Side Link Positioning Initialization in 5G Network

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 generally relates to fifth generation wireless access network (5G) network technology, and more particularly to the initialization of sidelink communication between an anchor user equipment (UE) and a target UE for supporting sidelink positioning with or without reliance on the 5G network for resource communication allocation.

Background Art

[0002] Cross - Reference to Related Applications This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 336,046, titled "Method and Apparatus of Sidelink Positioning", filed on April 28, 2022, which is incorporated herein by reference.

[0003] Some features related to fifth generation (5G) new radio access technology are under development and standardization by the Third Generation Partnership Project (3GPP). As an example, one work item includes requirements for a 5G new radio (NR) vehicle - to - everything (V2X) wireless communication mechanism aimed at providing high - speed and reliable connectivity that is 5G - compatible 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 a positioning signal from one or more anchor UEs via sidelink communication. The method further includes performing a positioning measurement based on the positioning signal. A UE, such as a vehicle, phone, computer, tablet, industrial device, or other wireless network-based computing device, may wish to determine its current location. Further, such a device may move out of network range, and thus the network may not be able to provide the UE with a location 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 enables either the anchor UE or the target UE to determine the location of the target UE with respect to the anchor UE via sidelink communication between the target UE and the anchor UE without using, for example, direct interaction by a corresponding 5G network. The anchor UE can indicate, via signaling, the respective willingness and capabilities of the UEs acting as anchor UEs. The target UE can then select one or more anchor UEs. The target UE and the anchor UEs can reserve time and frequency communication resources for signaling via an opportunistic mechanism or via an allocation by the 5G network. The 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 an 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 send the request to the target UE for further communication to the 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 other examples, the location information is sent based on a condition without a request.Once the location information is sent, the target UE either measures the location of the target UE or sends it back to an anchor UE such as the serving anchor UE, enabling the anchor UE to measure the location of the target UE. The location information from the cooperating UE 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 using interactions by the 5G network). The UE can then determine the location of the target UE based on measurements made on the location information without relying on the location system in the 5G network. Thus, this mechanism enables beneficial functions for the UE, such as allowing the UE (e.g., a vehicle) to determine its location even when outside the network coverage area.

[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 a 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 reservation 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 further provides including selecting one or more anchor UEs before sending a positioning request to the anchor UE.

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

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

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

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

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

[0014] Optionally, in any of the preceding aspects, another implementation of the aspect provides that 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 acting as an anchor UE and whether the corresponding UE is enabled to act 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 further provides for reselection of one or more anchor UEs after obtaining an anchor UE location, 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 a positioning measurement for the target UE based on the positioning signal. UEs such as vehicles, phones, computers, tablets, industrial devices, or other wireless network-based computing devices may wish to determine their current location. Further, such devices may move out of network range, and thus the network may not be able to provide the UE with a location 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 enables 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 without using direct interaction by, for example, the corresponding 5G network. The anchor UE can indicate, via signaling, the respective intent and capabilities of the UEs acting as anchor UEs. The target UE can then select one or more anchor UEs. The target UE and the anchor UE can reserve time and frequency communication resources for signaling via an opportunistic mechanism or via an allocation by the 5G network. The 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 the cooperating anchor UEs, or send the request to the target UE for further communication to the cooperating anchor UEs. Upon receiving the request, the anchor UE responds with location information. In an example, the request is triggered by a condition. In other examples, the location information is sent based on a condition without a request.Once the location information is sent, the target UE either measures the location of the target UE or sends it back to an anchor UE such as the serving anchor UE, enabling the anchor UE to measure the location of the target UE. The location information from the cooperating UE 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 using interactions by the 5G network). The UE can then determine the location of the target UE based on measurements made on the location information without relying on the location system in the 5G network. Thus, this mechanism enables the UE (e.g., a vehicle) to perform useful functions such as determining their location even when outside the network coverage area.

[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 a sensing-based resource selection of 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 reservation 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 further provides including estimating the location of the target UE based on the positioning measurement.

[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 further provides including receiving location information from one or more cooperating anchor UEs.

[0026] Optionally, in any of the preceding aspects, another implementation of the aspect further provides including transmitting 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 condition includes reference signal received power (RSRP) for a first threshold, distance for a second threshold, number of UE anchors for a third threshold, channel condition for a fourth threshold, or a combination thereof.

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

[0030] Optionally, in any of the preceding aspects, another implementation of the aspect further provides for transmitting 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.

[0031] Optionally, in any of the preceding aspects, another implementation of the aspect provides for one or more anchor UEs to be 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 for sidelink positioning measurement reports to compromise 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 implement a 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 implement a 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 comprises receiving means for receiving a positioning signal from the one or more anchor UEs via sidelink communication. The UE further comprises measuring means for performing a positioning measurement based on the positioning signal.

[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 transmission means for transmitting a positioning request to a target UE via sidelink communication. The UE further comprises receiving means for receiving a positioning signal from the target UE via sidelink communication. The UE further comprises measurement means for performing a positioning measurement 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 the claims.

Brief Description 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, in which like reference numerals represent like parts.

[0042]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

[0043]

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Figure 23

DETAILED DESCRIPTION OF THE INVENTION

[0044] Exemplary implementations of one or more embodiments are provided below, but it should be understood first that the disclosed systems and / or methods can be implemented using any number of techniques, whether currently known or existing. 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 together with their full range of equivalents.

[0045] 3GPP provided the basis for NR side - link communication for applications such as security systems and autonomous driving. High data rates, low latency, and high reliability were part of the investigated and standardized areas. 3GPP also provided a side - link enhancement work item to further expand the capabilities and performance of side - link communication. One of the objectives of that work item was to introduce a UE - to - UE cooperation mechanism where one UE shares resources that may be preferred or not preferred for another UE to use in its resource selection, or sends a collision indication to other UEs when there is a collision on reserved resources.

[0046] A further work item required NR positioning support, 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 required NR positioning enhancements aimed at supporting high - accuracy, low - latency, network efficiency, and device - efficiency requirements for commercial use cases. This work item was related to methods, measurements, signaling, and procedures for improving positioning accuracy relative to other exemplary positioning methods. Research items related to the deployment and improvement of NR positioning included research on side - link positioning solutions. In this disclosure, techniques and signaling for enabling side - link positioning are described.

[0047] FIG. 1 is a schematic diagram showing an example 100 of in-network coverage operation and out-of-network coverage operation using 5G network compliant technology. Sidelink communication 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) exists and can be used to manage sidelink communication 103 between UEs 105. This is known as mode 1. In operation mode 2, the system operation is sufficiently decentralized and UEs 105 select resources themselves to support sidelink communication 103 between UEs 105. In the present disclosure, it may also be possible that some UEs are facilitated / supported in selecting their resources. In mode 2, the UEs can be either in-coverage or out-of-coverage (OOC).

[0048] FIG. 2 is a schematic diagram of an exemplary resource pool 200 in a resource grid for sidelink communication. The resource pool 200 is a set of resources that can be used for sidelink communication. The resources in the 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), and the like.

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

[0050] In NR mobile broadband (MBB), each physical resource block (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. Thus, each resource block contains 12×14 resource elements (REs). When used as a frequency-domain unit, a PRB is 12 consecutive subcarriers. When the normal cyclic prefix (CP) is used, there are 14 symbols in a slot, and when the extended cyclic prefix (ECP) is used, there are 12 symbols in a slot. The symbol duration is inversely proportional to the subcarrier spacing (SCS). For {15, 30, 60, 120} kilohertz (kHz) SCS, the slot duration is {1, 0.5, 0.25, 0.125} milliseconds (ms), respectively. Each PRB can be allocated to a combination of control channels (CCHs), shared channels (SCHs), feedback channels, reference signals (RSs), etc. Additionally, some REs of a PRB may be reserved. Communication resources can use PRBs, sets of PRBs, codes (when code division multiple access (CDMA) is used as in the physical uplink control channel (PUCCH)), physical sequences, sets of REs, etc.

[0051] Figure 3 is a schematic diagram of an exemplary resource grid 300 with PSCCH 301, PSSCH 303, and PSFCH 305 resources. PSCCH 301 carries sidelink control information (SCI). The source UE uses the SCI to schedule data transmission on PSSCH 303. The SCI can carry the time and frequency resources of PSSCH 303, parameters of hybrid automatic repeat request (HARQ) processing, such as redundancy version, process identifier (id), new data indicator, and resources for PFSCH 305. PFSCH 305 can carry an indication, such as a HarQ acknowledgment (HARQ-ACK) of an acknowledgment (ACK) or negative acknowledgment (NACK), as to whether the receiving / destination UE correctly decoded the payload carried on PSSCH 303. The SCI can also carry a bitfield indicating the representation of the source UE's identification. In addition, the SCI can also carry a bitfield indicating the representation of the destination UE's identification. Other fields include the modulation and 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 priority of the payload (transmission).

