Devices and methods for allocating resources for sidelink positioning

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 communication in wireless communication networks. More specifically, the present disclosure relates to devices and methods for resource allocation for sidelink positioning in wireless communication networks.

BACKGROUND ART

[0002] Communication between mobile devices, also referred to as user equipment (UE), has been standardized in the form of sidelink (SL) communication since Release 12 of Long Term Evolution (LTE) in the 3rd Generation Partnership Project (3GPP) standards. Resources for sidelink communication may either be allocated by the network when the UE is within network coverage and using licensed spectrum, or may be allocated in an autonomous distributed manner by each UE when the UE is out of network coverage or using unlicensed spectrum.

[0003] Some Vehicle-to-Everything (V2X) and public safety use cases can benefit from sidelink positioning, that is, 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 its Release 18 (Rel.18) as part of the work item on enhanced and improved new radio (NR) positioning.

SUMMARY OF THE INVENTION

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

[0005] The aforementioned and other objectives are achieved by the subject matter of the independent claims. Further forms of implementation are evident from the dependent claims, specification, and drawings.

[0006] In a first aspect, a user device, UE, is provided for transmitting time and frequency resource allocations for transmitting one or more sidelink positioning reference signals, SL-PRS. The UE is configured to transmit allocations using two-stage allocations, which include a first-stage allocation indicating one or more first time and frequency resources from 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 from a plurality of time and frequency resources having a second granularity, where one or more second time and frequency resources are subsets of one or more first time and frequency resources. As used herein, one or more second time and frequency resources being a subset of one or more first time and frequency resources includes cases where one or more second time and frequency resources include all of one or more first time and frequency resources, i.e., the first time and second time and frequency resources are identical.

[0007] In further possible implementations, the UE is configured to transmit first-stage sidelink control information, SCI, where the first-stage SCI includes first-stage assignment.

[0008] In further possible implementations, the UE is configured to transmit second-stage sidelink control information, SCI, where the second-stage SCI includes second-stage assignment.

[0009] In further possible implementations, the first-stage SCI includes information indicating the existence 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 existence of a second-stage allocation.

[0011] In further possible implementations, multiple time and frequency resources comprise multiple slots and multiple subchannels.

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

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

[0014] In further possible implementations, the UE is configured to transmit the two-stage allocation in a slot preceding one or more slots that contain the first time and frequency resources indicated by the two-stage allocation.

[0015] In further possible implementations, the UE is configured to transmit a two-stage allocation within a slot containing the first time and frequency resources indicated by the two-stage allocation.

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

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

[0018] In further possible implementations, the UE is configured to transmit time and frequency resource allocations using a two-stage allocation for the transmission of one or more SL-PRS signals by another UE (further UE).

[0019] In further possible implementations, the first granularity is the size of the slot's subchannels, i.e., the size of the slot's subchannels.

[0020] In further possible implementations, multiple time and frequency resources include one or more configured or pre-configured semi-dedicated SL-PRS resources having a second granularity.

[0021] In further possible implementations, multiple time and frequency resources comprise one or more configured or pre-configured semi-dedicated SL-PRS resources, and a UE, and / or another UE, is configured to transmit one or more SL-PRS signals using, i.e., one or more of the SL-PRS resources.

[0022] In further possible implementations, the UE is configured to transmit a two-stage allocation on one or more time and frequency resources, which are different from one or more SL-PRS resources.

[0023] In further possible implementations, the UE is configured to transmit data across one or more time and frequency resources, including one or more SL-PRS resources.

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

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

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

[0027] In further possible implementations, the UE is configured to transmit one or more identifiers of one or more UEs that are intended to receive one or more SL-PRS, using the second time and frequency resources.

[0028] According to a second aspect, there is provided 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 comprises transmitting the allocation using a two-stage allocation, including a first-stage allocation indicating 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 indicating one or more second time and frequency resources among a 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, that the one or more second time and frequency resources are 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 frequency resources 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. Accordingly, further features of the method according to the second aspect of the present disclosure directly arise from the functions of the UE according to the first aspect of the present disclosure, as well as the different implementations thereof described above and below.

[0030] According to the 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 among 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 among a 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, that the one or more second time and frequency resources are 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, that is, the first and second time and frequency resources are the same.

