WO2022184240A1

WO2022184240A1 - Method and apparatus for user device positioning based on sidelink

Info

Publication number: WO2022184240A1
Application number: PCT/EP2021/055178
Authority: WO
Inventors: Xitao Gong; Qi Wang; Richard Stirling-Gallacher; Mario Hernán CASTAÑEDA GARCIA
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2021-03-02
Filing date: 2021-03-02
Publication date: 2022-09-09
Also published as: EP4295621A1; CN116918399A

Abstract

The present disclosure relates to a user device for positioning based on sidelink, wherein the user device is configured to: obtain a sidelink, SL, positioning resource information, wherein the sidelink positioning resource information indicates a resource characteristic of a sidelink positioning reference signal, SL-PRS, a positioning assistance data, AD, or location information, LI; and perform sidelink positioning based on the sidelink positioning resource information.

Description

METHOD AND APPARATUS FOR USER DEVICE POSITIONING BASED ON SIDELINK

TECHNICAL FIELD

The present disclosure relates to techniques for sidelink positioning, in particular to methods and apparatus for user device positioning based on sidelink. The disclosure particularly relates to resource allocation and signaling for enabling sidelink positioning.

BACKGROUND

In current location service (LCS) provided in long term evolution (LTE) and new radio (NR), radio access technology (RAT) dependent positioning techniques are applied only based on downlink and/or uplink transmissions between user equipment (UE) and base station(s)/transmission and reception point(s). Recently, LCS coping with use cases for user equipment in partial coverage and out-of-coverage scenarios have caught enormous interest in 3GPP discussions, especially for vehicle-to-everything (V2X) and public safety services. Consequently, there is a need for applying RAT-dependent positioning techniques also via sidelink (SL) transmissions between UE(s). For the sidelink resource allocation, currently developed in 3GPP, the main goal is tailored to transmission and reception of data or discovery signals, but not for addressing sidelink positioning challenges.

SUMMARY

It is an objective of this disclosure to enhance current positioning protocols for sidelink positioning, especially for partial-coverage and out-of-coverage scenarios.

A further objective is to configure efficient resource allocation for sidelink positioning reference signal (SL-PRS), transferring assistance data (AD) and/or location information (LI) to meet sidelink positioning requirements.

One or more of these objectives is achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

In order to enable sidelink positioning, this disclosure provides a solution to the above described problems. A concept is presented for efficient configuration of resource allocation for sidelink positioning reference signal (SL-PRS), transferring assistance data (AD) and/or location information (LI) meeting the sidelink positioning requirements. A basic idea of this disclosure is to introduce a new resource indication mechanism for SL- PRS resource, resource set, and repetition pattern under SL resource indication framework, with fine-granularity indication in both time and frequency domain, i.e. symbol-level and fractional-subchannel level. This mechanism offers flexible indication of resource, e.g., consecutive/non-consecutive repetition/allocation in time and frequency, fractional subchannel-based frequency hopping. In addition, this disclosure also presents resource reservation indication under requested constraints (e.g., latency requirements).

Signaling procedures to support such new resource allocation and indication in sidelink are also introduced, including request procedures with requested resource requirements, as well as procedures to deliver the configuration of resource allocation and reservations.

In this disclosure, positioning based on sidelink is presented. Sidelink is defined as a communication paradigm in which two user devices are communicating without traversing any network node, applying to various services such as in V2X, public safety, and/or internet of things (IOT) services. Specifically, UE’s positioning is performed based on sidelink measurements for these RAT-dependent sidelink positioning methods, while sidelink is exploited for the transmission/reception of reference signals. Data communication via V2X sidelink for in-coverage, partial coverage, and out-of-coverage has been evolved in Rel. 16 for advanced use case and will be enhanced in Rel. 17, see “New WID on NR sidelink enhancement, LG Electronics, 3GPP TSG RAN Meeting #86, December 9-12, 2019”, wherein resource allocation is one of the main technical component.

This disclosure introduces a resource allocation mechanism for SL-PRS, SL-LI and/or SL-AD which is different from the current mechanism for data or for other reference signals. The new mechanism allows for flexible resource configuration with fine granularity and flexibility in time and frequency, in order to meet the positioning requirement and increase the chance to find the resource.

According to a first aspect, the disclosure relates to a user device for positioning based on sidelink, wherein the user device is configured to: obtain a sidelink, SL, positioning resource information, wherein the sidelink positioning resource information indicates a resource characteristic of a sidelink positioning reference signal, SL-PRS, a positioning assistance data, AD, or location information, LI; and perform sidelink positioning based on the sidelink positioning resource information. Such a user device provides the technical advantage of an enhanced sidelink positioning, especially for partial-coverage and out-of-coverage scenarios. The user device is configured for efficient resource allocation for sidelink positioning reference signal (SL-PRS), transferring assistance data (AD) and/or location information (LI) meeting sidelink positioning requirements.

The user device may be a Tx or Rx UE. So, it includes the behaviors of both UE, i.e. transmits PRS/AD/LI or receives PRS/AD/LI etc.

It should be understood that the user device, in some scenarios, acts as a transmitting device, but, in some other scenarios, acts as a receiving device. In some scenarios, the user device may act as both a transmitting device and a receiving device. The present disclosure may treat the user device as both transmitting device and receiving device, but it should be understood that the user device may act as only transmitting device or receiving device. The user device may refer as UE (User Equipment) in the present disclosure.

The user device is configured to obtain sidelink positioning resource information. In this context, the term “obtain” includes that the user devices is sending a request for sidelink positioning resource information to the network or that the user device is receiving sidelink positioning resource information from the network, or even that this sidelink positioning resource information is pre-configured. In the case of pre-configuration, the pre-configured sidelink positioning resource information may for example be stored in a memory of the user device. Note that these sidelink positioning resources are resources only for positioning via sidelink and not for communication via sidelink.

Sidelink or sidelink communication according to the disclosure is an adaptation of the core LTE standard that allows for communication between two or more nearby devices, using E-UTRAN technology (Evolved UMTS Terrestrial Radio Access Network) without the need of a base station. This technology can be used for the out-of-network coverage scenario. The functionality can also be used in conjunction with conventional LTE connections to mobile networks to open-up a wide variety of innovative connected car services, factory automation services, etc.

In an exemplary implementation of the user device, the resource characteristic comprises a latency information, wherein the latency information indicates latency requirement for the SL- PRS, the AD or the LI. Introducing latency information in the resource characteristic provides the advantage of improving the resource efficiency of the SL resource, since the SL resource is scare and precious. Always transmitting PRS/AD/LI would be a waste of SL resources. The latency information indicates latency requirement or latency characteristic of the SL-PRS/AD/LI.

A requirement as defined above, is a physical or functional need that a particular design, product or process aims to satisfy. A requirement is any necessary or desired function, attribute, capability, characteristic, or quality of a system or device for it to have value and utility to a user, customer, organization, etc. With respect to the resource characteristics, a latency requirement is a latency or latency range that should be met for the sidelink transmission. The latency requirement can specify a maximum latency from requesting SL transmission to the start of SL transmission in order to restrict the delay to activate SL transmission. The latency requirement can specify a latency window for SL transmission within one location session in order to restrict the delay of SL transmission within one location session.

The resource characteristic of the sidelink PRS may comprise a bandwidth information, wherein the bandwidth information indicates a bandwidth for the SL-PRS transmission.

This provides the advantage that the bandwidth for the SL-PRS transmission can be efficiently scheduled. Since the bandwidth is a precious resource, the user device can be efficiently schedule bandwidth usage for positioning.

The resource characteristic of the sidelink PRS may comprise a periodicity information, wherein the periodicity information indicates a periodicity of the SL-PRS transmission.

This provides the advantage that by knowing the periodicity information of the SL-PRS, detection of the SL-PRS can be efficiently performed by applying this periodicity information.

In an exemplary implementation of the user device, obtaining a sidelink, SL, positioning resource information comprises: sending a request for sidelink positioning resource information to a network entity, receiving the sidelink positioning resource information from a network entity, or obtaining pre-configured sidelink positioning resource information.

This provides the advantage that the user device can be flexibly configured for sending a request, receiving respective information or obtaining a pre-configured information. In an exemplary implementation of the user device, the user device is configured to receive or transmit the SL-PRS, AD or LI based on the sidelink positioning resource information.

This provides the advantage that the user device can efficiently perform sidelink transmission and reception based on the sidelink positioning resource information.

Sidelink positioning can be performed based on the sidelink positioning resource information. That means, SL-PRS signal can be transmitted or received by the user device to initiate or obtain corresponding measurements for positioning and calculation of sidelink position result; AD can be transmitted or received by the user device to request or obtain assistance data in sidelink positioning; LI can be transmitted or received by the user device to request or obtain location information in sidelink positioning.

The following implementations are related to Indication of SL-PRS resource, resource set and repetition pattern.

In an exemplary implementation of the user device, the SL positioning resource information is indicative of at least one of: discontinuous or consecutive symbol-level in time domain, intra slot or inter-slot repetition in time domain, discontinuous or consecutive fractional subchannel indication in frequency domain, frequency hopping in frequency domain.

This provides the advantage that the user device can efficiently divide the available resources down to smallest units in time and frequency domain.

In an exemplary implementation of the user device, the SL positioning resource information comprises a time-domain indication that comprises at least one of a symbol indication and a pattern index, wherein the symbol indication is indicative at least one of: one or more symbol indices inside a sidelink slot of the sidelink; or a length of sidelink symbols for transmission over the sidelink, a symbol offset of a first sidelink symbol with respect to a start sidelink symbol of a current sidelink slot of the sidelink and a start of the sidelink symbols inside the current sidelink slot, wherein the pattern index is indicative of: a pattern index of resource mapping patterns or an equivalent indication.

This provides the advantage that the user device can efficiently divide and use the SL positioning resources in time domain. The above implementation refers to the time-domain part of SLPRSConfig according to Figure 2 described below and is also valid for AD/LI.

