DEVICE AND METHOD FOR ALLOCATION OF RESOURCES FOR SIDELINK POSITIONING - Patent application

Abstract

Disclosed are devices and methods for allocating resources for sidelink positioning, e.g., a user equipment (UE) for transmitting an assignment of time and frequency resources for transmission of one or more sidelink positioning reference signals (SL-PRSs). The UE is configured to transmit the assignment using a two-stage assignment including a first-stage assignment of one or more first time and frequency resources of a plurality of time and frequency resources having a first granularity and a second-stage assignment of one or more second time and frequency resources of a plurality of time and frequency resources having a second granularity, where the one or more second time and frequency resources are a subset of the one or more first time and frequency resources.

Description

[Technical Field]

[0001] The present disclosure relates to sidelink communications in wireless communication networks, and more particularly, to devices and methods for allocating resources for sidelink positioning in wireless communication networks. [Background technology]

[0002] Communication between mobile devices, also called user equipment (UE), has been standardized in the form of sidelink (SL) communication since Release 12 of the Long Term Evolution (LTE) of the Third Generation Public Partnership (3GPP) standard. Resources for sidelink communication can be allocated either by the network when the UE is within network coverage and using licensed spectrum, or in an autonomous, distributed manner by each UE when it is outside network coverage or using unlicensed spectrum.

[0003] Several vehicle-to-everything (V2X) and public safety use cases can benefit from sidelink positioning, i.e., positioning based on the transmission and reception of sidelink positioning reference signals (SL-PRS). The 3rd Generation Partnership Project (3GPP) is currently studying SL positioning in their Release 18 (Rel. 18) as part of a study item on extended and improved new radio (NR) positioning. Summary of the Invention

[0004] An object of the present disclosure is to provide devices and methods for allocation of time and frequency resources for transmission of SL-PRS in wireless communication networks.

[0005] These and other objects are achieved by the subject matter of the independent claims. Further forms of implementation are evident from the dependent claims, the description and the drawings.

[0006] According to a first aspect, there is provided a user equipment (UE) for transmitting an allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals (SL-PRS). The UE is configured to transmit the allocation using a two-stage allocation including a first-stage allocation indicating one or more first time and frequency resources of a plurality of time and frequency resources having a first granularity and a second-stage allocation indicating one or more second time and frequency resources of the plurality of time and frequency resources having a second granularity, the one or more second time and frequency resources being a subset of the one or more first time and frequency resources. As used herein, the one or more second time and frequency resources being a subset of the one or more first time and frequency resources includes the case where the one or more second time and frequency resources include all of the one or more first time and frequency resources, i.e., the first and second time and frequency resources are identical.

[0007] In a further possible implementation, the UE is configured to transmit first-phase sidelink control information, SCI, where the first-phase SCI includes the first-phase allocation.

[0008] In a further possible implementation, the UE is configured to transmit second-phase sidelink control information, SCI, where the second-phase SCI includes the second-phase allocation.

[0009] In a further possible implementation, the first stage SCI includes information indicating the presence of a second stage allocation.

[0010] In further possible implementations, the first stage SCI further includes information regarding the format of the second stage SCI, and / or one or more reserved bits of the first stage SCI include information indicating the presence of a second stage allocation.

[0011] In a further possible implementation, the multiple time and frequency resources comprise multiple slots and multiple sub-channels.

[0012] In a further possible implementation, the UE is configured to transmit a two-stage allocation, namely a first allocation and a second allocation, within one or more subchannels of the plurality of slots and the plurality of subchannels.

[0013] In a further possible implementation, the UE is configured to transmit control information associated with one or more SL-PRSs within one or more subchannels of the plurality of slots and plurality of subchannels carrying the two-stage allocation.

[0014] In a further possible implementation, the UE is configured to transmit the two-stage allocation in a slot prior to one or more slots including the first time and frequency resource indicated by the two-stage allocation.

[0015] In a further possible implementation, the UE is configured to transmit the two-stage allocation in a slot that includes a first time and frequency resource indicated by the two-stage allocation.

[0016] In a further possible implementation, the UE is configured to transmit one or more SL-PRS in, i.e., using, second time and frequency resources as indicated by the second-phase allocation.

[0017] In a further possible implementation, the UE is configured to transmit one or more SL-PRS in, i.e., using, second time and frequency resources as indicated by the first phase allocation and the second phase allocation.

[0018] In a further possible implementation, the UE is configured to transmit an allocation of time and frequency resources for transmission of one or more of the one or more SL-PRSs by another UE (further UE) using a two-stage allocation.

[0019] In a further possible implementation, the first granularity is the size of a sub-channel of a slot, ie has the size of a sub-channel of a slot.

[0020] In a further possible implementation, the plurality of time and frequency resources includes one or more configured or pre-configured semi-dedicated SL-PRS resources having a second granularity.

[0021] In a further possible implementation, the plurality of time and frequency resources comprises one or more configured or pre-configured semi-dedicated SL-PRS resources, and the UE and / or another UE is configured to transmit one or more SL-PRSs in, i.e., using, one or more of the one or more SL-PRS resources.

[0022] In a further possible implementation, the UE is configured to transmit a two-stage allocation in one or more time and frequency resources of a plurality of time and frequency resources that are different from the one or more SL-PRS resources.

[0023] In a further possible implementation, the UE is configured to transmit data in one or more time and frequency resources of a plurality of time and frequency resources including one or more of the one or more SL-PRS resources.

[0024] In a further possible implementation, the UE is configured to transmit information associated with one or more of the one or more SL-PRS resources in one or more time and frequency resources of the plurality of time and frequency resources.

[0025] In a further possible implementation, the UE is configured to receive configuration information regarding one or more SL-PRS resources from the base station or from a second, different UE.

[0026] In a further possible implementation, the UE is configured to transmit one or more identifiers of one or more UEs intended to transmit one or more SL-PRSs in, i.e., using, the second time and frequency resources.

[0027] In a further possible implementation, the UE is configured to transmit one or more identifiers of one or more UEs intended to receive one or more SL-PRSs in the second time and frequency resources, i.e., using the second time and frequency resources.

[0028] According to a second aspect, there is provided a method for transmitting an assignment of time and frequency resources for transmission of one or more sidelink positioning reference signals (SL-PRS). The method comprises transmitting the assignment using a two-stage assignment, the first-stage assignment indicating one or more first time and frequency resources of a plurality of time and frequency resources having a first granularity, and a second-stage assignment indicating one or more second time and frequency resources of the plurality of time and frequency resources having a second granularity, wherein the one or more second time and frequency resources are a subset of the one or more first time and frequency resources. As used herein, the one or more second time and frequency resources being a subset of the one or more first time and frequency resources includes the case where the one or more second time and frequency resources include all of the one or more first time and frequency resources, i.e., the first time and the second time and frequency resources are identical.

[0029] The method according to the second aspect of the present disclosure may be performed by a UE according to the first aspect of the present disclosure, and therefore further features of the method according to the second aspect of the present disclosure result directly from the functionality of the UE according to the first aspect of the present disclosure and its different implementation forms described above and below.

[0030] According to a third aspect, a user equipment (UE) is provided for receiving an allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals (SL-PRS). The UE is configured to receive the allocation using a two-stage allocation including a first-stage allocation indicating one or more first time and frequency resources of a plurality of time and frequency resources having a first granularity and a second-stage allocation indicating one or more second time and frequency resources of the plurality of time and frequency resources having a second granularity, where the one or more second time and frequency resources are a subset of the one or more first time and frequency resources. As used herein, the one or more second time and frequency resources being a subset of the one or more first time and frequency resources includes the case where the one or more second time and frequency resources include all of the one or more first time and frequency resources, i.e., the first and second time and frequency resources are identical.

[0031] In a further possible implementation, the UE is configured to receive first-phase sidelink control information, SCI, where the first-phase SCI includes the first-phase allocation.

[0032] In a further possible implementation, the UE is configured to determine that the first stage SCI includes a first stage allocation by determining that the first stage SCI indicates a second stage allocation.

[0033] In a further possible implementation, the UE is configured to receive second-stage sidelink control information, SCI, where the second-stage SCI includes the second-stage allocation.

[0034] In a further possible implementation, the first stage SCI includes information indicating the presence of a second stage allocation.

[0035] In further possible implementations, the first stage SCI further includes information regarding the format of the second stage SCI, and / or one or more reserved bits of the first stage SCI include information indicating the presence of a second stage allocation.

[0036] In a further possible implementation, the multiple time and frequency resources include multiple slots and multiple subchannels.

[0037] In a further possible implementation, the UE is configured to receive a two-stage allocation, namely a first allocation and a second allocation, within the plurality of slots and one or more subchannels of the plurality of subchannels.

[0038] In a further possible implementation, the UE is configured to receive control information associated with one or more SL-PRSs within one or more subchannels of the plurality of slots and plurality of subchannels carrying the two-stage allocation.

[0039] In a further possible implementation, the UE is configured to receive the two-stage allocation in a slot prior to one or more slots that include the first time and frequency resource indicated by the two-stage allocation.

[0040] In a further possible implementation, the UE is configured to receive the two-stage allocation in a slot that includes a first time and frequency resource indicated by the two-stage allocation.

[0041] In a further possible implementation, the UE is configured to transmit one or more SL-PRS in, i.e., using, second time and frequency resources as indicated by the second-phase allocation.

[0042] In a further possible implementation, the UE is configured to transmit one or more SL-PRS in, i.e., using, second time and frequency resources as indicated by the first phase allocation and the second phase allocation.

[0043] In a further possible implementation, the UE is configured to receive one or more SL-PRSs in, i.e., using, second time and frequency resources as indicated by the second-stage allocation.

[0044] In a further possible implementation, the UE is configured to receive one or more SL-PRSs in, i.e., using, second time and frequency resources as indicated by the first phase allocation and the second phase allocation.

[0045] In a further possible implementation, the first granularity is the size of a sub-channel of a slot, ie has the size of a sub-channel of a slot.

[0046] In a further possible implementation, the plurality of time and frequency resources comprises one or more configured or pre-configured semi-dedicated SL-PRS resources having a second granularity, i.e., the same resolution as the one or more second time and frequency resources.

[0047] In a further possible implementation, the plurality of time and frequency resources comprises one or more configured or pre-configured semi-dedicated SL-PRS resources, wherein the UE and / or another UE is configured to transmit one or more SL-PRSs in, i.e., using, one or more of the SL-PRS resources.

[0048] In a further possible implementation, the UE is configured to receive a two-stage allocation in one or more time and frequency resources of a plurality of time and frequency resources that are different from the one or more SL-PRS resources.

[0049] In a further possible implementation, the UE is configured to transmit data in one or more time and frequency resources of a plurality of time and frequency resources including one or more of the one or more SL-PRS resources.

[0050] In a further possible implementation, the UE is configured to receive data in one or more time and frequency resources of a plurality of time and frequency resources including one or more of the one or more SL-PRS resources.

[0051] In a further possible implementation, the UE is configured to transmit information associated with one or more of the one or more SL-PRS resources in one or more time and frequency resources of the plurality of time and frequency resources.

[0052] In a further possible implementation, the UE is configured to receive information associated with one or more of the one or more SL-PRS resources in one or more time and frequency resources of the plurality of time and frequency resources.

[0053] In a further possible implementation, the UE is configured to receive configuration information regarding one or more SL-PRS resources from the base station or from a second, different UE.

[0054] In a further possible implementation, the UE is configured to receive one or more identifiers of one or more UEs intended to transmit one or more SL-PRSs in the second time and frequency resources, i.e., using the second time and frequency resources.

[0055] In a further possible implementation, the UE is configured to receive one or more identifiers of one or more UEs intended to receive one or more SL-PRSs in the second time and frequency resources, i.e., using the second time and frequency resources.

[0056] According to a fourth aspect, there is provided a method for receiving an allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals (SL-PRS). The method comprises receiving an allocation using a two-stage allocation including a first-stage allocation indicating one or more first time and frequency resources of a plurality of time and frequency resources having a first granularity and a second-stage allocation indicating one or more second time and frequency resources of the plurality of time and frequency resources having a second granularity, wherein the one or more second time and frequency resources are a subset of the one or more first time and frequency resources. As used herein, the one or more second time and frequency resources being a subset of the one or more first time and frequency resources means that the one or more second time and frequency resources include all of the one or more first time and frequency resources, i.e., including the case where the first and second time and frequency resources are identical.

[0057] The method according to the fourth aspect of the present disclosure may be performed by a UE according to the third aspect of the present disclosure. Accordingly, further features of the method according to the fourth aspect of the present disclosure result directly from the functionality of the UE according to the third aspect of the present disclosure and its different implementation forms described above and below.