[0031] In a further possible implementation, the UE is configured to receive first-stage sidelink control information, SCI, wherein the first-stage SCI comprises the first-stage allocation.

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

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

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

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

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

[0038] In further possible implementations, the UE is configured to receive control information associated with one or more SL-PRS within one or more subchannels of a plurality of slots and a plurality of subchannels that carry two-stage assignments.

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

[0040] In further possible implementations, the UE is configured to receive a two-stage allocation within a slot containing the first time and frequency resources, as indicated by the two-stage allocation.

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

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

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

[0044] In further possible implementations, the UE is configured to receive one or more SL-PRS in, i.e., using, the second time and frequency resources, as indicated by the first and second stage allocations.

[0045] In further possible implementations, the first granularity is the size of the slot's subchannels, i.e., the size of the slot's subchannels.

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

[0047] In further possible implementations, multiple time and frequency resources comprise one or more configured or pre-configured semi-dedicated SL-PRS resources, where UE and / or another UE are configured to transmit one or more SL-PRS signals using, i.e., on, one or more of the SL-PRS resources.

[0048] In further possible implementations, the UE is configured to receive a two-stage allocation on one or more time and frequency resources, which are different from one or more SL-PRS resources.

[0049] In further possible implementations, the UE is configured to transmit data across one or more time and frequency resources, including one or more SL-PRS resources.

[0050] In further possible implementations, the UE is configured to receive data on one or more time and frequency resources, which include one or more SL-PRS resources.

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

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

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

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

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

[0056] A method is provided for receiving allocations of time and frequency resources for transmitting one or more sidelink positioning reference signals, SL-PRS, according to a fourth aspect. The method includes the step of receiving an allocation using a two-stage allocation, which includes a first-stage allocation indicating one or more first time and frequency resources from 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 from a plurality of time and frequency resources having a second granularity, wherein one or more second time and frequency resources are a subset of one or more first time and frequency resources. As used herein, one or more second time and frequency resources being a subset of one or more first time and frequency resources means that one or more second time and frequency resources include all of one or more first time and frequency resources, including the case where the first time and second time and frequency resources are the same.

[0057] The method according to the fourth aspect of this disclosure may be performed by a UE according to the third aspect of this disclosure. Accordingly, further features of the method according to the fourth aspect of this disclosure arise directly from the functionality of the UE according to the third aspect of this disclosure, as well as from its different implementations described above and below.

[0058] A computer program product is provided according to the fifth aspect, and when the program code is executed by a computer or processor, it includes a computer-readable storage medium for storing the program code, which causes the computer or processor to execute the program code in the manner according to the second aspect or the manner according to the fourth aspect.

[0059] Details of one or more embodiments are described in the accompanying drawings and the following description. Other features, purposes, and advantages will become apparent from the description, drawings, and claims. [Brief explanation of the drawing]

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

[0061] In the following, the same reference numeral refers to the same feature or at least a functionally equivalent feature. [Modes for carrying out the invention]

[0062] The following description refers to the accompanying drawings, which form part of the present disclosure and illustrate specific aspects of the embodiments of the present disclosure, or specific aspects in which the embodiments of the present disclosure may be used. It is understood that the embodiments of the present disclosure may be used in other embodiments and may include structural or logical modifications not shown in the drawings. The following detailed description should therefore not be constrained to be restrictive, and the scope of the present disclosure is defined by the accompanying claims.

[0063] For example, it should be understood that the methods described and the related disclosures apply to the corresponding devices or systems configured to perform the methods, and vice versa. For example, if one or more specific method steps are described, the corresponding device may include one or more units, e.g., functional units, to perform the one or more method steps described (e.g., one unit performing one or more steps, or multiple units each performing one or more of multiple steps), even if such one or more units are not explicitly described or illustrated. On the other hand, for example, if a particular device is described based on one or more units, e.g., functional units, the corresponding method may include one step for performing the function of one or more units (e.g., one step performing the function of one or more units, or multiple steps each performing one or more functions of multiple units), even if such one or more steps are not explicitly described or illustrated. Furthermore, it should be understood that the features of the various exemplary embodiments and / or aspects described herein may be combined with each other unless otherwise specified.