In an exemplary implementation of the user device, the SL positioning resource information comprises a frequency-domain indication, wherein the frequency-domain indication comprises at least one of: a lowest subcarrier of absolute frequency of a reference resource block for all sidelink positioning resources allocated for transmission over the sidelink channel, a lowest subcarrier of a frequency occupied by resource blocks allocated to one configuration of the sidelink positioning resources allocated for transmission over the sidelink channel, a bandwidth for one SL-PRS or AD or LI signal occasion, comprising at least one of: a frequency resource occupied by a SL-PRS or AD or LI , a proportion of a subchannel size for a fractional occupation on subchannel level.

This provides the advantage that the user device can efficiently divide and use the SL positioning resources in frequency domain.

The above implementation refers to the frequency-domain part of SLPRSConfig according to Figure 2 described below and is also valid for AD/LI.

In an exemplary implementation of the user device, the SL positioning resource information comprises a resource type indicative of a repetition property of the sidelink positioning resources in time domain, wherein the resource type comprises at least one of the following types: aperiodic which indicates an aperiodic resources allocation for the sidelink positioning in time domain, wherein the aperiodic resources are scheduled dynamically, semi-persistent which indicates a semi-static resources allocation for the sidelink positioning in time domain, wherein the semi-static resources are used repeatedly once been activated, periodic which indicates a periodic resources of the sidelink positioning in time domain, wherein the periodic resources are used once configured.

This provides the advantage that the available resources can be efficiently utilized by the user device for sidelink positioning.

Dynamically scheduling means that the scheduling is performed in a manner characterized by constant change, activity or progress. Dynamically scheduling is in contrast to a static scheduling where the scheduling is without movement or change in time, e.g. preconfigured. The schedule may be scheduled by other network elements e.g. BS or other ResCtl, or UE may schedule resource for other UEs or even for UE itself if it acts as ResCtl. In this respect, dynamically scheduling means that the scheduling is initiated by other entities or for other entities or that the UE autonomously schedules resource by itself (according to resource allocation mode 2).

The above implementation refers to the SLPRSResourceType of SLPRSConfig (see Figures 3 and 4 and is also valid for AD/LI.

In an exemplary implementation of the user device, the SL positioning resource information comprises a resource repetition factor indicative of a time-domain repetition of a sidelink positioning resource within one sidelink slot of the sidelink.

This provides the advantage that by using the resource repetition factor the user device can be efficiently informed about the sidelink positioning resources.

The SL positioning resource information may comprise a frequency hopping pattern indicative of a frequency hopping pattern of the sidelink positioning resources in frequency domain. The frequency hopping pattern may comprise at least one of: a frequency hopping configuration that is indicative of a frequency hopping pattern, a frequency offset that is indicative of a frequency domain offset with respect to a last sidelink positioning signal occasion.

The above implementation refers to Indication of SL-PRS/AD/LI resource request which is also referred to as “sidelink positioning resource information” herein.

In an exemplary implementation of the user device, the SL positioning resource information comprises: a frequency hopping tag for enabling or disabling frequency hopping and/or frequency offset of the sidelink positioning resources.

This provides the advantage of an efficient utilization of the SL positioning resources, in particular in frequency domain.

In an exemplary implementation of the user device, the latency requirement comprises at least one of: a maximum latency from requesting a SL-PRS, AD or LI transmission over the sidelink to a start of the SL-PRS, AD or LI transmission over the sidelink, a latency window for a SL- PRS, AD or LI transmission over the sidelink for one session of location-based services.

This provides the advantage that the user device can meet latency requirements for sidelink positioning. In an exemplary implementation of the user device, the sidelink positioning resource information indicates priority of the sidelink positioning resource information.

This provides the advantage that the user device can assign priorities to the sidelink positioning resources.

In an exemplary implementation of the user device, the sidelink positioning resource information indicates a sidelink positioning resources reservation for a forward link transmission or a reverse link transmission over the sidelink.

This provides the advantage that the user device can reserve sidelink positioning resources for both, forward link and reverse link transmission.

In an exemplary implementation of the user device, the sidelink positioning resource information comprises at least one of: forward link transmission characteristics indicative of requirements for the forward link transmission over the sidelink, reverse link transmission characteristics indicative of requirements for the reverse link transmission over the sidelink, a latency bound indicative of a maximum allowed latency between a first transmission over the sidelink and a second transmission over the sidelink, wherein the second transmission is over a forward link or over the reverse link.

This provides the advantage that requirements for forward link and reverse link transmission can be met.

The sidelink positioning resource information may further comprise a frequency hop tag indicative of whether a frequency offset between the first transmission and the second transmission over the sidelink is allowed.

This provides the advantage that flexible transmission requirements with respect to frequency offset can be implemented.

In an exemplary implementation of the user device, the sidelink positioning resource information comprises at least one of: a time gap indicative of a time offset of a sidelink positioning resource for the first transmission over the sidelink and a sidelink positioning resource for the second transmission over the sidelink, a frequency offset indicative of a frequency offset of the sidelink positioning resource for the first transmission over the sidelink and the sidelink positioning resource for the second transmission over the sidelink.

This provides the advantage that flexible time and frequency requirements can be implemented.

The following implementations relate to signaling procedures.

In an exemplary implementation of the user device, the user device is configured to obtain the sidelink positioning resource information via at least one of the following interfaces: a Radio Resource Control, RRC, interface, a PC5-RRC interface for sidelink positioning, a MAC Control Element, MAC-CE interface, a sidelink control information, SCI, interface.

This provides the advantage that the user device is flexible with respect to the interfaces on which the information can be obtained. A lot of different interfaces are supported.

In an exemplary implementation of the user device, the user device is configured to receive an update signal indicative of an update of the sidelink positioning resource information; and is configured to update the sidelink positioning resource information responsive to reception of the update signal.

This provides the advantage that the user device can efficiently update its sidelink positioning resources.

According to a second aspect, the disclosure relates to a method for positioning based on sidelink, the method comprising: obtaining, by a user device, a sidelink, SL, positioning resource information, wherein the sidelink positioning resource information indicates a resource characteristic of a sidelink positioning reference signal, SL-PRS, a positioning assistance data, AD, or location information, LI; and performing, by the user device, sidelink positioning based on the sidelink positioning resource information.

Such a method provides the technical advantage of supporting an enhanced sidelink positioning, especially for partial-coverage and out-of-coverage scenarios. By this method a user device can be configured for efficient resource allocation for SL-PRS, transferring AD and/or LI meeting sidelink positioning requirements. According to a third aspect, the disclosure relates to a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the method according to the second aspect described above.

The computer program product may run on any of the components of a communication system described below with respect to Figure 13. For example, the computer program product may run on a user device 1301a as shown in Figure 13. Such a user device may comprise a processing circuitry 1303a for instance, a processor 1303a, for processing and generating data, e.g. the program code described above, a transceiver 1305a, including, for instance, an transmitter, a receiver and an antenna, for exchanging data with the other components of the communication system 1300, and a non-transitory memory 1307a for storing data, e.g. the program code described above. The computer program product may also run on a second user device 1301b as shown in Figure 13. The computer program product may also run on a network device 1320 such as a base station as shown in Figure 13.

Using such a computer program product improves resource allocation for SL-PRS, transferring AD and/or LI meeting sidelink positioning requirements and can be efficiently applied in radio communication networks, e.g. such as transmission over the 5G radio network.

According to a fourth aspect, the disclosure relates to a computer-readable medium storing instructions that, when executed by a computer, cause the computer to execute the method according to the second aspect. Such a computer readable medium may be a non-transient readable storage medium. The computer may be, for example, a user device, e.g. the user device according to the first aspect comprising a processor, a transceiver and a memory as shown in Figure 13. The computer-readable medium may be stored in the memory of the user device. The instructions stored on the computer-readable medium may be executed by the processor of the user device.

This disclosure provides a method and apparatus for providing resource allocation for sidelink positioning reference signals, assistance data and/or location information, wherein the resource allocation requirement needs to be fulfilled in order to satisfy the positioning requirements. It supports both UE-initiated and network-initiated resource allocation request with requirements, as well as UE-based/network-based positioning methods. The disclosed method allows for flexible resource allocation and resource update for sidelink positioning purpose and increases the success of obtaining the required resources. BRIEF DESCRIPTION OF THE DRAWINGS

Further embodiments of the invention will be described with respect to the following figures, in which:

Fig. 1 shows a schematic diagram illustrating an exemplary scenario 100 for sidelink positioning according to the disclosure;

Fig. 2 shows a schematic diagram illustrating an example of sidelink positioning reference signal (SL-PRS) resource allocation 200 in one sidelink slot according to the disclosure;

Fig. 3 shows a schematic diagram illustrating an example of sidelink positioning reference signal (SL-PRS) resource repetition and periodicity 300 according to the disclosure;

Fig. 4 shows a schematic diagram illustrating an example of sidelink positioning reference signal (SL-PRS) resource set indication 400 according to the disclosure;

Fig. 5 shows a schematic diagram illustrating an example of resource reservation indication 500 for reserve-link sidelink positioning reference signal (SL-PRS) transmission according to the disclosure;

Fig. 6 shows a schematic diagram illustrating an exemplary scheduling configuration 600 for sidelink positioning reference signal (SL-PRS) transmission based on UE-initiated resource request according to the disclosure for resource allocation mode 1 for dynamic grant (Fig. 6a), configured grant type 1 (Fig. 6b) and configured grant type 2 (Fig. 6c);

Fig. 7 shows a schematic diagram illustrating an example of resource sensing and selection for sidelink positioning reference signal (SL-PRS) transmission 700 based on UE-initiated resource request for resource allocation mode 2;

Fig. 8 shows a schematic diagram illustrating an exemplary communication system 800 according to the disclosure, where UEs are in coverage; network/UE-initiated sidelink resource request and sidelink mode 1 resource allocation;

