serving anchor UE, either directly or via the target UE. By using one or more of these mechanisms, the exchange of location information is triggered via sidelink communication (e.g., directly between UEs without interaction through the 5G network). The UE can then determine the target UE's location through measurements made on the location information without having to rely on a location system in the 5G network. This mechanism therefore enables UEs to perform useful functions, such as enabling UEs (e.g., vehicles) to determine their location even when they are out of network coverage.

[0005] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the target UE communicates with one or more anchor UEs according to sensing-based resource selection of sidelink resources.

[0006] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the target UE communicates with one or more anchor UEs via resource reservations provided by a fifth-generation (5G) base station (gNB).

[0007] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the positioning signal includes a sidelink positioning reference signal (SL-Pos-RS).

[0008] Optionally, in any of the preceding aspects, another implementation of the aspect provides further including selecting one or more anchor UEs prior to sending the positioning request to the anchor UE.

[0009] Optionally, in any of the preceding aspects, another implementation of the aspect provides further including estimating a location of the target UE based on the positioning measurements and locations of the one or more anchor nodes.

[0010] Optionally, in any of the preceding aspects, another implementation of the aspect provides further including receiving an initial positioning request from a serving anchor UE via sidelink communication prior to sending the positioning request to the anchor UE.

[0011] Optionally, in any of the preceding aspects, another implementation of the aspect provides further including sending position measurements via sidelink communication to a serving anchor UE for estimating a location of the target UE.

[0012] Optionally, in any of the preceding aspects, another implementation of the aspect provides that sending the positioning request is triggered by a condition.

[0013] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the conditions include a reference signal received power (RSRP) for a first threshold, a distance for a second threshold, a number of UE anchors for a third threshold, a channel condition for a fourth threshold, or a combination thereof.

[0014] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the one or more anchor UEs are selected based on a UE anchor indication and a UE anchor level.

[0015] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the UE anchor indication indicates whether the corresponding UE is capable of serving as an anchor UE and whether the corresponding UE is enabled to serve as an anchor UE.

[0016] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the UE anchor level is set based on a synchronization source, a priority level, a location accuracy, a maximum bandwidth, an in-coverage indicator, a sidelink synchronization signal identifier (SLSSID), or a combination thereof.

[0017] Optionally, in any of the preceding aspects, another implementation of the aspect provides further including reselecting one or more anchor UEs after obtaining anchor UE locations, channel measurements, timing measurements, or a combination thereof.

[0018] In an embodiment, the present disclosure includes a method implemented by an anchor user equipment (UE). The method includes transmitting a positioning request to a target UE via sidelink communication. The method further includes receiving a positioning signal from the target UE via sidelink communication. The method further includes performing positioning measurements on the target UE based on the positioning signal. A UE, such as a vehicle, phone, computer, tablet, industrial device, or other wireless network-based computing device, may desire to determine its current location / position. Furthermore, such a device may travel outside of network coverage, and thus the network may not be able to provide the UE with a location / position using a positioning system. This aspect includes a mechanism for initiating sidelink positioning between an anchor UE and a target UE. Sidelink positioning is a mechanism that allows either the anchor UE or the target UE to determine the target UE's location relative to the anchor UE via sidelink communication between the target UE and anchor UE without direct interaction, e.g., through a corresponding 5G network. The anchor UE can indicate its respective willingness and capability to serve as anchor UE via signaling. The target UE can then select one or more anchor UEs. The target UE and anchor UE can reserve time and frequency communication resources for signaling via an opportunistic mechanism or via allocation by the 5G network. A positioning request is then sent. The request can be sent by the target UE to one or more anchor UEs. In another example, the request can be sent by the anchor UE to the target UE. In another example, the anchor UE can act as a serving anchor UE and send the request to the target UE and coordinating anchor UEs, or to the target UE for further communication to the coordinating anchor UE. Upon receiving the request, the anchor UE responds with location information. In an example, the request is triggered by a condition. In another example, the location information is sent based on a condition without a request.Once the location information is sent, the target UE can either measure the target UE's location or send the location information back to an anchor UE, such as a serving anchor UE, allowing the anchor UE to measure the target UE's location. Location information from cooperating UEs can also be sent to the serving anchor UE, either directly or via the target UE. By using one or more of these mechanisms, the exchange of location information is triggered via sidelink communication (e.g., directly between UEs without interaction through the 5G network). The UE can then determine the target UE's location through measurements made on the location information without having to rely on a location system in the 5G network. This mechanism therefore enables UEs to perform useful functions, such as enabling UEs (e.g., vehicles) to determine their location even when they are out of network coverage.

[0019] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the anchor UE communicates with the target UE according to sensing-based resource selection of the sidelink resources.

[0020] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the anchor UE communicates with the target UE via resource reservations provided by a fifth generation (5G) base station (gNB).

[0021] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the positioning signal includes a sidelink positioning reference signal (SL-Pos-RS).

[0022] Optionally, in any of the preceding aspects, another implementation of the aspect provides further including estimating a location of the target UE based on the positioning measurements.

[0023] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the positioning request signals the target UE to send one or more second positioning requests to one or more cooperating anchor UEs.

[0024] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the positioning signal from the target UE includes location information from one or more cooperating anchor UEs.

[0025] Optionally, in any of the preceding aspects, another implementation of the aspect provides further including receiving location information from one or more cooperating anchor UEs.

[0026] Optionally, in any of the preceding aspects, another implementation of the aspect provides further including sending one or more second positioning requests to one or more cooperating anchor UEs.

[0027] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the positioning request is triggered by a condition.

[0028] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the conditions include a reference signal received power (RSRP) for a first threshold, a distance for a second threshold, a number of UE anchors for a third threshold, a channel condition for a fourth threshold, or a combination thereof.

[0029] Optionally, in any of the preceding aspects, another implementation of the aspect provides further including transmitting a UE anchor indication indicating whether the anchor UE is capable of serving as an anchor UE and whether the anchor UE is enabled to serve as an anchor UE.

[0030] Optionally, in any of the preceding aspects, another implementation of the aspect provides further including transmitting the UE anchor level set based on a synchronization source, a priority level, a location accuracy, a maximum bandwidth, an in-coverage indicator, a sidelink synchronization signal identifier (SLSSID), or a combination thereof.

[0031] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the one or more anchor UEs are selected according to a line-of-sight (LOS) / non-line-of-sight (NLOS) indicator.

[0032] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the sidelink positioning measurement report impairs a line-of-sight (LOS) / non-line-of-sight (NLOS) indicator.

[0033] In an embodiment, the present disclosure includes a UE comprising one or more processors, a transmitter coupled to the one or more processors, and a receiver coupled to the one or more processors, wherein the one or more processors, the transmitter, and the receiver are configured to perform the method of any of the preceding aspects.

[0034] In an embodiment, the present disclosure includes a non-transitory computer-readable medium comprising a computer program product for use by a UE, the computer program product comprising computer-executable instructions stored on the non-transitory computer-readable medium that, when executed by one or more processors, cause the UE to perform the method of any of the preceding aspects.

[0035] In an embodiment, the present disclosure includes a UE comprising transmitting means for transmitting a positioning request to one or more anchor UEs via sidelink communication, the UE further comprising receiving means for receiving positioning signals from the one or more anchor UEs via sidelink communication, and the UE further comprising measuring means for performing positioning measurements based on the positioning signals.

[0036] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the UE is further configured to perform the method of any of the preceding aspects.

[0037] In an embodiment, the present disclosure includes a UE comprising transmitting means for transmitting a positioning request to a target UE via sidelink communication, the UE further comprising receiving means for receiving a positioning signal from the target UE via sidelink communication, and the UE further comprising measuring means for performing positioning measurements on the target UE based on the positioning signal.

[0038] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the UE is further configured to perform the method of any of the preceding aspects.

[0039] For clarity, any one of the above embodiments may be combined with any one or more of the other above embodiments to create new embodiments within the scope of the present disclosure.

[0040] These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims. [Brief explanation of the drawings]

[0041] For a more complete understanding of the present disclosure, reference is now made to the following brief description, taken in conjunction with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

[0042] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of in-network coverage operation and out-of-network coverage operation using 5G network compliant technology. [Figure 2] FIG. 1 is a schematic diagram of an example resource pool in a resource grid for sidelink communication. [Figure 3]FIG. 1 is a schematic diagram of an example resource grid with physical sidelink control channel (PSCCH), physical sidelink shared channel (PSSCH), and physical sidelink feedback channel (PSFCH) resources; [Figure 4] FIG. 1 is a schematic diagram of an exemplary structure of a Sidelink Synchronization Signal Block (S-SSB) block; [Figure 5] 1 is a schematic diagram of an exemplary uplink (UL) sounding reference signal (SRS). [Figure 6] FIG. 1 is a schematic diagram of an exemplary downlink (DL) positioning reference signal (PRS). [Figure 7] FIG. 10 is a schematic diagram of an exemplary sensing and resource selection window. [Figure 8] FIG. 1 is a schematic diagram illustrating sidelink positioning. [Figure 9] FIG. 1 is a schematic diagram illustrating sidelink positioning triggered by a target UE. [Figure 10] FIG. 1 is a schematic diagram illustrating sidelink positioning triggered by an anchor UE. [Figure 11] 10 is a flowchart of an example method for request-triggered positioning at a target UE. [Figure 12] 10 is a flowchart of an example method for a hybrid procedure for positioning at an anchor UE. [Figure 13] 10 is a flowchart of an example method for a UE to determine and indicate an anchor level to support UE anchor selection.

[0043] [Figure 14] 1 is a flowchart of an example method for anchor UE selection. [Figure 15] FIG. 1 is a schematic diagram showing an anchor UE broadcasting a Sidelink Positioning Reference Signal (SL-Pos-RS) and location information. [Figure 16] 1 is a schematic diagram of an example of line-of-sight (LOS) and non-line-of-sight (NLOS) sidelink positioning. [Figure 17] FIG. 1 is a schematic diagram of an example of a positioning reference signal (PRS) resource set. [Figure 18] FIG. 1 is a schematic diagram of an example UL PRS resource configuration. [Figure 19] FIG. 1 is a schematic diagram of an exemplary sidelink synchronization signal block (S-SSB). [Figure 20] FIG. 1 is a schematic diagram of an example UE for sidelink communication. [Figure 21] FIG. 1 is a schematic diagram of an exemplary embodiment of a UE for sidelink positioning. [Figure 22] 10 is a flowchart of an example method for performing sidelink-based positioning at a target UE; [Figure 23] 10 is a flowchart of an example method for performing sidelink-based positioning at an anchor UE; DETAILED DESCRIPTION OF THE INVENTION

[0044] While exemplary implementations of one or more embodiments are provided below, it should be understood at the outset that the disclosed systems and / or methods may be implemented using any number of techniques, whether currently known or in existence. The present disclosure should in no way be limited to the exemplary implementations, drawings, and techniques shown below, including the exemplary designs and implementations shown and described herein, but may be modified within the scope of the appended claims along with their full range of equivalents.

[0045] 3GPP provided the basis for NR sidelink communications for applications such as safety systems and autonomous driving. High data rates, low latency, and high reliability were some of the areas investigated and standardized. 3GPP also provided a sidelink enhancement work item to further enhance the capabilities and performance of sidelink communications. One of the objectives of that work item was to introduce an inter-UE coordination mechanism whereby one UE shares preferred or non-preferred resources for another UE to use in its resource selection, or sends a contention indication to other UEs when there is contention on reserved resources.

[0046] A further work item requested NR positioning support, which provides positioning support in 5G NR, including DL and UL reference signals for various positioning techniques (DL-TDOA, DL-AoD, UL-TDOA, UL-AoA, multi-cell RTT, and E-CID), as well as UE and gNB measurements for NR positioning. A further work item requested NR positioning extensions aimed at supporting high accuracy, low latency, network efficiency, and device efficiency requirements for commercial use cases. This work item concerned methods, measurements, signaling, and procedures for improving positioning accuracy relative to other exemplary positioning methods. Research items related to deployed and improved NR positioning include the study of sidelink positioning solutions. This disclosure describes techniques and signaling for enabling sidelink positioning.

[0047] FIG. 1 is a schematic diagram illustrating an example 100 of in-network and out-of-network coverage operation using 5G network-compliant technology. Sidelink communications can be either in-coverage or out-of-coverage. In in-coverage (IC) operation, a central node 101, such as a 5G base station (gNB) or a fourth-generation evolved Node B base station (eNB), may be present and used to manage sidelink communications 103 between UEs 105. This is known as Mode 1. In operation Mode 2, system operation is fully distributed, and UEs 105 select resources themselves to support sidelink communications 103 between UEs 105. In the present disclosure, some UEs may also be facilitated / assisted in selecting their resources. In Mode 2, UEs can be either in-coverage or out-of-coverage (OOC).

[0048] 2 is a schematic diagram of an example resource pool 200 in a resource grid for sidelink communications. Resource pool 200 is a set of resources that can be used for sidelink communications. The resources in resource pool 200 are configured for various channels, including control channels, shared channels, feedback channels, synchronization signals, reference signals, broadcast channels (e.g., master information blocks), etc.

[0049] The resource pool 200 for the sidelink may be organized in units of slots in the time domain and in units of physical resource blocks (PRBs) or subchannels in the frequency domain. A subchannel contains one or more PRBs. Figure 2 shows an example of a resource pool 200 in a time-frequency resource grid.