[0052] NR sidelink control information (SCI) can be transmitted in the first-stage SCI and the 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 the resources for the second-stage SCI.

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

[0054] [Number]

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

[0056] [Number]

[0057] bits. - Time resource allocation - When the value of the upper layer parameter sl-MaxNumPerReserve is configured to 2, 5 bits, or when the value of the upper layer parameter sl-MaxNumPerReserve is configured to 3, 9 bits. - Resource reservation period - When 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, or 0 bits otherwise. - DMRS pattern -

[0060] [Number]

[0061] bits, where N patternis the number of DMRS patterns configured by the higher layer parameter sl-PSSCH-DMRS-TimePatternList. If sl-PSSCH-DMRS-TimePatternList is not configured, it is 0 bits. - Second-stage SCI format - 2 bits. - Beta_offset indicator - 2 bits as provided by the higher 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 higher layer parameter sl-Additional-MCS-Table, 2 bits if two MCS tables are configured by the higher layer parameter sl-Additional-MCS-Table, otherwise 0 bits. - PSFCH overhead indication - 1 bit when the higher layer parameter sl-PSFCH-period = 2 or 4, otherwise 0 bits. - Reserved - The number of bits determined by the higher layer parameter sl-NumReservedBits with the value set to 0.

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

[0063]

Number

[0064] 。 - New data indicator - 1 bit. - Long version - 2 bits. - Source ID - 8 bits. - Destination ID - 16 bits. - HARQ feedback activation / deactivation 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 the PSSCH together with HARQ operations when the 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 process number -

[0067]

Number

[0068] bits. - New data indicator - 1 bit. - Long version - 2 bits. - Source ID - 8 bits. - Destination ID - 16 bits. - HARQ feedback activation / deactivation indicator - 1 bit. - Zone ID - 12 bits. - Communication range requirement - 4 bits.

[0069] SCI format 2-C is used for decoding the PSSCH and for providing or requesting inter-UE cooperation information. The following information is transmitted by SCI format 2-C. - HARQ process number - 4 bits - New data indicator - 1 bit - Redundancy 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 the value 0 indicates that SCI format 2-C is used to provide inter-UE coordination information, and the value 1 indicates that SCI format 2-C is used to request inter-UE coordination information

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

[0071]

Table 2

[0072] When the "provide / request indicator" field is set to 0, all the remaining fields are set as follows. - Resource combination -

[0073]

Number

[0074] bit, where - When the upper layer parameter sl-MultiReserveResource is configured,

[0075]

Number

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

[0077]

Number

[0078] is sl-NumSubchannel, the number of subchannels in the resource pool provided by the upper layer parameter - The first resource location - 8 bits. - The reference slot location -

[0079]

Number

[0080] bits. - The resource set type - 1 bit, where the value 0 indicates a preferred resource set and the value 1 indicates a non-preferred resource set. - The lowest subchannel index -

[0081]

Number

[0082] bits.

[0083] When the "Provide / Request Indicator" field is set to 1, all the remaining fields are set as follows. - Priority - 3 bits. The value "000" of the priority field corresponds to the priority value "1", the value "001" of the priority field corresponds to the priority value "2", and so on. - Number of sub-channels -

[0084]

Number

[0085] bits. - Resource reservation period - When 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 0 bits. - Resource selection window location -

[0088]

Number

[0089] bits. - Resource Set Type - 1 bit, where when the upper layer parameter determineResourceSetTypeScheme1 is configured to "UE-B's request", value 0 indicates a request for UE-to-UE cooperation information that provides a preferred resource set, value 1 indicates a request for UE-to-UE cooperation information that provides a non-preferred resource set, and otherwise, 0 bits. - Padding bit.

[0090] Sidelink UE-to-UE cooperation (IUC) is specified to improve mode 2 reliability by overcoming problems such as hidden nodes, exposed nodes, and half-duplex that affect sidelink performance. In particular, two IUC schemes are defined, namely, as follows. · Scheme 1: UE-to-UE cooperation information signaling from UE-A to UE-B 〇 Set of preferred resources for UE-B's transmission 〇 Set of non-preferred resources for UE-B's transmission · Scheme 2: UE-to-UE cooperation information signaling from UE-A to UE-B 〇 Presence of expected / potential resource conflicts on the resources indicated by UE-B's SCI

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

[0092] The conditions for two IUC triggering scenarios are also specified. For an IUC triggered by an explicit request, one of the two conditions is configured for the resource pool level. These include alt1, which depends on the implementation of UE-B, and alt2, which can be triggered only when UE-B has data to send to UE-A. Similarly, for an IUC triggered by a condition, two conditions are used, and one of them is enabled by the resource pool level (pre-)configuration. These include alt1, which depends on the implementation of UE-A, and alt2, which can be triggered only when UE-A has data to send to UE-B along with cooperation information.

[0093] The criteria for generating cooperation information, in which a preferred resource set and a non-preferred resource set are defined, are as follows. · Preferred resource set: 〇 Condition 1-A-1: Resources excluding overlapping reserved resources of other UEs with a reference signal received power (RSRP) greater than a threshold. 〇 Condition 1-A-2: Resources excluding slots in which UE-A does not expect to perform SL reception from UE-B as the Rx of UE-B. · Non-preferred resource set: 〇 Condition 1-B-1: Reserved resources of other UEs identified by RSRP measurement. · Option 1: Reserved resources of other UEs identified by UE-A where the RSRP measurement is greater than a (pre-)configured RSRP threshold. · Option 2: Reserved resources of other UEs identified by UE-A where the RSRP measurement is less than a (pre-)configured RSRP threshold when UE-A is the destination of the TB transmitted by the UE. 〇 Condition 1-B-2: Resources (e.g., slots) in which UE-A does not expect to perform SL reception from UE-B when it is the intended receiver of UE-B.

[0094] For sending explicit requests and coordination information, Media Access Control protocol (MAC) explicit requests and coordination information (MAC-CE) are used as a container. When configured, the second-stage SCI (SCI-2C) is also used for explicit requests or coordination information.

[0095] In coordination triggered by an explicit request, only unicast is supported for the transmission of both the explicit request and the coordination information. In coordination triggered by a condition, unicast is supported for the transmission of both types of coordination information. Broadcast and groupcast are supported only for an unfavorable set of resources.

[0096] The coordination information and the explicit request can be multiplexed and transmitted with data only if the source / destination ID pair is the same.

[0097] Figure 4 is a schematic diagram of an exemplary structure of an S-SSB block 400. The synchronization slot in sidelink is shown 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 PSBCH. However, like a regular sidelink slot, the first symbol is used for the alignment of automatic gain control (AGC). 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 the guard period (GP) as in a regular sidelink slot. PSBCH carries the sidelink master information block (SL-MIB).

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

[0099] Figure 5 is a schematic diagram of an exemplary UL SRS500. In NR, SRS resources using one, two, or four antenna ports are supported, and these are

[0100] [Number]

[0101] capable of being mapped to consecutive OFDM symbols. In the frequency domain, K TC = two or four or eight RE per combination transmissions are supported. In addition, the cyclic shift is equal to 8, 12, and 6 respectively when the size of the comb is 2, 4, and 8, the maximum number of cyclic shifts

[0102] [Number]

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

[0104]

Number

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

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

[0107] In the time domain at the slot level, the SRS resource can be configured periodically with the periodicity (T SRS ) and slot offset (T offset ) in the slot.

[0108]

Table 3

[0109]

Table 4

[0110] Figure 6 is a schematic diagram of an exemplary DL-PRS600. The PRS is a downlink reference signal for positioning purposes. The PRS is also sometimes referred to as the DL-PRS600, while the SRS configured for positioning is sometimes called the UL-PRS500.

[0111] The DL-PRS600 has a starting symbol

[0112]

Number

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

[0114]

Number

[0115] This is

[0116]

Number

[0117] selected from a specified subset of combinations of

[0118]

Number

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

[0120]

Table 5

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

[0122]

Number

[0123] and slot offset

[0124]

Number

[0125] and additional slot offset

[0126]

Number

[0127] and can be composed of. The bandwidth of DL-PRS can be composed in steps of 4 PRBs within 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 items related to the deployment and improvement of NR positioning include the following purposes of SL positioning. ● To study and evaluate the performance and feasibility of potential solutions for SL positioning considering relative positioning, ranging, and absolute positioning: [RAN1, RAN2] Evaluating the bandwidth requirements needed to meet the identified accuracy requirements [RAN1] Research on positioning methods (such as TDOA, RTT, AOA / D, etc.) that include combinations of SL positioning measurements with other RAT-dependent positioning measurements (such as Uu-based measurements) [RAN1] Research on side-link reference signals for positioning purposes from a physical layer perspective, including signal design, resource allocation, measurement, related procedures, etc., that reuse existing reference signals, procedures, etc. from side-link communication and positioning as much as possible [RAN1]. Research on positioning architectures and signaling procedures (such as configuration, measurement reporting, etc.) to enable side-link positioning that covers both UE-based positioning and network-based positioning [RAN2, including coordination and alignment with RAN3 and SA2 as required]

[0130] Side-link resource allocation is discussed next. In NR V2X side-link mode 1, the gNB performs side-link scheduling. Therefore, the gNB allocates SL resources for SL communication, and the resource allocation is sent to the UE through the (Uu) interface from the NR Universal Mobile Telecommunications System Terrestrial Radio Access Network (UTRAN) to the UE. Therefore, side-link 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 an individual side-link carrier.