Fig. 9 shows a schematic diagram illustrating exemplary signaling procedures 900 according to the disclosure for network/UE-initiated resource request for sidelink positioning applicable for sidelink resource allocation mode 1 ; Fig. 10 shows a schematic diagram illustrating an exemplary communication system 1000 according to the disclosure, where UEs are in coverage or in partial coverage; network/UE- initiated sidelink resource request and sidelink mode 2 resource allocation;

Fig. 11 shows a schematic diagram illustrating exemplary signaling procedures 1100 according to the disclosure for network/UE-initiated resource request for sidelink positioning applicable for sidelink resource allocation mode 2;

Fig. 12 shows a schematic diagram illustrating exemplary signaling procedures 1200 according to the disclosure for UE-initiated resource request for sidelink positioning applicable for sidelink resource allocation mode 2;

Fig. 13 shows a schematic diagram illustrating a communication system 1300 for positioning based on sidelink according to the disclosure; and

Fig. 14 shows a schematic diagram illustrating a method 1400 for positioning based on sidelink according to the disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

In order to describe the invention in detail, the following terms, abbreviations and notations will be used:

UE user equipment

RAT radio access technology

LTE long term evolution

NR new radio

LCS location service

V2X vehicle-to-everything

TRP transmit-receive point

PRS positioning reference signal

SL sidelink

LI location information

AD assistance data

RA resource allocation

ARP antenna reference point

RS reference signal

RSRP reference signal receive power LMF location management function

LPP LTE positioning protocol

NRPPa new radio positioning protocol annex

SIB system information block

PSBCH physical sidelink broadcast channel

PSSCH physical sidelink shared channel

PSCCH physical sidelink control channel

MAC CE medium access control control element

PC5-RRC PC5 radio resource control

ID identity

LMF location management function

AMF access and mobility management function

HTTP hypertext transfer protocol

IE information element

RAN radio access network

In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

The methods, devices and systems described herein may be implemented in radio network, in particular LTE, 5G, or 5G beyond. The described devices may include integrated circuits and/or passives and may be manufactured according to various technologies. For example, the circuits may be designed as logic integrated circuits, analog integrated circuits, mixed signal integrated circuits, optical circuits, memory circuits and/or integrated passives. The devices described herein may be configured to transmit and/or receive radio signals. Radio signals may be or may include radio frequency signals radiated by a radio transmitting device (or radio transmitter or sender). However, devices described herein are not limited to transmit and/or receive radio signals, also other signals designed for transmission in deterministic communication networks may be transmitted and/or received.

The devices and systems described herein may include processors or processing devices, memories and transceivers, i.e. transmitters and/or receivers. The term “processor” or “processing device” describes any device that can be utilized for processing specific tasks (or blocks or steps). A processor or processing device can be a single processor or a multi-core processor or can include a set of processors or can include means for processing. A processor or processing device can process software or firmware or applications etc.

The devices and systems described herein may include transceivers or transceiver devices. A transceiver is a device that is able to both transmit and receive information or signal through a transmission medium, e.g. a radio channel. It is a combination of a transmitter and a receiver, hence the name transceiver. Transmission is usually accomplished via radio waves. By combining a receiver and transmitter in one consolidated device, a transceiver allows for greater flexibility than what either of these could provide individually.

In the present disclosure, the device may be referred to as user device in some embodiments, and a device may be, for example, a mobile phone, an intelligent terminal, a tablet computer (tablet), a notebook computer (laptop), a video game console, a multimedia player, vehicle, device to device (D2D) equipment, or any smart device which supports a positioning function. The user device may also be referred to as user equipment (UE) in some embodiments of the present disclosure.

The present disclosure provides method and apparatus for positioning based on sidelink. A user device is configured to: obtain a sidelink, SL, positioning resource information, wherein the sidelink positioning resource information indicates a resource characteristic of a sidelink positioning reference signal, SL-PRS, a positioning assistance data, AD, or location information, LI; and perform sidelink positioning based on the sidelink positioning resource information.

The resource characteristic comprises a latency information, wherein the latency information indicates latency requirement for the SL-PRS, the AD or the LI. Resource reservation and resource allocation for the sidelink positioning resource information are specifically disclosed. The resource reservation and allocation for sidelink may be based on Resource allocation (RA) mode 1 or mode 2.

In resource allocation (RA) mode 1 , next-generation radio access network (NG-RAN) may schedule transmission resources for periodical, semi-persistent, and/or a-periodical messages. As a prerequisite of this mode, the UE needs to be in RRC_CONNECTED state in order to transmit data. Within this mode, two sub-modes are supported. The first is called dynamic grant (DG) wherein NG-RAN can either dynamically allocate resources to the UE on physical downlink control channels (PDCCHs). The second sub-mode is to allocated resource with configured grant(s), which consists of two types, namely, configured grant (CG) type 1 wherein radio resource control (RRC) directly provides the configured sidelink grant, and configured grant type 2 wherein RRC defines the periodicity of the configured sidelink grant and PDCCH can either signal/activate, or deactivate it.

In resource allocation (RA) mode 2, the UE may autonomously select transmission resources from a pool of resources. For this mode, the UE can be in- or out-of-coverage and in any RRC state. Specifically, the UE may perform sensing-based resource selection/reselection based on decoding scheduling assignment (SA) of other UEs and measuring received energy (e.g. reference signal received power (RSRP)). It may also allow for the temporary usage of random selection for sidelink transmission based on configuration of the exceptional resource pool.

The disclosure presents a sidelink resource allocation mechanism that can fully address the requirements of sidelink positioning. In particular, signaling procedures and resource allocation patterns are presented which are suitable for positioning reference signals operating on a slot/subchannel level in the time/frequency domain, respectively, at targeted high accuracy.

Regarding resource allocation (RA) mode 2, in current 5G-NR LCS architecture, links for positioning procedures (including capability transfer/delivery, assistance data transfer/delivery, reference signal transmission/reception, measurements request/reporting, and/or position estimate transfer) are already established, such as LTE positioning protocol (LPP), LTE positioning protocol A /NR positioning protocol A (LPPa/NRPPa), and RRC between eNB/gNB and UE, wherein resource are controlled or scheduled by network. For example, the location server handles the requests of location/assistance data/reference signals, notifies the UE or corresponding base station (BS) over LPP/LPPa or NRPPa, collects measurements and calculates UE position. Base station is in charge of scheduling and controlling of resource for reference signal configurations and transferring assistance data from/to the location server. The UE transmits or measures the positioning reference signals according to the configurations signaled from location server or base station, reports measurements to location server or calculates its position if needed.

Positioning protocols described in this disclosure may be applied in sidelink positioning scenarios. In particular, dedicated protocols or signaling (LPP/LPPa/NRPPa/RRC) are presented in sidelink for positioning procedures. Protocols presented in this disclosure can be applied for sidelink positioning in in-coverage, partial coverage, or out-of-coverage scenarios. These protocols may provide more flexible/fine-granularity resource allocation than currently available protocols. When applying these protocols for sidelink positioning especially for UE autonomous resource allocation mode, the chance to find available resources can be increased, while the success of allocating resource in legacy positioning procedures is guaranteed by network.

Fig. 1 shows a schematic diagram illustrating an exemplary scenario 100 for sidelink positioning according to the disclosure. The scenario shows a street section with an exemplary number of UEs 110, 120, 130 which are cars in this scenario.

Resource allocation for SL positioning may be performed for following tasks: transmitting and receiving SL-PRS(s), delivering positioning AD, and transferring LI which includes measurement report and/or location estimate. In the following, resource allocation mechanisms for SL positioning are presented, which mainly include two parts: signaling procedures for requesting and configuring resource allocation for SL-PRS/AD/LI transmission, and resource indication for SL-PRS/AD/LI.

Before detailing the specific mechanisms, as a prerequisite, four entities are introduced first, which will be used throughout the following descriptions on RAT-dependent sidelink positioning methods:

1) SLRefSigTx: UE 110 (see Figure 1) which transmits (forward-link) SL-PRS.

2) SLRefSigRx: UE 120 (see Figure 1) which receives 111 (forward-link) SL-PRSs and obtains corresponding measurements. It might need to send reverse-link SL-PRS(s) depending on positioning method (e.g., round-trip time (RTT)).

3) PosCal: Entity which calculates SL position result based on the measurements and/or measurement reports. This entity is not shown in Figure 1. It can be any network entity or user entity. The location estimate result calculated at PosCal may need to be transferred to another entity. 4) ResCtrl: Resource control entity which allocates and configures resources for RAT- dependent SL positioning, which can be eNB/gNB or UE 130 (as shown in Figure 1).

It should be understood that a user device may include one or more of the above entities. For example, the user device may have an entity SLRefSigTx and SLRefSigRx at different times.

For example, considering the scenario depicted in Figure 1 , sidelink positioning is performed between the UEs connected by arrows, e.g., SLRefSigTX UE 110 and SLRefSigRX UE 120 herein. The arrow 111 shows the direction of (forward-link) SL-PRS transmission. The third UE 130 called ResCtrl UE is acted as the UE which controls the radio resource management. Note that the ResCtrl UE 130 can also be SLRefSigTXUE 110 or SLRefSigRXUE 120 itself. PosCal is not shown in Fig. 1 , which can be one of the three UEs in the figure or another external entity (e.g., location server in the network such as location management function in core network or base stations in radio access network).

With the above introduction of four entities used in sidelink positioning scenario, the details of resource allocation mechanism with the disclosed resource indications and supporting signaling procedures can be further described.

Resource indication for SL-PRS/AD/LI

Resource indication describes the time and frequency resources allocated for SL-PRS/AD/LI transmission. For the indication of SL-AD/LI, the indication mechanism for data transmission or (layer-1) L1 -measurement report can be followed. For the indication of resource allocation of SL-PRS, it requires flexible allocation and repetition pattern than normative data transmission, leading to a more intricate indication mechanism. Therefore, in this section, the focus lies on introducing the resource indication for SL-PRS. These new indication parameters are introduced by considering compatibility to current structure of SL slot. Specifically, an indication of SL-PRS resource allocation is introduced, an indication to request/update SL- PRS resource allocation is specified, and the indication for resource reservation is addressed in the following sections.