[0050] In NR mobile broadband (MBB), each PRB in the grid is defined as a slot of 14 consecutive orthogonal frequency division multiplexing (OFDM) symbols in the time domain and 12 consecutive subcarriers in the frequency domain. Therefore, each resource block contains 12 × 14 resource elements (REs). When used as a frequency domain unit, a PRB is 12 consecutive subcarriers. When a normal cyclic prefix (CP) is used, there are 14 symbols in a slot, and when an extended cyclic prefix (ECP) is used, there are 12 symbols in a slot. The duration of a symbol is inversely proportional to the subcarrier spacing (SCS). For {15, 30, 60, 120} kilohertz (kHz) SCSs, the slot durations are {1, 0.5, 0.25, 0.125} milliseconds (ms), respectively. Each of the PRBs may be allocated to a combination of a control channel (CCH), a shared channel (SCH), a feedback channel, a reference signal (RS), etc. Additionally, some REs of a PRB may be reserved. A communication resource may occupy a PRB, a set of PRBs, use a code (if code division multiple access (CDMA) is used, such as in a physical uplink control channel (PUCCH)), a physical sequence, a set of REs, etc.

[0051] 3 is a schematic diagram of an example resource grid 300 with PSCCH 301, PSSCH 303, and PSFCH 305 resources. PSCCH 301 carries sidelink control information (SCI). A source UE uses the SCI to schedule data transmission on PSSCH 303. The SCI can carry time and frequency resources for PSSCH 303, parameters of hybrid automatic repeat request (HARQ) processing, such as redundancy version, processing identifier (id), new data indicator, and resources for PFSCH 305. PFSCH 305 indicates whether a receiver / destination UE has correctly decoded the payload carried on PSSCH 303 (e.g., acknowledgement (ACK) or negative acknowledgement (NACK)). )The SCI may carry an indication such as a HarQ Acknowledgement (HARQ-ACK) of the source UE. The SCI may also carry a bit field indicating a representation of the identity of the source UE. Additionally, the SCI may also carry a bit field indicating a representation of the identity of the destination UE. Other fields include the modulation coding scheme (MCS) used to encode the payload and modulate the coded payload bits, the demodulation reference signal (DMRS) pattern, the antenna port, and the payload (transmission) priority.

[0052] NR sidelink control information (SCI) can be transmitted in a first-stage SCI and a second-stage SCI. The first-stage SCI uses SCI format 1-A. The second stage uses SCI format 2-A, SCI format 2-B, or SCI format 2-C. The first-stage SCI indicates resources for the second-stage SCI.

[0053] SCI format 1-A is used for scheduling of the PSSCH and for second-stage SCI on the PSSCH. By using SCI format 1-A, the following information is transmitted: - Priority - 3 bits - Frequency resource allocation - when the higher layer parameter sl-MaxNumPerReserve is configured with a value of 2,

[0054]

number

[0055] bit, otherwise when the value of the upper layer parameter sl-MaxNumPerReserve is configured to 3,

[0056]

number

[0057] bit. - Time resource allocation - 5 bits when the higher layer parameter sl-MaxNumPerReserve is configured with a value of 2, otherwise 9 bits when the higher layer parameter sl-MaxNumPerReserve is configured with a value of 3. - resource reservation period - if the upper layer parameter sl-MultiReserveResource is configured,

[0058]

number

[0059] bits, where N rsv_period is the number of entries in the upper layer parameter sl-ResourceReservePeriodList, otherwise a 0 bit. - DMRS pattern -

[0060]

number

[0061] bits, where N pattern is the number of DMRS patterns configured by the higher layer parameter sl-PSSCH-DMRS-TimePatternList, or 0 bit if sl-PSSCH-DMRS-TimePatternList is not configured. - Second stage SCI format - 2 bits. - Beta_offset indicator - 2 bits as provided by the upper layer parameter sl-BetaOffsets2ndSCI. - Number of DMRS ports - 1 bit. - Modulation and coding scheme - 5 bits. - Additional MCS table indicator -: 1 bit if one MCS table is configured by the upper layer parameter sl-Additional-MCS-Table, 2 bits if two MCS tables are configured by the upper layer parameter sl-Additional-MCS-Table, 0 bit otherwise. - PSFCH overhead indication - 1 bit if higher layer parameter sl-PSFCH-period = 2 or 4, otherwise 0 bit. - Reserved - the number of bits as determined by the higher layer parameter sl-NumReservedBits, with the value set to 0.

[0062] SCI format 2-A is used for decoding PSSCH together with HARQ-ACK operation when HARQ-ACK information includes ACK or NACK, or when there is no feedback of HARQ-ACK information. The following information is transmitted by SCI format 2-A: - HARQ transaction number -

[0063]

number

[0064] . - New Data Indicator - 1 bit. - Redundant version - 2 bits. - Source ID - 8 bits. - Destination ID - 16 bits. - HARQ feedback enable / disable indicator - 1 bit. - Cast Type Indicator - 2 bits as defined in Table 8.4.1.1-1. - CSI Request - 1 bit.

[0065] [Table 1]

[0066] SCI format 2-B is used for decoding PSSCH together with HARQ operation when HARQ-ACK information contains only NACK or when there is no feedback of HARQ-ACK information. The following information is transmitted by SCI format 2-B: - HARQ transaction number -

[0067]

number

[0068] bit. - New Data Indicator - 1 bit. - Redundant version - 2 bits. - Source ID - 8 bits. - Destination ID - 16 bits. - HARQ feedback enable / disable indicator - 1 bit. - Zone ID - 12 bits. - Range requirement - 4 bits.

[0069] SCI format 2-C is used for decoding the PSSCH and for providing or requesting inter-UE coordination information. The following information is transmitted by SCI format 2-C: - HARQ process number - 4 bits - New Data Indicator - 1 bit - Redundant version - 2 bits. - Source ID - 8 bits. - Destination ID - 16 bits. - HARQ feedback enable / disable indicator - 1 bit. - CSI Request - 1 bit. - Provide / Request Indicator - 1 bit, where value 0 indicates that SCI Format 2-C is used to provide UE-to-UE coordination information, and value 1 indicates that SCI Format 2-C is used to request UE-to-UE coordination information.

[0070] Upper Layer Messages SL-PSCCH-Config-r16 ::= SEQUENCE { sl-TimeResourcePSCCH-r16 ENUMERATED {n2,n3} OPTIONAL, -- M required sl-FreqResourcePSCCH-r16 ENUMERATED {n10,n12,n15,n20,n25} OPTIONAL, -- M required sl-DMRS-ScrambleID-r16 INTEGER (0..65535) OPTIONAL, -- M required sl-NumReservedBits-r16 INTEGER (2..4) OPTIONAL, -- M required ... }

[0071] [Table 2]

[0072] If the "Offered / Requested Indicator" field is set to 0, all remaining fields are set as follows: - Resource combination -

[0073]

number

[0074] Bit, where - If the upper layer parameter sl-MultiReserveResource is configured,

[0075]

number

[0076] and N rsv_period is the number of entries in the upper layer parameter sl-ResourceReservePeriodList, otherwise Y=0 -

[0077]

number

[0078] is the number of subchannels in the resource pool provided by higher layer parameters, sl-NumSubchannel - First resource location - 8 bits. - Reference slot location -

[0079]

number

[0080] bit. - Resource Set Type - 1 bit, where a value of 0 indicates a preferred resource set and a value of 1 indicates a non-preferred resource set. - lowest subchannel index -

[0081]

number

[0082] bit.

[0083] If the "Offered / Requested Indicator" field is set to 1, all remaining fields are set as follows: - Priority - 3 bits. A value of "000" in the priority field corresponds to a priority value of "1", a value of "001" in the priority field corresponds to a priority value of "2", etc. - Number of sub-channels -

[0084]

number

[0085] bit. - resource reservation period - if the upper layer parameter sl-MultiReserveResource is configured,

[0086]

number

[0087] bits, where N rsv_period is the number of entries in the upper layer parameter sl-ResourceReservePeriodList, otherwise a 0 bit. - Resource selection window location -

[0088]

number

[0089] bit. - Resource Set Type - 1 bit, where if the higher layer parameter determineResourceSetTypeScheme1 is configured to "UE-B request", a value of 0 indicates a request for UE-to-UE coordination information providing a preferred resource set, a value of 1 indicates a request for UE-to-UE coordination information providing a non-preferred resource set, otherwise a 0 bit. - Padding bits.

[0090] Sidelink Inter-UE Coordination (IUC) is specified to improve Mode 2 reliability by overcoming issues such as hidden nodes, exposed nodes, and half-duplex that affect sidelink performance. In particular, two IUC schemes are defined, namely: Method 1: UE-to-UE cooperative information signaling from UE-A to UE-B A set of preferred resources for UE-B's transmissions A set of resources that are not preferred for UE-B transmission Method 2: Inter-UE cooperative information signaling from UE-A to UE-B The presence of expected / potential resource contention on the resources indicated by UE-B's SCI

[0091] In IUC Scheme 1, two IUC triggering scenarios are considered and specified. These include 1) cooperation triggered by an explicit request, in which UE-B sends an explicit request to UE-A, and UE-A generates and sends cooperation information (preferred or non-preferred resource sets for UE-B) upon request, and 2) cooperation triggered by a condition other than an explicit request, in which a UE (UE-A) meeting a certain condition generates and sends cooperation information to UE-B.

[0092] Conditions for two IUC triggering scenarios are also specified. For IUC triggered by explicit request, one of two conditions is configured for the resource pool level. These include alt1, which is up to UE-B's implementation, and alt2, where the request can be triggered only when UE-B has data to be sent to UE-A. Similarly, for IUC triggered by condition, two conditions are used, one of which is enabled by resource pool level (pre-)configuration. These include alt1, which is up to UE-A's implementation, and alt2, where collaboration can be triggered only when UE-A has data to be sent to UE-B along with collaboration information.

[0093] The criteria for generating the coordination information, in which the preferred and non-preferred resource sets are defined, are as follows: Preferred resource set: Condition 1-A-1: Resources excluding overlapping reserved resources of other UEs with reference signal received power (RSRP) greater than a threshold. Condition 1-A-2: Resources excluding slots in which UE-A, as UE-B's Rx, does not expect to receive SL from UE-B. Unfavorable resource sets: Condition 1-B-1: Reserved resources of other UEs identified by RSRP measurements. · Option 1: Reserved resources of other UEs identified by UE-A whose RSRP measurements are greater than the (pre)configured RSRP threshold. · Option 2: Reserved resources of other UEs identified by UE-A whose RSRP measurements are smaller than the (pre)configured RSRP threshold when UE-A is the destination of a TB sent by the UE. Condition 1-B-2: Resources (e.g., slots) on which UE-A does not expect to perform SL reception from UE-B when it is the intended receiver of UE-B.

[0094] To send explicit requests and cooperative information, the Medium Access Control Protocol (MAC) Explicit Request and Cooperative Information (MAC-CE) is used as a container. If configured, the second-stage SCI (SCI-2C) is also used for explicit requests or cooperative information.

[0095] In collaboration triggered by explicit requests, only unicast is supported for transmission of both explicit requests and collaboration information. In collaboration triggered by conditions, unicast is supported for transmission of both types of collaboration information. Broadcast and groupcast are supported only for non-preferred resource sets.

[0096] Collaboration information and explicit requests can be multiplexed and sent with data only if the source / destination ID pair is the same.

[0097] Figure 4 is a schematic diagram of an example structure of an S-SSB block 400. The synchronization slot in the sidelink is denoted as S-SSB 400 and is designated for one UE to synchronize with another UE. As shown in Figure 4, the first OFDM symbol is for the PSBCH. However, as in a regular sidelink slot, the first symbol is used for automatic gain control (AGC) settling. After that, there are two symbols for S-PSS and two for S-SSS. Eight of the remaining nine symbols are for PSBCH transmission. The last symbol is a guard period (GP), as in a regular sidelink slot. The PSBCH carries the SL Master Information Block (SL-MIB).

[0098] In the frequency domain, S-SSB occupies 11 PRBs with a total of 132 subcarriers. While the PSBCH occupies all 11 PRBs, the synchronization signal size is 127, so S-PSS and S-SSS occupy 127 subcarriers. The S-SSB periodicity is 160 ms. The frequency location of the S-SSB is pre-configured. The number of S-SSB transmissions is set to 1 in FR1 and is configurable in FR2.

[0099] 5 is a schematic diagram of an example UL SRS 500. In NR, SRS resources using one, two, or four antenna ports are supported, which are:

[0100]

number

[0101] can be mapped to K consecutive OFDM symbols in the frequency domain. TC = 2, 4, or 8 RE combinatorial transmissions are supported. In addition, the cyclic shifts are limited to the maximum number of cyclic shifts equal to 8, 12, and 6 when the comb size is 2, 4, and 8, respectively.

[0102]

number

[0103] The SRS sequence ID is configured by higher layer parameters. The starting OFDM symbol l0 in the time domain is offset l from the end of the slot. offset is defined by, where l offset ∈{0,1,...,13} indicates that the start position can be any OFDM symbol in the slot. The frequency start position is also specified. For positioning, an additional offset in the frequency domain is

[0104]

number

[0105] is specified, which also depends on the OFDM symbols configured for SRS transmission. SRS resources can be configured for periodic, semi-persistent, or aperiodic SRS transmission. In the frequency domain, SRS allocation is aligned with a four-PRB grid. Frequency hopping is supported as in the case of Long Term Evolution (LTE). NR SRS bandwidth and hopping configurations are designed to cover larger span values ​​compared to those of LTE.

[0106] SRS resources are configured by the SRS-Resource IE for UL channel sounding or by the SRS-PosResource IE for positioning purposes. A UE can be configured with one or more SRS resource sets. For each SRS resource set, the UE may be configured with several SRS resources. The use cases of the SRS resource sets are configured by higher layer parameters. Such use cases may include beam management, codebook-based uplink MIMO, and non-codebook-based uplink multiple-input multiple-output (MIMO), as well as antenna switching, which is in fact for general downlink CSI acquisition.

[0107] In the time domain at slot level, the SRS resource is determined by the periodicity in slots (T SRS ) and slot offset (T offset ) can be periodically constructed.