[0064] Figure 1 shows a schematic diagram illustrating a wireless communication network, particularly a cellular communication network 100, having a base station 110 defining a cell of the wireless communication network 100, and a plurality of user devices, UE120a-120d, according to one embodiment for transmitting and / or receiving time and frequency resource allocations for the transmission of one or more sidelink positioning reference signals, SL-PRS. As an example, in Figure 1, UE120a transmits time and frequency resource allocations for the transmission of one or more sidelink positioning reference signals (SL-PRS).

[0065] As shown in Figure 1, UE120a may include a processor 121a, and a communication interface 123a, particularly an antenna, for sidelink communication with base station 110 and other UE120b-120d in the radio network 100. The processor 121a may be implemented in hardware and / or software. The hardware may include digital circuitry, or both analog and digital circuitry. The digital circuitry may include components such as application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), digital signal processors (DSPs), or one or more general-purpose processors. Furthermore, UE120a may include memory 125a, configured to store executable program code that, when executed by processor 121a, causes UE120a to perform the functions and operations described herein. Similar to UE120a, other UE120b-120d may also include a processor, a communication interface, and memory.

[0066] For example, several detailed embodiments are described below. Here, UE120a (also called the first UE) transmits time and frequency resource allocations for the transmission of one or more SL-PRS, while UE120b-120d may receive such allocations. Furthermore, for example, UE120d may be a legacy UE120d, as defined in more detail below.

[0067] Embodiments disclosed herein relate to the allocation of time and frequency resources in a sidelink for SL-PRS transmission. Sidelink transmission may use orthogonal frequency division multiplexing (OFDM) waveforms with cyclic prefixes (CPs). In the time domain, resources may consist of slots. A slot consists of 14 or 12 OFDM symbols, depending on whether a normal CP or an extended CP is employed. Hereinafter, OFDM symbols will be simply referred to as symbols, and it will be assumed that a slot consists of 12 symbols. In the frequency domain, resources may consist of resource blocks (RBs). An RB consists of multiple adjacent subcarriers having the same subcarrier spacing with respect to the OFDM waveform, for example, 12 subcarriers.

[0068] For sidelink data transmission, for example in NR-V2X under 3GPP Rel.16 / 17, a subset of available resources may be (pre)configured for use by UE120a-120d for SL transmission. This subset of resources available for SL transmission is called a resource pool (RP). The (pre)configuration refers to (a) a configuration defined by the network and signaled to UE120a-120d by the network device base station 110, i.e., a configuration when UE120a-120d is within network coverage, or (b) a configuration predefined in UE120a-120d, e.g., a configuration when UE120a-120d is outside network coverage. The network device base station 110 may be a next-generation node B (gNB), a base station (BS), a roadside unit (RSU), a transmit / receive point (TRP), etc. UE120a-120d may be a mobile phone, a handheld device, a vehicle-mounted device, or a robot-mounted device, etc. Hereafter, the term gNB is used with the understanding that the unit may generally be implemented as a network device 110. As already described above, for example, UE120d may be a legacy UE120d. On the other hand, UE120a-120c are implemented according to the embodiments disclosed herein.

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

[0070] Data is organized into transport blocks (TBs), and for example, a TB may contain an entire data packet. In NR V2X, the data payload, i.e., the TB, is carried on a Physical Sidelink Shared Channel (PSSCH). Depending on the size of the data packet, the PSSCH carrying the TB may occupy one or more subchannels. Sidelink control information (SCI) associated with the TB is transmitted in two stages: first-stage SCI and second-stage SCI. The first stage is carried on a Physical Sidelink Control Channel (PSCCH). The PSCCH is multiplexed with the associated PSSCH in non-overlapping resources within the subchannel occupied by the PSSCH. To assist in decoding the PSCCH, a demodulation reference signal (DMRS) is transmitted within the PSCCH, which is called PSCCH DMRS. The second-stage SCI is multiplexed with the TB within the PSSCH in terms of time and frequency. To assist in the decoding of the PSSCH, a demodulation reference signal (DMRS) is transmitted within the PSSCH, which is called the PSSCH DMRS. For the transmission of the TB, the transmitting UEs (Tx UE) 120a-120d transmit the PSCCH (carrying the first-stage SCI) along with the second-stage SCI multiplexed with the TB within the PSSCH on one or more subchannels.