[0058] According to a fifth aspect, there is provided a computer program product comprising a computer readable storage medium for storing program code which, when executed by a computer or processor, causes the computer or processor to perform a method according to the second aspect or a method according to the fourth aspect.

[0059] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will become apparent from the description, drawings, and claims. [Brief explanation of the drawings]

[0060] In the following, embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. [Figure 1] FIG. 1 shows a schematic diagram illustrating a wireless communication network with several UEs according to one embodiment for transmitting and / or receiving allocations of time and frequency resources for transmission of one or more sidelink positioning reference signals. [Figure 2] FIG. 2 shows a schematic diagram illustrating a two-stage assignment of time and frequency resources for transmission of one or more sidelink positioning reference signals performed by a UE according to one embodiment. [Figure 3] FIG. 3 shows a schematic diagram illustrating semi-dedicated SL-PRS resources used for a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals performed by a UE, according to one embodiment. [Figure 4] FIG. 4 shows a schematic diagram illustrating a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals performed by a UE according to one embodiment. [Figure 5] FIG. 5 shows a schematic diagram illustrating a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals implemented by a first UE and a second UE according to one embodiment. [Figure 6A] FIG. 6a shows a schematic diagram illustrating a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals performed by a UE according to one embodiment. [Figure 6B]FIG. 6b shows a schematic diagram illustrating a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals performed by a UE according to one embodiment. [Figure 7A] FIG. 7a shows a schematic diagram illustrating the configuration steps performed by a transmitting UE according to an embodiment for a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals. [Figure 7B] FIG. 7b shows a schematic diagram illustrating the configuration steps performed by a receiving UE according to an embodiment for a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals. [Figure 8] FIG. 8 shows a signaling diagram illustrating a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals performed by a UE according to one embodiment. [Figure 9] FIG. 9 shows a flowchart illustrating processing steps implemented by a transmitting UE according to one embodiment for a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals implemented by the UE according to one embodiment. [Figure 10] FIG. 10 shows a schematic diagram illustrating the processing steps performed by a transmitting UE according to one embodiment for a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals. [Figure 11] FIG. 11 shows a schematic diagram illustrating the processing steps performed by a transmitting UE according to one embodiment for a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals. [Figure 12] FIG. 12 shows a flowchart illustrating the processing steps performed by a transmitting UE according to one embodiment for a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals. [Figure 13] FIG. 13 shows a schematic diagram illustrating a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals performed by a UE according to one embodiment. [Figure 14] FIG. 14 shows a flowchart illustrating processing steps implemented by a receiving UE according to one embodiment for a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals. [Figure 15] FIG. 15 shows a schematic diagram illustrating semi-dedicated SL-PRS resources used for a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals implemented by a UE according to one embodiment. [Figure 16] FIG. 16 shows a signaling diagram illustrating a two-stage allocation of time and frequency resources based on semi-dedicated SL-PRS resources implemented by a UE for transmission of one or more sidelink positioning reference signals according to one embodiment. [Figure 17] 17 is a flow chart illustrating a method according to one embodiment for transmitting a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals; and [Figure 18] FIG. 18 is an illustrative flowchart illustrating a method according to one embodiment for receiving a two-stage allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals.

[0061] In the following, the same reference signs refer to the same features or at least functionally equivalent features. DETAILED DESCRIPTION OF THE INVENTION

[0062] In the following description, reference is made to the accompanying drawings which form a part of this disclosure and which show, by way of illustration, specific aspects of embodiments of the present disclosure or in which embodiments of the present disclosure may be used. It is understood that embodiments of the present disclosure may be used in other ways and may include structural or logical changes not shown in the drawings. 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.

[0063] For example, it should be understood that disclosure related to a described method may also apply to a corresponding device or system configured to perform the method, and vice versa. For example, when one or more particular method steps are described, the corresponding device may include one or more units, e.g., functional units, to perform the described one or more method steps (e.g., one unit performing one or more steps, or multiple units each performing one or more of the steps), even if such one or more units are not explicitly described or shown. Conversely, for example, when a particular apparatus is described based on one or more units, e.g., functional units, the corresponding method may include a step for performing the function of the one or more units (e.g., one step performing the function of one or more units, or multiple steps each performing the function of one or more of the units), even if such one or more steps are not explicitly described or shown in a figure. Furthermore, it is understood that features of various exemplary embodiments and / or aspects described herein may be combined with each other, unless otherwise specified.

[0064] 1 shows a schematic diagram illustrating a wireless communication network, in particular a cellular communication network 100, having a base station 110 defining a cell of the wireless communication network 100 and a plurality of user equipments, UEs 120a-120d, according to one embodiment for transmitting and / or receiving allocations of time and frequency resources for the transmission of one or more sidelink positioning reference signals (SL-PRS). By way of example, in FIG. 1, UE 120a transmits allocations of time and frequency resources for the transmission of one or more sidelink positioning reference signals (SL-PRS).

[0065] As shown in FIG. 1, the UE 120a may include a processor 121a and a communication interface 123a, particularly an antenna, for sidelink communication with the base station 110 and other UEs 120b-120d in the wireless network 100. The processor 121a may be implemented in hardware and / or software. The hardware may include digital circuits or both analog and digital circuits. The digital circuits may include components such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a digital signal processor (DSP), or one or more general-purpose processors. Additionally, the UE 120a may include a memory 125a configured to store executable program code that, when executed by the processor 121a, causes the UE 120a to perform the functions and operations described herein. Similar to the UE 120a, the other UEs 120b-120d may also include a processor, a communication interface, and a memory.

[0066] By way of example, further below, several detailed embodiments are described in which UE 120a (also referred to as a first UE) is transmitting an allocation of time and frequency resources for transmission of one or more SL-PRSs, while UEs 120b-120d may receive such allocations. Further, by way of example, UE 120d may be a legacy UE 120d, as defined in further detail below.

[0067] Embodiments disclosed herein relate to allocation of time and frequency resources in the sidelink for transmission of SL-PRS. Sidelink transmissions may use an Orthogonal Frequency Division Multiplexing (OFDM) waveform with a cyclic prefix (CP). In the time domain, resources may consist of a slot. A slot consists of multiple OFDM symbols, e.g., 14 or 12 OFDM symbols depending on whether a normal CP or an extended CP is employed. Hereinafter, an OFDM symbol is simply referred to as a symbol, and a slot is assumed to consist of 12 symbols. In the frequency domain, resources may consist of a resource block (RB). An RB consists of multiple adjacent subcarriers, e.g., 12 subcarriers, with the same subcarrier spacing for the OFDM waveform.

[0068] For data transmissions in the sidelink, e.g., NR-V2X in 3GPP Rel. 16 / 17, a subset of available resources can be (pre-)configured to be used by the UEs 120a-120d for their SL transmissions. The subset of resources available for SL transmissions is called a resource pool (RP). (Pre-)configuration refers to (a) a configuration defined by the network and signaled to the UEs 120a-120d by the network device base station 110, i.e., a configuration when the UEs 120a-120d are in network coverage, or (b) a configuration predefined in the UEs 120a-120d, e.g., a configuration when the UEs 120a-120d are out of network coverage. The network device base station 110 can be a next-generation Node B (gNB), a base station (BS), a roadside unit (RSU), a transmit / receive point (TRP), etc. The UEs 120a-120d may be mobile phones, handheld devices, devices on vehicles, devices on robots, etc. Hereinafter, the term gNB is used with the understanding that the units may be implemented generally as network devices 110. As already explained above, by way of example, the UE 120d may be a legacy UE 120d, while the UEs 120a-120c are implemented in accordance with embodiments disclosed herein.

[0069] In the time domain, the RP consists of contiguous or non-contiguous slots. Within a slot, all symbols or only a subset of the available symbols can be (pre)configured for sidelink transmission. The resource blocks in the resource pool are also called physical resource blocks (PRBs). In the frequency domain, the RP is divided into a (pre)configured number of contiguous subchannels. A subchannel consists of a set of adjacent PRBs within a slot. The number of PRBs within a subchannel is (pre)configured in the resource pool. A subchannel represents the smallest unit for scheduling data transmissions in the sidelink. A sidelink transmission can occupy one or more subchannels.

[0070] Data is organized into transport blocks (TBs), e.g., a TB may include an entire data packet. In NR V2X, the data payload, i.e., the TB, is carried in a physical sidelink shared channel (PSSCH). Depending on the size of the data packet, the PSSCH carrying the TB can occupy one or more subchannels. Sidelink control information (SCI) associated with the TB is transmitted in two phases: a first-phase SCI and a second-phase SCI. The first phase is carried in a physical sidelink control channel (PSCCH). The PSCCH is multiplexed with its associated PSSCH in non-overlapping resources within the subchannel occupied by the PSSCH. To aid in decoding the PSCCH, a demodulation reference signal (DMRS) is transmitted in the PSCCH, referred to as the PSCCH DMRS. The second-phase SCI is multiplexed in time and frequency with the TB in the PSSCH. To aid in decoding the PSSCH, a demodulation reference signal (DMRS) is transmitted within the PSSCH, which is referred to as the PSSCH DMRS. For transmission of the TB, the transmitting UEs (Tx UEs) 120a-120d transmit the PSCCH (carrying the first-stage SCI) along with the second-stage SCI multiplexed with the TB within the PSSCH in one or more subchannels.

[0071] The first-stage SCI indicates resources for the current TB transmission and may also indicate resources reserved for retransmission of the same TB. The current TB transmission may be referred to as the initial transmission. The initial transmission may correspond to a retransmission. The resources for a transmission include one or more subchannels within one slot. The resources for a transmission may be determined using a frequency resource location and a time resource location of the resources. The frequency resource location of the resources may be indicated using a starting subchannel index and the number of consecutively allocated subchannels for the transmission. The time resource location may be indicated using a slot index. The starting subchannel and slot of the resources for the current TB transmission correspond to the subchannel and slot in which the PSCCH (carrying the first-stage SCI associated with the TB) is located. Based on this, the resources for the current transmission may be determined using an indication of the number of consecutive subchannels occupied by the current transmission. The resources for a retransmission are indicated using a frequency indication and a time indication that specify the starting subchannel index, the number of consecutively allocated subchannels, and the subsequent slot index of the retransmission.

[0072] In addition, the first-stage SCI may also indicate a resource reservation period, which is the time period between resources selected for successive TB transmissions. This period indicates the periodicity of the resources selected by the UEs 120a-120d and is referred to as a resource reservation interval (RRI) in NR V2X. Using the RRI in the first-stage SCI, the UEs 120a-120d can indicate that the subchannel used for the current transmission of the TB can be reserved after the RRI for the transmission of a new TB. Multiple RRIs may be configured (pre-) in the resource pool.

[0073] Decoding the first-stage SCI can then enable the UEs 120a-120d to recognize the sub-channels occupied by the current transmission of the TB carried in the PSSCH, as well as the reserved sub-channels for future (re)transmissions of the same or new TB. The first-stage SCI also indicates the priority of the TB carried in the associated PSSCH. In addition, the first-stage SCI also indicates the format of the second-stage SCI, since the second-stage SCI can have a variable length. The second-stage SCI indicates the source ID and destination ID of the TB. Decoding the second-stage SCI enables the receiving UEs 120a-120d (Rx UEs) to know the source and destination of the TB, i.e., to recognize whether the Rx UEs 120a-120d are the target Rx UEs 120a-120d of the TB carried in the PSSCH.

[0074] For data transmission, i.e., for TB transmission, subchannels in the resource pool may be selected based on two resource allocation modes: Mode 1 and Mode 2. In Mode 1, subchannels for data transmission are assigned by the network; i.e., the base station or gNB 110 indicates to the UE 120a-120d the resources to use for data transmission. In Mode 2, the UE 120a-120d can autonomously select subchannels for data transmission.

[0075] For transmissions in Mode 2, the UEs 120a-120d identify candidate resources within a selection window based on a sensing procedure within a set of slots in a resource pool. This set of slots is referred to as the sensing window. As part of the sensing procedure, the UEs 120a-120d search for the PSCCH in all potential PSCCH positions within each subchannel of these slots and, if they find the PSCCH, decode the first-stage SCI. Based on the decoded first-stage SCI, the UEs 120a-120d recognize resources reserved for their transmissions by other UEs 120a-120d. Additionally, the UEs 120a-120d measure the reference signal received power (RSRP) of transmissions associated with the received first-stage SCI. Whether the UEs 120a-120d measure RSRP based on the PSCCH DMRS or the PSSCH DMRS can be configured (pre-configured) per resource pool. The measured RSRP and the corresponding resources reserved by the first stage SCI are considered to be the sensing results from the Mode 2 sensing of the UEs 120a-120d.