[0108] [Table 3]

[0109] [Table 4]

[0110] 6 is a schematic diagram of an exemplary DL-PRS 600. The PRS is a downlink reference signal for positioning purposes. The PRS is also referred to as the DL-PRS 600, while an SRS configured for positioning is sometimes referred to as the UL-PRS 500.

[0111] DL-PRS600 is a starting symbol

[0112]

number

[0113] , the size of the PRS (number of OFDM symbols) L PRS ∈{2,4,6,12}, frequency domain spacing (comb size) of two DL-PRS resource elements

[0114]

number

[0115] this is,

[0116]

number

[0117] and an initial frequency domain offset

[0118]

number

[0119] , and with an additional frequency domain offset k' specified in the table (Table 7.4.1.7.3-1) that varies per OFDM symbol, similar to the UL-SRS for positioning.

[0120] [Table 5]

[0121] In the time domain at the slot level, the DL-PRS600 detects periodic

[0122]

number

[0123] and slot offset

[0124]

number

[0125] , as well as additional slot offsets

[0126]

number

[0127] The bandwidth of the DL-PRS can be configured in steps of 4 PRBs in the range of 24 to 275 PRBs.

[0128] There is a need for 3GPP-based sidelink positioning solutions. Various use cases can benefit from SL positioning, such as vehicle-to-everything (V2x) and public safety use cases, ranging-based services, and industrial Internet of Things (IIoT) use cases.

[0129] Research topics for developing and improving NR positioning include the following SL positioning objectives: ● To study and evaluate the performance and feasibility of potential solutions for SL positioning, taking into account relative positioning, ranging and absolute positioning: [RAN1, RAN2] Evaluate the bandwidth requirements needed to meet the identified accuracy requirements [RAN1] Research into positioning methods (e.g., TDOA, RTT, AOA / D, etc.) that involve combining SL positioning measurements with other RAT-dependent positioning measurements (e.g., Uu-based measurements) [RAN1] Study of sidelink reference signals for positioning purposes from a physical layer perspective, including signal design, resource allocation, measurements, and related procedures, reusing existing reference signals, procedures, etc. from sidelink communications and from positioning as much as possible [RAN1]. Study of positioning architecture and signaling procedures (e.g. configuration, measurement reporting, etc.) to enable sidelink positioning covering both UE-based and network-based positioning [RAN2, including coordination and harmonization with RAN3 and SA2 as needed]

[0130] Sidelink resource allocation is discussed next. In NR V2X sidelink mode 1, the gNB performs sidelink scheduling. Thus, the gNB allocates SL resources for SL communication, and the resource allocation is sent to the UE through the NR Universal Mobile Telecommunications System Terrestrial Radio Access Network (UTRAN) to UE (Uu) interface. Therefore, sidelink mode 1 is applicable to UEs under the coverage of the gNB. The resources allocated in mode 1 can be on either the same carrier as cellular NR or a dedicated sidelink carrier.

[0131] There are three types of Mode 1 resource allocation. They include dynamic allocation, Type 1 Configuration Grant (CG), and Type 2 Configuration Grant. In dynamic allocation, the UE first sends a scheduling request (SR) per TB to the gNB via the PUCCH. The gNB then sends SL resource allocation to the UE via downlink control information (DCI) format 3_0 on the physical downlink control channel (PDCCH). In CG-based resource allocation, the UE first sends a message to the gNB with expected SL traffic, including periodicity, maximum traffic bandwidth (TB) size, and quality of service (QoS) information. The gNB provides the resource allocation. The gNB provides the CG to the UE using radio resource control (RRC) signaling. In Type 1 CG, the UE can use the resource allocation immediately. In Type 2 CG, the UE uses the allocated resources after being activated by the gNB via DCI.

[0132] FIG. 7 is a schematic diagram of an exemplary sensing and resource selection window 700. In sidelink mode 2, the UE transmits and receives information without the need for network management. The UE itself allocates resources from a resource pool for sidelink transmissions. Resource allocation relies on a sensing and reservation process as shown in FIG. 7. During the sensing procedure, the monitoring UE detects the SCI transmitted in each of the slots during the sensing window and measures the RSRP of the resources indicated in the SCI. The monitoring UE may also receive data transmissions and thus may also be a receiving UE. For periodic traffic, resource reservation for sidelink transmissions can be used. The UE may receive data in slots s k When occupying the resource on slot s, the UE k +q*RRI k where q is an integer and RRI k is the resource reservation interval for UE m detected by the sensing UE. Detecting the SCI includes receiving and decoding the PSCCH and processing the SCI in the PSCCH.

[0133] In aperiodic or dynamic transmission, the transmitting UE reserves multiple resources and indicates the next resource in the SCI. Therefore, based on the sensing result, the monitoring UE can determine which resources may be occupied in the future and, in a resource exclusion procedure, avoid them for its own transmission if the measured RSRP on the occupied resources during the sensing period exceeds the RSRP threshold.

[0134] Figure 7 shows timing information for sensing and resource selection for NR sidelink transmission, called full sensing. proc,0 ], when resource selection is triggered on slot n based on the sensing result during the sensing window, the transmitting UE selects a resource in the resource pool during the resource selection window on slot [n+T1, n+T2], where: T0: The number of slots with values ​​determined by the resource pool configuration, T proc,0 : the time required for the UE to complete the sensing process, T1: Processing time required for identifying candidate resources and selecting resources T1≦T proc,1 , T2: It is left to the UE implementation, but [T 2min ,PDB], the last slot of the resource pool for resource selection, where,T 2min is the minimum value of T2, PDB indicates the packet delay budget, the remaining time for the UE to transmit a data packet; and T proc,1 : The maximum time required for the UE to identify candidate resources and select new sidelink resources.

[0135] Some N R Positioning methods may be used, including DL-based solutions, UL-based solutions, and DL and UL-based solutions.

[0136] DL-based solutions are discussed next. A timing-based technique known as downlink time difference of arrival (DL-TDOA) can be used. Similar to observed time difference of arrival (OTDOA) in LTE, DL-TDOA positioning specified in NR measures the timing difference of DL-PRS on line-of-sight (LOS) paths from different gNBs. Downlink angle of departure (DL-AOD) is an example of an angle-based positioning technique used by the UE. In DL-AOD, the UE measures the received power based on the DL-PRS and estimates the angle of departure (AOD) from different gNBs based on the measured power difference between PRSs and / or beams from the same transmitting and receiving point (TRP).

[0137] UL-based solutions are discussed next. Uplink Time Difference of Arrival (UL-TDOA) is an exemplary timing-based technique. NR introduces a UL positioning technique that uses UL positioning signals configured using UL SRS. The gNB measures the UL timing difference from the UE. Uplink Angle of Arrival (UL-AOA) is an exemplary angle-based technique. Similar to DL-AOD, the gNB measures the AOA from the UE using UL SRS configured for positioning purposes. The gNB measures both zenith and azimuth AOA to obtain a three-dimensional (3D) location.

[0138] DL and UL-based solutions are discussed next. Multi-cell round trip time (multi-RTT) is an exemplary timing-based technique. In multi-RTT, the UE measures the UE's receive-to-transmit (Rx-Tx) time difference, and the gNB measures the gNB's Rx-Tx time difference. The round trip time (RTT) can be estimated using the two Rx-Tx time differences for each UE-gNB pair. For the Rx-Tx time difference measurement, DL PRS and UL SRS are configured and transmitted from the gNB and UE, respectively. Enhanced Cell ID (E-CID) is a positioning technique based on radio resource management (RRM) measurements such as RSRP and resource signal received quality (RSRQ) via SSB measurements and synchronization signals such as channel state information reference signals (CSI-RS). UL AOA is also supported. 。

[0139] Positioning method selection, reference signal (SRS, PRS) configuration, and measurement collection are orchestrated by a Location Management Function (LMF) resident in the network. The LMF manages support of various location services for the target UE, including UE positioning and providing assistance data to the UE. The LMF may interact with the serving gNB or serving ng-eNB for the target UE to obtain UE position measurements. Such position measurements include uplink measurements made by the Next Generation Radio Access Network (NG-RAN) and downlink measurements made by the UE that are provided to the NG-RAN as part of other functions, such as for handover support.

[0140] Figure 8 is a schematic diagram illustrating sidelink positioning 800. Radio Access Technology (RAT)-dependent positioning in cellular systems uses various procedures. For NR positioning, the functions and procedures are similar to those used in LTE. Several techniques and UL reference signals are introduced for NR. However, for SL positioning, the procedures and reference signaling have not yet been defined.

[0141] 8, a sidelink positioning 800 system may include multiple location reference UEs, shown as anchor UE 801 and target UE 803. The sidelink positioning 800 acquires the location of the target UE 803 based on the location information of the anchor UE 801 through reference signal measurements exchanged between the target UE 803 and the anchor UE 801. Reference signaling for the SL positioning measurements is shown as the SL Positioning Reference Signal (SL Pos-RS) 805.

[0142] In NR positioning, DL and UL positioning signaling are well synchronized and orchestrated. The network can provide signaling configuration for positioning, such as DL PRS or UL SRS, and measurement reporting. Unlike the NR Uu link, sidelink transmissions are opportunistic, with multiple transceiver links coexisting in the same resource pool. To minimize the impact of resource allocation conflicts between different UE-to-UE links, which can lead to interference, sidelink transmissions are based on resource reservation through the gNB using centralized planning under the gNB's coverage (Mode 1) or through UE sensing for Mode 2. Therefore, positioning procedures and resource allocation are different in the sidelink. In this document, procedure and / or protocol designs are provided for SL positioning and reference signal configuration.

[0143] Disclosed herein is a mechanism for initiating sidelink positioning between an anchor UE and a target UE. Sidelink positioning is a mechanism that allows either the anchor UE or the target UE to determine the location of the target UE relative to the anchor UE via sidelink communication between the target UE and the anchor UE, for example, without direct interaction with a corresponding 5G network. The anchor UE can indicate each UE's willingness and ability to serve as an anchor UE via signaling. The target UE can then select one or more anchor UEs. The target UE and anchor UE can reserve time and frequency communication resources for signaling via an opportunistic mechanism or through allocation by the 5G network. A positioning request is then sent. The request can be sent by the target UE to one or more anchor UEs. In another example, the request can be sent by the anchor UE to the target UE. In another example, the anchor UE can act as a serving anchor UE and send the request to the target UE and a cooperating anchor UE, or to the target UE for further communication to a cooperating anchor UE. Upon receiving the request, the anchor UE responds with location information. In an example, the request is triggered by a condition. In another example, the location information is sent based on a condition without a request. Once the location information is sent, the target UE can either measure the location of the target UE or send the location information back to an anchor UE, such as a serving anchor UE, to enable the anchor UE to measure the location of the target UE. Location information from cooperating UEs can also be sent to the serving anchor UE, either directly or via the target UE. By using one or more of these mechanisms, the exchange of location information is triggered via sidelink communication (e.g., directly between UEs without interaction through the 5G network).The UE can then determine the location of the target UE by measurements made on the location information without having to rely on a location system in the 5G network. This mechanism therefore enables UEs to perform useful functions, such as enabling UEs (e.g., vehicles) to determine their location even when they are outside of network coverage.

[0144] The SL Pos-RS and the exchange of positioning information and measurement reports require SL resources. To achieve a certain accuracy for positioning, especially for timing-based positioning techniques, sufficient bandwidth must be allocated for the SL Pos-RS. Therefore, SL positioning must be an on-demand or as-needed process. Otherwise, the resource pool will be overwhelmed by unnecessary transmissions of reference signals and information exchanges, which will increase the system load and lead to a large number of resource collisions.

[0145] Sidelink inter-UE cooperation is also specified to reduce potential resource contention. In cooperation scheme 1, a UE (UE-A) provides cooperation information, e.g., a preferred or non-preferred resource set, to help another UE (UE-B) select appropriate resources for its transmission. Cooperation can be triggered at an explicit request from UE-B or when certain conditions are met at UE-A.

[0146] Below is an example design of a sidelink positioning system that can be triggered on a request or condition.

[0147] Six positioning methods are selected for the NR RAT-dependent positioning solution: DL-TDOA, DL-AOD, UL-TDOA, UL-AOA, multi-RTT, and E-CID. Timing-based techniques can also be applied in sidelink communications. Because there is neither DL nor UL, the sidelink DL-TDOA and UL-TDOA techniques can be generalized as SL time difference of arrival (SL-TDOA). However, as shown in FIG. 8, the target UE's location can be requested and estimated at either the target UE 803 or the anchor UE 801. Additional procedures are described so that the information exchange and positioning signals are in different directions.

[0148] Multi-RTT is also an efficient positioning technique to take sidelink into account. Multi-RTT based positioning does not require synchronization, so if synchronization is not required between anchor UEs, multi-RTT based positioning can be used. Positioning can facilitate sidelink positioning.

[0149] E-CID is a positioning method that requires only signal strength measurements, e.g., RSRP and RSRQ. In the sidelink, a procedure based on RSRP measurements can be specified for SL positioning. For illustrative purposes, we denote this sidelink positioning technique as Extended Sidelink ID (E-SID).

[0150] In angle-based techniques, since the sidelink supports at most two antenna ports, the angle measurements and estimations, i.e., AOD and AOA, may not be accurate enough for positioning. Although angle-based positioning techniques may be associated with some drawbacks of sidelink based on existing specification support for the number of antenna ports, the design of positioning procedures or protocols and positioning signaling can be applied to angle-based positioning techniques as well.

[0151] The sidelink positioning procedure is discussed next. First, the indication of the anchor UE 801 is discussed. The anchor UE 801 serves as a reference UE with a known location. A UE that supports sidelink positioning and is capable of being the anchor UE 801 due to location capabilities can be the anchor UE 801. Since there may be multiple positioning techniques, the anchor UE may support one or more positioning techniques. The target UE 803 may request positioning reference signaling, location information, or measurements from the anchor UE 801. In one embodiment, the anchor UE 801 (or positioning reference UE) signals another UE that it can be the anchor UE 801.