[0131] There are three types of Mode 1 resource allocations. 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) for each transport block (TB) to the gNB via the PUCCH. Then, the gNB sends the sidelink (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 the expected SL traffic, including periodicity, traffic bandwidth (TB) maximum 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 they are activated by the gNB via DCI.

[0132] Figure 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 transmission. The resource allocation relies on sensing and reservation processes as shown in Figure 7. During the sensing procedure, the monitoring UE detects the Scheduling Control Information (SCI) transmitted in each slot during the sensing window and measures the Reference Signal Received Power (RSRP) of the resources indicated in the SCI. The monitoring UE may also receive data transmission and thus may also be the receiving UE. For periodic traffic, resource reservation for sidelink transmission can be used. When the UE occupies the resources in slot s k above, the UE will also occupy the resources in slot s k +q*RRI k above, 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 Physical Sidelink Control Channel (PSCCH) and processing the SCI within the PSCCH.

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

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

[0135] Several NP positioning methods can be used. The NR positioning methods include DL-based solutions, UL-based solutions, and DL and UL-based solutions.

[0136] The DL-based solutions are discussed next. A timing-based technique known as downlink time difference of arrival (DL-TDOA) can be used. Similar to the observed time difference of arrival (OTDOA) in LTE, the DL-TDOA positioning specified in NR measures the timing difference of DL-PRS on the line-of-sight (LOS) paths from different gNBs. The 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 the PRS and / or beams from the same transmit and receive point (TRP).

[0137] The UL-based solutions are discussed next. The uplink time difference of arrival (UL-TDOA) is an exemplary timing-based technique. NR introduces a UL positioning technique that uses a UL positioning signal configured using UL SRS. The gNB measures the UL timing difference from the UE. The 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 the UL SRS configured for positioning purposes. The gNB measures both the zenith AOA and the azimuth AOA to obtain a three-dimensional (3D) location.

[0138] The following is discussed for DL and UL-based solutions. 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 for each UE-gNB pair using two Rx-Tx time differences. For Rx-Tx time difference measurement, DL PRS and UL SRS are respectively configured and transmitted from the gNB and the UE. Extended cell ID (E-CID) is a positioning technique based on radio resource management (RRM) measurements such as RSRP and resource signal reception quality (RSRQ) via synchronization signals such as SSB measurements and channel state information reference signal (CSI-RS). UL AOA is also supported

[0139] Positioning method selection, configuration of reference signals (SRS, PRS), and collection of measurements are orchestrated by a location management function (LMF) residing in the network. The LMF manages the support of various location services including positioning of the UE and provision of assistance data to the UE for the target UE. The LMF can interact with the serving gNB or serving ng-eNB for the target UE to obtain the UE's position measurement. Such position measurements include uplink measurements performed by the NG-RAN and downlink measurements performed by the UE provided to the NG-RAN as part of other functions such as for support of handover

[0140] Figure 8 is a schematic diagram showing sidelink positioning 800. Radio access technology (RAT)-dependent positioning in a cellular system uses various procedures. In NR positioning, the functions and procedures are similar to those used in LTE. Some techniques and UL reference signals are introduced for NR. However, in SL positioning, the procedures and reference signaling are not yet defined

[0141] As shown in FIG. 8, the sidelink positioning 800 system may include a plurality of location reference UEs shown as anchor UE 801 and target UE 803. Sidelink positioning 800 obtains the position of target UE 803 based on the location information of anchor UE 801 through reference signal measurements exchanged between target UE 803 and anchor UE 801. The reference signaling for SL positioning measurements is shown as SL positioning reference signal (SL Pos-RS) 805.

[0142] In NR positioning, DL and UL positioning signaling are well synchronized and scheduled. The network can provide the configuration of signaling for positioning, such as DL PRS or UL SRS, and measurement reports. Unlike the NR Uu link, sidelink transmissions are opportunistic, and multiple transceiver links coexist in the same resource pool. To minimize the impact of resource allocation conflicts between different UE-to-UE links that cause interference, sidelink transmissions are based on resource reservation through gNB using centralized planning under the coverage of the gNB (mode 1), or through UE sensing for mode 2. Therefore, the positioning procedure and resource allocation are different in the sidelink. In this document, procedures and / or protocol designs are provided for SL positioning as well as 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 enables 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 without using, for example, direct interaction by the corresponding 5G network. The anchor UE can indicate the intention and capabilities of each UE acting as an anchor UE via signaling. The target UE can then select one or more anchor UEs. The target UE and the anchor UE can reserve time and frequency communication resources for signaling via an opportunistic mechanism or via an 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 the cooperating anchor UEs or send it to the target UE for further communication to the cooperating anchor UEs. Upon receiving the request, the anchor UE responds with location information. In an example, the request is triggered by a condition. In other examples, the location information is sent based on a condition without a request. When 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 the serving anchor UE, enabling the anchor UE to measure the location of the target UE. The location information from the cooperating UE 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 using interaction by the 5G network).The UE can then determine the location of the target UE by measurements made on the location information without relying on the location system in the 5G network. Therefore, this mechanism enables the UE, such as a vehicle, to perform useful functions, such as determining their locations even when they are outside the network coverage area.

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

[0145] Also, sidelink UE-to-UE cooperation is specified to reduce potential resource contention. In cooperation mode 1, the UE (UE-A) provides cooperation information, such as a preferred resource set or a non-preferred resource set, to help the other UE (UE-B) select appropriate resources for its transmission. The cooperation can be triggered by an explicit request from UE-B or when a certain condition is met in UE-A.

[0146] The following is an exemplary design of a sidelink positioning system that can be triggered by a request or a condition.

[0147] For NR RAT-dependent positioning solutions, six positioning methods are selected, namely DL-TDOA, DL-AOD, UL-TDOA, UL-AOA, multi-RTT, and E-CID. In sidelink communication, it is also possible to apply timing-based techniques. Since there is neither DL nor UL, the sidelink DL-TDOA and UL-TDOA techniques can be generalized as the sidelink time difference of arrival (SL-TDOA). However, as shown in Figure 8, the position of the target UE can be requested and estimated at either the target UE 803 or the anchor UE 801. Additional procedures are described such that the information exchange and positioning signals are in different directions.

[0148] Multi-RTT is also an efficient positioning technique for considering sidelink. Since multi-RTT-based positioning does not require synchronization, if synchronization is not required between anchor UEs, the multi-RTT-based position can facilitate sidelink positioning.

[0149] E-CID is a positioning method that only requires signal strength measurements, such as RSRP and RSRQ. In sidelink, procedures based on RSRP measurement can be specified for SL positioning. For illustrative purposes, we refer to this sidelink positioning technique as extended sidelink ID (E-SID).

[0150] In angle-based techniques, since the maximum number of antenna ports supported in sidelink is two, the measurement and estimation of angles, namely AOD and AOA, may not be accurate enough for positioning. Angle-based positioning techniques may be associated with some drawbacks of sidelink based on the existing specification support for the number of antenna ports, but the positioning procedure or protocol design, and positioning signaling can also be applied to angle-based positioning techniques in the same way.

[0151] The side link 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 can support side link positioning and can be the anchor UE 801 for location functions can be the anchor UE 801. Since there may be multiple positioning techniques, the anchor UE can 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 to another UE that it can be the anchor UE 801.

[0152] When the UE can be the anchor UE 801, the UE may not always desire to serve as the anchor UE 801. For example, the UE may not meet certain conditions for being the anchor UE 801. Therefore, an indication of the anchor UE 801 may be used. For example, the UE may indicate whether it can be 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-SSB. Since S-SSB is sent periodically, the UE can indicate that it can 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-SSB. For example, one reserved bit in the SL-MIB in the S-SSB can indicate whether the UE can be the anchor UE 801. Here, the indication can be used to indicate both cases, including whether the UE can be an anchor UE and whether the UE intends to become an anchor UE. The effective duration of the indication in 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 reserved bits in the SCI format 1-A. The indication can also be provided through RRC signaling.