[0076] In mode 2, the UEs 120a-120d determine candidate resources in the selection window after excluding resources in the selection window based on half-duplex operation and based on sensing results. Due to half-duplex operation, the UEs 120a-120d cannot sense reservations from other UEs 120a-120d in slots in the sensing window in which the UEs 120a-120d were transmitting. Based on this, the UEs 120a-120d exclude slots in the selection window with potentially reserved resources due to the RRI periods indicated in the first stage that were transmitted in slots of the sensing window when the UEs 120a-120d were transmitting. The UEs 120a-120d may also exclude slots that, if selected by the UEs 120a-120d for resources to be used with a given RRI period (selected by the UEs 120a-120d for its transmission), may result in future collisions with potentially reserved resources of other UEs 120a-120d. In addition, based on the sensing results, the UEs 120a-120d may also exclude reserved resources in the selection window with an associated measured RSRP greater than a (pre-)configured threshold, which depends on the priority of the TB transmitted by the UEs 120a-120d. The UEs 120a-120d may also exclude resources that, if selected by the UEs 120a-120d for use with a given RRI period, may result in future collisions with reserved resources of other UEs 120a-120d. After the exclusion, the UEs 120a-120d check whether the percentage of available candidate resources remaining in the selection window is above a threshold that depends on the priority of the TB to be transmitted by the UEs 120a-120d. If not, the RSRP threshold used to exclude reserved resources is increased by 3 dB, and the sensing-based resource exclusion is repeated. Among the remaining candidate resources in the selection window, the UEs 120a-120d randomly select resources for the initial transmission and retransmission of the TB.The UEs 120a-120d may use the selected resources for multiple time periods, ie, with a given RRI selected by the UEs 120a-120d, to transmit multiple TBs.

[0077] Mechanisms for enhancing mode 2 operation include reassessment and preemption. With reassessment, a UE 120a-120d can check whether the selected resource for the TB is reserved by another UE 120a-120d based on new sensing results prior to the UE 120a-120d's transmission of the TB. If so, the UE 120a-120d drops the selected resource and selects a new resource for the TB. With preemption, the UE 120a-120d can also check whether the selected resource for the TB is reserved, similar to the reassessment mechanism. However, with preemption, the UE 120a-120d only selects a new resource for the TB transmission if the resource is reserved by another UE 120a-120d for a transmission that has a higher priority compared to the priority of the UE's transmission. The UE 120a-120d may also select a new resource for its transmission if the priority associated with the reserved resource is higher than a (pre-)configured threshold in the resource pool.

[0078] For resource allocation of SL-PRS, 3GPP has discussed that Scheme 1 and Scheme 2, similar to Mode 1 (i.e., network controlled) and Mode 2 (autonomous selection by UE) for data transmission, should be introduced, respectively. In the following, Scheme 1 is referred to as Mode 1, and Scheme 2 is referred to as Mode 2.

[0079] For SL-PRS transmission, time and frequency resources in the sidelink are required. Similar to data transmission in the sidelink, resources in a resource pool can be used for SL-PRS transmission. For this purpose, whether to use a dedicated shared resource pool and / or a shared resource pool for SL-PRS, including (pre-)configuring one of them, has been discussed in 3GPP. A dedicated resource pool refers to a resource pool with resources used for SL-PRS transmission and possibly for transmitting SCI or other information associated with the SL-PRS resources. A PSCCH can be transmitted in the dedicated resource pool, where the PSCCH carries the SCI associated with the SL-PRS transmission. A PSSCH associated with the SL-PRS transmission can also be transmitted in the dedicated resource pool, e.g., a PSSCH carrying measurement reports for the SL-PRS transmission. A shared resource pool refers to a resource pool with resources used for data and SL-PRS transmission and for transmitting information associated with these transmissions (e.g., SCI). Additionally, it has been agreed in 3GPP that backward compatibility for legacy UEs, such as exemplary UE 120d, should be supported in the shared resource pool. A legacy UE, such as exemplary UE 120d, refers to a UE of a previous release, i.e., a UE in Rel. 16 or Rel. 17 NR V2X. As used herein, non-legacy refers to a UE of a later release, such as Rel. 18, such as, for example, UEs 120a-120c shown in FIG. 1.

[0080] Data transmissions are allocated in units of subchannels. SL-PRS may span multiple PRBs (e.g., the entire resource pool) in the frequency domain and occupy multiple symbols in the time domain. Therefore, SL-PRS resources may not correspond to one or more subchannels. As a result, the resource granularity of data transmissions in the sidelink and SL-PRS may be different. The shared resource pool needs to support resource selection and scheduling for these two types of transmissions with different resource granularity.

[0081] In addition, it has been proposed to multiplex the SL-PRS with the PSSCH. However, UEs 120a-120c that want to transmit the SL-PRS may not necessarily need to transmit the PSSCH. In addition, the SL-PRS may need to span multiple sub-channels, while the PSSCH may not need to occupy as many sub-channels. Furthermore, the SL-PRS may not need to span all symbols in a slot.

[0082] The shared resource pool supports data transmission from the Rel. 16 / 17 / 18 Tx UE 120d to the Rel. 16 / 17 / 18 Rx UEs and from the Rel. 18 Tx UEs 120a-120c to the Rel. 18 Rx UEs 120a-120c. The Rel. 16 / 17 Rx UEs 120d do not need to receive SL-PRS, and backward compatibility in the shared resource pool is guaranteed for legacy Rx UEs 120d as long as these Rx UEs 120d can receive their intended data. Backward compatibility must be guaranteed for the 16 / 17 Tx UEs 120d in Scheme 1 (Mode 1) and Scheme 2 (Mode 2). In Mode 1, resources for data and SL-PRS can be configured by the network for the Rel. 16 / 17 Tx UE 120d and the Rel. 18 Tx UEs 120a-120c. To ensure backward compatibility, the Rel. 16 / 17 Tx UE 120d performing Mode 2 sensing needs to recognize SL-PRS resources reserved by the Rel. 18 Tx UEs 120a-120c without being able to identify that such resources are for SL-PRS. However, the Rel. 16 / 17 Tx UE 120d performing Mode 2 sensing can only recognize resource reservations at subchannel granularity. Meanwhile, the Rel. 18 Tx UEs 120a-120c performing Mode 2 sensing (to transmit SL-PRS) need to recognize SL-PRS resource reservations (made by other Rel. 18 Tx UEs 120a-120c) at SL-PRS resource granularity.

[0083] The use of a dedicated resource pool may be inefficient because resources dedicated for SL-PRS may not necessarily be used, while reducing the resources available for data transmission in the sidelink. A shared resource pool provides better resource utilization but may require backward compatibility. In addition, the shared resource pool needs to accommodate scheduling of transmissions with different resource granularity. Furthermore, multiplexing the SL-PRS in the PSSCH may impose that the PSSCH needs to be transmitted together with the SL-PRS and that the PSSCH spreads across more subchannels than necessary. Multiplexing the SL-PRS in the PSSCH may limit the design of the SL-PRS.

[0084] The embodiments disclosed herein provide a shared resource pool to support data transmission and SL-PRS transmission (i.e., Rel. 18 UEs 120a-120c), allowing for different granularity of resources for both types of transmission, e.g., in units of subchannels for data transmission and SL-PRS resources for SL-PRS. The design of the shared resource pool ensures backward compatibility for legacy UEs 120d, i.e., Rel. 16 and Rel. 17 UEs 120d. Data transmission in the shared resource pool can be performed by all UEs, i.e., Rel. 16 / 17 / 18 UEs 120a-120d. SL-PRS transmission can be performed by non-legacy UEs, i.e., Rel. 18 UEs 120a-120c.

[0085] As shown in FIG. 2, embodiments disclosed herein generally provide a scheme for two-phase allocation (also referred to as two-phase reservation) of one or more SL-PRS resources. A first-phase allocation 210a (also referred to as a first-phase reservation) allocates, i.e., reserves, a set of contiguous sub-channels that include one or more SL-PRS resources. A second-phase allocation 210b (also referred to as a second-phase reservation) allocates, i.e., reserves, one or more resources within the set of sub-channels for one or more SL-PRS resources. The allocation of time and frequency resources is also referred to as a reservation, and the terms "assignment" and "reservation" are used interchangeably herein.

[0086] More specifically, to transmit an assignment of time and frequency resources for transmission of one or more SL-PRSs, for example, UE 120a is configured to transmit the assignment using a two-stage assignment including a first-stage assignment 210a indicating one or more first time and frequency resources 220 of the plurality of time and frequency resources 200 having a first granularity and a second-stage assignment 210b indicating one or more second time and frequency resources 230 of the plurality of time and frequency resources 200 having a second granularity, where the one or more second time and frequency resources 230 are a subset of the one or more first time and frequency resources 220. As used herein, the one or more second time and frequency resources 230 being a subset of the one or more first time and frequency resources 220 includes cases where the one or more second time and frequency resources 230 include all of the one or more first time and frequency resources 220, i.e., the first and second time and frequency resources 220, 230 are identical.

[0087] Similarly, to receive an assignment of time and frequency resources for transmission of one or more SL-PRSs, for example, UE 120b is configured to receive the assignment using a two-stage assignment including a first-stage assignment 210a indicating one or more first time and frequency resources 220 of the plurality of time and frequency resources 200 having a first granularity, and a second-stage assignment 210b indicating one or more second time and frequency resources 230 of the plurality of time and frequency resources 200 having a second granularity. As already explained above, the one or more second time and frequency resources 230 are a subset of the one or more first time and frequency resources 220.

[0088] The advantage of the two-phase allocation is that it supports allocation of SL-PRS resources in a shared resource pool while allowing allocation of SL-PRS resources with a different granularity than the granularity of data transmission. The example shown in FIG. 2 illustrates a two-phase allocation for one SL-PRS resource per symbol. The SL-PRS resources within a set of sub-channels can span multiple symbols and can be spread across the set of sub-channels in a comb pattern or structure. The first-phase allocation 210a is intended for all UEs 120a-120d, i.e., UEs 120a-120d (legacy and non-legacy) that intend to transmit or receive data or SL-PRS, while the second-phase allocation 210b is intended for UEs 120a-120c (non-legacy) that intend to transmit or receive SL-PRS. The two-stage assignment may be transmitted by the Rel. 18 Tx UEs 120a-120c that wish to reserve SL-PRS resources for future transmissions of SL-PRS. In the first stage reservation 210a, the Rel. 18 Tx UEs 120a-120c indicate a reservation of the entire set of subchannels, while actually aiming to reserve only a portion of the resources in the set of subchannels, i.e., one or more resources in the set of subchannels for one or more SL-PRS resources. One or more SL-PRS resources are identified and reserved in the second stage reservation 210b. The second stage reservation 210b only needs to be received and interpreted by the Rel. 18 UEs 120a-120c, i.e., the Tx UEs 120a-120c performing Mode 2 sensing to transmit SL-PRS and / or the SL-PRS Rx UEs 120a-120c.

[0089] In one embodiment, the first-phase assignment 210a may be transmitted in a first-phase SCI carried in the PSCCH subchannel. The first-phase assignment 210a may be indicated using one of up to two assignments in the first-phase SCI used in legacy systems for allocating resources for TB retransmissions. This has the advantage of ensuring backward compatibility. In particular, an advantage of transmitting the first-phase assignment 210a in the first-phase SCI is that it can be interpreted by Mode 2 sensing UEs (Rel. 16 / 17 / 18) 120a-120d that intend to transmit data without requiring those UEs 120a-120d to understand that the assignment is for a reservation, i.e., an SL-PRS. For a Rel. 16 / 17 Tx UE 120d performing mode 2 sensing (i.e., transmitting data), the first-stage allocation 210a of SL-PRS resources is transparent, i.e., the UE 120d does not need to know that these resources are reserved for SL-PRS, regardless of whether all resources in the set of subchannels are actually allocated using the second-stage allocation 210b.

[0090] In one embodiment, the Rel. 18 Rx UEs 120a-120c may be configured to interpret an assignment conveyed in the first-stage SCI as a first-stage assignment 210a of SL-PRS resources if the assignment is for a given number of sub-channels, e.g., an assignment of all sub-channels in a resource pool in a future slot. In this case, the Rel. 18 UEs 120a-120c are permitted to assign a given number of contiguous sub-channels, e.g., all sub-channels in a RP, to allocate SL-PRS resources. Furthermore, the Rel. 18 Rx UEs 120a-120c may be configured to interpret an assignment conveyed in the first-stage SCI as a first-stage assignment 210a of SL-PRS resources if the assignment is for a given set of sub-channels (hereinafter referred to as semi-dedicated resources). In this case, the Rel. 18 UEs 120a-120c are permitted to allocate a given set of contiguous subchannels. The Rel. 18 Rx UEs 120a-120c may also be configured to interpret the allocation conveyed in the first-stage SCI as a first-stage allocation 210a of SL-PRS resources based on the presence of a second-stage allocation 210b of SL-PRS resources. Thus, according to one embodiment, only after the Rx UEs 120a-120c become aware of the presence of the second-stage allocation 210b can they know that the allocation in the first-stage SCI is a first-stage allocation 210a of SL-PRS resources. If the UEs 120a-120c determine that the allocation is a first-stage allocation 210a, they proceed to decode the second-stage allocation 210b to determine the assigned SL-PRS resources.