[0152] Even if a UE is capable of being an anchor UE 801, the UE may not always want to serve as the anchor UE 801. For example, the UE may not meet certain conditions for being an anchor UE 801. Therefore, an indication of the anchor UE 801 may be used. For example, the UE may indicate whether it is capable of being the anchor UE 801 for sidelink positioning via periodic, semi-static, or dynamic signaling. For better positioning accuracy, the target UE 803 may synchronize with the anchor UE 801. However, this is not necessary for some positioning methods, such as multi-RTT. SL synchronization can be achieved via S-SSBs. Because S-SSBs are sent periodically, the UE can indicate its ability to be the anchor UE 801 or its availability for positioning as the anchor UE 801 via one or more reserved bits in the SL-MIB carried in the PSBCH transmitted in the S-SSBs. For example, one reserved bit in the SL-MIB in the S-SSB may indicate whether the UE is capable of being the anchor UE 801. Here, the indication can be used to indicate both cases, including whether the UE is capable of being the anchor UE and whether the UE is willing to become the anchor UE. The valid duration of the indication during the S-SSB can be the S-SSB transmission period, such as 160 ms, some other specified value, such as before the next S-SSB transmission, or a configured or pre-configured value. Alternatively, for a more dynamic indication, the UE can use a reserved bit in SCI format 1-A. The indication can also be provided through RRC signaling.

[0153] The anchor indication can be enabled / disabled by (pre)configuration, which is mostly for dynamic indication, such as using reserved bits in S-SSB or PSCCH SCI-1A. The indication is in addition to signaling in UE capabilities.

[0154] The anchor availability indication and support for a particular positioning method / technique may be indicated by various means. For example, the anchor indication may be available for all supported SL positioning techniques. Alternatively, it may be specified for a subset of positioning techniques, such as timing-based and / or angle-based techniques. For E-SID positioning based on signal strength measurements (e.g., RSRP), dynamic indication may not be employed. UE Characteristics Between Target UE 803 and Anchor UE 801 Noshi Gunning Exchange Ability may be used for signaling as explained above. RTT-based ranging or multi-RTT-based positioning may use more signaling exchanges, such as Rx-Tx time difference measurements. RTT-based capabilities are different from timing-based techniques. The indications can be different. Different positioning techniques may have different indications. For separate indications, more bits must be specified. Examples of such indications are bitmap, table indications, etc. entries, those Combination each etc.

[0155] The sidelink positioning procedure and SL Pos-RS transmission are discussed next. Positioning techniques use the transmission of positioning reference signals. In the Uu link, reference signals can be configured by the network and broadcast to every UE connected to the network or gNB. However, reference signals in SL may require resource reservation. For example, SL CSI-RS transmitted using PSSCH and CSI-RS is only used for unicast communication. For positioning, sidelink Pos-RS transmission may also require SL resource reservation even when there is no data to be transmitted. Because positioning requests can be on-demand, which may require triggering from either the target UE or the anchor UE, this triggering procedure extends the procedure used for UE-to-UE cooperation. The sidelink positioning procedure is discussed below, for example, based on SL Pos-RS transmission. This disclosure describes a scenario in which positioning estimation is performed at the target UE 803. The proposed design and solution may also be applied to a scenario in which positioning estimation is performed at the anchor UE 801.

[0156] Triggering of sidelink Pos-RS transmission is discussed next. UE-B may trigger cooperation by sending an explicit request to UE-A, which will provide cooperation information including a preferred or non-preferred resource set to UE-B for UE-B's resource selection. Cooperation may also be triggered by a condition in UE-A. When the condition is met, UE-A generates and sends cooperation information to UE-B. In SL positioning, either the target UE 803 or the anchor UE 801 can trigger the SL positioning process, which initiates the transmission of the SL Pos-RS and the corresponding information exchange. The information exchange may include location information of the anchor UE 801 relative to the target UE 803, or measurements at the anchor UE 801 relative to that anchor UE 801 that perform location estimation of the target UE 803. Some examples of triggering the sidelink positioning process or, in particular, the transmission of SL Pos-RS signaling are presented below.

[0157] 9 is a schematic diagram illustrating sidelink positioning 900 triggered by a target UE 903. Sidelink positioning and SL Pos-RS transmission may be triggered by an explicit request 905. Depending on which device performs the positioning or timing / angle measurements, the explicit request 905 can be sent from the target UE 903 or the anchor UE 901.

[0158] As shown in FIG. 9, when a target UE performs positioning or measurement, the target UE 903 may send an explicit request 905 for positioning and SL Pos-RS to the anchor UE 901. Through the indication of the anchor UE 901's presence, the target UE 903 may know the availability of the anchor UE 901 and select a set of UEs as anchor UEs 901 for the target UE 903's positioning request. Not all UEs designated as anchor UEs 901 may be or need to be selected by the target UE 903. The selection may be based on several criteria. To achieve certain positioning reliability, a synchronization (sync) source for the anchor UE 901 may be important. A UE may have certain requirements for the sync source or location accuracy, which allow the UE to indicate whether the UE can be the anchor UE 901. The target UE 903 may have different or stricter requirements for anchor UE 901 selection. In addition, the target UE 903 may select the anchor UE 901 based on the channel conditions between the target UE 903 and the anchor UE 901. For example, the target UE 903 may select a UE with a clear dominant LOS channel path as the anchor UE 901. For example, for a multipath channel, the anchor UE 901 may be selected when there is one path that is significantly stronger than all others. The threshold for LOS determination may use power difference for path comparison and may be configured to be pre-configured. Non-LOS (NLOS) channels for the target UE 903 may introduce errors into the position determination, and therefore the corresponding anchor UE 901 may be given lower priority in anchor selection.

[0159] 10 is a schematic diagram illustrating sidelink positioning 1000 triggered by an anchor UE 1002. In one example, the anchor UE may initiate the positioning process. The anchor UE may act as a serving anchor UE 1002 and may send an explicit positioning request 1005 to the target UE 1003, requesting the transmission of an SL Pos-RS. Meanwhile, the anchor UE 1002 may send a different request 1007 to other anchor UEs 1001 to coordinate measurements. Such other anchor UEs 1001 may also be referred to as coordinating anchor UEs. This is not necessary when only ranging between the anchor UE 1002 and the target UE 1003 is performed.

[0160] The request may be sent from the serving anchor UE 1002 to the target UE 1003 via one of three alternative means as presented above. A one-bit triggering request can be used to initiate a (pre-)configured S-SSB, SL CSI-RS transmission, a (pre-)configured SL PRS, or a (pre-)configured SL SRS (like SL-Pos-RS) from the target UE 1003. A request via the second-stage SCI or MAC-CE can trigger an SL Pos-RS transmission in the target UE 1003, with some settings such as signaling options, SL Pos-RS configuration, bandwidth, SL Pos-RS power control, etc. In this disclosure, the term anchor UE may be equivalent to the term anchor node, since many devices, such as a roadside unit (RSU), may be used as anchors for position determination.

[0161] When location estimation is performed in a serving anchor UE 1002, the serving anchor UE 1002 may send a request to another anchor UE 1001. An anchor UE 1002 that needs to estimate the location of a target UE 1003 may send a request in the capacity of the node as the serving anchor UE 1002.

[0162] The participating anchor UEs 1001 may then send their locations to the serving anchor UE 1002 and report their measurements to the serving anchor UE 1001. When the anchor UE 1001 is a UE with a fixed location, such as an RSU, location information may only be exchanged once, even when the UE indicates that it cannot currently serve as the anchor UE 1001. For UEs with low mobility and slowly changing locations, location information can be exchanged semi-statically, for example, via direct communication interface (PC5) RRC. For UEs with rapidly changing locations, location information must be exchanged or updated dynamically or with a smaller periodicity with the serving anchor UE 1002. In one example, the periodicity of information exchange is related to the speed or Doppler spread of the RS. For example, when the RS has a larger Doppler spread, frequent information exchange can occur. A strict mapping between Doppler value and periodicity may be (pre-)configured and provided along with the positioning request 1005 and / or positioning coordination request 1007. For positioning accuracy, location information must be obtained when the anchor UE 1001 performs measurements, and these measurements must be sent dynamically to the serving anchor UE 1002.

[0163] 11 is a flowchart of an example method 1100 for request-triggered positioning in a target UE. In step 1101, the target UE selects one or more anchor UEs. In one example, there is a metric (e.g., a number between 0 and 1) to characterize the degree of LOS / NLOS for the channel. The anchor selection may be made by combining the RSRP of the positioning RS with the LOS / NLOS metric and other criteria (zone, reference synchronization, mobility indicator, velocity, Doppler spread, etc.).

[0164] Once the anchor UE is selected, in step 1103, the target UE can send a positioning request to the anchor UE. The request can be triggered simply via a one-bit indication. For such an indication, one reserved bit of the first-stage SCI, e.g., SCI 1A, can be used, or one one-bit in the second-stage SCI can be used. The request can also be sent by the second-stage SCI to provide more information, e.g., SL Pos-RS signaling options and / or configurations. In another example, the request can be sent by the MAC-CE for more information, including SL Pos-RS signaling options and / or configurations and / or preferred resources for SL Pos-RS transmission. The request can be implemented using RRC signaling.

[0165] The 1-bit triggering request can be used in the anchor UE for S-SSB or SL CSI-RS transmission, SL PRS pre-configured by the anchor UE, or SL SRS (such as SL Pos-RS), default SL Pos-RS configuration, or semi-static RRC configuration. In the second stage, the SCI or MAC-CE can be used as a container for the positioning request and can carry more bits. Thus, SL Pos-RS signaling options, SL Pos-RS configuration, bandwidth, SL Pos-RS power control, etc. can be sent in the request.

[0166] The SL Pos-RS configuration can be dynamic or semi-static and can be sent by the target UE in a request or via RRC signaling. Triggering can likewise be dynamic or semi-static. In general, physical layer (PHY) signals such as one-bit requests, second-stage SCIs, and MAC-CEs can be considered dynamic triggering, while RRC signaling is semi-static. A hybrid approach is one in which the configuration can be sent to the anchor UE via RRC signaling or MAC-CE. When the target UE determines to estimate its location, it sends an explicit request to the anchor UE.

[0167] In a different example, the triggering bit is sent to a group of UEs by groupcast. In addition to the triggering bit, a response condition can be provided. A potential anchor node will only join if it meets the provided condition, such as a condition related to RSRP, synchronization source, zone ID, etc.

[0168] In step 1105, all anchor UEs transmit SL Pos-RS signals in response to the positioning requests sent in step 1103. The target UEs can then perform positioning measurements based on the SL Pos-RS signals. The target UEs can then estimate their location based on the measurements in step 1107.

[0169] FIG. 12 is a flowchart of an example method 1200 for a hybrid procedure for positioning in an anchor UE. The hybrid mode for positioning using an anchor UE is described next. In step 1201, a serving anchor UE may send a request to a target UE. The target UE first sends a request to other cooperating anchor UEs in step 1203. The cooperating anchor UEs may then join and transmit an SL Pos-RS to the target UE in step 1205. The target UE may perform positioning measurements. The target UE then sends a measurement report to the serving anchor UE in step 1207. In some examples, the cooperating anchor UEs may send their location information directly to the serving anchor UE. In other examples, the cooperating anchor UEs send their location information to the target UE. The target UE then sends the location information of the cooperating anchors to the serving anchor UE along with the measurement report in one or separate transmissions in step 1207.

[0170] The conditions for positioning triggered by an explicit request are discussed next. Several conditions can be specified for either the target UE or the anchor UE to trigger the positioning process or simply the SL Pos-RS transmission. The conditions for triggering an explicit request can be set as a resource pool level (pre-) configuration. One or more of the following alternatives can be enabled or disabled as the conditions for triggering an explicit request:

[0171] In one example, triggering an explicit request is up to the UE implementation (either the target UE or the anchor UE). In another example, request generation can be triggered by an RSRP measurement greater than a threshold. The RSRP measurement can be between the target UE and the serving anchor UE. In another example, distance can trigger an explicit request. For example, the distance can be determined based on a zone ID (e.g., included in SCI format 2-B) and / or its change, which indicates the location of the target UE itself and the anchor UE. The center or edge of the zone can be estimated based on historical communications, for example, based on the time the target UE remains in the same zone. In another example, the number of possible anchor nodes can be greater than a threshold for triggering an explicit request. This condition indicates whether SL positioning is possible or whether basic constraints on positioning accuracy are met. This can be a sufficient condition for SL positioning. Note that these conditions depend on the positioning purpose, e.g., absolute positioning or ranging. A condition related to the number of possible anchor nodes relative to a threshold can be applied for positioning. For example, one anchor UE is sufficient to enable ranging.

[0172] Sidelink positioning may also be triggered based on conditions other than an explicit request. In some scenarios, the UE may perform positioning periodically or when certain conditions are met. Thus, the anchor UE or target UE may transmit the SL Pos-RS when triggered by a condition. One example is that in some areas, an RSU may send the SL Pos-RS when a target UE appears or is within a certain range. Another example relates to cyber-physical control in smart factories. In some work areas or to perform certain tasks, the target UE may need to estimate its location, or the anchor UE may need to estimate the target UE's position. In these scenarios, the SL positioning procedure may not need to be triggered by a request. In addition, sidelink positioning can also be triggered by a condition. In condition-triggered sidelink positioning, the SL Pos-RS configuration can be (pre-)configured or determined by the UE implementation. The SL Pos-RS power control can be specified or determined by the UE transmitting the SL Pos-RS.