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

[0154] The anchor availability indication, and the support for specific positioning methods / techniques, can be indicated in various ways. For example, the anchor indication can be made 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. In E-SID positioning based on signal strength measurements (e.g., RSRP), dynamic indication may not be adopted. The UE characteristic signaling exchange between the target UE 803 and the anchor UE 801 can be used for signaling as described above. RTT-based ranging or multi-RTT-based positioning may use more signaling exchanges, such as Rx-Tx time difference measurement. The RTT-based capabilities are different from the timing-based techniques. The indication can be different. Different positioning techniques may have different indications. For separate indications, more bits may have to be specified. Examples of such indications can be bitmaps, entries for each combination of table indications, etc.

[0155] The side link positioning procedure and SL Pos-RS transmission are discussed next. The positioning technique uses the transmission of positioning reference signals. In the Uu link, the reference signals are configured by the network and can be broadcast to any UE connected to the network or gNB. However, the reference signals in SL may require resource reservation. For example, the SL CSI-RS transmitted using PSSCH and CSI-RS is only used for unicast communication. For positioning, side link Pos-RS transmission may also require SL resource reservation even when there is no data to be transmitted. Since the positioning request may be on-demand and 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 side link positioning procedure, for example based on SL Pos-RS transmission, is discussed below. In the present disclosure, a scenario is described where the positioning estimation is at the target UE 803. The proposed design and solution may also be applicable to a scenario where the positioning estimation is performed at the anchor UE 801.

[0156] The triggering of sidelink Pos-RS transmission is discussed next. UE-B may trigger cooperation by sending an explicit request to UE-A, and UE-A will provide cooperation information including a preferred resource set or a non-preferred resource set to UE-B for UE-B's resource selection. Cooperation may also be triggered conditionally at UE-A. When the condition is met, UE-A generates cooperation information and sends it to UE-B. In SL positioning, either the target UE803 or the anchor UE801 can trigger the SL positioning process that starts the transmission of SL Pos-RS and the corresponding information exchange. The information exchange may include the location information of the anchor UE801 with respect to the target UE803, or the measurements at the anchor UE801 for performing the location estimation of the target UE803 at that anchor UE801. Some examples of triggering the sidelink positioning process or particularly the transmission of SL Pos-RS signaling are presented below.

[0157] Figure 9 is a schematic diagram showing sidelink positioning 900 triggered by target UE903. 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 measurement, the explicit request 905 can be sent from either the target UE903 or the anchor UE901.

[0158] As shown in FIG. 9, when the 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. Based on the indication of the presence of the anchor UE 901, the target UE 903 may know the availability of the anchor UE 901 and select a set of UEs as the anchor UE 901 for the positioning request of the target UE 903. Not all UEs shown as the anchor UE 901 may be or need to be selected by the target UE 903. The selection may be based on several criteria. To achieve a certain positioning reliability, the sync source of the anchor UE 901 may be important. The UE may have some requirements for the sync source or position accuracy that enable the UE to indicate whether the UE can be the anchor UE 901. The target UE 903 may have different or more stringent requirements for anchor UE 901 selection. In addition, the target UE 903 can 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 the others. The threshold for LOS determination may use the power difference for path comparison or may be configured as pre-configured. The non-LOS (NLOS) channel for the target UE 903 may introduce errors in positioning, and thus the corresponding anchor UE 901 may be given a lower priority in anchor selection.

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

[0160] The request may be sent from serving anchor UE 1002 to target UE 1003 via one of the three alternative means presented above. Using a 1-bit triggering request, it is possible to initiate (pre-)configured S-SSB, SL CSI-RS transmission, (pre-)configured SL PRS, or (pre-)configured SL SRS (such as SL-Pos-RS) from target UE 1003. The request via the second-stage SCI or MAC-CE can trigger SL Pos-RS transmission at target UE 1003 with several settings such as signaling options, SL Pos-RS configuration, bandwidth, SL Pos-RS power control, etc. In the present disclosure, the term anchor UE may be equivalent to the term anchor node since many devices such as roadside units (RSUs) may be used as anchors for positioning.

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

[0162] Next, the participating anchor UEs 1001 send their locations to the serving anchor UE 1002 and may also 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, the location information may be exchanged only once even when the UE indicates that it cannot currently act as the anchor UE 1001. For UEs with low mobility and slowly changing locations, the location information can be exchanged semi-statically, for example, via a direct communication interface (PC5) RRC. For UEs with rapidly changing locations, the 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 the information exchange is related to the speed of the RS or the Doppler spread. For example, when the RS has a larger Doppler spread, frequent information exchange can be performed. A precise mapping between the Doppler value and the periodicity may be (pre-)configured and provided together with the positioning requirement 1005 and / or the positioning cooperation requirement 1007. For positioning accuracy, the location information must be obtained when the anchor UE 1001 performs a measurement, and this measurement must be sent dynamically to the serving anchor UE 1002.

[0163] Figure 11 is a flowchart of an exemplary method 1100 for positioning in a target UE triggered by a request. 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) for characterizing the degree of LOS / NLOS for a channel. The selection of the anchor may be performed by combining the RSRP of the positioning RS with the LOS / NLOS metric and other criteria (zone, reference synchronization, mobility indicator, speed, Doppler spread, etc.).

[0164] Once the anchor UE is selected, at step 1103, the target UE can send a positioning request to the anchor UE. The request can be a trigger via a simple 1-bit indication. For such an indication, one reserved bit of the first-stage SCI, e.g., SCI 1A, can be used, or one 1-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 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 realized using RRC signaling.

[0165] The 1-bit triggering request can be used at the anchor UE for S-SSB or SL CSI-RS transmission, SL PRS preconfigured 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 configurations, bandwidth, SL Pos-RS power control, etc. can be sent during the request.

[0166] The SL Pos-RS configuration can be dynamic or semi-static and can be sent by the target UE during a request or via RRC signaling. The triggering can likewise be dynamic or semi-static. Generally, physical layer (PHY) signals such as 1-bit requests, second-stage SCIs, and MAC-CEs can be considered as dynamic triggering, and RRC signaling is semi-static. The hybrid approach is that the configuration can be sent to the anchor UE via RRC signaling or MAC-CE. When the target UE decides to estimate its location, the target UE sends an explicit request to the anchor UE.

[0167] In different examples, the triggering bit is sent to a group of UEs by groupcast. In addition to the triggering bit, response conditions can be provided. A potential anchor node participates only if it meets the provided conditions such as conditions 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 request sent in step 1103. The target UE can then perform positioning measurements based on the SL Pos-RS signals. The target UE can then estimate its location based on the measurements in step 1107.

[0169] FIG. 12 is a flowchart of an exemplary method 1200 for a hybrid procedure for positioning in an anchor UE. The hybrid mode for positioning using an anchor UE is described next. At step 1201, the serving anchor UE can send a request to the target UE. The target UE can first send a request to other cooperating anchor UEs at step 1203. The cooperating anchor UEs can then participate at step 1205 and can send SL Pos-RS to the target UE. The target UE can perform positioning measurements. The target UE then sends a measurement report to the serving anchor UE at step 1207. In some examples, the cooperating anchor UEs can 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 at step 1207, either separately or in the same transmission along with the measurement report.

[0170] The conditions for positioning triggered by an explicit request are discussed next. Some conditions can be specified such that either the target UE or the anchor UE triggers 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 conditions for triggering an explicit request.

[0171] In one example, triggering an explicit request depends on the implementation of the UE (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 the zone ID (e.g., included in SCI format 2-B) indicating the location of the target UE itself and the location of the anchor UE and / or a change thereof. The center or edge of the zone can be estimated based on historical communication, e.g., based on the time the target UE has remained 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 objective, e.g., absolute positioning or ranging. The condition related to the number of possible anchor nodes for the threshold can be applied for positioning. For example, one anchor UE is sufficient to enable ranging.

[0172] Side-link positioning may also be triggered based on conditions other than explicit requests. In some scenarios, the UE may perform positioning periodically or when certain conditions are met. Thus, the anchor UE or the target UE may send SL Pos-RS when triggered by conditions. One example is that in some areas, the RSU may send SL Pos-RS when the target UE appears or is within a certain range. Another example relates to cyber-physical control in a smart factory. In some work areas or to perform a certain task, the target UE may need to estimate its location, or the anchor UE may need to estimate the location of the target UE. In these scenarios, the SL positioning procedure may not need to be triggered by a request. Additionally, side-link positioning can also be triggered by conditions. In side-link positioning triggered by conditions, 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 that sends the SL Pos-RS.

[0173] Similar to the conditions for SL positioning requests, the conditions for SL Pos-RS transmission can be (pre-)configured at the resource pool level that enables and / or disables one or more of the following conditions.