[0091] In one embodiment, the second-stage assignment 210b may be transmitted together with the first-stage assignment 210a. In particular, the second-stage assignment 210b may be transmitted in a subchannel that also carries the associated first-stage assignment 210a. This has the advantage that Rel. 18 UEs 120a-120c, i.e., UEs 120a-120c performing Mode 2 sensing to transmit SL-PRS and / or SL-PRS Rx UEs 120a-120c, only need to examine the first-stage and second-stage assignments 210a, 210b in one subchannel to determine one or more assigned SL-PRS resources. In particular, the second-stage assignment 210b may be transmitted in a second-stage SCI. The second-stage assignment 210b may also be transmitted in a PSSCH associated with the PSCCH that carries the first-stage assignment 210a. The presence of the second-stage assignment 210b in a subchannel may be indicated based on control information in the subchannel. In particular, the presence of the second-stage assignment 210b may be indicated by one of the reserved bits in the first-stage SCI. In addition, it may also be indicated using an indication in the second-stage SCI format associated with the SL-PRS. The second-stage SCI associated with the SL-PRS may carry the second-stage assignment 210b and may be transmitted in the same subchannel carrying the corresponding first-stage SCI. The second-stage SCI associated with the SL-PRS may also carry additional information associated with the SL-PRS.

[0092] In one embodiment, the first and second stage assignments 210a, 210b may be transmitted by the UEs 120a-120c on subchannels in slots earlier than the assigned set of subchannels, i.e., on subchannels of the earlier slots, which has the advantage that the UEs 120a-120c are aware of the assigned resources prior to transmitting the SL-PRS.

[0093] In one embodiment, the subchannel carrying the two-stage assignment may be used to transmit other pertinent information associated with or necessary for receiving the assigned SL-PRS transmission. This information may comprise the SL-PRS configuration and parameters for each SL-PRS resource, such as the type of sequence used for the SL-PRS (e.g., Zaduff-Chu sequence, Gold sequence, etc.), sequence identification information, sequence initialization, SL-PRS periodicity, resource repetition, comb size, staggering pattern, quasi-co-location information, parameters for power control of the SL-PRS transmission, etc. This pertinent information may be transmitted in the SCI (e.g., the second-stage SCI) or in the PSSCH within the subchannel carrying the two-stage assignment.

[0094] For Rel. 18 Tx UEs 120a-120c transmitting two-stage allocations, the subchannel resource allocation may follow the conventional resource allocation procedure, i.e., Mode 1 or Mode 2. Additionally, the resource allocation for SL-PRS may also be based on the Mode 1 and Mode 2 procedures adapted for SL-PRS, which are described in more detail below.

[0095] In one embodiment, the priority of the reserved SL-PRS resources may be transmitted in the SCI (eg, the second tier SCI) or in the PSSCH within the subchannel carrying the two-tier reservation.

[0096] In one embodiment, the first-stage and second-stage assignments 210a, 210b may be transmitted by the UEs 120a-120c within an assigned set of subchannels. This means that the first-stage and second-stage assignments are transmitted within semi-dedicated resources, including the SL-PRS resources indicated by the two-stage assignments. The first-stage and second-stage assignments are then transmitted in the same slot as the SL-PRS. This has the advantage that the UEs 120a-120c can receive the SL-PRS and the associated first- and second-stage assignments in the same slot. In addition, the source and destination IDs of the SL-PRS may also be transmitted within the assigned set of subchannels. Transmitting the SL-PRS with associated first-stage and second-stage assignments in the same slot, i.e., within the assigned subchannels, may be considered for the shared resource pool as well as for the dedicated resource pool.

[0097] In one embodiment, the set of sub-channels reserved by first-stage allocation 210a may correspond to semi-dedicated resources 260 for SL-PRS. As used herein, semi-dedicated resources 260 for SL-PRS may correspond to a pre-configured set of sub-channels in pre-configured slots in a resource pool, as shown in FIG. 3. Multiple SL-PRS resources may be pre-configured within semi-dedicated resources 260, as shown in FIG. 3. FIG. 3 shows an example of SL-PRS resources in one symbol. The SL-PRS resources within semi-dedicated resources 260 may span multiple symbols and may span a set of sub-channels in a comb pattern or structure. Multiple SL-PRS resources may be multiplexed within semi-dedicated resources 260. Multiple semi-dedicated resources 260 for SL-PRS may be pre-configured within a resource pool. An advantage of (pre-)configuring semi-dedicated resources 260 is that it allows Rel. 18 UEs 120a-120c to have a common understanding regarding SL-PRS resources. In particular, this allows UEs 120a-120c, i.e., Rel. 18 UEs, to know the set of subchannels on which SL-PRS may be transmitted, as well as the configuration of SL-PRS resources within the set of subchannels, i.e., within semi-dedicated resources 260 (i.e., the time / frequency allocation of SL-PRS resources). In particular, semi-dedicated resources 260 may be (pre-)configured within a shared resource pool. This has the advantage that subchannels within the semi-dedicated resources may be considered for SL-PRS in the shared resource pool.

[0098] In one embodiment, different numbers of subchannels may be (pre-)configured for different semi-dedicated resources 260, e.g., to support SL-PRS resources with different bandwidths, as shown in Figure 3. More specifically, the semi-dedicated resources 260 may include all subchannels in a slot of a resource pool, which has the advantage that the SL-PRS resources may occupy the entire bandwidth of the resource pool.

[0099] In one embodiment, the semi-dedicated resources 260 may be configured by the network 110, i.e., base station 110, for example, when the UEs 120a-120c are in network coverage or may be pre-configured for out-of-network coverage. Configuration by the network 110, i.e., base station 110, has the advantage that the configuration of the semi-dedicated resources 260 can be adapted by the network 110, i.e., base station 110, depending on, for example, traffic load and SL-PRS resource requirements. Pre-configuration has the advantage that the semi-dedicated resources 260 can be used in out-of-network coverage situations. In one embodiment, the semi-dedicated resources 260 may also be configured dynamically, i.e., among a group of UEs 120a-120c. This allows the UEs 120a-120c in the group to have a common understanding of the SL-PRS resources in the group.

[0100] In one embodiment, semi-dedicated resources 260 need to be configured (pre-configured) only for Rel. 18 UEs 120a-120c because only Rel. 18 UEs 120a-120c need to be aware of semi-dedicated resources 260 for SL-PRS. For Rel. 16 / 17 UE 120d, semi-dedicated resources 260 are transparent and correspond to regular subchannels like other subchannels in the resource pool. Allocation of SL-PRS resources can be performed based on Mode 1 or Mode 2. In Mode 1, network 110, i.e., base station 110, can allocate resources among semi-dedicated resources 26 for SL-PRS or for data transmission, for example, on demand. When resources are allocated for SL-PRS, network 110, i.e., base station 110, can indicate which SL-PRS resources can be used by a given Tx UE 120a-120c. In Mode 2, Rel. 16 / 17 Tx UE 120d can use a subchannel in semi-dedicated resources 260 if it senses it is free. In Mode 2, Rel. 18 Tx UEs 120a-120c can use SL-PRS in semi-dedicated resources 260 if it senses it is free. Due to the two-stage reservation of SL-PRS resources, the Mode 2 sensing procedure for finding SL-PRS resources can be enhanced to support SL-PRS resource selection, as described in more detail below in the context of a different, more detailed embodiment.

[0101] The reservation, i.e., allocation, of SL-PRS resources within the semi-dedicated resources 260 is indicated using a two-stage reservation transmitted in a subchannel transmitted in a slot prior to the slot having the semi-dedicated resources 260. For the embodiments disclosed herein, there is no need to transmit SCI or other related information required to receive the SL-PRS within the semi-dedicated resources 260. The information required to receive the SL-PRS can be transmitted in a subchannel carrying the corresponding two-stage reservation. An advantage of not having SCI or other information related to the SL-PRS within the semi-dedicated resources 260 is that all resources within the semi-dedicated resources 260 can be used for SL-PRS resources. If the semi-dedicated resources 260 span all subchannels in a slot of a resource pool, the entire slot can be used for SL-PRS resources, e.g., 12 SL-PRS resources plus automatic gain control (AGC) symbols and guard symbols. If an SCI or other information related to the SL-PRS is multiplexed with the SL-PRS in non-overlapping resources among the semi-dedicated resources 260, i.e., in a first-stage SCI carried on the PSCCH among the semi-dedicated resources 260, this may lead to a reduction in resources for the SL-PRS, e.g., a smaller number of SL-PRS resources among the semi-dedicated resources 260. In addition, if an SCI or other information related to the SL-PRS is multiplexed with the SL-PRS in overlapping resources among the semi-dedicated resources 260, this may affect positioning estimation using the SL-PRS. In this regard, multiplexing the second-stage SCI with the SL-PRS resources, i.e., among the semi-dedicated resources 260, may be undesirable. However, in the embodiments disclosed herein, the SCI associated with the SL-PRS may be transmitted in the semi-dedicated resources 260, e.g., at the expense of reduced resources available for the SL-PRS. The SCI may be transmitted on the PSCCH.This can be thought of as having the SCI transmitted along with the SL-PRS transmission in the same slot, similar to how the SCI is transmitted along with the data transmission in one or more subchannels.

[0102] Multiple first-phase assignments, i.e., reservations, may also be transmitted to indicate allocation of multiple semi-dedicated resources 260. Two first-phase assignments 210a, 210a' may be indicated using two assignments in the first-phase SCI, which may be used in legacy systems to allocate resources for two retransmissions of a TB. Multiple first-phase assignments may also be indicated by assigning a period to the multiple semi-dedicated resources 260. Multiple first-phase assignments 210a, 210a' of multiple semi-dedicated resources 260 with a period may be indicated using an RRI transmitted in the first-phase SCI carried in the PSCCH, which is used in legacy systems to indicate periodic reserved resources for future TB transmissions. Furthermore, the second-phase assignment 210b may also indicate multiple SL-PRS resources in different reserved semi-dedicated resources 260. An example of a two-phase assignment for multiple semi-dedicated resources is shown in FIG. 4. For each first-stage assignment 210a, 210a', the second-stage assignment 210b, 210b' may or may not be the same. For example, for reserved semi-dedicated resources 260 with a certain duration, the second-stage assignments 210b, 210b' may be the same. That is, the reserved SL-PRS resources within the semi-dedicated resources 260 are the same (see the example of FIG. 4). For each first-stage assignment 210a, 210a', there may be a second-stage assignment 210b, 210b'. That is, when the reserved semi-dedicated resources 260 span different numbers of subchannels, different second-stage assignments 210b, 210b' may be needed to indicate the different reserved SL-PRS resources in each semi-dedicated resource 260.

[0103] If multiple Rel. 18 Tx UEs 120a-120c are assigned, i.e., reserve, different SL-PRS resources among the semi-dedicated resources 260, the Rel. 18 Tx UEs 120a-120c may transmit first-stage assignments 210a, 210a' for the same semi-dedicated resources 260, as shown in Figure 5. More specifically, as shown in Figure 5, the first and second stage assignments 210a, 210b of a first two-stage assignment may assign first and second resources 220, 230, while the first and second stage assignments 210a', 210b' of a further two-stage assignment may assign first and second resources 220', 230'. Because multiple assignments for the same set of sub-channels may be transmitted, this increases the likelihood that the semi-dedicated resources 260 will be used for SL-PRS transmissions and not for data transmissions. If one or more sub-channels in the semi-dedicated resources 260 are assigned by another UE 120b, 120c, the Rel. 18 Tx UE 120a may preempt one or more sub-channels with one or more SL-PRS assignments in the semi-dedicated resources 260. In this case, the priority of the SL-PRS transmissions may be configured (in advance) to be higher than the data transmissions of other UEs to enable the preemption mechanism, as detailed in the embodiments.

[0104] The set of subchannels is referred to as semi-dedicated resources because they can be used for both data transmission and SL-PRS transmission. That is, they are not fully dedicated to SL-PRS. However, the embodiments disclosed herein enable the use of these resources for SL-PRS transmission. Additionally, the embodiments disclosed herein enable UEs 120a-120c to have a common understanding of the SL-PRS resources within the semi-dedicated resources.