[0173] Similar to the conditions for SL positioning requests, the conditions for SL Pos-RS transmissions can be (pre-)configured at the resource pool level, which can enable and / or disable one or more of the following conditions:

[0174] In one example, which condition triggers an SL Pos-RS transmission is up to the UE implementation (either the target UE or the anchor UE). In another example, an SL Pos-RS transmission can be triggered by an RSRP measurement greater than a threshold. The RSRP measurement can be between the target UE and the serving anchor UE. In another example, distance can trigger an SL Pos-RS transmission. For example, the distance can be determined based on the target UE's own location and a zone ID indicating the anchor UE's location and / or changes thereto. In another example, the anchor UE may consider its location accuracy to be an important condition for the anchor UE to be an anchor UE. The location accuracy can be determined based on a sync source used by the anchor UE. Accordingly, changing location accuracy can trigger or disable an SL Pos-RS transmission. In another example, channel conditions between the anchor UE and the target UE can trigger or disable an SL Pos-RS transmission. The channel conditions between the anchor UE and the target UE can be determined based on the LOS channel with the dominant LOS path.

[0175] Once the enabling condition is met, the anchor UE or target UE, acting as UE-A, transmits the SL Pos-RS. The above conditions may also depend on the positioning scenario, for example, based on absolute positioning, ranging, and / or positioning techniques. In RTT-based ranging to determine varying position accuracy, the location accuracy of the anchor UE or other reference UEs may not be required.

[0176] Hybrid request and condition-based approaches are discussed next. Instead of triggering SL positioning by an explicit request or based on a condition, a hybrid approach can be chosen. As described above, the target UE can send a request for positioning, including SL Pos-RS transmission, to the anchor UE, or the serving anchor UE can send a positioning request to the target UE. However, the anchor UE or target UE may not immediately transmit the SL Pos-RS. Instead, the anchor UE or target UE can start sending the SL Pos-RS and / or sending measurement reports only when one or more condition sets for positioning are met.

[0177] The method or container for the request can be any of the approaches discussed above. Similarly, the conditions of condition-based positioning can be applied in such a hybrid approach.

[0178] The location information of the anchor / reference UE is discussed next. In NR positioning, the base station location is sent to the UE via a System Information Block (SIB) message. However, there is no SIB message for SL. The location information of the anchor UE must be provided to the target UE or serving anchor UE in some other way. The anchor UE may reserve resources independently and send their location information to other UEs via unicast, groupcast, or broadcast. The location information can be multiplexed with the SL Pos-RS transmission.

[0179] The location information of a UE may be private information. The UE may be requested to give approval to share its location information with other UEs. This may be used as an indication for the anchor UE. Its approval to share its location, if requested, may be a prerequisite for the UE to be an anchor UE. Only if the UE approves sharing its location information can the UE indicate to other UEs that it may be an anchor UE.

[0180] The Sidelink Positioning Reference Source (SL Pos-RS) is discussed next. SL Pos-RS may be used to indicate a general positioning reference signal. Different positioning signals may be used for each technique. Several reference signals are specified. Among these, suitable reference signals for positioning may be synchronization signals or generally S-SSB, and SL CSI-RS. These two reference signals may be sufficient for RSRP or RSSI measurements in E-SID positioning techniques. For timing or angle estimation, additional positioning signals for SL may be useful. These reference signals and potential configurations are discussed next.

[0181] As explained above, the periodicity of the S-SSB with the SL synchronization signal may be set to 160 ms. The number of S-SSB transmissions in each period is (pre)configured. The following number of S-SSB transmissions in one period for (pre)configuration is specified, which is SCS- and frequency band-dependent: For FR1: For 15kHz SCS, {1} For 30kHz SCS, {1,2} For 60kHz SCS, {1,2,4} For FR2: For 60kHz SCS, {1,2,4,8,16,32} For 120kHz SCS, {1,2,4,8,16,32,64}

[0182] In addition to the number of transmissions within a 160 ms period, the transmission of S-SSBs is based on two settings that can be (pre)configured: the offset slot for the first S-SSB, and the slot spacing between two consecutive S-SSBs. Besides these settings, the number of periods of S-SSB transmissions can be configured. In summary, the following is a list of configuration parameters, one or more of which can be taken into account for SL positioning: Number of submissions Slot offset for the first S-SSB transmission in a period Interval between two consecutive S-SSB Transmission period

[0183] In addition, for SL positioning purposes the following can be introduced: · Time domain repetition: repeated S-SSB transmissions, e.g. interval Multiple S-SSB transmissions on each of the Frequency domain repetition: Multiple S-SSB transmissions on different sets of PRBs within a configured S-SSB slot.

[0184] Generally, the configuration of S-SSB cannot be changed dynamically. For positioning purposes, the following approach can be used for the configuration of S-SSB transmissions: The configuration is provided in the request message. Two pre-configured sets of S-SSBs. The S-SSBs configured for positioning are transmitted once positioning is triggered. S-SSB for synchronization and PSBCH o Additional purposes, e.g., S-SSB for positioning Various (pre)configurations of S-SSB. Upon positioning triggering, S-SSB with one (pre)configuration for positioning is transmitted. The configuration can be selected by request or by the UE itself. o For positioning, when S-SSBs are transmitted from multiple anchor UEs within a short period of time, e.g., one 160 ms period, various configurations could mitigate S-SSB collisions.

[0185] The SL CSI-RS is discussed next. To improve SL transmission efficiency, the CSI-RS signal is used by the Rx UE to measure the sidelink channel quality for link adaptation. The CSI-RS for the sidelink is the same as that for the Uu link, including the CSI-RS pattern. However, the difference is that in the sidelink, the CSI-RS is sent on scheduled PSSCH resources. Therefore, it is multiplexed with the coded transport block. Because the transmission of SL data is based on resource reservation, the multiplexed CSI-RS transmission can avoid collisions with CSI-RS transmissions from other UEs.

[0186] In SL, the number of antenna ports for CSI-RS is up to two. In SL positioning, only one antenna port is used for SL Pos-RS transmission unless two antenna ports are considered to be co-located. In such cases, both can be used as positioning references. The transmission and configuration of SL PRS can modify the existing positioning configuration / procedures described below.

[0187] The SL Pos-RS (SL PRS or SL SRS) based on the DL SRS or UL SRS for positioning is discussed next. Due to the small bandwidth of S-SSB and the low density of CSI-RS, they may not be suitable for use as the SL Pos-RS for timing-based or angle-based positioning measurements. A different SL Pos-RS may be desired. The UL SRS can be deployed with more signals for positioning purposes. Since the UL SRS is designed for UE transmission, the UL SRS can be used for SL positioning, i.e., as one of the SL Pos-RS, in NR positioning.

[0188] The following can be configured on the UL SRS for positioning: Comsize K TC :2, 4, 8 Number of OFDM symbols for UL SRS

[0189]

number

[0190] Offset offset The starting OFDM symbol defined by Frequency domain offset SRS Sequence ID Time domain periodicity T SRS and offset T offset Number of SRS BW or PRB

[0191] The SRS as a SL Pos-RS can be configured via one of the following alternative approaches: The SRS configuration is provided in the request message. Various (pre)configurations of SRS for positioning, e.g. in the SL-SRS-PosResourceSet. Upon SL positioning triggering, one (pre)configured SL SRS for positioning is transmitted. The configuration can be selected via request or by the UE itself (condition triggered positioning / SL Pos-RS transmission).

[0192] Because the bandwidth (BW) of the reference signal can be important for positioning accuracy using timing-based positioning techniques, the configuration of the SRS BW or the number of PRBs for the SRS as the SL Pos-RS may be important. Since the SRS is transmitted over four consecutive PRBs, the subchannels for SRS transmission in the sidelink as the SL Pos-RS transmission must be a multiple of four consecutive PRBs. The number of subchannels for the SL SRS transmission can be (pre-)configured. For SL positioning, the number of subchannels for the SRS can be specified within a range with a lower bound for the minimum number of subchannels (or the minimum number of PRBs) and an upper bound for the maximum number of subchannels (or the maximum number of PRBs). The upper bound can be the total number of subchannels or PRBs in the SL resource pool. The anchor UE may reserve resources for transmitting the SL Pos-RS. For efficient transmission, the configuration on the BW and / or the number of PRBs for the SL Pos-RS can be a range or a minimum number of subchannels. The anchor UE may determine the actual number of subchannels for the SL Pos-RS transmission.

[0193] It should be noted that for positioning purposes, the configuration and transmission of SL Pos-RS may not be limited to one type of SL Pos-RS. Multiple SL Pos-RS may be configured and transmitted, such as S-SSB and SL PRS.

[0194] The behavior of positioning / target UEs and the hierarchy of anchor / reference UEs are discussed next. For the two types of UEs in an SL positioning system, the UE that provides the location reference is called the anchor UE, and the UE whose location is to be estimated (either at the UE itself or at the anchor UE) is called the target UE. The following terminology is also sometimes used for the two types of UEs: A UE with a location reference may be known as an anchor UE, reference UE, location reference UE, responding UE, and / or source UE. A UE whose location is to be estimated may be known as a positioning UE, target UE, location request UE, requesting UE, and / or initiating UE.

[0195] The UE whose location is to be estimated may be called the requesting UE or initiating UE, although the positioning request or initiation may not always occur at this UE. The anchor UE may also request or initiate the positioning process, including SL Pos-RS transmission, at the target UE. Also, anchor UEs may have different location accuracy depending on their sync signal / source, which can be translated into a priority level based on whether the original source is a Global Navigation Satellite System (GNSS) or a gNB / eNB.

[0196] The sidelink synchronization references, priorities, and hierarchies of SL positioning anchors are discussed next. In the sidelink, there are four possible synchronization sources for a UE: GNSS, gNB / eNB, synchronization reference (SyncRef) UE via S-SSB, and the UE's own internal clock. Among these synchronization sources, GNSS or eNB / gNB is considered the highest-quality source. SyncRef can be distinguished from the number of steps (hops) away from the GNSS or gNB / eNB. For example, one directly synchronized to the GNSS or gNB / eNB is one step away from the GNSS or gNB / eNB. The sidelink synchronization procedure defines a hierarchy or set of priorities among such synchronization references, encouraging all UEs to continuously search the hierarchy to reach the highest-quality synchronization reference they can find. The synchronization preference order is described by the following hierarchical priority levels, where lower numbers indicate higher priorities: Level 1. Either GNSS or eNB / gNB, depending on (pre)configuration. Level 2. SyncRef UE synchronized directly to a Level 1 source. Level 3. SyncRef UE synchronized to a Level 2 source, i.e. indirectly synchronized to a Level 1 source. Level 4. Either GNSS or eNB / gNB that was not (pre)configured as a Level 1 source. Level 5. SyncRef UE directly synchronized to a Level 4 source. Level 6. A SyncRef UE synchronized to a Level 5 source, i.e. indirectly synchronized to a Level 4 source. Level 7. Any other SyncRef UE. Level 8. UE internal clock.

[0197] Based on different sync criteria, the qualification of a UE to be a positioning anchor can have several levels of hierarchy with different timing and location accuracy. An SL UE may acquire / derive its own location information from sources other than the sync source. It is also possible for there to be different hierarchies of levels. For example, a gNB and a GNSS as sync sources are considered at the same level. However, in terms of positioning performance, they may not be the same. Also, an SL UE connected to a gNB may acquire / derive its location from SL positioning, which can be treated with less priority / accuracy as an anchor. An SL UE may broadcast or signal its level of being an anchor UE for SL positioning to target UEs.

[0198] Meanwhile, there are eight priority levels for sidelink data traffic, indicated by a three-bit number, p=0,...,7, in the priority field of SCI 1-A. Lower numbers indicate higher priority. The lowest level means the highest priority. The priority levels are set by the application layer and provided to the physical layer. The level of the anchor UE and the corresponding SL Pos-RS transmission can be translated and indicated by eight PHY priority levels.

[0199] Therefore, the sync source or priority level can be a condition for a UE to serve as an anchor UE or a target UE to select an anchor UE. In addition, the location accuracy of a UE based on a positioning source (which may be different from its sync source) can also set the UE's eligibility to be an anchor UE. The sync source or priority range can be determined by the in-coverage indicator I sent in the S-SSB and SL-MIB. ICand SLSS ID. Correspondingly, the location information when transmitted can be assigned a certain priority according to the Sync reference source level. Note that since location information in general is high priority information in SL positioning, the mapping may not be one-to-one with strict correspondence.

[0200] FIG. 13 is a flowchart of an example method 1300 for a UE to determine and indicate an anchor level to support UE anchor selection.

[0201] In step 1301, the UE may determine pre-configured or specified requirements for sync source, location accuracy, and / or maximum bandwidth to be an anchor. Given one or more hierarchical level structures of anchor UEs, the UE may determine whether it is capable of being an anchor UE in step 1303. The determination may be made according to the (pre-)configured requirements for the anchor level of being an anchor UE based on the UE's sync source and / or priority, positioning source or positioning accuracy, and / or maximum BW. Using the hierarchical level structure, the UE may determine its anchor level. The UE may then set its own anchor level based on the hierarchical level defined for the anchor UE. The anchor level may be a single-level metric that can be converted or mapped to an SL PHY priority. The anchor level may also be a list of metrics each with a different associated anchor level, such as the UE's sync source, UE's positioning source, etc. When the UE is qualified to be an anchor UE, the UE may send a signal for anchor indication in step 1305. The UE may also send the UE's anchor level. In some examples, the UE may signal that the UE is not and / or no longer qualified to be an anchor UE in step 1305. The target UE receives the anchor indication, and the anchor UE receives the anchor level. In step 1307, the target UE then selects an anchor UE according to its own requirements based on the anchor UE indication, metric, and / or anchor level received from the anchor UE.