[0071] The first-stage SCI indicates the resources for the current TB transmission and may also indicate resources reserved for retransmissions of the same TB. The current TB transmission may be called the initial transmission. The initial transmission may correspond to a retransmission. Resources for a transmission include one or more subchannels within a single slot. The resources for a transmission may be determined using the resource's frequency resource location and time resource location. The resource's frequency resource location may be indicated using the starting subchannel index and the number of subchannels consecutively allocated for the transmission. The time resource location may be indicated using the slot index. The starting subchannel and slot of the resources for the current TB transmission correspond to the subchannel and slot where 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. Resources for a retransmission are indicated using frequency and time indications that specify the starting subchannel index, the number of consecutively allocated subchannels, and the slot index following the retransmission.

[0072] In addition, the first stage SCI can also indicate a resource reservation period, which is the time interval between resources selected for consecutive TB transmissions. This period indicates the periodicity of the resources selected by UE120a-120d and is called the resource reservation interval (RRI) in NR V2X. Using the RRI in the first stage SCI, UE120a-120d can indicate that a subchannel used for the current TB transmission may be reserved after the RRI for the transmission of a new TB. Multiple RRIs may be configured (in advance) in the resource pool.

[0073] Decoding the first stage SCI then allows UE120a-120d to recognize the subchannels occupied by the current transmission of the TB being carried within the PSSCH, as well as the subchannels reserved for future (re)transmissions of the same or new TBs. The first stage SCI also indicates the priority of the TB being carried within the associated PSSCH. In addition, the first stage SCI also indicates the format of the second stage SCI, since the second stage SCI may have a variable length. The second stage SCI indicates the source ID and destination ID of the TB. Decoding the second stage SCI allows the receiving UE120a-120d (Rx UE) to know the source and destination of the TB; that is, it allows Rx UE120a-120d to recognize whether the TB being carried within the PSSCH is the target Rx UE120a-120d.

[0074] For data transmission, i.e., TB transmission, subchannels within the resource pool can be selected based on two resource allocation modes, namely Mode 1 and Mode 2. In Mode 1, subchannels for data transmission are allocated by the network; that is, the base station or gNB 110 indicates to the UE120a-120d which resources to use for data transmission. In Mode 2, the UE120a-120d can autonomously select subchannels for data transmission.

[0075] For transmissions in Mode 2, UE120a-120d identify candidate resources within a selection window based on a sensing procedure within a set of slots in the resource pool. This set of slots is called the sensing window. As part of the sensing procedure, UE120a-120d searches for PSCCHs at all potential PSCCH locations within each subchannel of these slots, and if a PSCCH is found, decodes the first-stage SCI. Based on the decoded first-stage SCI, UE120a-120d recognizes resources reserved for their transmissions by other UE120a-120d units. In addition, UE120a-120d measures the reference signal received power (RSRP) of the transmission associated with the received first-stage SCI. Whether UE120a-120d measures RSRP based on PSCCH DMRS or PSSCH DMRS can be configured (pre-configured) per resource pool. The measured RSRP and the resources reserved by the corresponding first-stage SCI are considered to be the sensing results from mode 2 sensing of UE120a-120d.

[0076] In Mode 2, UE120a-120d determine candidate resources in the selection window after excluding resources in the selection window based on half-duplex operation and sensing results. Due to half-duplex operation, UE120a-120d cannot sense reservations from other UE120a-120d in slots within the sensing window that UE120a-120d was transmitting. Based on this, UE120a-120d excludes slots in the selection window that potentially contain reserved resources due to the RRI period indicated in the first stage transmitted within the sensing window slot when UE120a-120d was transmitting. UE120a-120d can also exclude slots that, if selected by UE120a-120d for use with a given RRI period (selected by UE120a-120d for its transmission), could result in future conflicts with potentially reserved resources of other UE120a-120d. In addition, based on sensing results, UE120a-120d also exclude reserved resources in selection windows with associated measured RSRPs greater than a (pre-configured) threshold, depending on the priority of TB transmitted by UE120a-120d. UE120a-120d can also exclude resources that, if selected by UE120a-120d for use with a given RRI period, could result in future conflicts with reserved resources of other UE120a-120d. After exclusion, UE120a-120d checks if the percentage of available candidate resources remaining in the selection window exceeds a threshold that depends on the priority of the TB to be sent by UE120a-120d. If not, the RSRP threshold used to exclude reserved resources is increased by 3dB, and resource exclusion based on the sensing results is repeated. From the remaining candidate resources in the selection window, UE120a-120d randomly selects resources for the initial and retransmission of the TB.UE120a-120d can use selected resources for multiple periods, i.e., with a given RRI selected by UE120a-120d, to transmit multiple TBs.