[0174] In one example, which conditions trigger SL Pos-RS transmission depends on the implementation of the UE (either the target UE or the anchor UE). In another example, 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 SL Pos-RS transmission. For example, the distance can be determined based on the zone ID indicating the location of the target UE itself and the location of the anchor UE and / or a change thereof. In another example, the anchor UE may consider its position accuracy as an important condition for being an anchor UE. The position accuracy can be determined based on the sync source used by the anchor UE. Accordingly, the changing position accuracy can trigger or deactivate SL Pos-RS transmission. In another example, the channel condition between the anchor UE and the target UE may trigger or deactivate SL Pos-RS transmission. The channel condition between the anchor UE and the target UE can be determined based on a LOS channel with a dominant LOS path.

[0175] Once the conditions for activation are met, the anchor UE or the target UE acts as UE-A and transmits 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 for determining changing position accuracy, the location accuracy of the anchor UE or another reference UE may not be necessary.

[0176] The hybrid request and condition-based approach is discussed next. Instead of triggering SL positioning by an explicit request or based on conditions, a hybrid approach can be selected. As explained 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 the target UE may not send the SL Pos-RS immediately. Instead, the anchor UE or the target UE can start sending the SL Pos-RS and / or sending measurement reports only when one or more sets of conditions for positioning are met.

[0177] The method or container for the request can be any of the approaches discussed above. Similarly, the conditions for 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 the System Information Block (SIB) message. However, there is no SIB message for SL. The location information of the anchor UE has to be provided to the target UE or the serving anchor UE in other ways. The anchor UE can 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] UE's location information may be private information. The UE may be required to give approval to share the location information with other UEs. This can be used as an indication for the anchor UE. Its approval regarding the sharing of the UE's location can be a requirement for the UE to be an anchor UE if requested. Only if the UE approves to share its location information, can the UE indicate to other UEs that it can be an anchor UE.

[0180] The sidelink positioning reference signal (SL Pos-RS) is discussed next. The SL Pos-RS can be used to indicate a common positioning reference signal. Different positioning signals can be used for different techniques. Several reference signals are specified. Among these, the appropriate reference signals for positioning can be the synchronization signal or generally S-SSB, and SL CSI-RS. These two reference signals can be sufficient for RSRP or RSSI measurements in the E-SID positioning technique. For timing or angle estimation, additional positioning signals for the sidelink may be helpful. These reference signals and potential configurations are discussed next.

[0181] As described above, the periodicity of the S-SSB with the SL synchronization signal can 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-dependent and frequency-band-dependent. · For FR1: 〇 For 15 kHz SCS, {1} 〇 For 30 kHz SCS, {1,2} 〇 For 60 kHz SCS, {1,2,4} · For FR2: 〇 For 60 kHz SCS, {1,2,4,8,16,32} 〇 For 120 kHz 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-SSB is based on two configurable (pre-)configurations, the offset slot for the first S-SSB, and the slot interval between two consecutive S-SSBs. In addition to these configurations, the number of periods of S-SSB transmission can be configured. In summary, the following is a list of configuration parameters for which one or more of them can be considered for SL positioning. · Number of transmissions · Slot offset for the first S-SSB transmission in one period · Interval between two consecutive S-SSBs · Transmission period

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

[0184] Generally, the configuration of S-SSB cannot be changed dynamically. For positioning purposes, the following approaches can be used for the configuration of S-SSB transmission. · The configuration is provided in the request message. · Two sets of pre-configurations of S-SSB. The S-SSB configured for positioning is transmitted once positioning is triggered. 〇 S-SSB for synchronization and PSBCH 〇 Additional purposes, e.g., S-SSB for positioning · Various (pre-)configurations of S-SSB. At the time of positioning triggering, the S-SSB with one (pre-)configuration for positioning is transmitted. The configuration can be selected by request or by the UE itself. In positioning, when S-SSBs are transmitted from multiple anchor UEs within a short period, for example, within one 160 ms period, various configurations may be able to mitigate S-SSB collisions.

[0185] SL CSI-RS is discussed next. To improve SL transmission efficiency, CSI-RS signals are used and the Rx UE measures the sidelink channel quality for link adaptation. CSI-RS for sidelink is the same as that for Uu link, such as the CSI-RS pattern. However, the difference is that in sidelink, CSI-RS is sent on the resources of the scheduled PSSCH. Therefore, it is multiplexed with the coded transport block. Since 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 2. In SL positioning, unless the collocation of two antenna ports is considered, only one antenna port is used for SL Pos-RS transmission. In such cases, both can be used as positioning references. The transmission and configuration of SL PRS can modify the existing positioning configuration / procedure described below.

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

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

[0189]

Number

[0190] · Offset l offset Start 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] SRS as SL Pos-RS can be configured via one of the following alternative approaches. · The SRS configuration is provided in the request message. · For example, various (pre-)configurations of SRS for positioning in SL-SRS-PosResourceSet. When SL positioning is triggered, one (pre-)configured SL SRS for positioning is transmitted. The configuration can be selected via a request or by the UE itself (positioning / SL Pos-RS transmission triggered by conditions).

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

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

[0194] The behavior in the positioning / target UE and the hierarchy of the anchor / reference UE are discussed next. For the two types of UEs in the 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 in the UE itself or in the anchor UE) is called the target UE. The following terms may also be used for these two types of UEs. The UE with the location reference may be known as the anchor UE, reference UE, location reference UE, response UE, and / or source UE. The UE whose location is to be estimated may be known as the positioning UE, target UE, location request UE, request UE, and / or initiating UE.

[0195] The UE with the location to be estimated can be called the request UE or the initiating UE, but the positioning request or initiation may not always occur in this UE. The anchor UE may also request or initiate a positioning process including SL Pos-RS transmission in the target UE. Also, the anchor UE may have different location accuracies depending on those sync signals / sources, which can be converted to priority levels based on the original source being the global navigation satellite system (GNSS) or gNB / eNB.

[0196] The side-link synchronization criteria, priorities, and hierarchy of the SL positioning anchor are discussed next. In side-link, there are four possible synchronization sources for the UE, which include GNSS, gNB / eNB, the 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 by the number of steps (hops) away from GNSS or gNB / eNB. For example, those directly synchronized to GNSS or gNB / eNB are one step away from GNSS or gNB / eNB. The side-link synchronization procedure defines a set of hierarchies or priorities among such synchronization criteria, encouraging all UEs to continuously explore the hierarchy to reach the highest quality synchronization criteria they can find. The synchronization preference order is described by the following hierarchical priority levels, where a lower number indicates a higher priority. Level 1. Either GNSS or eNB / gNB by (pre-)configuration. Level 2. SyncRef UE directly synchronized 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 not (pre-)configured as a Level 1 source. Level 5. SyncRef UE directly synchronized to a Level 4 source. Level 6. 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. The UE's internal clock.

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

[0198] On the other hand, in the priority field of SCI 1-A, there are 8 priority levels for sidelink data traffic, indicated by 3 bits, p = 0,..., 7. Lower numbers indicate higher priorities. 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 converted and indicated by 8 PHY priority levels.

[0199] Therefore, the sync source or priority level can be a condition for selecting the UE serving as the anchor UE or the target UE for the anchor UE. In addition, the location accuracy of the UE based on the positioning source (which may be different from its sync source) can also set the qualification for the UE to be an anchor UE. The sync source or priority range is the coverage indicator I sent in the S-SSB and SL-MIB ICAnd can be roughly estimated based on the 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 an exact match.

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

[0201] In step 1301, the UE can determine the pre-configuration or specified requirements for a sync source, location accuracy, and / or maximum bandwidth for being an anchor. If one or more hierarchical level structures of the anchor UE are provided, the UE can determine, in step 1303, whether it is possible for it to be an anchor UE. The determination can 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 can determine its anchor level. The UE can then set its own anchor level based on the hierarchical level defined for the anchor UE. The anchor level can be a single-level metric that can be converted or mapped to an SL PHY priority. The anchor level can also be a respective list of metrics with different associated anchor levels, such as the UE's sync source, the UE's positioning source, etc. When the UE is given the qualification for being an anchor UE, the UE can, in step 1305, send a signal for the anchor indication. The UE can also send its anchor level. In some examples, the UE can, in step 1305, send a signal indicating that the UE is not and / or is no longer given the qualification for being an anchor UE. 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 indication, metric, and / or anchor level of the anchor UE received from the anchor UE.

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

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

[0204] Therefore, if the UE qualification hierarchy level of being an anchor is given, several hierarchical structures can be used to select the anchor UE. For example, such a hierarchical level can also include the channel quality when the SL positioning is triggered.

[0205] Similarly, when positioning is performed at the serving anchor UE, the serving anchor UE may select an additional anchor UE after obtaining location information and / or use measurement reports from a subset of cooperative anchor UEs. The behavior of the target UE can be scenario-dependent, for example, it can also be absolute positioning or ranging.