[0202] FIG. 14 is a flowchart of an example method 1400 for anchor UE selection. In step 1401, a UE may indicate that it can be the anchor UE when certain requirements / conditions are met. Such requirements / conditions may include synch source requirements, location accuracy, and / or any other conditions discussed herein. In step 1403, a target UE selects an anchor UE based on certain conditions. Such conditions may include sync source requirements, channel conditions—LOS / NLOS, and / or any other conditions discussed herein. In step 1405, the target UE may reselect an anchor UE for positioning after obtaining the anchor UE location and / or after channel and timing measurements, for example, based on synch source requirements, improved channel measurements—LOS / NLOS, the anchor UE's actual location, the BW of the SL Pos-RS (e.g., SL PRS), and / or any other conditions discussed herein.

[0203] In addition to the set of conditions for a UE to be an anchor UE or a target UE for selecting an anchor UE, the target UE may further reselect anchor UEs according to step 1405, excluding some UE's SL Pos-RS and location information for positioning. This may be done after the SL Pos-RS transmission and based on other conditions, such as the anchor UE's sync source and / or priority level, as well as the BW of the SL Pos-RS signaling and the anchor UE's location information. Because the target UE does not know the anchor UE's location, location-based selection can be done after the anchor UE's location transmission. For example, the target UE may select one or more anchor UEs from a group of UEs that may be very close to each other.

[0204] Therefore, given the hierarchical level of a UE's eligibility to be an anchor, several hierarchical structures for selecting an anchor UE can be used, for example, such hierarchical levels can also include the channel quality when SL positioning is triggered.

[0205] Similarly, when positioning is performed in the serving anchor UE, the serving anchor UE may select additional anchor UEs after obtaining location information and / or use measurement reports from a subset of cooperating anchor UEs. The behavior of the target UE may also be scenario-dependent, e.g., absolute positioning or ranging.

[0206] The cast types of transmissions in the SL positioning process are discussed next. In many cases or scenarios, the S-SSB transmission is broadcast. In the case of SL positioning or SL Pos-RS transmission, the following cast types for different types of transmissions may be supported: Sending an explicit request when SL Pos-RS is triggered by a request: Unicast: The target UE sends a request independently to each of the anchor UEs. Groupcast: After anchor UE selection, a group of anchor UEs is formed by higher layers. The target UE groupcasts the request to the group of anchor UEs. · SL CSI-RS transmission: ○ Reuse rel-16 behavior, unicast is supported. SL Pos-RS (e.g. SL PRS) transmission: Unicast: Each anchor UE reserves resources and sends the SL Pos-RS to the target UE via unicast. o Broadcast: The anchor UE or target UE (if positioning is done in the serving anchor UE) broadcasts the SL Pos-RS. o Groupcast: The target UE can groupcast the SL Pos-RS to the selected anchor UE.

[0207] Broadcast or groupcast may be preferred for condition-triggered SL positioning or SL Pos-RS transmission.

[0208] FIG. 15 is a schematic diagram 1500 illustrating anchor UEs broadcasting SL-Pos-RS and location / position information. Note that location information and position information may be used interchangeably herein. In some scenarios, for example, when an RSU is acting as an anchor UE, a broadcast technique is more useful. Therefore, interaction between the anchor UE and target UEs may preferably be very limited. The anchor UE's location information can also be broadcast to every UE, either multiplexed with the SL Pos-RS transmission or in a separate transmission. With the broadcast of the SL Pos-RS and anchor UE's location information, UEs within range of these anchor UEs benefit from the positioning information. FIG. 1500 shows an exemplary case of V2x in which the anchor UE 1501 is an RSU. The anchor UE 1501 broadcasts 1505 the SL Pos-RS and their location information. In the E-SID SL positioning technique, the SL S-SSB may be needed only as the SL Pos-RS. The target UE 1503 may measure the DMRS in the PSBCH and / or the RSRP in the S-PSS or S-SSS in the S-SSB.

[0209] While positioning via timing-based measurements uses the large bandwidth of the SL Pos-RS for high accuracy, broadcasting may still be preferable for some scenarios / areas in V2X, public safety, and / or IIoT applications. Resource allocation may not be as critical in these scenarios. Therefore, more positioning and less communication may be desired. Each anchor UE 1501 may broadcast the SL Pos-RS as well as the anchor UE's location for a period of time whenever positioning information is triggered by a request or condition as described herein. information Resources can be reserved for broadcasting

[0210] SL resource allocation is discussed next. Resource allocation is used for various transmissions during SL location processing, such as transmitting explicit requests, transmitting SL Pos-RS, transmitting measurement reports, and / or transmitting anchor UE location information.

[0211] Generally, each Tx UE can select resources for its own transmission based on (pre-)configured transmission settings, e.g., periodicity, etc. In one example, transmission of SL reference signals for positioning purposes may also use resource reservation. In some SL scenarios, anchor UEs may move or be deployed dynamically. In one example, anchor UEs may indicate that their locations may change frequently. Thus, anchor UEs may update their locations and communicate with target UEs. Also, measurements between anchor UE and target UE may be exchanged depending on where the target UE's location has been estimated. These transmissions also use resource allocation.

[0212] The positioning procedure involves information exchange between two sides, and IUC method 1 can be modified as follows to assist other UEs for SL positioning transmission. Besides the request, the target UE as UE-A sends to each of the anchor UEs (as UE B) a preferred set of resources for its SL Pos-RS transmission. With such coordination, SL Pos-RS collisions can be avoided. The target UE as UE-A also sends to each of the anchor UEs (as UE-B) a preferred resource set for transmitting its location. The (serving) anchor UE as UE-A sends the preferred resource set for the target UE (as UE-B) to transmit the SL Pos-RS. The (serving) anchor UE as UE-A sends the preferred resource set for the target UE (as UE-B) to send the measurement report.

[0213] Data multiplexing is discussed next. Explicit request and SL Pos-RS transmissions may be multiplexed with other data. In the example, for explicit requests, transmissions can only be multiplexed with data if the source / destination ID pair is the same. In the example, for explicit requests, retransmission of transmissions is supported.

[0214] For SL Pos-RS transmission, the following can be specified: S-SSB: With the current frame structure, S-SSB is not multiplexed with data. SL CSI-RS: Based on the Rel-16 specification, it can be multiplexed with data SL PRS (SL SRS): o Unicast case: For the same behavior as CSI-RS, it must be multiplexed with data (e.g. location information or measurement reports). o In case of groupcast / unicast, it can be multiplexed with data (e.g. location information or measurement reports). Note that for SL PRS transmission, even if it is triggered by a specific UE and / or for a specific target UE, the source / destination ID pair may not need to be the same as that of the data, as SL PRS does not require a destination ID. o In case of broadcast, it can also be multiplexed with data (e.g. location information of anchor UEs, or measurement reports from target UEs to anchor UEs or from cooperating anchor UEs to serving anchor UEs) if needed.

[0215] For location information transmissions, retransmissions may not be required because the location may change during the retransmission. Retransmissions may be dropped or disabled based on the quality of the location information, for example, if the change in location exceeds a threshold or if the velocity of the UE exceeds a threshold.

[0216] For PSSCH RE mapping of multiplexed data, the NR positioning DL PRS RE mapping rule can be revised for SL to enable backward compatibility by puncturing data-modulated symbols on SL Pos-RS (SL PRS, SL SRS) RE to support legacy UEs that do not recognize SL Pos-RS.

[0217] Due to the large bandwidth of each SL Pos-RS transmission, it may also be preferable for multiple UEs to transmit different SL Pos-RSs that are orthogonal in time and frequency on the same resource in the same slot but in the same RB. UL SRSs from different UEs can be sent on the same resource as long as they are on different REs. For sidelink, when SL Pos-RS signals from multiple anchor UEs are sent on the same resource, inter-symbol interference may occur due to different reception times at the UE. This can be mitigated by configuring the SL Pos-RSs in SL Pos-RS REs that do not appear on the same subcarrier for two consecutive OFDM symbols. Alternatively, this problem can be solved by configuring each PRS / SRS with a different offset so that there are one or more guard symbols between any two PRS / SRSs in the time domain. In this case, the number of OFDM symbols per PRS / SRS is four or less.

[0218] Additional control signaling support is used for SL Pos-RS signals from different UEs on the same resources, for example, only one UE may send a PSSCH for resource reservation, or the PSCCH may be enabled to signal overlapping resources for SL Pos-RS transmission without multiplexing with data.

[0219] Therefore, this disclosure focuses on the first artificial intelligence (AI) of SL positioning with respect to potential solutions for SL positioning, considering relative positioning, ranging, and absolute positioning. To this end, reference signals for positioning are considered, including signal design, measurements, and related procedures, while reusing reference signals, procedures from sidelink communications and positioning as much as possible.

[0220] Signal bandwidth and signal-to-noise ratio (SNR) are discussed next. Channel bandwidth and received SNR determine the positioning accuracy of methods based on time-of-flight (TOF) / time-of-arrival (TOA) distance measurements. From Cramer-Rao lower bound (CRLB) analysis, the variance of TOA measurements in LOS channels is approximately bounded by

[0221]

number

[0222] where β denotes the effective signal bandwidth,

[0223]

number

[0224] where SNR is the signal-to-noise ratio, f is the frequency, and S(f) is the Fourier transform of the transmitted signal. The above inequality implies that higher signal bandwidth improves TOA measurement accuracy. An investigation of the impact of bandwidth on location accuracy may indicate whether SL positioning solutions should be extended to unlicensed spectrum.

[0225] FIG. 16 is a schematic diagram 1600 of an example of LOS and NLOS sidelink positioning. If there is a direct LOS path 1611 between the anchor UE 1601 node and the target UE 1603 node, the larger positioning signal bandwidth enables better resolution of multipath components, which increases the accuracy of finding the first path and therefore reduces errors caused by multipath bias in TOA, RTT, and TDOA-based methods. However, if such a direct LOS path 1611 does not exist and communication between the anchor UE 1601 node and the target UE 1603 node occurs via NLOS reflections 1613, the range between the anchor UE 1601 node and the target UE 1603 node will be overestimated due to the increased TOF. Angle of Arrival (AOA) and Angle of Departure (AOD) estimations may also be affected by NLOS propagation, leading to lower accuracy in location estimation.

[0226] Time synchronization is discussed next. When TOF- and / or TOA-based positioning methods are used, the receiver can estimate the TOF, and therefore the range, between the transmitter and receiver using a timestamp from the transmitter. However, even when the channel is LOS, if the clocks at the transmitter and receiver are not synchronized, additional errors are introduced, which affect ranging and position estimation. The network synchronization error is defined as a truncated Gaussian distribution of the root-mean-square (rms) value, denoted as (T1), in nanoseconds (ns), between an anchor node and a timing reference source assumed to have perfect timing, which suffers a maximum timing difference of T2 ns, where T2 = 2 * T1. That is, the range of the timing error is [-T2, T2]. Two exemplary values ​​of T1 include 0 ns (perfectly synchronized) and 50 ns.

[0227] While some positioning methods, such as Multi-RTT, are robust with respect to time synchronization, assuming that clock drift is negligible over the duration over which the difference between the reception and transmission times of the positioning signal is measured, others are more sensitive to synchronization errors (such as TOA). Therefore, when investigating SL positioning solutions, the synchronization error between the target node and the anchor node must be considered.

[0228] In the example, SL positioning studies should investigate the impact of BW size, non-ideal synchronization, and NLOS propagation on SL positioning accuracy. Methods for location determination are discussed next.

[0229] RAT-dependent methods for positioning are based on reference signal (RS) exchange between an anchor node (gNB) and a target node (UE). In this disclosure, a target UE is a UE that requests a position / location determination, and anchor nodes are those nodes, such as a UE, a gNB, and / or an RSU, that can be considered as a reference for relative or absolute positioning of the target UE. RAT-dependent positioning methods exist in addition to RAT-independent methods for positioning, such as GNSS, Wi-Fi, Bluetooth, terrestrial beacon systems (TBS), and motion-based sensors. RAT-dependent methods are as follows: NR signal-based NR extended cell ID method (NR E-CID) Multi-round trip time positioning (multi-RTT based on NR signals) Downlink Angle of Departure (DL-AoD) based on NR signal Downlink Time Difference of Arrival (DL-TDOA) based on NR signals Uplink Time Difference of Arrival (UL-TDOA) based on NR signals, Uplink Angle of Arrival (UL-AoA), including A-AoA and Z-AoA based on NR signals Hybrid positioning using multiple methods from the list of positioning methods above is also supported.

[0230] The measurements to support the above method are as follows: Downlink PRS Reference Signal Received Power (DL PRS RSRP) Downlink PRS Reference Signal Receive Path Power (DL PRS RSRPP) Downlink PRS Reference Signal Time Difference (DL PRS RSTD) · UE Rx-Tx time difference

[0231] In sidelink positioning scenarios, at least one positioning reference signal is provided via the sidelink (PC5), and thus the SL UE may combine and measure the sidelink Pos-RS and DL PRS and transmit the sidelink Pos-RS and UL PRS. In sidelink mode 2 (expected in out-of-coverage scenarios), the reference node (anchor node) may be less reliable than for in-coverage anchor nodes such as gNBs. In these scenarios, it may be preferable to use a positioning method such as multi-RTT, which is more robust with regard to clock synchronization between the anchor node and the target node.

[0232] For sidelink mode 2 operation, robust positioning methods such as multi-RTT may be preferred. Physical layer standards may be modified to support SL UE positioning methods and measurements. For position determination, SL UEs must support aggregation of DL PRS resources with SL positioning resources.

[0233] One basic scenario for positioning in 5G services is support of positioning in out-of-context scenarios when all devices involved in SL positioning are outside of the line of sight (LMF). OOC scenario positioning is part of the Study Item Description (SID). 5G systems must provide positioning information to UEs that are out of network coverage with an accuracy of < 1 m relative to other UEs that are in the vicinity and within network coverage. This positioning support allows data to be made available to the UE, thereby enabling UE-based positioning and positioning in out-of-context scenarios.