[0077] Mechanisms to enhance Mode 2 operation include re-evaluation and preemption. Using re-evaluation, UE120a-120d can check whether the selected resource for TB is reserved by another UE120a-120d based on new sensing results prior to the TB transmission by UE120a-120d. If so, UE120a-120d drops the selected resource and selects a new resource for TB. Using preemption, UE120a-120d can also check whether the selected resource for TB is reserved, similar to the re-evaluation mechanism. However, with preemption, UE120a-120d will only select a new resource for that TB transmission if the resource is reserved by another UE120a-120d for a transmission with a higher priority compared to the UE's transmission priority. UE120a-120d can also select a new resource for transmission if the priority associated with a reserved resource is higher than a (pre-configured) threshold in the resource pool.

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

[0079] For SL-PRS transmission, time and frequency resources on the sidelink are required. Resources in a resource pool may be used for SL-PRS transmission, similar to data transmission on the sidelink. For this purpose, whether to use a dedicated shared resource pool and / or a shared resource pool for SL-PRS, including configuring one of them (in advance), 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 SL-PRS resources. A PSCCH may be transmitted in a dedicated resource pool, where the PSCCH carries the SCI associated with the SL-PRS transmission. A PSSCH associated with an SL-PRS transmission may also be transmitted in a dedicated resource pool, for example, in a PSSCH carrying the measurement report 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). In addition, it has been agreed within 3GPP that backward compatibility for legacy UEs, such as the exemplary UE120d, should be supported in the shared resource pool. Legacy UEs, such as the exemplary UE120d, refer to UEs from previous releases, i.e., UEs in NR V2X of Rel. 16 or Rel. 17. Non-legacy as used herein corresponds to UEs from later releases, e.g., Rel. 18, such as UE120a-120c shown in Figure 1.

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

[0081] In addition, it has been proposed to multiplex SL-PRS with PSSCH. However, UE120a-120c that wish to transmit SL-PRS do not necessarily need to transmit PSSCH. Furthermore, SL-PRS may need to span multiple sub-channels, while PSSCH does not need to occupy as many sub-channels. Moreover, SL-PRS does not need to span all symbols in the slot.

[0082] The shared resource pool supports data transmission from Rel.16 / 17 / 18 Tx UE120d to Rel.16 / 17 / 18 Rx UE, and from Rel.18 Tx UE120a-120c to Rel.18 Rx UE120a-120c. For Rel.16 / 17 Rx UE120d, backward compatibility in the shared resource pool is guaranteed, as long as legacy Rx UE120d can receive their intended data, and Rel.16 / 17 Rx UE120d do not need to receive SL-PRS. Backward compatibility must be guaranteed for 16 / 17 Tx UE120d in Scheme 1 (Mode 1) and Scheme 2 (Mode 2). In Mode 1, data and resources for SL-PRS may be comprised of networks for Rel.16 / 17 Tx UE120d and Rel.18 Tx UE120a-120c. To ensure backward compatibility, a Rel.16 / 17 Tx UE120d performing Mode 2 sensing must be able to recognize SL-PRS resources reserved by Rel.18 Tx UE120a-120c without being able to identify that such resources are for SL-PRS. However, a Rel.16 / 17 Tx UE120d performing Mode 2 sensing can only recognize resource reservations at the subchannel granularity. On the other hand, a Rel.18 Tx UE120a-120c performing Mode 2 sensing (to transmit SL-PRS) must be able to recognize SL-PRS resource reservations (made by other Rel.18 Tx UE120a-120c) at the SL-PRS resource granularity.