Indication of SL-PRS resource, resource set, repetition pattern

Two requirements may be considered to indicate the SL-PRS resource or resource set. On the one hand, it may need to be compatible with present sidelink resource allocation mechanism and structure (e.g., sidelink resource pool configuration and slot structure). On the other hand, it needs to allow flexible resource indication for SL-PRS scheduling to increase the chance for successful resource allocation and selection. Such flexibility in resource allocation is represented in two-fold: in time domain, discontinuous or consecutive symbol-level indication and intra-slot/inter-slot repetition are allowed; in frequency domain: discontinuous or consecutive fractional subchannel indication and frequency hopping are allowed. In the following, the new information element SLPRSConfig to indicate the resource allocation for SL-PRS is introduced, wherein SLPRSConfig contains the newly disclosed parameters.

Fig. 2 shows a schematic diagram illustrating an example of sidelink positioning reference signal (SL-PRS) resource allocation 200 in one sidelink slot according to the disclosure. The resource block (RB) starts 201 with symbol 0, where the first three symbols 211 are not used as SL symbols. The SL symbols start 202 with symbol number 3 and have a length 203 of 11. The first sidelink symbol is AGC (adaptive gain control) 212. The second and third SL symbols are partitioned into PSSCH 213 and PSCCH 214. The fourth SL symbol is PSSCH 213. The fifth and sixth SL symbols are SL-PRS 215. The seventh SL symbol is PSSCH 213. The eighth SL symbol is GAP 216, i.e. a gap symbol. The ninth SL symbol is AGC 212. The tenth SL symbol is PSFCH 217. The eleventh SL symbol is GAP 216.

Figure 2 exemplifies SL-PRS resource allocation within one sidelink slot. Following parameters and explanations are used to indicate the allocation of SL-PRS resource inside SLPRSConfig·.

Time-domain indication

- Symbol indication, which can be

- SLPRSSymbollndex·. symbol index inside a SL slot. These symbols can be either discontinuous or consecutive.

- lengthSLPRSsymbols, and SLPRSSymbolOffset or startSLPRSsymbols represent length of SL-PRS symbols, symbol offset of first SL-PRS symbol offset with respect to startSLsymbol of the current SL slot, and the start of SL-PRS symbols inside the current SL slot, respectively. These parameters indicate the SL-PRS allocation in consecutive- symbol-level or mini-slot level. Similar indication as start and length indicator value (SLIV) can also be used here.

- SLPRSPatternlndex: Selected pattern index within the (pre-) configured SL-PRS resource mapping patterns, or some equivalent indication. Frequency-domain indication

- SLPRS-pointA : lowest subcarrier of absolute frequency of the reference resource block (RB) for all SL-PRS resource/resource set, (e.g., startRB-Subchannel of resource pool). Note that it may also use absoluteFrequencyPointA-SL as a reference point.

- startRB-SLPRS: the lowest subcarrier of the frequency occupied by the RB(s) allocated to one configuration of a SLPRS resource. Herein startRB-SLPRS is defined w.r.t. certain reference point, e.g., SLPRS-pointA.

- Bandwidth for one SL-PRS occasion, which can be

- frequencyResourceSLPRS: indicating the frequency resource occupied by SL-PRs. The unit can be RB or subchannel, and the range can be either discontinuous or consecutive.

- RatioSubchannel·. proportion of subchannelsize, allowing the fractional occupation of subchannel level.

Fig. 3 shows a schematic diagram illustrating an example of sidelink positioning reference signal (SL-PRS) resource repetition and periodicity 300 according to the disclosure. Figure 3 depicts a slot 301 in time domain and a subchannel 302 in frequency domain. A SL-PRS resource occasion 310 is periodically repeated in time. A SL-PRS repetition factor 303 can be for example 2 indicating one repetition of the SL-PRS resource occasion 310 per slot. A periodicity and offset in time 304 can be indicated.

Similar to legacy positioning reference signals for downlink and uplink-based method, sidelink PRS resource can also be sent with repetition. In the following, the parameters to indicate SL- PRS resource repetition and periodicity pattern are introduced by taking into consideration of current sidelink slot structure.

- SLPRSResourceType: Periodicity property of SL-PRS resource in time domain which can be:

- Aperiodic. For this type, SLPRSResourceSlotOffset is used as the slot offset with respect to a reference point in time domain, e.g., the first slot of the SL PRS resource set.

- Semi-persistent (SP-). For this type, SLPRSperiodicityAndTimeOffset-sp is defined as the periodicity of semi-persistent SL-PRS and the time offset in temporal unit, e.g., [slot] or [ms], w.r.t. a reference point in time domain (e.g., the first slot of the SL PRS resource set). - Periodic (P-). For this type, SLPRSperiodicityAndTimeOffset-p defines the periodicity of SL-PRS and the time offset in [slot] or [ s] with regard to a reference point in time domain (e.g., the first slot of the SL PRS resource set).

- SLPRSRepetitionFactor. Time-domain repetition factor of a SL PRS resource within at least one SL slot.

- Frequency hopping pattern which can be:

-SLPRSFreqHoppingConfiguration: Indication of frequency hopping pattern, e.g., in [RB] or [subchannels]; -SLPRSFreqOffset Frequency domain offset with respect to the last SL-PRS occasion (e.g., in [RB] or [subchannel]).

If the parameter for indicating frequency hopping pattern is void or null, then the semi- persistent or periodic types in SLPRSResourceType may fall back to conventional semi- persistent or periodic transmissions with periodicity both in time and frequency, respectively.

Fig. 4 shows a schematic diagram illustrating an example of sidelink positioning reference signal (SL-PRS) resource set indication 400 according to the disclosure. Figure 4a depicts a slot 401 in time domain and a subchannel 402 in frequency domain. In this example, a resource set includes three resources: first resource 411, second resource 412 and third resource 413. The following parameters apply: SLPRSResourceSetSlotOffset = X;

SLPRSResourceSlotOffset = 0/2/4 for first, second and third resources 411, 412, 413; SLPRSResourceRepetitionFactor = 2; SLPRSResourceTimeGap = 1. The three SL-PRS resources are periodically repeated in time. The SL-PRS resource repetition factor is 2 indicating one repetition of the respective SL-PRS resource 411, 412, 413 per resource set.

Figure 4b depicts a periodicity of the resource set. The first resource 411 is used and repeated. The second resource 412 is used and repeated. The third resource 413 is used and repeated. After a block of the three resources with respective repetitions a periodicity Y with respect to a number of slots 404 is applied which can be described by the parameter SLPRSResourceSetPeriodicity = Y number of slots.

SL-PRS resource set can be defined corresponding to a collection of SL-PRS resources. For example, one SL-PRS resource set contains beamformed PRSs from a single TRP or collocated antenna set. In the following, we propose the indication of SL-PRS resource set under the consideration of sidelink slot structure. Figure 4 provides one example on the SL- PRS resource set. Following parameters are introduced with the explanation of their functions: - SLPRSResourceSetSlotOffset: the first slot or mini-slot for a SL-PRS Resource set with regard to a reference point in time domain, e.g., system frame number (SFN)#0 or direct frame number (DFN)#0 or a reference SFN for SL-PRS.

- SLPRSResourceRepetitionFactor: The number of SL slots or mini-slots which contain SL- PRS resource(s) with the same Resource ID within one SL-PRS Resource Set.

- SLPRSResourceTimeGap: The slot or mini-slot offset between two repeated instances of a SL-PRS Resource within one SL-PRS Resource Set.

- SLPRSResourceSetPeriodicity. Periodicity of SL-PRS resource set in time unit, e.g., [slot], [mini-slot] or [ms].

Periodicity and offset of SL-PRS resource or resource set can also be indicated indirectly via “configuration index” and mapping table.

In this disclosure reference is made mainly to “sidelink slot(s)”. It understands that the term sidelink slot(s) includes sidelink minislot(s) as well.

Indication of SL-PRS/AD/LI resource request

While in the above sub-section, the indication of SL-PRS resource allocation was introduced, in this subsection, the indication to request/update SL-PRS resource allocation is specified. The following parameters can be specified:

- ReqSLPRSTransCharacteristics: Information element (IE) to indicate the requested resource characteristics of SL-PRS. Apart from the similar parameters indicating the required bandwidth, periodicity, spatial-relation-information of SL-PRS, the following parameters for this IE are additionally introduced:

- ReqLatency: Latency requirement for SL-PRS transmission with the following:

- maxLatencyReqtoTransSLPRS. it defines the maximum latency from requesting SL- PRS transmission to the start of the SL-PRS transmission, in order to restrict the delay to activate the SL-PRS transmission;

LatencyWinTransSLPRS. indicating latency window for SL-PRS transmission(s) for one location session, in order to restrict the delay of transmitting SL-PRS within one location session.

- Frequency-hopping-tag (optional): Flag to allow or disable frequency hopping/offset of SL- PRS allocation.

- ReqSLADResCharacteristics. indicating the requested characteristics of positioning assistance data. It is applicable if the resource of AD needs to be explicitly requested. Bandwidth, slot, mini-slot or symbol size: requested frequency/time resources for AD transmission.

ReqLatency: Latency requirement for SL-AD transmission. E.g., maxLatencyReqtoTransSLAD. maximum latency from requesting AD transmission to the start of the AD transmission.

- ReqSLLIResCharacterstics: indicating the requested characteristics of location information (including measurement report and/or location estimate). It is applicable if the resource of LI needs to be explicitly requested.

Bandwidth, slot, mini-slot or symbol size: requested frequency/time resources for LI transmission.

ReqLatency: Latency requirement for SL-LI transmission, which may include the following parameters:

- maxLatencyReqtoTransSLLl·. maximum latency from requesting/configuring LI transmission to the start of the LI transmission.