[0206] Next, the cast types of transmissions in the SL positioning process are discussed. In many cases or scenarios, S-SSB transmissions are broadcast. In the case of SL positioning or SL Pos-RS transmissions, the following cast types for different types of transmissions can be supported. · Transmission of explicit requests when SL Pos-RS is triggered by a request: 〇 Unicast: The target UE sends requests independently to each of the anchor UEs. 〇 Groupcast: After anchor UE selection, a group of anchor UEs is formed by the upper layer. The target UE groupcasts requests to the group of anchor UEs. · SL CSI-RS transmission: 〇 Resource rel-16 behavior, unicast is supported. · SL Pos-RS (e.g., SL PRS) transmission: 〇 Unicast: Each of the anchor UEs reserves resources and sends SL Pos-RS to the target UE via unicast. 〇 Broadcast: The anchor UE or the target UE (when positioning is performed at the serving anchor UE) broadcasts SL Pos-RS. 〇 Groupcast: The target UE can groupcast the SL Pos-RS to the selected anchor UE.

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

[0208] FIG. 15 is a schematic diagram 1500 showing an anchor UE 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, the broadcast technique is more useful. Thus, the interaction between the anchor UE and the target UE may preferably be very limited. The location information of the anchor UE can also be broadcast to all UEs, either multiplexed with the SL Pos-RS transmission or in a separate transmission. By using the broadcast of SL Pos-RS and the location information of the anchor UE, UEs within the range of these anchor UEs can benefit from the positioning information. FIG. 1500 shows an exemplary case of V2x where 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 only be required as the SL Pos-RS. The target UE 1503 can measure the RSRP in the DMRS in the PSBCH and / or the S-PSS or S-SSS in the S-SSB.

[0209] Positioning via timing-based measurements uses the large bandwidth of SL Pos-RS for high accuracy, but 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. Thus, more positioning and less communication may be desired. Each of the anchor UEs 1501 can reserve resources to broadcast SL Pos-RS as well as the location formation of the anchor UEs for a period of time whenever positioning information is requested or conditionally triggered as described herein.

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

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

[0212] The positioning procedure involves information exchange between two sides, and the IUC mode 1 can be revised as follows to assist other UEs for SL positioning transmissions. · In addition to the requirements, as UE-A, the target UE sends a preferred set of resources to each of the anchor UEs (as UE B) for its SL Pos-RS transmission. Using such cooperation, it is possible to avoid SL Pos-RS collisions. · The target UE as UE-A also sends a preferred resource set for each of the anchor UEs (as UE-B) to transmit its location. · The (serving) anchor UE as UE-A sends a preferred resource set for the target UE (as UE-B) to transmit SL Pos-RS. · The (serving) anchor UE as UE-A sends a preferred resource set for the target UE (as UE-B) to send measurement reports.

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

[0214] For SL Pos-RS transmission, the following can be specified. · S-SSB: Using 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): 〇 In the case of unicast: If it has the same behavior as CSI-RS, it must be multiplexed with data (e.g., location information or measurement reports). 〇 In the case of groupcast / unicast, it can be multiplexed with data (e.g., location information or measurement reports). Note that in SL PRS transmission, even if it is triggered by a specific UE and / or for a specific target UE, since the SL PRS does not require a destination ID, the source / destination ID pair may not need to be the same as that of the data. 〇 In the case of broadcast, it can also be multiplexed with data (e.g., location information of the anchor UE, or measurement reports from the target UE to the anchor UE or from the cooperating anchor UE to the serving anchor UE) if necessary.

[0215] In the transmission of location information, retransmission may not be required because the location may change during retransmission. Retransmission can be dropped or invalidated based on the quality of the location information, for example, if the change in location exceeds a threshold or the speed of the UE exceeds a threshold.

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

[0217] Depending on the respective large bandwidths of SL Pos-RS transmissions, it may also be preferable for multiple UEs to transmit different SL Pos-RSs that are orthogonal in time and frequency but within the same RB on the same resource on the same slot. UL SRSs from different UEs can be transmitted on the same resource as long as they are on different REs. For sidelink, when SL Pos-RS signals from multiple anchor UEs are transmitted on the same resource, inter-symbol interference may occur due to different reception times at the UE. This can be mitigated by constructing the SL Pos-RS with SL Pos-RS REs that do not appear on the same subcarrier for two consecutive OFDM symbols. Alternatively, this problem can be solved by constructing each of the PRS / SRSs with different offsets such that there is 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 4 or less.

[0218] Additional control signaling support is used for SL Pos-RS signals from different UEs on the same resource. For example, only one UE may be able to 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] Accordingly, the present disclosure focuses on a first artificial intelligence (AI) for SL positioning with respect to potential solutions for SL positioning, considering relative positioning, ranging, and absolute positioning. For this purpose, reference signals for positioning are considered, including signal design, measurement, and related procedures, while reusing as much as possible reference signals and procedures from sidelink communication and positioning.

[0220] The signal bandwidth and the signal-to-noise ratio (SNR) are discussed next. The channel bandwidth and the received SNR determine the positioning accuracy of the method based on the time-of-flight (TOF) / time-of-arrival (TOA) distance measurement. From the Cramér–Rao lower bound (CRLB) analysis, the variance of the TOA measurement of the LOS channel approximately reaches the lower bound,

[0221] [Number]

[0222] where β represents 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 a higher signal bandwidth improves the TOA measurement accuracy. Investigating the influence of the bandwidth on the location accuracy may indicate whether the SL positioning solution should be extended to the unlicensed spectrum.

[0225] FIG. 16 is a schematic diagram 1600 of an example of LOS and NLOS sidelink positioning. When there is a direct LOS path 1611 between the anchor UE 1601 node and the target UE 1603 node, a larger positioning signal bandwidth enables better resolution of multipath components, which increases the accuracy of finding the first path and thus reduces the error caused by the multipath bias of TOA, RTT, and TDOA-based methods. However, when such a direct LOS path 1611 does not exist and the communication between the anchor UE 1601 node and the target UE 1603 node is performed via NLOS reflection 1613, the range between the anchor UE 1601 node and the target UE 1603 node is overestimated due to the increased TOF. The estimation of the angle of arrival (AOA) and the angle of departure (AOD) may also be affected by NLOS propagation, which leads to low accuracy of location estimation.

[0226] Time synchronization is discussed next. When a TOF and / or TOA-based positioning method is used, the receiver can estimate the TOF between the transmitter and the receiver, and thus the range, using the time stamp from the transmitter. However, even when the channel is LOS, additional errors are introduced if the clocks at the transmitter and the receiver are not synchronized, which affects ranging and position estimation. The network synchronization error is defined as a truncated Gaussian distribution of the root mean square (rms) value in nanoseconds (ns) (T1) between the 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 (fully synchronized) and 50 ns.

[0227] Some positioning methods, such as multi-RTT, are robust with respect to time synchronization if clock drift can be ignored over the duration during which the difference between the reception time and the transmission time of the positioning signal is measured, while 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 taken into account.

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

[0229] RAT-dependent methods for positioning are based on the exchange of reference signals (RS) between an anchor node (gNB) and a target node (UE). In the present disclosure, the target UE is the UE that requests position / location determination, and the anchor nodes are those nodes such as UEs, gNBs, and / or RSUs that can be considered as a reference for the 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. The RAT-dependent methods are as follows. · NR Extended Cell ID method (NR E-CID) based on NR signals · Multi-round trip time positioning (multi-RTT based on NR signals) · Downlink departure angle (DL-AoD) based on NR signals · 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 above list of positioning methods is also supported

[0230] Measurements for supporting the above method are as follows. · Downlink PRS reference signal received power (DL PRS RSRP) · Downlink PRS reference signal received path power (DL PRS RSRPP) · Downlink PRS reference signal time difference (DL PRS RSTD) · UE Rx-Tx time difference

[0231] In the sidelink positioning scenario, 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 that is more robust with respect to clock synchronization between the anchor node and the target node.

[0232] In sidelink mode 2 operation, a robust positioning method such as multi-RTT may be preferable. The physical layer standard may be modified to support SL UE positioning methods and measurements. For positioning, the SL UE must support the aggregation of DL PRS resources with SL positioning resources.

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

[0234] The 5G system must be able to make location-related data available to applications or application servers that are either inside the 5G network, outside the 5G network, or in the user equipment. In the OOC case, it is not clear whether an entity similar to the LMF is still required and, if so, where it must be located. The target UE must support a function that enables it to calculate an estimate of its location. Such functionality and complexity may depend on the scenarios covered by OOC, such as ranging, relative positioning, or absolute positioning.

[0235] The SL positioning solution for the OOC scenario must be able to select a positioning method, configure and activate sidelink reference signal transmissions triggered per request or by an event, select anchor nodes, activate RRC connectivity if necessary, obtain location information or request SL Pos-RS transmissions, provide or exchange location information if requested, and configure and activate the collection of SL positioning measurements to estimate relative or absolute positions.