[0083] Dedicated resources for SL-PRS are not necessarily used, and using a dedicated resource pool can be inefficient because it reduces the resources available for data transmission on sidelinks. A shared resource pool offers better resource utilization but may require backward compatibility. In addition, a shared resource pool needs to accommodate scheduling transmissions with different resource granularities. Furthermore, multiplexing SL-PRS within a PSSCH may impose the need for the PSSCH to be transmitted along with SL-PRS, and may cause the PSSCH to spread to more subchannels than necessary. Multiplexing SL-PRS within a PSSCH may limit the design of SL-PRS.

[0084] Embodiments disclosed herein provide a shared resource pool for supporting data transmission and SL-PRS transmission (i.e., Rel.18 UE120a-120c), taking into account different granularities of resources for both types of transmission, for example, in units of subchannels for data transmission and units of SL-PRS resources for SL-PRS. The design of the shared resource pool ensures backward compatibility for legacy UE120d, i.e., UE120d of Rel.16 and Rel.17. Data transmission in the shared resource pool can be performed by all UEs, i.e., UE120a-120d of Rel.16 / 17 / 18. SL-PRS transmission can be performed by non-legacy UEs, i.e., UE120a-120c of Rel.18.

[0085] As shown in Figure 2, embodiments disclosed herein generally provide schemes for two-stage assignment (also called two-stage reservation) of one or more SL-PRS resources. A first-stage assignment 210a (also called a first-stage reservation) assigns, i.e., reserves, a set of consecutive sub-channels containing one or more SL-PRS resources. A second-stage assignment 210b (also called a second-stage reservation) assigns, i.e., reserves, one or more resources within the set of sub-channels for one or more SL-PRS resources. Assignments of time and frequency resources are also called reservations, and the terms “assignment” and “reservation” are used interchangeably herein.

[0086] More specifically, to transmit time and frequency resource allocations for one or more SL-PRS transmissions, for example, UE120a is configured to transmit allocations using two-stage allocations, which include a first-stage allocation 210a indicating one or more first time and frequency resources 220 from a plurality of time and frequency resources 200 having a first granularity, and a second-stage allocation 210b indicating one or more second time and frequency resources 230 from a plurality of time and frequency resources 200 having a second granularity, where one or more second time and frequency resources 230 are subsets of one or more first time and frequency resources 220. As used herein, one or more second time and frequency resources 230 being subsets of one or more first time and frequency resources 220 includes the case where one or more second time and frequency resources 230 include all of 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 time and frequency resource allocations for one or more SL-PRS transmissions, for example, UE120b is configured to receive allocations using a two-stage allocation, which includes a first-stage allocation 210a indicating one or more first time and frequency resources 220 from a plurality of time and frequency resources 200 having a first granularity, and a second-stage allocation 210b indicating one or more second time and frequency resources 230 from a plurality of time and frequency resources 200 having a second granularity. As already described above, one or more second time and frequency resources 230 are subsets of one or more first time and frequency resources 220.

[0088] The advantage of two-stage allocation is that it supports the allocation of SL-PRS resources in a shared resource pool while enabling the allocation of SL-PRS resources with a different granularity than that of data transmission. The example shown in Figure 2 illustrates two-stage allocation for one SL-PRS resource within one symbol. SL-PRS resources within a set of sub-channels can spread across multiple symbols and can spread across a set of sub-channels in a comb pattern or structure. The first-stage allocation 210a targets all UE120a-120d, i.e., UE120a-120d (legacy and non-legacy) intended to transmit or receive data or to transmit or receive SL-PRS, while the second-stage allocation 210b targets UE120a-120c (non-legacy) intended to transmit or receive SL-PRS. A two-stage allocation may be transmitted by Rel.18 Tx UE120a-120c, which wishes to reserve SL-PRS resources for future transmissions of SL-PRS. In the first-stage reservation 210a, Rel.18 Tx UE120a-120c indicates a reservation of an entire set of subchannels, while in practice it may aim 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 Rel.18 UE120a-120c, i.e., Tx UE120a-120c performing mode 2 sensing to transmit SL-PRS, and / or Rx UE120a-120c of SL-PRS.