- minLatencyReqtoTransSLLI : minimum latency from requesting/configuring LI transmission to the start of the LI transmission, e.g., due to the waiting time for receiving SL-PRS and processing time of generating measurement report and/or location estimate. The range from minLatencyReqtoTransSLLI to maxLatencyReqtoTransSLLl can also be indicated as a latency window.

- PrioritylD (optional): priority indicator for above resource request (e.g., for prioritization or pre-emption)

Fig. 5 shows a schematic diagram illustrating an example of resource reservation indication 500 for reserve-link sidelink positioning reference signal (SL-PRS) transmission according to the disclosure.

In the time frequency diagram, a first resource block is shown with a first slot containing SLPRS resource/s 511 for forward link and a second resource block is shown with a first slot containing pair-wise SLPRS resource/s 512 for reverse link.

A latency bound 501 specifies the maximum latency, e.g. in slots, mini-slots or milliseconds, for a pair-wise PRS transmission from the reverse-link. A frequency offset 502 describes the frequency offset to the resource, e.g. in subchannels for reverse PRS transmission. A Time Gap 503 describes the time offset to the allocated resource, e.g. in slot or milliseconds for reverse PRS transmission. Indication of resource reservation

Resource reservation may be beneficial for positioning by leveraging the predictable resource usage, which may lead to the reduction of positioning latency and increase the success rate of finding available SL resources.

For example, SL-PRS needs to be sent bi-directionally when RTT based positioning method is performed. Therefore, the resource for forward-link (from SLRefSigTx to SLRefSigRx) and reverse-link SL-PRS transmission (from SLRefSigRx to SLRefSigTx) can be reserved in advance. Other applications could be for positioning assistant data, measurement report, and/or location estimate, if its transmission is anticipated based on certain conditions. For instance, resource of measurement report can be reserved beforehand if the reporting configuration and PRS transmission schedule are obtained in advance. Note that resource reservation can also be advantageous to downlink/uplink-based positioning, e.g., in dynamic environment with predictable UE’s motion, or inside dense network with resource scarcity.

Figure 5 shows the example of resource reservation indication for reverse-link SL-PRS transmission. Several parameters are introduced for reservation procedures as follows, where it is described how to reserve the resource of the second/reserved transmission with respect to the initial/first transmission.

Resource request for reserving may include:

- RequestedRevLinkSLPRSCharactersitic: indicating the request characteristics for reverse- link SL-PRS, which is similar to the aforementioned IE RequestedSLPRSCharacteristics. This message may be signaled or bypassed to ResCtrl for SLRefSigRX.

- ReqLatency: indicating the maximum allowed latency in time unit (e.g., [slot], [mini-slot] or [ms]) between the initial (first) and reserved (second) transmission. For example, in Figure 5, ReqLatency here represents the latency from the transmission of forward-link PRS and the pairwise PRS transmission from the reserve-link. Note that the signaling of latency bound may trigger the failure message due to insufficient available resource or trigger the resource re- selection/re-schedule procedures.

- FreqHopTag·. whether it allows frequency offset between the initial (first) and reserved (second) transmission, e.g., the SL-PRS from the forward-link and reverse-link.

Resource indication of the reserved/second transmission may include:

- TimeGap : Time offset of the allocation resources (e.g., in [slot] or [ms]) between the initial (first) and reserved (second) transmission, e.g., the forward-link PRS and reverse link PRS. - FreqOffset: Frequency offset (e.g, in [subchannels]) between the initial (first) and reserved (second) transmission, e.g., from forward-link to reverse PRS transmission.

Signaling procedures for requesting and configuring resource allocation for SL- PRS/AD/LI transmissions

In order to support the aforementioned resource indication, signaling procedures for requesting resource characteristics for SL-PRS/AD/LI and configuring resource allocation are introduced in this disclosure. The request can be initiated either from the UE or from the network. In this section, the signaling procedures are addressed based on both UE-initiated and network- initiated case to show how the parameters introduced above can be delivered to support sidelink positioning.

In the following resource request procedures using their applications for SL-PRS are presented. The procedures can be analogously applied to AD/LI. The procedures mainly contain the following:

- Request SL-PRS transmission characteristics by transferring lEs as introduced above:

For UE-initiated case, either SLRefSigTX or SLRefSigRX may initiate the request to ResCtrl (can be UE or the base station) by sending the requirements for SL-PRS resource, with new signaling via RRC, PC5-RRC, MAC Control Element (MAC-CE), uplink control information (UCI), or sidelink control information (SCI) including information element ReqSLPRSTranCharacteristics and/or ReqLatency.

For network-initiated case, location server (e.g., LMF) may transmit the request SL-PRS transmission characteristics (including e.g. ReqSLPRSTransCharacteristics, ReqLatency, etc) to resource control entity (e.g., serving gNB or ResCtrlUE): If the resource control entity is base station, new lEs may be transmitted via LPPa/NRPPa between the gNB and LMF; If the resource control entity is the UE, new information elements can be transmitted via LPP between the ResCtrlUE and the LMF.

- ResCtrl (Serving gNB(s)/ResCtrlUE(s)) may determine SL-PRS resource configuration for transmissions between SLRefSigTX and SLRefRX.

- ResCtrl (Serving gNB(s)/ResCtrlUE(s)) may indicate successful or unsuccessful resource allocation with new signaling information elements (e.g., SLPRSConfig as introduced above). Depending on the type of resource control entity, the information may be transmitted via different signaling. If the resource is controlled by base station, new information elements can be transmitted via RRC/MAC-CE/DCI between from gNB to the UE. If the resource control entity is the UE, new information elements can be transmitted via PC5-RRC/MAC-CE/SCI from the ResCtrlUE from/to the UE,

- (Update operation) optionally, ResCtrl can update resource configuration upon triggers. The triggering conditions can be, e.g., RA mode 2 resource reselection triggers, in-/out-of coverage transition, RA model/mode 2 transition.

- (Abort) ResCtrl can abort resource configuration for SL-PRS (by sending SLPRSAbort) due to some event.

Depending on whether ResCtrl is eNB/gNB or the UE-type, the resource allocation can be performed in mode 1 and mode 2, respectively. In the following, we address the resource allocation procedures applying to both mode 1 and mode 2 resource allocation.

Fig. 6 shows a schematic diagram illustrating an exemplary scheduling configuration 600 for sidelink positioning reference signal (SL-PRS) transmission based on UE-initiated resource request according to the disclosure for resource allocation mode 1 for dynamic grant (Fig. 6a), configured grant type 1 (Fig. 6b) and configured grant type 2 (Fig. 6c).

Considering the resource allocation mode 1 where the eNB/gNB schedules the transmission resource for sidelink positioning, the following scheduling configuration procedures for SL- PRS/AD/LI are introduced based on UE-initiated resource request with requested resource characteristics and requirements. The procedures are exemplarily illustrated using SL-PRS as an example in Figure 6 with the remark that the procedures are directly applicable to AD/LI resource allocation.

Figure 6(a) shows the procedure for enhanced dynamic grant in RA mode 1 tailored to SL- PRS. First, if there is no SL grant available, either the SLRefSigTX 110 or SLRefSigRX 120 may send a scheduling request (SR) 601 to the base station 810/820 to obtain the SL grant 602. Then, the resource request message 603 may be used as introduced above as a counterpart of buffer status report to request SL-PRS resource via RRC/MAC-CE: the message 603 may include ReqSLPRSTransCharacterstics, and/or ReqLatency, et al. As a response 604, gNB 810/820 may determine SL-PRS configuration and signal SLPRSConfig 604 via DCI 604 to the sidelink positioning UEs 110/120. Figure 6(b) shows the procedure for enhanced configured grant type 1 in RA mode 1 for SL- PRS. Firstly, UE 110 may trigger to send configured grant assistance information based on its own implementation. Then the UE 110 may provide e.g. ReqSLPRSTransCharacteristics, ReqLatency inside SL-Scheduling-Request-lnformation of UEAssistancelnformation 611 via RRC. Afterwards, gNB 810/820 may configure SLPRSConfig 612 via RRC reconfiguration messages including the parameter (e.g. ConfigureSidelinkGrant) to allow SL-PRS to transmit without the detection of any SL grant. MinTimeGapRRCtoTrans (optional) can be indicated with SLPRSConfig to set the minimum time gap between RRC reconfiguration to the activation of SL-PRS transmission, which may be applicable for resource reservation for future transmissions (e.g., SL-PRS from the reverse-link and/or AD/LI for positioning). The rest of procedures after RRC reconfiguration may follow legacy configured grant procedures for communications.

Figure 6(c) depicts the procedure for enhanced configured grant type 2 in RA mode 1 for SL- PRS. The first step 621 corresponds to the first step 611 of enhanced configured grant type 1 shown in Figure 6(b). The difference from CG type 1 starts from RRC Reconfiguration step. At the stage of RRC reconfiguration of CG type 2, SLPRSConfig may be indicated 622 to the UE 110 without activation/deactivation of configured grant transmission. MinTimeGapActivationTrans (optional) can be indicated to set the minimum time gap between activation of configured grant transmission to the start of the transmission, which maybe applicable for resource reservation for future transmissions (e.g., SL-PRS from the reverse- link or AD/LI for positioning). The following procedures are similar to the legacy steps for CG type 2, in which DCI activation 623 may be signaled to the UE 110 later to enable a fast activation or modification of semi-persistent allocated resources for SL-PRS transmissions, followed by UE confirmation 624 via MAC/CE.

Fig. 7 shows a schematic diagram illustrating an example of resource sensing and selection for sidelink positioning reference signal (SL-PRS) transmission 700 based on UE-initiated resource request for resource allocation mode 2.