[0105] Furthermore, in accordance with embodiments disclosed herein, the source ID and destination ID of an SL-PRS transmission may be transmitted in the same subchannel carrying the first and second phase assignments 210a, 210b, as illustrated in FIG. 6a. More specifically, the source ID / destination ID may be carried in the second phase SCI in the subchannel carrying the two-phase assignment. The source ID is the identifier of the UE transmitting the transmission, i.e., the SL-PRS transmission. The destination ID is the identifier of the UE that is the intended recipient of the transmission, i.e., the SL-PRS transmission. The destination ID is examined by the Rel. 18 Rx UEs 120a-120c to determine whether they are the target recipients of the assigned SL-PRS resources to be transmitted in the semi-dedicated resources 260. Transmitting the source ID and destination ID in the subchannel in which the two-stage assignment is transmitted allows the Rel. 18 Rx UE 120a-120c to know in advance whether it is the target Rx UE for the SL-PRS in the semi-dedicated resource 260.

[0106] In the case of multiple first-phase and second-phase assignments, a destination ID and a source ID may be provided for each first-phase and second-phase assignment. In the case of multiple first-phase and second-phase assignments, the destination ID and the source ID may be the same. Additionally, the UE 120a-120c sending the two-phase assignment for SL-PRS resources may or may not be the same UE 120a-120c sending the SL-PRS resources. Thus, the destination ID may be an identifier of a UE 120a-120c different from the UE 120a-120c sending the two-phase assignment. This has the advantage that a UE 120a-120c can send a reservation for SL-PRS resources to be sent by another UE 120a-120c.

[0107] A variation of the embodiment shown in FIG. 6a is illustrated in FIG. 6b. Here, a first UE 120a sends a two-stage reservation for SL-PRS resources to be transmitted by a second UE 120b and a third UE 120c. More specifically, with the two-stage allocation shown in FIG. 6b, the first UE 120a reserves a second resource 230′ for the second UE 120b and a second resource 230″ for the third UE 120c. In this embodiment, the UEs 120a-120c may be part of a group of UEs. The first UE 120a is the group leader and may obtain resources for the SL-PRS transmissions of the UEs 120a-120c in the group.

[0108] As already explained above, the UEs 120a-120c disclosed herein may include, among other things, handheld terminal devices and in-vehicle devices that can communicate with each other in the SL of the wireless communication network 100 and transmit and receive reference signals in the sidelink for positioning purposes. Furthermore, as already explained above, one objective of the present disclosure is to enable sharing of resources in a resource pool for data transmissions and SL-PRS transmissions with different granularity.

[0109] 7a and involves the (pre-)configuration of UEs 120a-120c for semi-dedicated SL-PRS resources 260 and for the transmission of a two-stage assignment of the SL-PRS resources. The configuration may be provided by the network 110, i.e., base station 110, by another UE 120a-120c, or may be pre-configured in the UE 120a-120c. The (pre-)configuration of the semi-dedicated resources 260 may include the (pre-)configuration and indication of the slot in the resource pool with the semi-dedicated resources 260, as well as the frequency resource location, i.e., the starting subchannel index and the number of consecutive subchannels, for each of the semi-dedicated resources 260. In addition, the (pre-)configuration may include the periodicity of the semi-dedicated resources 260. Additionally, the (pre-)configuration may comprise the (pre-)configuration of SL-PRS resources within each subchannel, i.e., how many SL-PRS resources exist within each semi-dedicated resource 260, as well as the time and frequency allocation of each SL-PRS resource within the semi-dedicated resource 260. The (pre-)configuration may also include SL-PRS parameters for each SL-PRS resource, such as the type of sequence used for SL-PRS (e.g., Zaduff-Chu sequence, Gold sequence, etc.), sequence identification information, parameters for sequence initialization, SL-PRS periodicity, resource repetition, comb size, staggering pattern, quasi-co-location information, parameters for power control of SL-PRS transmissions, etc. The (pre-)configuration of semi-dedicated resources enables UEs 120a-120c, i.e., Rel. 18 UEs, to have a common understanding of SL-PRS resources in a shared resource pool. In particular, the (pre-)configuration of the semi-dedicated resources 260 enables the UEs 120a-120c to know the resources on which they can transmit the SL-PRS. The (pre-)configured semi-dedicated resources 260 may consist of all subchannels in a slot in a resource pool. In particular, all (pre-)configured semi-dedicated resources 260 may each span all subchannels of the resource pool.

[0110] 7a further illustrates a (pre)configuration for transmission of a two-stage assignment. This (pre)configuration indicates how to transmit first-stage 210a and second-stage 210b assignments of SL-PRS resources to UE 120-c. The (pre)configuration of the two-stage assignment may comprise an indication 240 of where and how first-stage 210a and second-stage 210b assignments should be transmitted, i.e., their locations within the subchannels. The (pre)configuration may indicate that UE 120a-120c transmits first-stage assignment 210a in a first-stage SCI carried in the PSCCH. The (pre)configuration may include an indication 240 that UE 120a-120c reserving SL-PRS resources can only transmit first-stage assignment 210a in one or more semi-dedicated resources 260. The (pre-)configuration may comprise an indication 240 that a UE 120a-120c allocating SL-PRS resources indicates the presence of a second-phase assignment 210b of SL-PRS resources using one of the reserved bits in the first phase SCI. The (pre-)configuration may comprise an indication 240 that a UE 120a-120c allocating SL-PRS resources indicates the presence of a second-phase assignment 210b of SL-PRS resources using an indication in the first phase SCI of a second phase SCI format associated with the SL-PRS. The (pre-)configuration may indicate that a UE 120a-120c transmits the second-phase assignment in the second phase SCI. The second phase SCI may be associated with the first phase SCI carrying the first-phase assignment 210a. The (pre-)configuration may indicate that the UEs 120a-120c transmit the first and second stage assignments 210a, 210b together in one subchannel. Based on the (pre-)configuration for transmission of the two-stage assignments, the UEs 120a-120c then know how to transmit the two-stage assignments for the SL-PRS resources.

[0111] The second main embodiment is shown in FIG. 7b and involves the (pre)configuration of the UEs 120a-120c for semi-dedicated resources 260 and for receiving a two-phase allocation of SL-PRS resources. The configuration can be provided by the network 110 or pre-configured in the UEs 120a-120c. The (pre)configuration of the semi-dedicated resources 260 corresponds to the (pre)configuration of the semi-dedicated resources 260 described above in the context of the first main embodiment. The (pre)configuration of the semi-dedicated resources 260 enables the UEs 120a-120c to have a common understanding of the SL-PRS resources in a shared resource pool. In particular, the (pre)configuration of the semi-dedicated resources 260 enables the UEs 120a-120c to know on which resources they can receive SL-PRS.

[0112] 7b further illustrates a (pre)configuration for receiving two-phase assignments. This (pre)configuration indicates to the UEs 120a-120c where to find and how to determine the first-phase 210a and second-phase 210b assignments of SL-PRS resources, i.e., their locations within a subchannel. The (pre)configuration may indicate that the first-phase 210a and second-phase 210b assignments are transmitted together, for example, in one subchannel. The (pre)configuration may indicate that the first-phase assignment 210a may be located in a first-phase SCI carried in the PSCCH. The (pre)configuration may indicate that one or more semi-dedicated resource 260 assignments correspond to the first-phase SL-PRS assignment 210a. The (pre-)configuration may comprise an indication that UEs 120a-120c interpret a resource assignment in the first-phase SCI as a first-phase assignment of SL-PRS resources 210a based on the presence of second-phase assignment of SL-PRS resources 210b. The (pre-)configuration may indicate that the presence of second-phase assignment of SL-PRS resources 210b may be indicated using one of the reserved bits in the first-phase SCI or using an indication in the first-phase SCI of a second-phase SCI format associated with the SL-PRS. The (pre-)configuration may also indicate that the presence of second-phase assignment 210b may be indicated in an assignment in the first-phase SCI of a given number of subchannels or in an assignment in the first-phase SCI of semi-dedicated resources 260. In this case, in one embodiment, only Rel. 18 UEs 120a-120c may be configured to be allowed to allocate a given number of contiguous subchannels, e.g., all subchannels in a RP, for SL-PRS resource allocation. Legacy UE 120d may then be configured not to allocate more than the given number of subchannels for data transmission. The (pre)configuration may also indicate that second-phase assignment 210b is located in a second-phase SCI. In particular, the second-phase SCI may be associated with the first-phase SCI carrying first-phase assignment 210a.Based on the (pre)configuration for receiving the two-stage allocation, the UEs 120a-120c then know how to receive the two-stage allocation for SL-PRS resources, and therefore know where to receive the SL-PRS.

[0113] A third main embodiment is shown in FIG. 8 for a network coverage scenario, in which the base station or gNB 110 provides the UEs 120a-120d with configurations of semi-dedicated resources 260 for SL-PRS and two-stage allocation. In one embodiment, both configurations are provided to the Rel. 18 UEs 120a-120c, i.e., the legacy UE 120d is unaware of the configuration related to SL-PRS. This means that the configurations may be release-specific. In FIG. 8, it is assumed that the first UE 120a (UE1) and the second UE 120b (UE2) are Rel. 18 UEs. The configurations of semi-dedicated resources 260 for SL-PRS and for two-stage allocation may be included in information elements signaled by the network to the UEs 120a, 120b that specify configuration information for a resource pool (e.g., SL-ResourcePool).

[0114] When the gNB 110 configures a resource pool for sidelink communications, i.e., for data transmissions on the sidelink, the gNB 110 may also configure a resource pool for SL-PRS transmissions. The resource pool becomes a shared pool for sidelink communications and SL-PRS transmissions. The configuration of a resource pool as a shared resource pool may be performed only for the Rel. 18 UEs 120a-120c. The configuration of a resource pool as a shared resource pool may correspond to the configuration of semi-dedicated resources 260 for SL-PRS and / or two-stage allocation. Thus, the Rel. 18 UEs 120a-120c recognize that the resource pool is a shared resource pool when given the configuration of semi-dedicated resources 260 for SL-PRS and / or two-stage allocation. The configuration of semi-dedicated resources 260 for SL-PRS and two-stage allocation may be provided to the Rel. 18 UEs 120a-120c. The subsequent gNB 110 may then provide additional configuration to configure the resource pool to be a shared resource pool. The legacy UE 120d is unaware of the shared resource pool.

[0115] As shown in step 801 of FIG. 8 , the gNB 110 provides a configuration of semi-dedicated resources 260 to Rel. 18 UEs, e.g., the first UE 120a and the second UE 120b (step 801 of FIG. 8 ). This configuration includes the configuration and indication of semi-dedicated resources 260 as described above in the context of the first main embodiment above. The configuration of semi-dedicated resources 260 provided to the UEs 120a-120c enables the UEs 120a-120c to have a common understanding of the SL-PRS resources in the shared resource pool. In particular, the configuration of semi-dedicated resources 260 enables the Tx UE, e.g., UE 120a, to know the resources on which it can transmit SL-PRS, and enables the Rx UE, e.g., UE 120b, to know the resources on which it can receive SL-PRS.

[0116] Additionally, the gNB 110 provides a two-phase allocation configuration to the Rel. 18 UEs 120a-120c (step 803 of FIG. 8 ). This configuration includes configurations for transmitting and receiving the two-phase allocations. This configuration indicates where and how to transmit the first-phase and second-phase allocations 210a, 210b of SL-PRS resources, i.e., subchannels, to a Tx UE, e.g., UE 120a, and where and how to find and determine the first-phase and second-phase allocations 210a, b of SL-PRS resources to an Rx UE, e.g., UE 120b. The two-phase allocation configuration corresponds to the two-phase allocation configurations for transmission and reception described above in the context of the first and second main embodiments, respectively. In particular, only Rel. 18 UEs 120a-120c are allowed to reserve a given number of consecutive subchannels, e.g., all subchannels in a RP, to reserve SL-PRS resources. Legacy UEs 120d may be configured to reserve a given number of subchannels minus one. That is, legacy UEs 120d are not permitted to reserve a given number of subchannels for transmission. Rel. 18 UEs 120a-120c may also be configured to interpret a reservation of a given number of subchannels as a first-stage reservation 210a of SL-PRS and then search for second-stage reservations 210b within the same subchannels to determine reserved SL-PRS resources within the reserved given number of subchannels.

[0117] 8, it is assumed that UEs 120a, 120b are configured to transmit / receive first stage reservations 210a and 210b in first and second stage SCIs, respectively. UEs 120a, 120b are also configured such that the presence of second stage reservations 210b is indicated using an indication in the second stage SCI format associated with an SL-PRS. Based on the presence of the second stage SCI associated with an SL-PRS, UEs 120a, 120b recognize that the reservation conveyed in the first stage SCI corresponds to first stage reservation 210a of SL-PRS resources.