[0234] 5G systems must be able to make location-related data available to applications or application servers that may be inside the 5G network, outside the 5G network, or in the user equipment. In the OOC case, it is unclear whether an entity similar to an LMF is still required, and if so, where it must be located. The target UE must support functionality that allows it to calculate a location estimate. Such functionality and complexity may depend on the scenarios covered by the OOC, such as ranging, relative positioning, or absolute positioning.

[0235] An SL positioning solution for OOC scenarios must be able to select a positioning method, configure and enable sidelink reference signal transmissions on demand or triggered by events, select an anchor node, enable RRC connectivity if required, obtain location information or request SL Pos-RS transmissions, provide or exchange location information if requested, and configure and enable collection of SL positioning measurements to estimate relative or absolute position.

[0236] Some positioning methods involve an exchange between the target node and the anchor node. For example, in UE-based positioning multi-RTT, the anchor node must provide the SL UE target node with Rx-Tx measurements, which are combined with the Rx-Tx measurements at the target node to obtain a final position estimate. Another example of a data exchange between the target node and the anchor node could be absolute location coordinates provided by the anchor node to the target node. Such an exchange may occur only after an RRC connection has been established between the target node and the anchor node, which would enable data encryption, and therefore privacy.

[0237] The SL positioning solution must support configuration and control for OOC SL positioning. These scenarios for an OOC SL positioning solution can be achieved by two possible approaches. One option is to start from scratch and define the protocols and signaling that should support the SL positioning method. Another option is to build on the SL design and extend the protocol with signaling that implements the SL positioning method. Inter-UE coordination (IUC) features are candidates that can be considered and extended to support SL positioning solutions for OOC scenarios. IUC features provide a framework for requesting and responding to measurement and location information, configuring and triggering the necessary signaling, and coordinating anchor node transmissions. Additionally, using IUC features should minimize the impact on the specification.

[0238] The IUC framework for OOC SL positioning solutions may be extended and / or used.

[0239] Position reference signals are discussed next. The RAT-dependent method for positioning is based on reference signal (RS) exchange between an anchor node (gNB) and a target UE. More precisely, the gNB transmits DL positioning RS (DL PRS) signals. The UE transmits UL sounding reference signals (UL PRS) based on the configuration provided by SRS-PosResourceSet, which is different from the SRS used for UL channel estimation based on the configuration given by SRS-ResourceSet.

[0240] The DL PRS signal is a length 31 Gold QPSK sequence, where the pseudo-random sequence generator generates the slot number, DL PRS sequence ID,

[0241]

number

[0242] and is initialized based on the OFDM symbol index in the slot to which the sequence is mapped. The PRS sequence ID enables frequency reuse, while the slot and symbol index enable TOF, TOA, TDOA, and RTT determination.

[0243] In the time domain, the size of the DL PRS resource is L PRS ∈{2,4,6,12} symbols, which is given by the upper layer parameter dl-PRS-NumSymbols.

[0244] In the frequency domain, the PRS resource has a comb distribution (e.g., resource elements (REs) spaced apart in each of the symbols of the DL-PRS resource), where comb size K comb PRS∈{2,4,6,12} is given by the upper layer parameter dl-PRS-CombSizeN-AndReOffset for downlink PRS resources configured for RTT-based propagation delay compensation, otherwise it is given by the upper layer parameter dl-PRS-CombSizeN, so that the combination {LL PRS ,K comb PRS} can be one of {2,2}, {4,2}, {6,2}, {12,2}, {4,4}, {12,4}, {6,6}, {12,6} and {12,12}.

[0245] Comb distribution allows for a wider bandwidth of the RS signal and therefore better accuracy of TOA estimation. However, gaps in frequency create aliases in time, which can be compensated for by repeating and coherently combining the PRS in time. For example, if two symbols with Comb-4 are coherently combined, the result is equivalent to a Comb-2 PRS signal.

[0246] The frequency offset between symbols is chosen so that there is no staircase pattern. This has the primary advantage of increasing robustness (e.g., against Doppler shifts) when using only the first symbol for coherent combining. In addition, the comb design and the frequency offset between successive symbols provide increased robustness against wideband fading and orthogonality with respect to other PRS signals from other TRPs.

[0247] A PRS resource is defined by an ID, sequence ID {0,...,4095}, remaining symbol comb size {2,4,6,12} and RE offset, resource slot offset, resource symbol offset, and QCL information. A DL PRS resource set is configured by NR-DL-PRS-ResourceSet and contains one or more DL PRS resources, where each of the resources has an associated spatial transmit filter (transmit direction).

[0248] 17 is a schematic diagram of an example positioning reference signal (PRS) resource set 1700. The PRS resource set 1700 is characterized by an ID, subcarrier spacing, periodicity (of resource set transmission), resource list, resource repetition factor (number of repetitions of each resource in an instance of a resource set), resource time gap (number of slots between consecutive repetitions of resources), comb size, resource bandwidth (between 24 PRBs and 272 PRBs in increments of 4 PRBs), starting PRB index, and number of resource symbols in a PRS slot. The PRS resource set 1700 can be placed anywhere in the frequency grid via the starting PRB index, which is an offset relative to a reference frequency point A.

[0249] The PRS resource set is per PRS ∈2 μ Sent by the gNB with a periodicity of {4,5,8,10,16,20,32,40,64,80,160,320,640,1280,2560,5120,10240} slots.

[0250] The PRS resource repetition factor defines how many times each of the DL-PRS resources is repeated for a single instance of the DL-PRS resource set, and has a value T rep PRS ∈{1, 2, 4, 6, 8, 16, 32}. All DL PRS resources in a resource set have the same resource repetition factor.

[0251] Strong PRS signals may be muted to mitigate interference with weaker PRS signals. The muting pattern is specified by a bit string of {2, 4, 8, 16, 32} bits in each of the cells, where a bit indicates whether the PRS transmission in the corresponding slot is muted or not.

[0252] An RRC connected UE is required to measure only DL PRS that are in an active bandwidth part (BWP) and have the same numerology as the active BWP. The UE may request serving gNB measurement gaps that can be used to measure DL PRS that are outside the active BWP and have a different numerology.

[0253] For a 15 kHz SCS, the minimum DL PRS is about 5 megahertz (MHz) and the maximum DL PRS is about 50 MHz. For a 120 kHz SCS, the minimum DL PRS bandwidth is about 34 MHz and the maximum bandwidth is about 400 MHz.

[0254] Figure 18 is a schematic diagram of an exemplary UL PRS1800 resource configuration. UL PRS1800 is based on the Sounding RS (SRS) and is referred to as the SRS for positioning. The UL PRS1800 sequence is a 31-bit Zadoff-Chu sequence, which provides a good peak-to-average ratio. UL PRS1800 may span {1, 2, 4, 8, 12} consecutive OFDM symbols in time, which may be positioned anywhere within a slot. Similar to the DL PRS, UL PRS1800 has a comb-N pattern in frequency with a comb size of {2, 4, 8}. Like the UL PRS1800, DL PRS has a comb offset that defines the relative frequency shift between consecutive OFDM symbols. This offset provides similar benefits relative to the DL PRS. Through coherent combining, only the first few symbols may be considered for TOA measurement. Like the DL PRS, UL PRS1800 may be transmitted periodically with a certain periodicity and slot offset. However, semi-persistent configurations are activated and deactivated via MAC-CE signaling. The aperiodic UL PRS 1800 is transmitted only when the UE is instructed by the gNB via downlink control information (DCI). The UL PRS 1800 supports spatial relationships, where the spatial relationship can be either a DL reference signal (SSB, CSI-RS, or DL-PRS) or due to a previously transmitted SRS or UL-PRS 1800. The UL PRS 1800 can also have spatial relationships with neighbor transmission / reception points (TRPs).

[0255] Another property of UL PRS1800 is power transmission control, where the UE estimates the UL path loss of the serving and neighboring TRPs based on DL measurements and sets the UL PRS1800 power accordingly. A UL PRS1800 resource set contains one or more UL PRS resources and is defined by a resource set ID, a resource type (aperiodic, semi-persistent, periodic), a value alpha characterizing fractional power control, a desired received power p0 at the TRP, a path loss reference RS, and a UL PRS resource list.

[0256] The UL resource is described by ID, transmission comb, resource mapping (symbol location in the UL PRS1800 slot), frequency domain shift, bandwidth indication (as part of frequency hopping, not used for frequency hopping indication for SRS case), resource type (periodic, semi-persistent, aperiodic), corresponding periodicity, sequence ID used to initialize pseudo-random groups, sequence hopping, and spatial relationship information.

[0257] As with DL PRS, a UE may be configured with multiple UL PRS resource sets.

[0258] Reference signals for sidelink positioning are discussed next.

[0259] Figure 19 is a schematic diagram of an exemplary S-SSB 1900. The S-SSB 1900 is a broadcast signal used for synchronization purposes, consisting of the Sidelink Primary Synchronization Signal (S-PSS), the Sidelink Secondary Synchronization Signal (S-SSS), and the Physical Sidelink Broadcast Channel (PSBCH). There are 672 unique physical layer Sidelink synchronization identities, which are divided into two sets {0, 1, ..., 335} and {336, ..., 671}. The Sidelink Synchronization Signal ID (SLSSID) indicates the source of the time reference (GNSS, gNB, or another SL UE (SyncRef UE)) and therefore provides information about the accuracy of the time reference. Before starting to send the S-SSB 1900, the SL UE must select its own time reference and signal it via the SLSSID.

[0260] In the frequency domain, the S-SSB 1900 occupies 11 physical resource blocks (PRBs), i.e., 132 subcarriers, where the S-PSS and S-SSS each occupy 127 subcarriers and are repeated twice in the S-SSB slot. The PSBCH occupies 132 subcarriers over a duration of eight symbols (Figure 5). The first PSBCH symbol serves automatic gain control (AGC) purposes. Each S-SSB transmission is repeated once or several times during each of the 16 subframe periods. The frequency location of the S-SSB is fixed.

[0261] S-SSB1900 may be primarily used by a receiver SL UE to acquire synchronization with a transmitter SL device, or by a target SL UE to measure the time difference of arrival (TDOA) between two SyncRef UEs synchronized to the same reference time. Thus, the target SL UE will be able to estimate its relative position with respect to the SyncRef UE.

[0262] S-SSB can be adapted to estimate TDOA between anchor SL devices. The accuracy of the TDOA estimate is increased when S-SSB sources have the same reference time (SLSSID). The use of S-SSB for positioning can enable SL UE positioning in the RRC_INACTIVE state. S-SSB-based SL position determination can be supported by the network.

[0263] The Sidelink Positioning Signals (SL Pos-RS) are discussed next. One of the topics of this research item concerns the study of Sidelink Reference Signals for positioning purposes from a physical layer perspective, including signal design, resource allocation, measurements, related procedures, etc., using reference signals, procedures, etc. from Sidelink communications and from positioning as much as possible.

[0264] In an out-of-coverage (OOC) scenario, a target SL UE may rely on sidelink (PC5) reference signals received from other SL devices (SL UEs, RSUs) to determine range or location. The signal bandwidth plays a role in the estimation accuracy. The bandwidth of S-SSB may not be sufficient, and furthermore, the S-SSB periodicity (160 ms) may add additional latency to the position determination. Therefore, RAN1 may define an SL Pos-RS that shares some of the common characteristics of the DL and UL PRSs, such as: Flexible bandwidth size Comb-N distribution in frequency Repetition with frequency offset in consecutive symbols Different time lengths and periodicity of resource sets Aperiodic, semi-static and periodic transmission

[0265] The Zadoff-Chu (ZC) sequences used for the uplink PRS provide better PAPR properties (smaller power variations in time and frequency) than the Gold sequences used for the DL PRS, which may be desirable for SL UEs to avoid nonlinear signal distortions.

[0266] RAN1 may consider UL PRS design as a starting point for SL Pos-RS design. SL UEs at the outer edge of network coverage may participate in SL positioning exchanges with other SL UEs in partial coverage. Therefore, the serving gNB must be able to control and configure SL Pos-RS UE transmissions within its coverage to minimize interference and maximize capacity. SL Pos-RS configuration may be controlled by the gNB when SL UEs are in coverage or partial coverage.

[0267] The SL positioning architecture is discussed next.

[0268] UE positioning can be performed in the NG-RAN. Positioning methods, positioning architectures, and signaling protocols and interfaces have been defined. The positioning solution relies on the LTE Positioning Protocol (LPP) and the Location Management Function (LMF). In particular, the LMF is used to organize the positioning methods and protocols.

[0269] For positioning of the target UE, the LMF determines the positioning method to be used based on factors that may include the LCS client type, required QoS, UE positioning capability, gNB positioning capability, and ng-eNB positioning capability. The LMF then invokes these positioning methods in the UE, serving gNB, and / or serving ng-eNB. The positioning methods are UE-based. Positioning The method may include location estimation and / or UE-assisted and network-based PositioningThe method may result in positioning measurements, and the LMF may combine all received results to determine a single location estimate for the target UE (hybrid positioning).

[0270] When an SL UE participating in a positioning exchange is within the coverage of a gNB, the positioning protocol (LTE positioning protocol) must still be supported. The LMF must be able to coordinate and process measurements for positioning through the Uu connection and the SL relay. At the same time, the gNB may forward measurements from the SL UE to the LMF to estimate the location of the SL UE in partial coverage.

[0271] FIG. 20 is a schematic diagram of an example UE 2000 for sidelink communications. The UE 2000 can be used as a target UE, an anchor UE, or any other UE described herein. Accordingly, the UE 2000 can be configured to implement or support the schemes / features / methods described herein. For example, the features / methods in this disclosure can be implemented using hardware, firmware, and / or software installed to run on the hardware. Those skilled in the art will recognize that the term UE encompasses a broad range of devices, and the UE 2000 is merely an example of such a device. The UE 2000 is included for clarity of discussion and is in no way intended to limit the application of the present disclosure to a particular network device embodiment or class of network device embodiments.