A sensing window 701 and a selection window 702 are shown. A resource Y 711 is in the sensing window 701. Candidate resource X 712 is in the selection window 702. Potential resources 713, 714 that can be used, are in the selection window 702. A next instance of resource Y 715 is successive in time out of the selection window 702. In the selection window 702 resources 713, 714 are allowed 704 for mini-slot/symbol-level resource reservation and frequency hopping/offset. Optionally, resource selected can be set in the selections window 702 by considering minTimeGapT ItoTransmit 703. Considering the resource allocation mode 2 where the UE(s) may autonomously select the transmission resource for sidelink communications or positioning, the procedures for SL- PRS/AD/LI are illustrated in Figure 7. Basically, the procedures follow the legacy RA mode 2 procedures with sensing 701, selection 702, re-evaluation and resource re-selection, under the consideration of obtained request of resource allocation at the UE. As shown above, such information contained in the resource allocation (e.g. SLPRSConfig) allows flexible resource reselection to increase the chance of successfully obtaining resource for SL positioning. For example, slot, mini-slot or symbol-level reselection for SL-PRS with frequency-hopping/offset allowed 704. minTimeGapTItoTransmit (optional) 703, which is defined as the minimum time gap between T1 (T1 has been already defined in setting selection window in current RA mode 2 procedures) and the activation of transmission, can be used to decide the starting point of the selection window instead of T1 for reserve resources for future transmission (e.g., SL-PRS from the reverse-link or AD/LI for positioning).

In the following Figures 8 to 10 three examples for resource requesting and allocation of sidelink positioning are presented in three scenarios, namely UE(s) are in-coverage, partial- coverage and out-of-coverage.

Fig. 8 shows a schematic diagram illustrating an exemplary communication system 800 according to the disclosure, where UEs are in coverage; network/UE-initiated sidelink resource request and sidelink mode 1 resource allocation.

Resource allocation of sidelink positioning when UEs are in coverage

In Figure 8 a scenario is considered when two UEs (SLRefSigTX UE 110 and SLRefSigRX UE 120) performing sidelink positioning are both in coverage of a respective gNB 810, 820. As in the example, two gNBs 810, 820 take charge of resource scheduling and allocation of two UEs 110, 120 that are involved in sidelink positioning 111. Consequently, the communication link between the location server (e.g., LMF in the core network or gNB in RAN) and the UEs can be assumed to be established.

The detailed signaling procedures are shown in Figure 9 and described in the following.

Fig. 9 shows a schematic diagram illustrating exemplary signaling procedures 900 according to the disclosure for network/UE-initiated resource request for sidelink positioning applicable for sidelink resource allocation mode 1. The detailed signaling procedures are described as follows. 1. Resource request for SL-PRS transmission may be initiated by network 902 (1a): “NRPPa POSITIONING INFORMATION REQUEST (incl. ReqSLPRSTransCharacteristics)" 911 or by the UE (1b): “RRC/MAC-CE/UCI (incl. ReqSLPRSTransCharacteristics)" 912. The request message may mainly contain the requirements of SL-PRS transmission characteristics, latency requirements, etc.

2. eNB(s)/gNB(s) 810/820 may determine the resource allocation of SL-PRS 913 applying SL RA mode 1.

3. For the network-initiated mode, eNB(s)/gNB(s) may send to LMF 902, SLRefSigTX and/or SLRefSigRX (optional) the SL-PRS configuration 914 (3a): “NRPPa POSITIONING INFORMATION RESPONSE (incl. SLPRSConfig)” 915, (3b): “RRC/MAC-CE/DCI/SCI (incl. SLPRSConfig)” . For the UE-initiated mode, eNB(s)/gNB(s) 810/820 may inform the SLRefSigTX 110 and/or SLRefSigRX 120 (optional) about the SL-PRS configuration (3b). Optionally such information can also be forwarded to the LMF 902 (3a). Note that the detailed signaling steps (3a) (3b) depend on which sub-modes (e.g., DG, CG1 and CG2) in RA mode 1 is used.

4. Resource request 921 for SL-AD transmission can be initiated by network 902 or by the UE 110, 120. The request message “RRC/MAC-CE/LPP/NRPPaASSISTANCE DATA REQUEST (optional: ReqADResCharacteristics)” mainly contains the requirements of AD transmission characteristics, latency requirements, etc. Note that step (4)-(6) is only required if explicit resource request of AD is needed. Under some circumstance, steps (4)-(6) can be omitted, e.g., when the AD is transmitted with high-layer control signaling (e.g., LPP, NRPPa, RRC).

5. eNB(s)/gNB(s) 810/820 may determine the resource allocation of AD 922 applying SL RA mode 1.

6. eNB(s)/gNB(s) may signal the configured or reserved sidelink resource for AD transmission 923 “PC5-RRC/RRC/MAC-CE/LPP/NRPPa/DCI/SCI ASSISTANCE DATA RESPONSE (optional: in configured/reserved AD SL-resource)” to the involved entities, e.g., the entity to measure, report, calculate, and report the location estimate.

7. Resource request for SL location information and configuration 924 “SL LOCATION INFORMATION REQUEST AND CONFIGURATION (optional: SL-LI RA)”. Step (7) is similar to step (4)-(6), and optional if explicit resource allocation is desired for location information. 8. Due to the dynamic variations of SL resource allocation (e.g., pre-emption of ultra-reliable and low-latency communication (URLLC) transmission), the scheduled/selected SL-resource can be re-evaluated, re-scheduled, and updated 925 before the activation of transmission: “SL_Resource re-evaluation, re-scheduling and updating (e.g. SL-PRS ResConfigUpdate)”.

9. Entities involved in sidelink positioning (e.g., SLRefSigTX 110, SLRefSigRX 120 , PosCal 901) may perform SL-PRS/AD/LI transmissions and receptions 926 using the allocated resource: “SL-PRS transmission, measurement, measurement report; SL-position calculation, and/or position estimate delivery”.

Note that the above procedures are not required to be sequentially performed or be executed in a fixed order, for the sake of improved flexibility in positioning procedures. For example, the request of SL-PRS and AD can be instigated in parallel, and the determination of SL-PRS and AD resource allocation can also be performed simultaneously. However, certain order is expected, for instance, delivery of SL-PRS and/or AD need to occur before the delivery of measurement report or location estimate.

Besides the application shown above, this embodiment can also be applied to other SL positioning for V2X where UE-type nodes are involved in sidelink positioning and under network coverage, such as including but limited to vulnerable roadside unit (VRU) protection, network-assisted autonomous driving, unmanned aerial vehicles management. In addition, it can also be applied other scenarios for positioning between UEs, such as high-precision location within factory site under the network control, or latency-critical positioning (e.g., for public safety) within cell range.

Fig. 10 shows a schematic diagram illustrating an exemplary communication system 1000 according to the disclosure, where UEs are in coverage or in partial coverage; network/UE- initiated sidelink resource request and sidelink mode 2 resource allocation.

Resource allocation of sidelink positioning when UEs are in-/partial- coverage

In Figure 10, a scenario may be considered when the resource control UE 130 is in-coverage, and one or both of UEs (SLRefSigTX UE 110 and SLRefSigRX UE 120) performing sidelink positioning are out-of-coverage. One example of such settings is depicted in Figure 10, wherein the SLRefSigTX 110 and ResCtrlUE 130 are in coverage and SLRefSigRX 120 is out- of-coverage. Note that ResCtrlUE 130 can also act as SLRefSigTX 110 or SLRefSigRX 120. Under such circumstance, the resource request can be received from the network/UE and the resource allocation for sidelink positioning can be performed in an UE autonomous mode, i.e., mode 2.

The detailed signaling procedures are shown in Figure 11 and described in the following.

Fig. 11 shows a schematic diagram illustrating exemplary signaling procedures 1100 according to the disclosure for network/UE-initiated resource request for sidelink positioning applicable for sidelink resource allocation mode 2. The detailed signaling procedures are described as follows.

1. Resource request for SL-PRS transmission can be initiated by network 902 (1a) “LPP POSITIONING INFORMATION REQUEST (incl. ReqSLPRSTransCharacteristics)" 1111 or by the UE 110, 120 (1b) “PC5-RRC/MAC-CE/SCI (incl. ReqSLPRSTransCharacteristics)" 1112 to ResCtrl entity 130 (ResCtrl UE(s) 130 here).

2. ResCtrlUE(s) 130 may determine 1113 the resource allocation of SL-PRS applying SL RA mode 2.

3. For the network-initiated mode, ResCtrlUE(s) 130 may send to LMF 902 (optional), SLRefSigTX 110 and/or SLRefSigRX 120 (optional) the SL-PRS configuration (3a): “LPP POSITIONING INFORMATION RESPONSE (incl. SLPRSConfig)" 1114, (3b): “PC5- RRC/MAC-CE/SCI (incl. SLPRSConfig) 1115”. For the UE-initiated mode, ResCtrlUE(s) 130 informs the SLRefSigTX 110 and/or SLRefSigRX 120 (optional) UEs about the SL-PRS configuration (3b).

4. Resource request “PC5-RRC/MAC-CE/LPP/SCI ASSISTANCE DATA REQUEST (optional: ReqADResCharacteristics)” 1121 for SL-AD transmission can be initiated by network 902 or by the UE 110, 120. The request message may mainly contain the requirements of AD transmission characteristics, latency requirements, etc. Note that step (4)-(6) is only required if explicit resource request of AD is needed. These steps can be omitted under some circumstance, e.g., AD is transmitted with high-layer control signaling (e.g., LPP, PC5-RRC).

5. ResCtrlUE(s) 130 may determine 1122 the resource allocation of SL-AD by applying SL RA mode 2. 6. ResCtrlUE(s) 130 may signal “PC5-RRC/MAC-CE/LPP/SCI ASSISTANCE DATA RESPONSE (optional: in configured/reserved AD SL-resource)” 1123 the selected sidelink resource for SL-AD transmission to involved entities (e.g., the entity to measure, report, calculate the positioning, and/or deliver positioning estimate).