[0118] Due to the availability of network coverage, resource selection of SL-PRS resources may be performed using Mode 1 resource allocation. Resource selection can also be performed using Mode 2 resource allocation when in network coverage. In the embodiment shown in FIG. 8, SL-PRS resources are selected based on Mode 1 resource allocation. In this case, the first UE 120a requests resources from the gNB 110 for SL-PRS transmission (step 805 of FIG. 8). The first UE 120a may also obtain resources based on autonomous resource selection, e.g., in Mode 2. The first UE 120a may also provide further relevant information that enables the gNB 110 to determine appropriate resources for the SL-PRS, i.e., positioning requirements, bandwidth requirements of the SL-PRS, etc. The gNB 110 provides the first UE 120a with a configuration of resources (i.e., one subchannel) on which the first UE 120a will transmit its two-stage reservation (step 807 of FIG. 8). This configuration may comprise a time and frequency allocation of resources. The gNB 110 provides resources for the SL-PRS to the first UE 120a (step 809 of FIG. 8), indicating which SL-PRS resources on which semi-dedicated resources 260 the first UE 120a should use for its SL-PRS transmissions.

[0119] After the gNB 110 provides the configuration of resources for the two-stage reservation and the associated SL-PRS, the first UE 120a transmits the first and second stage reservations 210a, 210b, i.e., together, on the configured resources (steps 811 and 813 of FIG. 8). More specifically, the first UE 120a transmits the first stage reservation 210a in a first stage SCI and the second stage reservation 210b in an associated second stage SCI, where the format of the second stage SCI is associated with the SL-PRS. In the second stage SCI carried in the resources, the first UE 120a may also transmit the source ID and destination ID of the SL-PRS in the second stage SCI (step 815 of FIG. 8). The second UE 120b receives the two-stage reservation and the source ID and destination ID of the SL-PRS. The second UE 102b is configured to interpret the two-stage reservation of SL-PRS based on the configuration provided by the gNB 110. The second UE 120b is also aware of the SL-PRS resources in the semi-dedicated resources 260, where it receives the SL-PRS. The first UE 120a then transmits the SL-PRS on the configured SL-PRS resources (step 817 of FIG. 8). The second UE 120b receives the SL-PRS transmitted by the first UE 120a. Another UE 120c may be configured to transmit the SL-PRS on other SL-PRS resources in the semi-dedicated resources from which the first UE 120a transmits the SL-PRS.

[0120] Figure 9 shows a flowchart illustrating a fourth main embodiment based on Mode 2 resource allocation for SL-PRS resources. More specifically, Figure 9 illustrates the steps for selection of SL-PRS resources based on a Mode 2 sensing procedure with two-stage reservation. The complete procedure is provided only for Rel. 18 UEs 120a-120c, since legacy UE 120d does not recognize SL-PRS in the resource pool.

[0121] The UEs 120a-120c first search for a PSCCH (step 901 in FIG. 9). Similar to legacy Mode 2 sensing, i.e., Mode 2 sensing in Rel. 16 and Rel. 17, the UEs 120a-120c may search for a PSCCH at all potential positions of the PSCCH in each subchannel within a slot of a resource pool, e.g., within a slot of a sensing window. The presence of a PSCCH may be detected based on the PSCCH DMRS. If a PSCCH is found (step 903 in FIG. 9), the UEs 120a-120c decode the first-stage SCI carried by the PSCCH and determine the resource reservation indicated by the first-stage SCI (step 905 in FIG. 9). The UEs 120a-120c then need to determine whether the indicated resource reservation is for a data transmission or an SL-PRS transmission. The UEs 120a-120c check whether the resource reservation indicated by the first phase SCI corresponds to a first phase reservation 210a of SL-PRS resources (step 907 of FIG. 9). This may be determined in different ways. The UEs 120a-120c may determine that a resource reservation of a given number of sub-channels corresponds to a first phase reservation 210a of SL-PRS resources. The UEs 120a-120c may also determine that a resource reservation of semi-dedicated resources 260 corresponds to a first phase reservation 210a of SL-PRS. The UEs 120a-120c may also determine that a resource reservation is a first phase reservation 210a based on the presence of a second phase reservation 210b. The presence of a second phase reservation 210b may be indicated using one of the reserved bits in the first phase SCI or using an indication in the second phase SCI format associated with the SL-PRS.

[0122] When the UE 120a-120c detects the first stage reservation 210a of SL-PRS resources, it proceeds to decode the second stage reservation 210b of SL-PRS resources (step 913 of FIG. 9). Based on (pre-)configuration, the UE 120a-120c knows where and how to find the second stage reservation 210b. The second stage reservation 210b may be carried in the same subchannel that carries the first stage reservation 210a. In particular, the second stage reservation 210b may be carried in a second stage SCI associated with the first stage SCI. After decoding the second stage reservation 210b, the UE 120a-120c determines the reserved SL-PRS resources (step 915 of FIG. 9).

[0123] If the resource reservation indicated by the first-stage SCI does not correspond to first-stage reservation 210a, UE 120a-120c then checks whether the resource reservation indicates a reservation of a subchannel within semi-dedicated resources 260 for SL-PRS (step 909 of FIG. 9). The resource reservation may also be based on the periodicity of the reserved resources, i.e., based on the RRI. In this manner, UE 120a-120c may determine the reserved subchannel within the semi-dedicated resources.

[0124] Based on the resource reservation in semi-dedicated resources 260, i.e., of the SL-PRS resources or of the subchannels within the semi-dedicated resources, UE 120a-120c may then perform resource selection for the SL-PRS resources (step 911 in FIG. 9 ). To this end, it may perform resource exclusion based on the resource reservation in semi-dedicated resources 260.

[0125] FIG. 10 illustrates a mode 2 sensing procedure in UEs 120a-120c, i.e., for selecting resources for SL-PRS for Rel. 18 UEs. As shown in step 1001 of FIG. 10, UEs 120a-120c may determine subchannel reservations within the semi-dedicated resources, for example, based on the procedures previously described in the context of the fourth main embodiment. The reserved subchannels may be indicated in a first-stage SCI carried in a PSCCH received by UEs 120a-120c. UEs 120a-120c also determine RSRPs associated with the reserved subchannels. The RSRPs may be measured based on the DMRS in the PSCCH carrying the first-stage SCI indicating the reserved subchannels. This RSRP should be considered for resource exclusion in the mode 2 sensing procedure. The UEs 120a-120c are (pre)configured to measure RSRP associated with resource reservations based on the PSCCH DMRS of the PSCCH, which carries a first-stage SCI indicating resource reservation. In particular, the (pre)configuration to measure RSRP based on the PSCCH DMRS for resource selection may be part of the (pre)configuration of the resource pool. In this case, all UEs 120a-120c using the resource pool may measure RSRP associated with resource reservations based on the PSCCH DMRS of the corresponding PSCCH. The (pre)configuration may be indicated using a higher layer parameter, i.e., sl-RS-ForSensing. The (pre)configuration may be indicated in the (pre)configuration of the SL-ResourcePool information element, i.e., by setting the parameter sl-RS-ForSensing-r16 to pscch. Additionally, the UEs 120a-120c may determine a priority associated with transmissions on reserved subchannels. The priority may be indicated in the first-stage SCI indicating resource reservation for the subchannel.

[0126] As shown in step 1003 of FIG. 10 , the UEs 120a-120c may determine a reservation for SL-PRS resources based on, for example, the procedure previously described in the context of the fourth main embodiment. The reserved SL-PRS resources may be determined using a two-stage reservation, i.e., a first-stage reservation 210a conveyed in the first-stage SCI and a second-stage reservation 210b conveyed in the second-stage SCI. The UEs 120a-120c may also determine an RSRP associated with the reserved SL-PRS resources. The RSRP associated with the reserved SL-PRS resources may be measured based on the SL-PRS transmitted in the reserved SL-PRS resources. This may be considered when the UE transmitting the SL-PRS is different from the UE transmitting the two-stage reservation. The RSRP may also be measured based on the DMRS in the PSCCH, which carries the first-stage SCI indicating the first-stage reservation 210a. This may be considered when the UE transmitting the SL-PRS is the same UE transmitting the two-stage reservation. RSRP is considered for resource exclusion in the Mode 2 sensing procedure. UEs 120a-120c may be (pre)configured to measure RSRP associated with first-stage reservation 210a of SL-PRS resources based on the PSCCH DMRS of the PSCCH carrying a first-stage SCI indicating first-stage reservation 210a. In particular, the (pre)configuration to measure RSRP based on the PSCCH DMRS for resource selection may be part of a resource pool (pre)configuration for UEs 120a-120c in Rel. 18. The (pre)configuration may be indicated using higher layer parameters. It may be indicated in a (pre)configuration of an SL-ResourcePool information element. Additionally, UEs 120a-120c may determine a priority associated with the reserved SL-PRS resources. The priority may be indicated in the first-stage SCI or in a second-stage SCI associated with the first-stage SCI carrying first-stage reservation 210a.

[0127] As described in step 1005 of FIG. 10 , UE 120a-120c then performs resource selection for SL-PRS resources based on the reserved sub-channels in semi-dedicated resources 260, the RSRPs associated with the reserved sub-channels, the priorities associated with transmissions on the reserved sub-channels, the reserved SL-PRS resources, the RSRPs associated with the reserved SL-PRS resources, and, optionally, the priorities associated with the reserved SL-PRS resources. UE 120a-120c first determines candidate SL-PRS resources. To determine the candidate resources, UE 120a-120c may exclude resources based on the reserved resources in semi-dedicated resources 260 and the reserved resources' associated RSRPs and priorities. For example, if more than X sub-channels are reserved in semi-dedicated resources 260, UE 120a-120c may exclude all SL-PRS resources in semi-dedicated resources 260. For resource exclusion, UEs 120a-120c may be configured (in advance) to exclude resources based on the associated RSRP and priority of the reserved subchannels. For example, if more than X subchannels are reserved among semi-dedicated resources 260 with an RSRP above RSRP threshold RSRP1, UEs 120a-120c may then exclude all SL-PRS resources among semi-dedicated resources 260. Furthermore, if more than X subchannels are reserved among semi-dedicated resources 260 with a higher priority than the priority of the SL-PRS on which UEs 120a-120c wish to transmit, UEs 120a-120c may then exclude all SL-PRS resources among semi-dedicated resources 260. The exclusion of semi-dedicated resources 260 may be based on both the condition for the associated RSRP and the priority of the reserved resources.

[0128] The UEs 120a-120c may also exclude SL-PRS resources based on reserved SL-PRS resources. That is, if an SL-PRS resource in semi-dedicated resources 260 is reserved, the UEs 120a-120c exclude this SL-PRS resource. For resource exclusion, the UEs 120a-120c may consider the RSRP and priority of the reserved SL-PRS resource. For example, the UEs 120a-120c may exclude an SL-PRS resource in semi-dedicated resources 260 if it has an associated RSRP that exceeds the RSRP threshold RSRP2. Furthermore, the UEs 120a-120c may exclude an SL-PRS resource in semi-dedicated resources 260 if it has an associated priority that exceeds the priority of the SL-PRS that the UEs 120a-120c wish to transmit. The exclusion of a semi-SL-PRS resource may be based on both the condition for the associated RSRP and the priority of the reserved SL-PRS resource.

[0129] The UEs 120a-120c may also exclude resources based on half-duplex constraints similar to the legacy Mode 2 sensing procedure. The SL-PRS resources remaining after resource exclusion, i.e., within the selection window, are considered candidate SL-PRS resources. The UEs 120a-120c may then select SL-PRS resources from among the candidate SL-PRS resources. For example, they may select randomly. If the percentage of candidate resources that are semi-dedicated falls below a (pre-)configured threshold, the UEs 120a-120c may increase the RSRP threshold used to exclude resources by a given amount, for example, 3 dB, and repeat the procedure for resource exclusion. The values ​​of X, RSRP1, and RSRP2 may be (pre-)configured for the UE, as shown in FIG. 10.

[0130] FIG. 11 shows a flowchart illustrating another embodiment. Here, only SL-PRS resource reservation is considered for resource selection using Mode 2. That is, resources are excluded based on reserved SL-PRS resources, but not based on reserved subchannels in dedicated resources. The following description of steps 1101 and 1103 in FIG. 11 is similar to that of the previous embodiment, but does not consider reserved subchannels in semi-dedicated resources. In the embodiment shown in FIG. 11, Rel. 18 UEs 120a-120c may reserve resources for SL-PRS in semi-dedicated resources 260 even if one or more subchannels in semi-dedicated resources 260 are reserved by another UE 120a-120d for data transmission. Rel. 18 UEs 120a-120c may ignore reservations of subchannels (i.e., for data transmission) in semi-dedicated resources 260. Rel. 18 UEs 120a-120c may not be aware of reservations of subchannels in semi-dedicated resources 260. If one or more subchannels are reserved in the semi-dedicated resources 260, and the Rel.18 UEs 120a-120c wish to transmit SL-PRS resources there, this may lead to a collision, i.e., a collision between the SL-PRS transmission of the Rel.18 UEs 120a-120c and the data transmission of the other UEs 120a-120d. To avoid this, a preemption mechanism may be considered, where the SL-PRS transmission is prioritized over the data transmission. For this purpose, the priority of the SL-PRS is configured (pre-) to be higher than the priority of the data transmission, i.e., of a different traffic type. For this purpose, a preemption mechanism may be enabled in the resource pool. Preemption in the resource pool may be enabled using a parameter, e.g., sl-PreemptionEnable-r16, in an information element, i.e., the SL-ResourcePool information element, that provides the (pre-)configuration of the resource pool.