[0272] The UE 2000 may be a device that communicates electrical, wireless, and / or optical signals through a network. As shown in FIG. 20 , the UE 2000 may comprise a transceiver (Tx / Rx) 2010, which may be a transmitter, a receiver, or a combination thereof. Each Tx / Rx 2010 may be coupled to multiple downstream ports 2020 (e.g., downstream interfaces) for transmitting and / or receiving frames from other nodes, and the Tx / Rx 2010 may be coupled to multiple upstream ports 2050 (e.g., upstream interfaces) for transmitting and / or receiving frames from other nodes. A processor 2030 may be coupled to the Tx / Rx 2010 for processing data signals and / or determining to which node the data signal should be sent. The processor 2030 may comprise one or more multi-core processors and / or a memory device 2032, which may function as a data store, buffer, etc. The processor 2030 may be implemented as a general processor or may be part of one or more application specific integrated circuits (ASICs) and / or digital signal processors (DSPs). The UE 2000 may include an SL positioning module 2014, which may be configured to use sidelink communication for an initial SL-based positioning mechanism as described herein. The SL positioning module 2014 may be implemented in a general-purpose processor, a field programmable gate array (FPGA), an ASIC, a DSP, a microcontroller, etc. In alternative embodiments, the SL positioning module 2014 may be implemented in the processor 2030 as computer-executable instructions stored in the memory device 2032 (e.g., as a computer program product stored on a non-transitory computer-readable medium), which may be executed by the processor 2030 and / or implemented partially in the processor 2030 and partially in the memory device 2032. The downstream port 2020 and / or the upstream port 2050 may, depending on the embodiment, include wireless, electrical, and / or optical transmitting and / or receiving components.

[0273] FIG. 21 is a schematic diagram of an example embodiment of a UE 2100 for sidelink positioning. The UE 2100 can be used as a target UE, an anchor UE, or any other UE described herein. The UE 2100 includes a receiver 2101, a measurement module 2103, and a transmitter 2107. In the example, the transmitter 2107 serves as a transmitting means for transmitting positioning requests to one or more anchor UEs via sidelink communication. Furthermore, the receiver 2101 serves as a receiving means for receiving positioning signals from one or more anchor UEs via sidelink communication. Additionally, the measurement module 2103 serves as a measuring means for performing positioning measurements based on the positioning signals.

[0274] In another example, the transmitter 2107 serves as a transmitting means for transmitting a positioning request to the target UE via sidelink communication. Further, the receiver 2101 serves as a receiving means for receiving a positioning signal from the target UE via sidelink communication. In addition, the measurement module 2103 serves as a measuring means for performing positioning measurements on the target UE based on the positioning signal.

[0275] 22 is a flowchart of an example method 2200 for performing sidelink-based positioning in a target UE. In step 2201, the target UE selects one or more anchor UEs. In an example, the one or more anchor UEs are selected based on a UE anchor indication and a UE anchor level. For example, the UE anchor indication may indicate whether the corresponding UE is capable of serving as an anchor UE and whether the corresponding UE is enabled to serve as an anchor UE. In an example, the UE anchor level may be set based on a synchronization source, a priority level, a location accuracy, a maximum bandwidth, an in-coverage indicator, an SLSSID, or a combination thereof.

[0276] The positioning may be managed by the target UE, by the anchor UE, and / or by the serving anchor UE in cooperation with the cooperating anchor UEs. In step 2203, the target UE may optionally receive an initial positioning request from the serving anchor UE via sidelink communication. This may occur when the serving anchor UE is managing the positioning.

[0277] In step 2205, the target UE transmits a positioning request to one or more anchor UEs via sidelink communication. In an example, the positioning request may be triggered by the target UE. In another example, the positioning request may be triggered by an initial positioning request from the serving anchor UE in step 2203, in which case the one or more anchor UEs are cooperating anchor UEs. In some examples, the positioning request is triggered by a condition. For example, the condition may include a comparison of RSRP against a first threshold, distance against a second threshold, number of UE anchors against a third threshold, channel conditions against a fourth threshold, or a combination thereof.

[0278] It should be noted that the target UE can communicate with the anchor UE according to Mode 1 or Mode 2. In Mode 1, the target UE is within the range of the 5G network. In such a case, the target UE may communicate with one or more anchor UEs via resource reservation provided by the gNB. In Mode 2, the target UE is out of the range of the network. In such a case, the target UE communicates with one or more anchor UEs according to sensing-based resource selection of sidelink resources. This approach may use opportunistic signaling to select communication resources without communication with the 5G network.

[0279] In step 2207, the target UE receives positioning signals from one or more anchor UEs via sidelink communication. The positioning signals may include SL-Pos-RS.

[0280] In step 2209, the UE may perform positioning measurements based on the positioning signals. For example, the target UE may estimate its location based on the positioning measurements and the locations of one or more anchor nodes.

[0281] In step 2211, the target UE may optionally send position measurements via sidelink communications to the serving anchor UE for estimation of the target UE's location. In some examples, the target UE instead sends a report to the serving anchor UE indicating the target UE's location based on step 2209. In some examples, the target UE may also send a report to the serving anchor UE related to positioning signals received from the cooperating anchor UE.

[0282] In step 2213, the target UE may optionally reselect one or more anchor UEs after obtaining anchor UE locations, channel measurements, timing measurements, or a combination thereof.

[0283] 23 is a flowchart of an example method 2300 for performing sidelink-based positioning at an anchor UE. In optional step 2301, the anchor UE may transmit a UE anchor indication indicating whether the anchor UE is capable of serving as an anchor UE and whether the anchor UE is enabled (e.g., willing) to serve as an anchor UE. In step 2303, the anchor UE may optionally transmit a UE anchor level set based on a synchronization source, a priority level, a location accuracy, a maximum bandwidth, an in-coverage indicator, a sidelink synchronization signal identifier (SLSSID), or a combination thereof. Optional steps 2301 and 2303 allow the anchor UE to indicate to potential target UEs whether the anchor UE is capable of being selected as an anchor UE for positioning and also allow the target UE to determine which anchor UE should be selected for best results.

[0284] In step 2305, the anchor UE transmits a positioning request to the target UE via sidelink communication. In some instances, the anchor node acts as a serving anchor node. In some examples, the positioning request may signal the target UE to send one or more second positioning requests to one or more cooperating anchor UEs. In some examples, the positioning request is triggered by a condition. For example, the condition may include RSRP for a first threshold, distance for a second threshold, number of UE anchors for a third threshold, channel conditions for a fourth threshold, or a combination thereof.

[0285] It should be noted that the anchor UE can communicate with the target UE according to Mode 1 or Mode 2. In Mode 1, the anchor UE is within the range of the 5G network. In such a case, the anchor UE may communicate with the target UE via resource reservation provided by the gNB. In Mode 2, the anchor UE is out of the range of the network. In such a case, the anchor UE communicates with the target UE according to sensing-based resource selection of sidelink resources. This approach may use opportunistic signaling to select communication resources without communication with the 5G network.

[0286] In optional step 2307, the anchor node may act as a serving anchor node and may send one or more second positioning requests to one or more cooperating anchor UEs instead of delegating such transmission to the target UE.

[0287] In step 2309, the anchor node receives a positioning signal from the target UE via sidelink communication. For example, the positioning signal may include an SL-Pos-RS. In some examples, the positioning signal from the target UE also includes location information from one or more cooperating anchor UEs.

[0288] In step 2311, the anchor UE may optionally receive location information from one or more cooperating anchor UEs instead of receiving such information via the target UE.

[0289] In step 2313, the anchor UE performs positioning measurements for the target UE based on the positioning signals.

[0290] In step 2315, the anchor UE may estimate the location of the target UE based on positioning measurements from the target UE and / or location information from one or more cooperating anchor UEs. In some examples, the target UE may instead estimate its own location. In such cases, the anchor UE may receive a report from the target UE indicating the position of the target UE.

[0291] Although several embodiments have been provided in this disclosure, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The examples are to be considered illustrative and not limiting, and the intention should not be limited to the details given herein. For example, various elements or components may be combined or combined in another system, or some features may be omitted, or not implemented.

[0292] Additionally, techniques, systems, subsystems, and methods described and illustrated in various embodiments as individual or separate may be combined with or incorporated into other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items illustrated or discussed as being coupled or directly coupled or in communication with each other may also be indirectly coupled or in communication through some interface, device, or intermediary, whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations will be ascertainable by those skilled in the art and could be made without departing from the spirit and scope disclosed herein.

Claims

1. 1. A method implemented by a target user equipment (UE), the method comprising: transmitting a positioning request to one or more anchor UEs via sidelink communication; receiving positioning signals from the one or more anchor UEs via the sidelink communication; performing positioning measurements based on the positioning signals; Including, the step of transmitting the positioning request is triggered by a condition, the condition including at least one of a reference signal received power (RSRP) of the positioning signal for a first threshold, a distance between the target UE and the one or more anchor UEs for a second threshold, a number of UE anchors for a third threshold, or a channel condition with a dominant LOS (line of sight) path for a fourth threshold.

2. 2. The method of claim 1, wherein the target UE communicates with the one or more anchor UEs according to sensing-based resource selection of sidelink resources.

3. 10. The method of claim 1, wherein the target UE communicates with the one or more anchor UEs via resource reservations provided by a fifth generation (5G) base station (gNB).

4. The method of claim 1 , wherein the positioning signal comprises a sidelink positioning reference signal (SL Pos-RS).

5. The method of claim 4 , wherein the positioning request includes at least one of an SL Pos-RS signaling option or an SL Pos-RS signaling configuration.

6. The method of claim 1 , further comprising the step of selecting the one or more anchor UEs from a plurality of additional anchor UEs prior to the step of transmitting the positioning request to the anchor UE.

7. The method of claim 1 , further comprising estimating a location of the target UE based on the positioning measurements and locations of the one or more anchor UEs.

8. 2. The method of claim 1, further comprising receiving an initial positioning request from a serving anchor UE via the sidelink communication prior to transmitting the positioning request to the one or more anchor UEs.

9. 10. The method of claim 1, further comprising sending the positioning measurements via the sidelink communication to a serving anchor UE for estimation of the location of the target UE.

10. The method of claim 1 , wherein the one or more anchor UEs are selected based on a UE anchor indication and a UE anchor level.

11. The method described in claim 10, wherein the UE anchor indication indicates whether the corresponding UE is capable of acting as an anchor UE and whether the corresponding UE is enabled to act as an anchor UE.

12. The method of claim 10, wherein the UE anchor level is set based on at least one of a synchronization source, a priority level, a location accuracy, a maximum bandwidth, an in-coverage indicator, or a sidelink synchronization signal identifier (SLSSID).

13. 10. The method of claim 1, further comprising: reselecting the one or more anchor UEs after obtaining at least one of anchor UE location, LOS or NLOS (non-line-of-sight) channel measurements, or timing measurements for TOF (time-of-flight) estimation.

14. 1. A method implemented by an anchor user equipment (UE), the method comprising: sending a positioning request to a target UE via sidelink communication; receiving a positioning signal from the target UE via the sidelink communication; performing positioning measurements on the target UE based on the positioning signals; Including, the positioning request is triggered by a condition, the condition including at least one of a reference signal received power (RSRP) of the positioning signal for a first threshold, a distance between the target UE and the anchor UE for a second threshold, a number of UE anchors for a third threshold, or a channel condition with a dominant line-of-sight path for a fourth threshold.

15. The method of claim 14, wherein the anchor UE communicates with the target UE according to sensing-based resource selection of sidelink resources.

16. 15. The method of claim 14, wherein the anchor UE communicates with the target UE via resource reservation provided by a fifth generation (5G) base station (gNB).

17. The method of claim 14, wherein the positioning signal comprises a Sidelink Positioning Reference Signal (SL Pos-RS).

18. The method of claim 14 , further comprising estimating a location of the target UE based on the positioning measurements.

19. The method of claim 14 , wherein the positioning request triggers the target UE to send one or more second positioning requests to one or more cooperating anchor UEs.

20. The method of claim 14 , wherein the positioning signal from the target UE includes location information from one or more cooperating anchor UEs.

21. 15. The method of claim 14, further comprising receiving location information from one or more cooperating anchor UEs.

22. The method of claim 14 , further comprising sending one or more second positioning requests to one or more cooperating anchor UEs.

23. 15. The method of claim 14, further comprising: transmitting a UE anchor indication indicating whether the anchor UE is capable of serving as an anchor UE and whether the anchor UE is enabled to serve as the anchor UE.

24. 15. The method of claim 14, further comprising transmitting the UE anchor level set based on at least one of a synchronization source, a priority level, a location accuracy, a maximum bandwidth, an in-coverage indicator, or a sidelink synchronization signal identifier (SLSSID).

25. The method of claim 1 , wherein the one or more anchor UEs are selected according to a line-of-sight (LOS) / non-line-of-sight (NLOS) indicator.

26. A user equipment (UE), one or more processors; a transmitter coupled to the one or more processors; and a receiver coupled to the one or more processors, wherein the one or more processors, the transmitter, and the receiver are configured to perform a method according to any one of claims 1 to 25. User Equipment (UE).

27. 26. A non-transitory computer-readable medium containing a computer program product for use by a user equipment (UE), the computer program product comprising computer-executable instructions stored on the non-transitory computer-readable medium that, when executed by one or more processors, causes the UE to perform a method according to any of claims 1 to 25.

28. A target user equipment (UE) comprising one or more means for implementing the method according to any of claims 1 to 13.

29. An anchor user equipment (UE) comprising one or more means for performing the method according to any of claims 15 to 25.

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