7. Resource request “SL LOCATION INFORMATION REQUEST AND CONFIGURATION (optional: SL-LI RA)” 1124 for SL location information and configuration. Step (7) is similar to step (4)-(6), and optional if explicit resource allocation is desired for measurement report and/or location estimate.

8. Due to the dynamic variations of SL resource allocation (e.g., pre-emption of URLLC transmission, legacy triggering conditions of sidelink resource reselection), the scheduled/selected SL-resource can be re-evaluated, re-scheduled, and updated “SL_Resource re-evaluation, re-scheduling and updating (e.g. SL-PRS ResConfig Update)”

1125 before the activation of transmission.

9. Entities involved in sidelink positioning (e.g., SLRefSigTX 110, SLRefSigRX 120, PosCal 901) may perform SL-PRS/AD/LI transmissions and receptions “SL-PRS transmission, measurement, measurement report; SL-position calculation, and/or position estimate delivery”

1126 using the allocated resource.

This embodiment can be applied to those applications where the location service continuity needs to be guaranteed due to temporary interruption of network coverage (e.g., vehicles entering the tunnel, handover area) or these applications wherein UEs are in coverage but cannot be connected to network due to radio link failure or in power-saving mode (e.g., RRC- inactive/idle mode).

Fig. 12 shows a schematic diagram illustrating exemplary signaling procedures 1200 according to the disclosure for network/UE-initiated resource request for sidelink positioning applicable for sidelink resource allocation mode 2.

Resource allocation of sidelink positioning when UEs are out-of-coverage

A scenario is considered when the resource control UE 130, SLRefSigTX UE 110 and SLRefSigRX UE 120 are all out-of-coverage. One example of such settings is depicted in Figure 1. Note that ResCtrlUE 130 can also be acted as SLRefSigTX 110 or SLRefSigRX 120. Under such circumstance, the resource request can be received only from the UE and the resource allocation for sidelink positioning are performed in a UE autonomous mode, i.e., mode 2.

The detailed signaling procedures are shown in Figure 12. Main procedures are similar to the ones shown in Figure 11 except for two differences. First, the network involved signaling options (1a) and (3a) inside Figure 11 are not available here in Figure 12 due to the unavailability of network support in out-of-coverage scenario. Second, the LPP signaling options inside steps (4) and (5) in Figure 11 may be removed in Figure 12 due to the same reason as before.

The detailed signaling procedures are described as follows.

1. Resource request for SL-PRS transmission can be initiated by the UE 110, 120 (1.) 1211 to ResCtrl entity 130 (ResCtrl UE(s) 130 here).

2. ResCtrlUE(s) 130 may determine 1212 the resource allocation of SL-PRS applying SL RA mode 2.

3. ResCtrl UE(s) 130 may inform 1213 the SLRefSigTX 110 and/or SLRefSigRX 120 (optional) UEs about the SL-PRS configuration (3.).

4. Resource request 1221 for SL-AD transmission can be initiated by the UE 110, 120. The request message may mainly contain the requirements of AD transmission characteristics, latency requirements, etc. Note that step (4)-(6) may be only required if explicit resource request of AD is needed. These steps can be omitted under some circumstance, e.g., AD is transmitted with high-layer control signaling (e.g., PC5-RRC).

5. ResCtrlUE(s) 130 may determine 1222 the resource allocation of SL-AD by applying SL RA mode 2.

6. ResCtrlUE(s) 130 may signal 1223 the selected sidelink resource for SL-AD transmission to involved entities (e.g., the entity to measure, report, calculate the positioning, and/or deliver positioning estimate).

7. Resource request 1224 for SL location information and configuration. Step (7) is similar to step (4)-(6), and optional if explicit resource allocation is desired for measurement report and/or location estimate. 8. Due to the dynamic variations of SL resource allocation (e.g., pre-emption of URLLC transmission, legacy triggering conditions of sidelink resource reselection), the scheduled/selected SL-resource can be re-evaluated, re-scheduled, and updated 1225 before the activation of transmission.

9. Entities involved in sidelink positioning (e.g., SLRefSigTX 110, SLRefSigRX 120, PosCal 901) may perform SL-PRS/AD/LI transmissions and receptions 1226 using the allocated resource.

This embodiment can be applied to those applications where network-coverage is not available, e.g., underground valet parking lots, driving inside a tunnel, rural area without network support. It can also be beneficial for the ubiquitous positioning service, e.g., for public safety positioning everywhere.

Fig. 13 shows a schematic diagram illustrating a communication system 1300 for positioning based on sidelink according to the disclosure.

The communication system 1300 may include a first user device 1301a or UE, respectively, according to an example, one or more second user devices or UEs 1301b and a network device or base station 1320. In the example shown in Figure 13, the first user device 1301a and the second user device 1301b are, by way of example, portable devices, in particular smartphones 1301a, 1301b. However, one or more of these user devices 1301a, 1301b may also be, by way of example, laptop computer 1301a, 1301b, mobile vehicle or machine-type device. The first user device 1301a, and the one or more second user devices 1301b may be configured to communicate with the base station 1320, for instance, via Uu channel 1304. The first user device 1301a, and the one or more second user devices 1301b are configured to communicate with each other by sidelink channel 1302 without the base station 1320.

As can be seen from Figure 13, the first user device 1301a may comprise a processing circuitry 1303a for instance, a processor 1303a, for processing and generating data, a transceiver 1305a, including, for instance, an transmitter, a receiver and an antenna, for exchanging data with the other components of the communication system 1300, and a non-transitory memory 1307a for storing data. The processor 1303a of the first user device 1301a may be implemented in hardware and/or software. The hardware may comprise digital circuitry, or both analog and digital circuitry. Digital circuitry may comprise components such as application-specific integrated circuits (ASICs), field- programmable arrays (FPGAs), digital signal processors (DSPs), or general-purpose processors. The non-transitory memory 1307a may store data as well as executable program code which, when executed by the processor 1303a, causes the first user device 1301a to perform the functions, operations and methods described in this disclosure.

In an example, the one or more second user devices 1301b may have a similar architecture as the first user device 1301a, i.e. may comprise a processor 1303b for processing and generating data, a transceiver 1305b for exchanging data with the other components of the communication system 1300 as well as a memory 1307b for storing data. Likewise, as illustrated in figure 13, the base station 1320 may comprise a processor 1313 for processing and generating data, a transceiver 1315 for exchanging data with the other components of the communication system 1300 as well as a non-transitory memory 1317 for storing data.

As described above, the first user device 1301a may comprise a processor 1303a, a transceiver 1305a and a memory 1307a for performing the following functionalities. The second user device 1301b may also comprise a processor 1303b, a transceiver 1305b and a memory 1307b for performing the following functionalities. In the following reference is made to a user device. This user device may be the first user device 1301 a or the second user device 1301b as shown in Figure 13.

The user device 1301a, 1301b, 110, 120 can be used for positioning based on sidelink 1302. The user device is configured to: obtain a sidelink, SL, positioning resource information 111, e.g. as shown in Figure 1 or Figures 8 or 10. The sidelink positioning resource information 111 indicates a resource characteristic of a sidelink positioning reference signal, SL-PRS, a positioning assistance data, AD, or location information, LI. The user device is configured to perform sidelink positioning based on the sidelink positioning resource information 111 , e.g. according to the description above with respect to Figures 1 to 12.

The resource characteristic may comprises a latency information, e.g. as described above with respect to Figures 2 to 5. The latency information indicates latency requirement for the SL- PRS, the AD or the LI.

Obtaining the sidelink, SL, positioning resource information 111 may comprises: send a request 912 for sidelink positioning resource information 111 to a network entity 810, 820, 1320, e.g. as described above with respect to Figures 8 to 12, in particular Figure 9; receive 915 the sidelink positioning resource information 111 from a network entity 810, 820, 1320, e.g. as described above with respect to Figures 8 to 12, in particular Figure 9; or obtain pre configured sidelink positioning resource information.

The user device 1301a, 1301b, 110, 120 may be configured to: receive or transmit 926 the SL- PRS, AD or LI based on the sidelink positioning resource information 111 , e.g. as described above with respect to Figures 8 to 12, in particular Figure 9.

The SL positioning resource information 111 may be indicative of at least one of: discontinuous or consecutive symbol-level in time domain, intra-slot or inter-slot repetition in time domain, discontinuous or consecutive fractional subchannel indication in frequency domain, frequency hopping in frequency domain, e.g. as described above with respect to Figures 2 to 5.

The SL positioning resource information 111 may comprise a time-domain indication that comprises at least one of a symbol indication and a pattern index, wherein the symbol indication is indicative at least one of: one or more symbol indices inside a sidelink slot of the sidelink; or a length of sidelink symbols for transmission over the sidelink, a symbol offset of a first sidelink symbol with respect to a start sidelink symbol of a current sidelink slot of the sidelink and a start of the sidelink symbols inside the current sidelink slot, wherein the pattern index is indicative of: a pattern index of resource mapping patterns or an equivalent indication, e.g. as described above with respect to Figures 2 to 5.

The SL positioning resource information 111 may comprise a frequency-domain indication, wherein the frequency-domain indication comprises at least one of: a lowest subcarrier of absolute frequency of a reference resource block for all sidelink positioning resources allocated for transmission over the sidelink channel, a lowest subcarrier of a frequency occupied by resource blocks allocated to one configuration of the sidelink positioning resources allocated for transmission over the sidelink channel, a bandwidth for one SL-PRS or AD or LI signal occasion, comprising at least one of: a frequency resource occupied by a SL-PRS or AD or LI, a proportion of a subchannel size for a fractional occupation on subchannel level, e.g. as described above with respect to Figures 2 to 5.

The SL positioning resource information 111 may comprises a resource type indicative of a repetition property of the sidelink positioning resources in time domain, wherein the resource type comprises at least one of the following types: aperiodic which indicates an aperiodic resources allocation for the sidelink positioning in time domain, wherein the aperiodic resources are scheduled dynamically, semi-persistent which indicates a semi-static resources allocation for the sidelink positioning in time domain, wherein the semi-static resources are used repeatedly once been activated, periodic which indicates a periodic resources of the sidelink positioning in time domain, wherein the periodic resources are used once configured, e.g. as described above with respect to Figures 2 to 5.