[0131] Furthermore, a legacy UE 120d intending to transmit data may be configured (in advance) to check whether another UE 120a-120d has reserved the same subchannel for a transmission with a higher priority before transmitting. That is, a preemption mechanism is enabled. The preemption mechanism may be enabled to avoid collisions because the UE 120a-120d drops its reservation of a subchannel in the semi-dedicated resources if it receives a reservation for the semi-dedicated resources (from a Rel. 18 UE 120a-120c wishing to transmit SL-PRS) for a transmission with a higher priority than the UE 120a-120d's intended transmission.

[0132] Moreover, the Rel. 18 UEs 120a-120c intending to transmit data may be (pre)configured during resource selection in Mode 2 to exclude all resources from the semi-dedicated resources 260. The Rel. 18 UEs 120a-120c may be aware of the semi-dedicated resources 260. In this way, the Rel. 18 UEs 120a-120c do not select subchannels in the semi-dedicated resources 260 for data transmission.

[0133] FIG. 12 shows a flowchart illustrating the processing steps of a further embodiment considering resource selection for SL-PRS and for resources carrying two-stage reservations. After a UE 120a-120c is triggered to transmit an SL-PRS, for example, by its own higher layers or by another UE 120a-120c, the UE 120a-120c selects SL-PRS resources (step 1201 of FIG. 12). Resource selection of the SL-PRS resources may be performed using Mode 1 resource allocation or Mode 2 resource allocation. The UE 120a-120c also selects resources for transmitting two-stage reservations (step 1203 of FIG. 12). The resources for transmitting two-stage reservations may consist of one subchannel. Resource selection of this resource may be performed using Mode 1 resource allocation or Mode 2 resource allocation. After selecting the SL-PRS resources and the resources that will carry the two-stage reservation, the UEs 120a-120c transmit the two-stage reservation on the selected resources and the SL-PRS on the selected SL-PRS resources (step 1205 of FIG. 12). The UEs 120a-120c may transmit the two-stage reservation with a higher transmit power compared to the transmit power of the data transmission, i.e., the PSSCH. In this exemplary embodiment, the UEs 120a-120c transmitting the two-stage reservation of the SL-PRS resources may be the same UEs 120a-120c that transmit the SL-PRS resources (step 1207 of FIG. 12). However, as already mentioned above, this may not be the case in general.

[0134] FIG. 13 illustrates a further embodiment of transmitting a two-stage reservation in a selected subchannel. The first-stage reservation for SL-PRS is transmitted in a first-stage SCI carried on the PSCCH in the selected subchannel. In Rel. 16 / 17 NR V2X, the first-stage SCI may indicate a reservation for the initial transmission of the TB (i.e., the current transmission) and one or two subsequent resources, for example, for retransmissions of the TB. The reservation includes an indication of the frequency resource location (i.e., the starting subchannel index and the number of subchannels occupied by the transmission) and the time resource location (i.e., the time slot) of the transmission. In accordance with embodiments disclosed herein, a two-stage reservation for SL-PRS resources may be transmitted in one subchannel. The first-stage reservation 210a is transmitted in a first-stage SCI carried by the PSCCH transmitted in the subchannel, as shown in FIG. 13. The first-stage reservation 210a indicates a reservation of semi-dedicated resources 260, which in this example occupies all subchannels in the resource pool. Because a two-stage reservation transmission occupies one subchannel, the reservation for the current transmission (i.e., initial transmission) of the two-stage reservation only needs to indicate that one subchannel is occupied. Meanwhile, the first-stage reservation 210a reserves all subchannels in the semi-dedicated resource pool, i.e., all subchannels in the resource pool, for the transmission of the SL-PRS. In Rel. 16 / 17 NR V2X, it is assumed that the number of subchannels occupied by the initial transmission and the retransmission are the same, i.e., the resource reservation for the initial transmission and the resource reservation for the retransmission reserve the same number of consecutive subchannels. However, the two-stage reservation transmission does not need to occupy the same number of subchannels as the reserved semi-dedicated resources. The first-stage reservation 210a can be indicated using the resource reservation carried by the first-stage SCI, which is usually used to indicate resource reservation for retransmissions. This means that the current transmission of the two-stage reservation also occupies the same number of channels as the reserved semi-dedicated resources.To this end, in accordance with embodiments disclosed herein, Rel. 18 UEs 120a-120c are (pre)configured to ignore the larger implicit reservation for a two-stage reservation transmission. After UE 120a-120c determines that a first-stage reservation 210a exists (i.e., detects the presence of a second-stage reservation 210b), it knows that the reservation indicated in the first-stage SCI is associated with an SL-PRS (i.e., is a first-stage reservation 210a) and can therefore ignore the larger "dummy" reservation for the current transmission of the two-stage reservation. It is only responsible for decoding information in the subchannel with the PSCCH that carries the first-stage SCI associated with the SL-PRS reservation. Thus, the larger reservation for the current transmission of the two-stage reservation is a dummy reservation. Rel. 18 UEs 120a-120c may also be (pre-)configured to ignore this larger "dummy" reservation for their Mode 2 sensing procedure.

[0135] FIG. 14 shows a flowchart illustrating one embodiment of receiving SL-PRS. The UEs 120a-120c first check whether they are pre-configured to receive SL-PRS (step 1401 in FIG. 14). This pre-configuration may be per UE 120a-120c or per resource pool. The UEs 120a-120c may be pre-configured not to receive SL-PRS to avoid searching for two-stage reservations and reduce their power consumption. If the UEs 120a-120c are pre-configured to receive SL-PRS, the UEs 120a-120c then search for the PSCCH (step 1403 in FIG. 14). Similar to legacy procedures in Rel. 16 and Rel. 17, the UEs 120a-120c may search for the PSCCH in all potential positions of the PSCCH in each subchannel within the slots of the resource pool. The presence of a PSCCH can be detected based on the PSCCH DMRS. If a PSCCH is found (step 1405 in FIG. 14), the UE 120a-120c decodes the first-phase SCI carried by the PSCCH and determines the resource reservation indicated by the first-phase SCI (step 1407 in FIG. 14). The UE 120a-120c then determines whether the indicated resource reservation is for a data transmission or an SL-PRS transmission (step 1409 in FIG. 14). The UE 120a-120c checks whether the resource reservation indicated by the first-phase SCI corresponds to first-phase reservation 210a of SL-PRS resources (step 1409 in FIG. 14). This can be determined in different ways. The UE 120a-120c can determine that the resource reservation of a given number of sub-channels corresponds to first-phase reservation 210a of SL-PRS resources. The UEs 120a-120c may also determine that the resource reservation of the semi-dedicated resources 260 corresponds to the first stage reservation 210a of the SL-PRS. The UEs 120a-120c may also determine that the resource reservation is a first stage reservation 210a based on the existence of the second stage reservation 210b.The presence of a second phase reservation 210b may be indicated using one of the reserved bits in the first phase SCI or using an indication in the second phase SCI format associated with the SL-PRS.

[0136] When a UE 120a-120c detects a first stage reservation of SL-PRS resources, it proceeds to determine a destination ID for the reserved SL-PRS resources (step 1411 in FIG. 14). The UE 120a-120c knows where and how to find the destination ID based on its (pre)configuration. The destination ID may be transmitted together with the source ID. The destination ID may be transmitted in the same subchannel that carries the first stage reservation 210a. In particular, the source ID and destination ID may be carried in a second stage SCI associated with the first stage SCI.

[0137] After determining the destination ID, the UE 120a-120c checks whether it is the target Rx UE of the SL-PRS (step 1413 in FIG. 14), i.e., whether the UE 120a-120c is the intended receiver of the SL-PRS. If the UE 120a-120c is the target Rx UE of the reserved SL-PRS resources, it proceeds to determine a second-stage reservation 210b of the SL-PRS resources (step 1415 in FIG. 14). Based on its (pre)configuration, the UE 120a-120c knows where and how to find the second-stage reservation 210b. The second-stage reservation 210b may be carried in the same subchannel that carries the first-stage reservation 210a. In particular, the second-stage reservation 210b may be carried in a second-stage SCI associated with the first-stage SCI. After decoding second stage reservation 210b, UEs 120a-120c determine the reserved SL-PRS resources.

[0138] After the UE 120a-120c determines the first and second phase reservations 210a,b of SL-PRS resources, it knows on which semi-dedicated resources 260 and on which SL-PRS resources it should receive SL-PRS (step 1417 of FIG. 14).

[0139] FIG. 15 illustrates one embodiment of the time and frequency allocation of some SL-PRS resources within the semi-dedicated resources. In the example shown in FIG. 15, eight SL-PRS resources are depicted, each spanning four symbols, and all subchannels within the semi-dedicated resources are arranged in a comb pattern. For simplicity, only a frequency chunk within the semi-dedicated resources is shown, but the comb pattern may be repeated throughout the remainder of the semi-dedicated resources. FIG. 15 also illustrates automatic gain control (AGC) symbols and gap or guard symbols. The AGC symbols allow Rx UEs to adjust the dynamic range based on the received signal. The guard symbols allow switching from transmit to receive or from receive to transmit. Due to the half-duplex constraint, UEs 120a-120c may not receive SL-PRS when they are transmitting SL-PRS simultaneously, i.e., in the same symbol. Therefore, UEs 120a-120c transmitting SL-PRS resource 1 cannot receive SL-PRS resource 2. However, UE 120a-120c transmitting SL-PRS resource 1 can receive SL-PRS resource 5. The illustrated example allows UE 120a-120c to transmit SL-PRS on SL-PRS resources 1, 2, 3, or 4 and receive SL-PRS on SL-PRS resources 5, 6, 7, or 8. This allows UE 120a-120c to transmit and receive SL-PRS within the same semi-dedicated resource, i.e., within the same slot. More SL-PRS resources can be multiplexed within the semi-dedicated resource, i.e., by having one AGC symbol (e.g., in a comb pattern) followed by 12 SL-PRS resources and finally a guard symbol within the 14 symbols in the slot.

[0140] FIG. 16 illustrates a further embodiment for a group of UEs 120a-120c in an out-of-network-coverage scenario. FIG. 16 shows a signaling diagram in which semi-dedicated resource configuration (step 1601 in FIG. 16) is performed dynamically between the group of UEs 120a-120c. This allows the UEs 120a-120c in the group to have a common understanding of the SL-PRS resources within the group. This configuration can be provided by one UE 120a to the other UEs 120b, 120c, or the UEs 120a-120c can agree on the configuration together. Pre-configuration for sending and receiving two-stage reservations is also shown (step 1603 in FIG. 16). Pre-configuration can be performed as in the above-described embodiment. The first UE 120a (UE1) can indicate to the second UE 120b (UE2) to select SL-PRS resources for the first UE 120a (step 1605 in FIG. 16). The second UE 102b selects resources for transmitting the two-stage reservation and SL-PRS resources for the first UE 120a and the second UE 120b (steps 1607 and 1609 in FIG. 16). As an example, the second UE 120b selects two SL-PRS resources among the semi-dedicated resources 260 for two transmissions of SL-PRS, i.e., one SL-PRS to be transmitted by the first UE 120a and one SL-PRS to be transmitted by the second UE 120b. The two SL-PRS resources may be multiplexed within the semi-dedicated resource 260 as described in the previous embodiment. The resource selection may be performed using Mode 2 resource allocation, i.e., as described in the previous embodiment. The UEs 120a-120c are also within network coverage and may select resources based on the Mode 2 resource allocation. The second UE 102b selects a subchannel for transmitting the two-stage reservation and the source ID and destination ID of the two SL-PRS resources, shown as SL-PRS1 and SL-PRS2 to be transmitted by the first UE 120a and the second UE 120b, respectively.The second UE 120b then transmits a two-stage reservation (steps 1611a, 1611b, and 1613a, 1613b in FIG. 16) and the source ID and destination ID of SL-PRS1 and SL-PRS2 on the selected subchannel (steps 1615a, 1615b in FIG. 16), which is received by the first UE 120a and the third UE 120c (UE3). The first UE 120a and the third UE 120c determine that a first-stage reservation 210a of SL-PRS resources exists. The third UE 120c also determines, based on the destination ID, that it is the target receiver of the two SL-PRS resources. The first UE 120a determines that the second UE 120b has reserved the SL-PRS resources for the first UE 120a, i.e., based on the source ID of SL-PRS1. The first UE 120a then transmits SL-PRS1 on the selected SL-PRS resource (step 1619 of FIG. 16). The second UE 120b then transmits SL-PRS2 on the selected SL-PRS resource (step 1617 of FIG. 16). The third UE 120c receives SL-PRS1 and SL-PRS2 based on the two-stage reservation and the destination IDs of both SL-PRS resources received on the selected subchannel. In the illustrated example, the first UE 120a is configured to check for the two-stage reservation sent by the second UE 120b.