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

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

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

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

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

[0241] [Number]

[0242] and 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 indices 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 higher 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 symbol of the DL-PRS resource), where the comb size K comb PRS∈{2, 4, 6, 12} is given by the upper layer parameter dl-PRS-CombSizeN-AndReOffset for the downlink PRS resources configured for RTT-based propagation delay compensation, otherwise by the upper layer parameter dl-PRS-CombSizeN, whereby the combination {LL PRS , K comb PRS} is one of {2, 2}, {4, 2}, {6, 2}, {12, 2}, {4, 4}, {12, 4}, {6, 6}, {12, 6}, and {12, 12}.

[0245] The comb distribution enables a wider bandwidth of the RS signal and thus better accuracy of TOA estimation. However, the gaps in frequency generate aliases in time, and these aliases can be compensated by the time repetition and coherent combination of the PRS in time. For example, when 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 selected such that there is no staircase pattern. This has the main advantage of increasing robustness (e.g., against Doppler shift) when using only the first symbol for coherent combination. In addition, the comb design and the frequency offset between consecutive symbols provide increased robustness against wideband fading and orthogonality to other PRS signals from other TRPs.

[0247] The PRS resources are defined by an ID, a sequence ID {0,..., 4095}, the comb size {2, 4, 6, 12} of the remaining symbols and the RE offset, the resource slot offset, the resource symbol offset, and the QCL information. The 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] FIG. 17 is a schematic diagram of an example of a positioning reference signal (PRS) resource set 1700. The PRS resource set 1700 is characterized by an ID, a subcarrier spacing, the periodicity (of resource set transmission), a resource list, a resource repetition factor (the number of repetitions of each resource during an instance of the resource set), a resource time gap (the number of slots between consecutive resource repetitions), a comb size, a resource bandwidth (between 24 PRBs and 272 PRBs in increments of 4 PRBs), a start of a PRB index, and the number of resource symbols in a PRS slot. The PRS resource set 1700 can be placed anywhere in the frequency grid via the start of the PRB index, which is an offset with respect to a reference frequency point A.

[0249] The PRS resource set is sent by the gNB with a periodicity of T per PRS ∈2 μ {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 DL-PRS resource is repeated for a single instance of the DL-PRS resource set, and the value T rep PRS ∈ {1, 2, 4, 6, 8, 16, 32} can be taken. All DL PRS resources within one resource set have the same resource repetition factor.

[0251] To mitigate interference to weak PRS signals, strong PRS signals may be muted. The muting pattern is specified by a {2, 4, 8, 16, 32}-bit bit string in each cell, where the bits indicate whether the PRS transmission in the corresponding slot is muted.

[0252] A UE in the RRC connected state is required to measure only DL PRS that is within the active bandwidth part (BWP) and has the same numerology as that active BWP. The UE may request a serving gNB measurement gap that is outside the active BWP and can be used to measure DL PRS with a different numerology.

[0253] For 15 kHz SCS, the minimum DL PRS is about 5 megahertz (MHz), and the maximum DL PRS is about 50 MHz. For 120 kilohertz (kHz) SCS, the DL PRS minimum 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 sounding RS (SRS) and is called SRS for positioning. The UL PRS1800 sequence is a 31-bit Zadoff-Chu that provides a good peak-to-average ratio. UL PRS1800 can span over {1, 2, 4, 8, 12} consecutive OFDM symbols that can be placed anywhere in the slot. Similar to DL PRS, UL PRS1800 has a comb size of {2, 4, 8} and has a comb-N pattern in frequency. Similar to UL PRS1800, DL PRS has a comb offset that defines the relative frequency shift between consecutive OFDM symbols. This offset provides similar advantages for DL PRS. Only the first few symbols may be considered for TOA measurement through coherent combination. Similar to DL PRS, UL PRS1800 may be transmitted periodically with a certain periodicity and slot offset. However, the semi-persistent configuration is made active and inactive via MAC-CE signaling. The aperiodic UL PRS1800 is transmitted only when the UE is commanded by the gNB via downlink control information (DCI). UL PRS1800 supports spatial relationships, where the spatial relationship can be either a DL reference signal (SSB, CSI-RS, or DL-PRS) or a previously transmitted SRS or UL-PRS1800. UL PRS1800 can also have a spatial relationship with a non-co-located transmit-receive point (TRP).

[0255] Another property of UL PRS1800 is power transmission control, where the UE estimates the UL path losses of the serving and neighboring TRPs based on DL measurements and sets the UL PRS1800 power accordingly. The UL PRS1800 resource set includes 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] UL resources are described by an ID, a transmission comb, a resource mapping (symbol location in the UL PRS1800 slot), a frequency domain shift, a bandwidth indication (as part of frequency hopping, not used for frequency hopping indication for SRS cases), a resource type (periodic, semi-persistent, aperiodic), a corresponding periodicity, a sequence ID used to initialize a pseudo-random group, sequence hopping, and spatial relation information.

[0257] As in the case of DL PRS, the UE can be composed of multiple UL PRS resource sets.

[0258] The reference signal for sidelink positioning is discussed next.

[0259] Figure 19 is a schematic diagram of an exemplary S-SSB1900. The S-SSB1900 is a broadcast signal used for synchronization purposes, and it consists of a sidelink primary synchronization signal (S-PSS), a sidelink secondary synchronization signal (S-SSS), and a physical sidelink broadcast channel (PSBCH). There are 672 unique physical layer sidelink synchronization identifications, 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 thus provides information on the accuracy of the time reference. Before starting to send the S-SSB1900, the SL UE must select its own time reference and notify it via the SLSSID.

[0260] In the frequency domain, the S-SSB1900 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 within the S-SSB slot. The PSBCH occupies 132 subcarriers over a duration of 8 symbols (Figure 5). The first PSBCH symbol serves for automatic gain control (AGC) purposes. Each transmission of the S-SSB is repeated once or several times during each period of 16 subframes. The frequency location of the S-SSB is fixed.

[0261] The S-SSB1900 is mainly used by the receiver SL UE to capture synchronization with a transmitter SL device or may be used for the 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] The S-SSB can be adapted to estimate the TDOA between anchor SL devices. The accuracy of the TDOA estimate is increased when the S-SSB generators 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 positioning can be supported by the network.

[0263] The sidelink positioning signal (SL Pos-RS) is discussed next. One of the topics of this research item relates to the study of sidelink reference signals for positioning purposes from a physical layer perspective, including signal design, resource allocation, measurement, related procedures, etc., using as much as possible reference signals, procedures, etc. from sidelink communication and positioning.

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

[0265] The Zadoff-Chu (ZC) sequence used for uplink PRS provides better PAPR properties (small power fluctuations in time and frequency) compared to the Gold sequence used for DL PRS. Such PAPR properties may be desirable for SL UEs to avoid non-linear signal distortion.

[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 within 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. The SL Pos-RS configuration can be controlled by the gNB when the SL UE is within 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 as well as signaling protocols and interfaces are defined. The positioning solution relies on the LTE positioning protocol (LPP) and the Location Management Function (LMF). In particular, the LMF is used for the compilation of positioning methods and protocols.

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

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

[0271] Figure 20 is a schematic diagram of an exemplary UE2000 for side link communication. The UE2000 can be used as the target UE, and the anchor UE, or any other UE described herein. Thus, the UE2000 can be configured to implement or support the methods / features / methods described herein. For example, the features / methods in the present disclosure can be implemented using hardware, firmware, and / or software installed to operate on the hardware. Those skilled in the art will recognize that the term UE encompasses a wide range of devices and that the UE2000 is merely an example of those devices. The UE2000 is included for the sake of clarity of discussion and is in no way intended to limit the application of the present disclosure to a specific network device embodiment or class of network device embodiments.

[0272] UE2000 can be a device that communicates electrical, wireless, and / or optical signals through a network. As shown in FIG. 20, UE2000 can include a transceiver (Tx / Rx) 2010 that can be a transmitter, a receiver, or a combination thereof. Each, Tx / Rx 2010 may be coupled to a plurality of downstream ports 2020 (e.g., downstream interfaces) to transmit and / or receive frames from other nodes, and Tx / Rx 2010 may be coupled to a plurality of upstream ports 2050 (e.g., upstream interfaces) to transmit and / or receive frames from other nodes. A processor 2030 may be coupled to Tx / Rx 2010 to process data signals and / or to determine to which node a data signal should be sent. Processor 2030 may include one or more multi-core processors and / or a memory device 2032 that can function as a data store, buffer, etc. Processor 2030 may be implemented as a general-purpose processor or may be part of one or more application-specific integrated circuits (ASICs) and / or digital signal processors (DSPs). UE2000 can include an SL positioning module 2014 configured to use sidelink communication to an initial SL-based positioning mechanism as described herein. SL positioning module 2014 can be implemented in a general-purpose processor, a field programmable gate array (FPGA), an ASIC, a DSP, a microcontroller, etc. In an alternative embodiment, SL positioning module 2014 can be executed by processor 2030 and / or can be implemented partially in processor 2030 and partially in memory device 2032, as computer-executable instructions stored in memory device 2032 (e.g., as a computer program product stored on a non-transitory computer-readable medium) and implemented in processor 2030. Downstream port 2020 and / or upstream port 2050 may, in some embodiments, include wireless, electrical, and / or optical transmit and / or receive components.