The SL positioning resource information 111 may comprise a resource repetition factor indicative of a time-domain repetition of a sidelink positioning resource within one sidelink slot of the sidelink, e.g. as described above with respect to Figures 2 to 5.

The SL positioning resource information 111 may comprise: a frequency hopping tag for enabling or disabling frequency hopping and/or frequency offset of the sidelink positioning resources, e.g. as described above with respect to Figures 2 to 5.

The latency requirement may comprise at least one of: a maximum latency from requesting a SL-PRS, AD or LI transmission over the sidelink to a start of the SL-PRS, AD or LI transmission over the sidelink, a latency window for a SL-PRS, AD or LI transmission over the sidelink for one session of location-based services, e.g. as described above with respect to Figures 2 to 5.

The sidelink positioning resource information 111 may indicate a priority of the sidelink positioning resource information.

The sidelink positioning resource information 111 may indicate a sidelink positioning resources reservation for a forward link transmission or a reverse link transmission over the sidelink, e.g. as described above with respect to Figure 5.

The sidelink positioning resource information 111 may comprise at least one of: forward link transmission characteristics indicative of requirements for the forward link transmission over the sidelink, reverse link transmission characteristics indicative of requirements for the reverse link transmission over the sidelink, a latency bound indicative of a maximum allowed latency between a first transmission over the sidelink and a second transmission over the sidelink, wherein the second transmission is over a forward link or over the reverse link, e.g. as described above with respect to Figure 5.

The sidelink positioning resource information may comprise at least one of: a time gap indicative of a time offset of a sidelink positioning resource for the first transmission over the sidelink and a sidelink positioning resource for the second transmission over the sidelink, a frequency offset indicative of a frequency offset of the sidelink positioning resource for the first transmission over the sidelink and the sidelink positioning resource for the second transmission over the sidelink, e.g. as described above with respect to Figures 2 to 5.

The user device 1301a, 1301b, 110, 120 may be configured to obtain the sidelink positioning resource information 111 via at least one of the following interfaces: a Radio Resource Control, RRC, interface, a PC5-RRC interface for sidelink positioning, a MAC Control Element, MAC- CE interface, a sidelink control information, SCI, interface.

The user device 1301a, 1301b, 110, 120 may be configured to receive an update signal indicative of an update of the sidelink positioning resource information 111 ; and may be configured to update the sidelink positioning resource information 111 responsive to reception of the update signal.

The method 1400 comprises obtaining 1401, by a user device, a sidelink, SL, positioning resource information, wherein the sidelink positioning resource information indicates a resource characteristic of a sidelink positioning reference signal, SL-PRS, a positioning assistance data, AD, or location information, LI.

The method comprises performing, by the user device, sidelink positioning based on the sidelink positioning resource information.

The present disclosure also supports a computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the performing and computing steps described herein, in particular the methods and procedures described above. Such a computer program product may include a readable non-transitory storage medium storing program code thereon for use by a computer. The program code may perform the processing and computing steps described herein, in particular the methods and procedures described above.

While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms “coupled” and “connected”, along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the invention beyond those described herein. While the present invention has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the present invention. It is therefore to be understood that within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described herein.

Claims

CLAIMS:

1. A user device (1301a, 1301b, 110, 120) for positioning based on sidelink (1302), wherein the user device is configured to: obtain a sidelink, SL, positioning resource information (111), wherein the sidelink positioning resource information (111) indicates a resource characteristic of a sidelink positioning reference signal, SL-PRS, a positioning assistance data, AD, or location information, LI; and perform sidelink positioning based on the sidelink positioning resource information

(111).

2. The user device (1301a, 1301b, 110, 120) of claim 1, wherein the resource characteristic comprises a latency information (300, 400, 500), wherein the latency information indicates latency requirement for the SL-PRS, the AD or the LI.

3. The user device (1301a, 1301b, 110, 120) of one of the preceding claims, wherein obtain a sidelink, SL, positioning resource information comprises: send a request (912) for sidelink positioning resource information (111) to a network entity (810, 820, 1320), receive (915) the sidelink positioning resource information (111) from a network entity (810, 820, 1320), or obtain pre-configured sidelink positioning resource information.

4. The user device (1301a, 1301b, 110, 120) of one of the preceding claims, configured to: receive or transmit (926) the SL-PRS, AD or LI based on the sidelink positioning resource information (111).

5. The user device (1301a, 1301b, 110, 120) of any of the preceding claims, wherein the SL positioning resource information (111) is indicative of at least one of: discontinuous or consecutive symbol-level in time domain, intra-slot or inter-slot repetition in time domain, discontinuous or consecutive fractional subchannel indication in frequency domain, frequency hopping in frequency domain.

6. The user device (1301a, 1301b, 110, 120) of any of the preceding claims, wherein the SL positioning resource information (111) comprises a time-domain indication that comprises at least one of a symbol indication and a pattern index, wherein the symbol indication is indicative at least one of: one or more symbol indices inside a sidelink slot of the sidelink; or a length of sidelink symbols for transmission over the sidelink, a symbol offset of a first sidelink symbol with respect to a start sidelink symbol of a current sidelink slot of the sidelink and a start of the sidelink symbols inside the current sidelink slot, wherein the pattern index is indicative of: a pattern index of resource mapping patterns or an equivalent indication.

7. The user device (1301a, 1301b, 110, 120) of any of the preceding claims, wherein the SL positioning resource information (111) comprises a frequency-domain indication, wherein the frequency-domain indication comprises at least one of: a lowest subcarrier of absolute frequency of a reference resource block for all sidelink positioning resources allocated for transmission over the sidelink channel, a lowest subcarrier of a frequency occupied by resource blocks allocated to one configuration of the sidelink positioning resources allocated for transmission over the sidelink channel, a bandwidth for one SL-PRS or AD or LI signal occasion, comprising at least one of: a frequency resource occupied by a SL-PRS or AD or LI, a proportion of a subchannel size for a fractional occupation on subchannel level.

8. The user device (1301a, 1301b, 110, 120) of any of the preceding claims, wherein the SL positioning resource information (111) comprises a resource type indicative of a repetition property of the sidelink positioning resources in time domain, wherein the resource type comprises at least one of the following types: aperiodic which indicates an aperiodic resources allocation for the sidelink positioning in time domain, wherein the aperiodic resources are scheduled dynamically, semi-persistent which indicates a semi-static resources allocation for the sidelink positioning in time domain, wherein the semi-static resources are used repeatedly once been activated, periodic which indicates a periodic resources of the sidelink positioning in time domain, wherein the periodic resources are used once configured.

9. The user device (1301a, 1301b, 110, 120) of any of the preceding claims, wherein the SL positioning resource information (111) comprises a resource repetition factor indicative of a time-domain repetition of a sidelink positioning resource within one sidelink slot of the sidelink.

10. The user device (1301a, 1301b, 110, 120) of any of the preceding claims, wherein the SL positioning resource information (111) comprises: a frequency hopping tag for enabling or disabling frequency hopping and/or frequency offset of the sidelink positioning resources.

11. The user device (1301a, 1301b, 110, 120) of claim 2, wherein the latency requirement comprises at least one of: a maximum latency from requesting a SL-PRS, AD or LI transmission over the sidelink to a start of the SL-PRS, AD or LI transmission over the sidelink, a latency window for a SL-PRS, AD or LI transmission over the sidelink for one session of location-based services.

12. The user device (1301a, 1301b, 110, 120) of any of the preceding claims, wherein the sidelink positioning resource information (111) indicates priority of the sidelink positioning resource information.

13. The user device (1301a, 1301b, 110, 120) of any of the preceding claims, wherein the sidelink positioning resource information (111) indicates a sidelink positioning resources reservation for a forward link transmission or a reverse link transmission over the sidelink.

14. The user device (1301a, 1301b, 110, 120) of claim 13, wherein the sidelink positioning resource information comprises at least one of: forward link transmission characteristics indicative of requirements for the forward link transmission over the sidelink, reverse link transmission characteristics indicative of requirements for the reverse link transmission over the sidelink, a latency bound indicative of a maximum allowed latency between a first transmission over the sidelink and a second transmission over the sidelink, wherein the second transmission is over a forward link or over the reverse link.

15. The user device (1301a, 1301b, 110, 120) of claim 14, wherein the sidelink positioning resource information comprises at least one of: a time gap indicative of a time offset of a sidelink positioning resource for the first transmission over the sidelink and a sidelink positioning resource for the second transmission over the sidelink, a frequency offset indicative of a frequency offset of the sidelink positioning resource for the first transmission over the sidelink and the sidelink positioning resource for the second transmission over the sidelink.

16. The user device (1301a, 1301b, 110, 120) of any of the preceding claims, configured to obtain the sidelink positioning resource information (111) via at least one of the following interfaces: a Radio Resource Control, RRC, interface, a PC5-RRC interface for sidelink positioning, a MAC Control Element, MAC-CE interface, a sidelink control information, SCI, interface.

17. The user device (1301a, 1301b, 110, 120) of any of the preceding claims, configured to receive an update signal indicative of an update of the sidelink positioning resource information (111); and configured to update the sidelink positioning resource information (111) responsive to reception of the update signal.

18. A method (1400) for positioning based on sidelink, the method comprising: obtaining (1401), by a user device (1301a, 1301b, 110, 120), a sidelink, SL, positioning resource information, wherein the sidelink positioning resource information indicates a resource characteristic of a sidelink positioning reference signal, SL-PRS, a positioning assistance data, AD, or location information, LI; and performing (1402), by the user device (1301a, 1301b, 110, 120), sidelink positioning based on the sidelink positioning resource information.

19. A computer program product including computer executable code or computer executable instructions that, when executed, causes at least one computer to execute the method (1400) according to claim 18.