[0141] 17 is a flow chart illustrating a method 1700 for transmitting a two-stage assignment of time and frequency resources for transmission of one or more sidelink positioning reference signals according to one embodiment. The method 1700 comprises transmitting an assignment using the two-stage assignment in step 1701, the first-stage assignment 210a being one or more first time and frequency resources 220 of the plurality of time and frequency resources 200 having a first granularity and the second-stage assignment 210b being one or more second time and frequency resources 230 of the plurality of time and frequency resources 200 having a second granularity, where the one or more second time and frequency resources 230 are a subset of the one or more first time and frequency resources 220.

[0142] 18 is an illustrative flowchart showing a method 1800 according to one embodiment for receiving a two-stage assignment of time and frequency resources for transmission of one or more sidelink positioning reference signals. The method 1800 comprises receiving 1801 an assignment using the two-stage assignment, the first-stage assignment 210a being one or more first time and frequency resources 220 of the plurality of time and frequency resources 200 having a first granularity, and a second-stage assignment 210b being one or more second time and frequency resources 230 of the plurality of time and frequency resources 200 having a second granularity, where the one or more second time and frequency resources 230 are a subset of the one or more first time and frequency resources 220.

[0143] Those skilled in the art will appreciate that the "blocks" ("units") of the various figures (method and apparatus) represent or describe functionality of embodiments of the present disclosure (not necessarily individual "units" in hardware or software), and thus equally describe functions or features of apparatus embodiments as well as method embodiments (units = steps).

[0144] In some embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the described embodiments of devices are merely examples. For example, unit divisions are merely logical functional divisions and may be otherwise implemented in actual implementations. For example, multiple units or components may be combined or integrated into another system, or some features may be omitted or not implemented. In addition, the shown or described mutual couplings, or direct couplings, or communication connections may be implemented by using some interfaces. Indirect couplings or communication connections between devices or units may be implemented in electronic, mechanical, or other forms.

[0145] The units described as separate parts may or may not be physically separate, and the parts shown as units may or may not be physical units, located in one location or distributed over multiple network units, and some or all of the units may be selected according to actual needs to achieve the objectives of the solutions according to the embodiments.

[0146] Additionally, the functional units in the embodiments of the present disclosure may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.

Claims

1. 1. A user equipment (UE) for transmitting an allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals (SL-PRS), the allocation comprising: the UE is configured to transmit the assignment using a two-stage assignment; the two-stage allocation includes a first-stage allocation of one or more first time and frequency resources among a plurality of time and frequency resources having a first granularity, and a second-stage allocation of one or more second time and frequency resources among the plurality of time and frequency resources having a second granularity; the one or more second time and frequency resources are a subset of the one or more first time and frequency resources. User equipment.

2. the UE is configured to transmit first stage sidelink control information (SCI); and the first stage SCI includes the first stage allocation; 10. The user equipment of claim 1.

3. the UE is configured to transmit second stage sidelink control information (SCI); and the second stage SCI includes the second stage allocation; The user equipment of claim 2 .

4. the first-stage SCI includes information indicating the existence of the second-stage allocation; The user equipment of claim 3 .

5. The first stage SCI further includes information regarding the format of the second stage SCI; and / or one or more reserved bits of the first phase SCI include information indicating the existence of the second phase allocation; 5. The user equipment of claim 4.

6. the plurality of time and frequency resources comprises a plurality of slots and a plurality of subchannels; 6. A user equipment according to any one of claims 1 to 5.

7. the UE is configured to transmit the two-stage assignment within the plurality of slots and one or more subchannels of the plurality of subchannels.

7. The user equipment of claim 6.

8. the UE is configured to transmit control information associated with the one or more subchannels of the plurality of slots and the one or more SL-PRSs in the plurality of subchannels carrying the second-phase assignment.

8. The user equipment of claim 7.

9. the UE is configured to transmit the two-stage allocation in one slot prior to one or more slots including the first time and frequency resources. A user equipment according to any one of claims 6 to 8.

10. the UE is configured to transmit the two-stage allocation within a slot including the first time and frequency resource. A user equipment according to any one of claims 6 to 8.

11. the UE is configured to transmit the one or more SL-PRSs in the second time and frequency resources as indicated by the second-phase allocation. A user equipment according to any one of claims 1 to 10.

12. the UE is configured to transmit the one or more SL-PRSs in the second time and frequency resources as indicated by the first-stage allocation and the second-stage allocation.

12. User equipment according to any one of claims 1 to 11.

13. the UE is configured to transmit an allocation of time and frequency resources for one or more transmissions associated with the one or more SL-PRSs by another UE using the two-stage allocation.

13. A user equipment according to any one of claims 1 to 12.

14. the first granularity is a subchannel of a slot; 14. User equipment according to any one of claims 1 to 13.

15. the plurality of time and frequency resources comprises one or more SL-PRS resources having the second granularity.

15. The user equipment of claim 14.

16. the plurality of time and frequency resources includes one or more SL-PRS resources; and the UE and / or another UE is configured to transmit the one or more SL-PRSs in one or more SL-PRS resources of the one or more SL-PRS resources.

16. A user equipment according to any one of claims 1 to 15.

17. the UE is configured to transmit the two-stage assignment in one or more time and frequency resources of the plurality of time and frequency resources that are different from the one or more SL-PRS resources.

17. The user equipment of claim 16.

18. the UE is configured to transmit data on one or more time and frequency resources of the plurality of time and frequency resources, including one or more of the one or more SL-PRS resources.

18. The user equipment of claim 17.

19. the UE is configured to transmit information associated with one or more of the one or more SL-PRS resources in one or more time and frequency resources of the plurality of time and frequency resources.

18. The user equipment of claim 17.

20. the UE is configured to receive configuration information regarding the one or more SL-PRS resources from a base station or from a second, different UE.

17. User equipment according to claim 15 or 16.

21. the UE is configured to transmit one or more identifiers associated with one or more UEs intended to transmit the one or more SL-PRSs on the second time and frequency resources.

21. User equipment according to any one of claims 1 to 20.

22. the UE is configured to transmit one or more identifiers associated with one or more UEs intended to receive the one or more SL-PRSs on the second time and frequency resources.

22. User equipment according to any one of claims 1 to 21.

23. 1. A method for transmitting an allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals, SL-PRS, the method comprising: transmitting said allocation using a two-stage allocation; the two-stage allocation includes a first-stage allocation of one or more first time and frequency resources among a plurality of time and frequency resources having a first granularity, and a second-stage allocation of one or more second time and frequency resources among the plurality of time and frequency resources having a second granularity; the one or more second time and frequency resources are a subset of the one or more first time and frequency resources. method.

24. 1. A user equipment (UE) for receiving an allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals (SL-PRS), the allocation comprising: the UE is configured to receive the assignment using a two-stage assignment; the two-stage allocation includes a first-stage allocation of one or more first time and frequency resources among a plurality of time and frequency resources having a first granularity, and a second-stage allocation of one or more second time and frequency resources among the plurality of time and frequency resources having a second granularity; the one or more second time and frequency resources are a subset of the one or more first time and frequency resources. User equipment.

25. the UE is configured to receive first stage sidelink control information (SCI); and the first stage SCI includes the first stage allocation; 25. The user equipment of claim 24.

26. the UE is configured to determine that the first-stage SCI includes the first-stage allocation by determining that the first-stage SCI indicates the second-stage allocation.

26. The user equipment of claim 25.

27. the UE is configured to receive second stage sidelink control information (SCI); and the second stage SCI includes the second stage allocation; 27. User equipment according to claim 25 or 26.

28. the first-stage SCI includes information indicating the existence of the second-stage allocation; 28. User equipment according to claim 26 or 27.

29. The first stage SCI further includes information regarding the format of the second stage SCI; and / or one or more reserved bits of the first phase SCI include information indicating the existence of the second phase allocation; 29. User equipment according to claim 27 or 28.

30. the plurality of time and frequency resources comprises a plurality of slots and a plurality of subchannels; 30. User equipment according to any one of claims 24 to 29.

31. the UE is configured to receive the two-stage allocation within the plurality of slots and one or more subchannels of the plurality of subchannels.

31. The user equipment of claim 30.

32. the UE is configured to receive control information associated with the one or more subchannels of the plurality of slots and the one or more SL-PRSs in the plurality of subchannels carrying the two-tier allocation.

32. The user equipment of claim 31.

33. the UE is configured to receive the two-phase allocation in one slot prior to one or more slots including the first time and frequency resource.

33. A user equipment according to any one of claims 30 to 32.

34. the UE is configured to receive the two-phase allocation within a slot that includes the first time and frequency resource.

33. A user equipment according to any one of claims 30 to 32.

35. the UE is configured to transmit the one or more SL-PRSs in the second time and frequency resources as indicated by the second-phase allocation.

35. User equipment according to any one of claims 24 to 34.

36. the UE is configured to transmit the one or more SL-PRSs in the second time and frequency resources as indicated by the first-stage allocation and the second-stage allocation.

35. User equipment according to any one of claims 24 to 34.

37. the UE is configured to receive the one or more SL-PRSs in the second time and frequency resources as indicated by the second-phase allocation.

37. User equipment according to any one of claims 24 to 36.

38. the UE is configured to receive the one or more SL-PRSs in the second time and frequency resources as indicated by the first-stage allocation and the second-stage allocation.

36. User equipment according to any one of claims 24 to 35.

39. the first granularity is a subchannel of a slot; 39. User equipment according to any one of claims 24 to 38.

40. the plurality of time and frequency resources comprises one or more SL-PRS resources having the second granularity.

40. The user equipment of claim 39.

41. the plurality of time and frequency resources include one or more SL-PRS resources; the UE and / or another UE is configured to transmit the one or more SL-PRSs in one or more SL-PRS resources of the one or more SL-PRS resources.

41. User equipment according to any one of claims 24 to 40.

42. 42. The user equipment of claim 41, wherein the UE is configured to receive the two-stage allocation on one or more time and frequency resources (200) that are different from the one or more SL-PRS resources.

43. the UE is configured to transmit data on one or more time and frequency resources of the plurality of time and frequency resources including one or more of the one or more SL-PRS resources.

43. The user equipment of claim 42.

44. the UE is configured to receive data on one or more time and frequency resources of the plurality of time and frequency resources including one or more of the one or more SL-PRS resources.

43. The user equipment of claim 42.

45. the UE is configured to transmit information associated with one or more of the one or more SL-PRS resources in one or more time and frequency resources of the plurality of time and frequency resources.

43. The user equipment of claim 42.

46. the UE is configured to receive, in one or more time and frequency resources of the plurality of time and frequency resources, information associated with one or more of the one or more SL-PRS resources.

43. The user equipment of claim 42.

47. the UE is configured to receive configuration information regarding the one or more SL-PRS resources from a base station or from a second, different UE.

45. User equipment according to any one of claims 40 to 44.

48. the UE is configured to receive one or more identifiers associated with one or more UEs intended to transmit the one or more SL-PRSs on the second time and frequency resources.

48. User equipment according to any one of claims 20 to 47.

49. the UE is configured to receive one or more identifiers associated with one or more UEs intended to receive the one or more SL-PRSs on the second time and frequency resource.

49. User equipment according to any one of claims 24 to 48.

50. 1. A method for receiving an allocation of time and frequency resources for transmission of one or more sidelink positioning reference signals, SL-PRS, the method comprising: receiving said allocation using a two-stage allocation; the two-stage allocation includes a first-stage allocation of one or more first time and frequency resources among a plurality of time and frequency resources having a first granularity, and a second-stage allocation of one or more second time and frequency resources among the plurality of time and frequency resources having a second granularity; the one or more second time and frequency resources are a subset of the one or more first time and frequency resources. method.

51. 1. A computer program product including a computer-readable storage medium having program code stored thereon, When the program code is executed by a computer or processor:

51. Causing the computer or processor to implement the method of claim 23 or the method of claim 50. Computer program products.

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