[0273] FIG. 21 is a schematic diagram of an exemplary embodiment of a UE 2100 for sidelink positioning. The UE 2100 can be used as a target UE, and 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 an example, the transmitter 2107 serves as transmission means for transmitting a positioning request to one or more anchor UEs via sidelink communication. Further, the receiver 2101 serves as reception means for receiving a positioning signal from one or more anchor UEs via sidelink communication. Additionally, the measurement module 2103 serves as measurement means for performing a positioning measurement based on the positioning signal.

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

[0275] FIG. 22 is a flowchart of an exemplary method 2200 for performing sidelink-based positioning at 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 can indicate whether the corresponding UE can serve as an anchor UE and whether the corresponding UE is allowed to serve as an anchor UE. In an example, the UE anchor level can be set based on a synchronization source, a priority level, a location accuracy, a maximum bandwidth, a coverage indicator, an SLSSID, or a combination thereof.

[0276] Positioning can be managed by the target UE, by the anchor UE, and / or by the serving anchor UE in cooperation with the cooperating anchor UE. 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 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 can be triggered by the target UE. In other examples, the positioning request can be triggered by the initial positioning request from the serving anchor UE in step 2203, and in this case, one or more of the 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 with a first threshold, distance with a second threshold, number of UE anchors with a third threshold, channel condition with a fourth threshold, or a combination thereof.

[0278] Note 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 can communicate with one or more anchor UEs via resource reservation provided by the gNB. In mode 2, the target UE is outside the network range. 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 can use opportunistic signaling to select communication resources without communicating with the 5G network.

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

[0280] In step 2209, the UE may perform positioning measurements based on the positioning signal. 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 location measurements to the serving anchor UE via sidelink communication for the estimation of the target UE's location. In some examples, the target UE may instead send a report indicating the location of the target UE based on step 2209 to the serving anchor UE. In some examples, the target UE may also send a report related to the positioning signal received from the cooperating anchor UE to the serving anchor UE.

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

[0283] FIG. 23 is a flowchart of an exemplary method 2300 for performing sidelink-based positioning at an anchor UE. In an optional step 2301, the anchor UE may transmit a UE anchor indication indicating whether the anchor UE is capable of acting as an anchor UE and whether the anchor UE is allowed to act as (e.g., desires to act 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, a coverage indicator, a sidelink synchronization signal identifier (SLSSID), or a combination thereof. The optional steps 2301 and 2303 allow the anchor UE to indicate to potential target UEs whether the anchor UE can be selected as an anchor UE for positioning, and also allow the target UE to determine which anchor UE should be selected for the best results.

[0284] In step 2305, the anchor UE transmits a positioning request to the target UE via sidelink communication. In some cases, the anchor node acts as a serving anchor node. In some examples, the positioning request may signal to 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 a RSRP with respect to a first threshold, a distance with respect to a second threshold, a number of UE anchors with respect to a third threshold, a channel condition with respect to a fourth threshold, or a combination thereof.

[0285] Note 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 can communicate with the target UE via resource reservation provided by the gNB. In mode 2, the anchor UE is outside the network range. In such a case, the anchor UE communicates with the target UE according to sensing-based resource selection of sidelink resources. This approach can select communication resources without communicating with the 5G network using opportunistic signaling.

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

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

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

[0290] In step 2315, the anchor UE may estimate the location of the target UE based on the positioning measurements from the target UE and / or the location information from one or more cooperative 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 location 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 this disclosure. This example should be considered as illustrative and not restrictive, and the intention should not be limited to the details given herein. For example, various elements or components may be combined or incorporated into another system, or some features may be omitted or not implemented.

[0292] In addition, the techniques, systems, subsystems, and methods described and illustrated in various embodiments as individual or discrete may be combined with or incorporated into other systems, modules, techniques, or methods without departing from the scope of this disclosure. Other items shown or discussed as being directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediary, whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and modifications will be apparent to those skilled in the art and may be made without departing from the spirit and scope disclosed herein.

Claims

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 a positioning signal from the one or more anchor UEs via the sidelink communication; performing a positioning measurement based on the positioning signal; and a method comprising the above steps.

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

3. The method according to claim 1 or 2, wherein the target UE communicates with the one or more anchor UEs via resource reservation provided by a fifth generation (5G) base station (gNB).

4. The method according to any one of claims 1 to 3, wherein the positioning signal includes a sidelink positioning reference signal (SL Pos-RS).

5. The method according to 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 according to any one of claims 1 to 5, further comprising, before the step of transmitting the positioning request to the anchor UE, selecting the one or more anchor UEs from a plurality of additional anchor UEs.

7. The method according to any one of claims 1 to 6, further comprising estimating the location of the target UE based on the positioning measurement and the locations of the one or more anchor UEs.

8. The method according to any one of claims 1 to 7, further comprising, before the step of transmitting the positioning request to the one or more anchor UEs, receiving an initial positioning request from a serving anchor UE via the sidelink communication.

9. The method according to any one of claims 1 to 8, further comprising sending the positioning measurement to the serving anchor UE via the sidelink communication for estimating the location of the target UE.

10. The step of transmitting the positioning requirement is triggered by a condition, and the condition includes at least one of reference signal received power (RSRP) for a first threshold, distance for a second threshold, number of UE anchors for a third threshold, or channel condition for a fourth threshold. The method according to any one of claims 1 to 9.

11. The method according to any one of claims 1 to 10, wherein the one or more anchor UEs are selected based on a UE anchor indication and a UE anchor level.

12. The method according to any one of claims 1 to 11, wherein the UE anchor indication indicates whether the corresponding UE can act as an anchor UE and whether the corresponding UE is allowed to act as an anchor UE.

13. The method according to any one of claims 1 to 12, 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).

14. The method according to any one of claims 1 to 13, further comprising the step of reselecting the one or more anchor UEs after obtaining at least one of an anchor UE position, a channel measurement, or a timing measurement.

15. A method implemented by an anchor user equipment (UE), the method comprising: transmitting a positioning requirement to a target UE via sidelink communication; receiving a positioning signal from the target UE via the sidelink communication; performing a positioning measurement on the target UE based on the positioning signal and including a method.

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

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

18. The method according to any one of claims 15 to 17, wherein the positioning signal includes a sidelink positioning reference signal (SL Pos-RS).

19. The method according to any one of claims 15 to 18, further comprising the step of estimating the location of the target UE based on the positioning measurement.

20. The method according to any one of claims 15 to 19, wherein the positioning request triggers the target UE to send one or more second positioning requests to one or more cooperating anchor UEs.

21. The method according to any one of claims 15 to 20, wherein the positioning signal from the target UE includes location information from the one or more cooperating anchor UEs.

22. The method according to any one of claims 15 to 20, further comprising the step of receiving location information from one or more cooperating anchor UEs.

23. The method according to any one of claims 15 to 22, further comprising the step of transmitting one or more second positioning requests to one or more cooperating anchor UEs.

24. The positioning request is triggered by a condition, the condition including at least one of a reference signal received power (RSRP) relative to a first threshold, a distance relative to a second threshold, a number of UE anchors relative to a third threshold, or a channel condition relative to a fourth threshold. The method according to any one of claims 15 to 23.

25. The method according to any one of claims 15 to 24, further comprising the step of transmitting a UE anchor indication indicating whether the anchor UE can function as an anchor UE and whether the anchor UE is enabled to function as the anchor UE.

26. The method according to any one of claims 15 to 25, further comprising the step of transmitting a UE anchor level set based on at least one of a synchronization source, a priority level, a location accuracy, a maximum bandwidth, a coverage area indicator, or a sidelink synchronization signal identifier (SLSSID).

27. The method according to any one of claims 1 to 27, wherein the one or more anchor UEs are selected according to a line of sight (LOS) / non-line of sight (NLOS) indicator.

28. A user equipment (UE), one or more processors, a transmitter coupled to the one or more processors, A user equipment (UE) comprising a receiver coupled to the one or more processors, the one or more processors, the transmitter, and the receiver being configured to implement the method according to any one of claims 1 to 27. User Equipment (UE). **Claim 29** A non-transitory computer-readable medium including 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 to cause the UE to implement the method according to any one of claims 1 to 27 when executed by one or more processors. **Claim 30** A target user equipment (UE) comprising one or more means for implementing the method according to any one of claims 1 to 14. **Claim 31** An anchor user equipment (UE) comprising one or more means for implementing the method according to any one of claims 15 to 27.

Images