[0089] In one embodiment, the first stage allocation 210a may be transmitted in the first stage SCI carried in the PSCCH within a subchannel. The first stage allocation 210a may be indicated using one of up to two allocations in the first stage SCI used in legacy systems for resource allocation for TB retransmission. The advantage of this is that backward compatibility can be ensured. In particular, the advantage of transmitting the first stage allocation 210a in the first stage SCI is that it can be interpreted by mode 2 sensing UEs (Rel. 16 / 17 / 18) 120a-120d intended to transmit data without requiring those UEs 120a-120d to understand that the reservation, i.e., the allocation, is for SL-PRS. For a Rel.16 / 17 Tx UE120d performing Mode 2 sensing (i.e., transmitting data), the first-stage allocation 210a of SL-PRS resources is transparent; that is, the UE120d does not need to know that these resources are reserved for SL-PRS. This is regardless of whether all resources in the subchannel set are actually allocated using the second-stage allocation 210b.

[0090] In one embodiment, if the allocation is for a given number of sub-channels, for example, for all sub-channels of a resource pool in a future slot, Rx UE120a-120c of Rel.18 may be configured to interpret the allocation carried in the first stage SCI as a first stage allocation 210a of an SL-PRS resource. In this case, UE120a-120c of Rel.18 is permitted to allocate a given number of consecutive sub-channels, for example, all sub-channels in the RP, in order to allocate an SL-PRS resource. Furthermore, Rx UE120a-120c of Rel.18 may be configured to interpret the allocation carried in the first stage SCI as a first stage allocation 210a of an SL-PRS resource if the allocation is for a given set of sub-channels (hereinafter referred to as semi-dedicated resources). In this case, UE120a-120c of Rel.18 are permitted to allocate a given set of consecutive subchannels. Rx UE120a-120c of Rel.18 may also be configured to interpret the allocation carried in the first stage SCI as the first stage allocation 210a of the SL-PRS resource, based on the presence of the second stage allocation 210b of the SL-PRS resource. Thus, according to one embodiment, only after Rx UE120a-120c becomes aware of the presence of the second stage allocation 210b can it know that the allocation in the first stage SCI is the first stage allocation 210a of the SL-PRS resource. If UE120a-120c has determined that the allocation is the first stage allocation 210a, it proceeds to decode the second stage allocation 210b to determine the allocated SL-PRS resource.

[0091] In one embodiment, the second stage allocation 210b may be transmitted together with the first stage allocation 210a. In particular, the second stage allocation 210b may be transmitted in a subchannel that also carries the associated first stage allocation 210a. This has the advantage that UE120a-120c of Rel.18, i.e., UE120a-120c and / or Rx UE120a-120c performing mode 2 sensing to transmit SL-PRS, only need to check the first and second stage allocations 210a, 210b in one subchannel to determine one or more allocated SL-PRS resources. In particular, the second stage allocation 210b may be transmitted in the second stage SCI. The second stage allocation 210b may also be transmitted in a PSSCH associated with a PSCCH that carries the first stage allocation 210a. The presence of the second-stage allocation 210b in a subchannel may be indicated based on the control information within the subchannel. In particular, the presence of the second-stage allocation 210b may be indicated by one of the reserved bits in the first-stage SCI. In addition, it may also be indicated using the second-stage SCI format indication associated with the SL-PRS. The second-stage SCI associated with the SL-PRS may carry the second-stage allocation 210b and may be transmitted in the same subchannel that carries the corresponding first-stage SCI. The second-stage SCI associated with the SL-PRS may also carry further information associated with the SL-PRS.

[0092] In one embodiment, the first and second stage allocations 210a, 210b may be transmitted by UE120a-120c in subchannels within a slot prior to the allocated set of subchannels, i.e., in subchannels of the earlier slots. This has the advantage that UE120a-120c are aware of the allocated resources prior to the transmission of the SL-PRS.

[0093] In one embodiment, a subchannel carrying a two-stage allocation may be used to transmit other relevant information associated with or necessary for receiving an allocated SL-PRS transmission. This information may include the configuration and parameters of each SL-PRS resource, e.g., 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, pseudo-collocation information, parameters for power control of the SL-PRS transmission, and so on. This relevant information may be transmitted in the SCI (e.g., the second-stage SCI) or in the PSSCH within the subchannel carrying the two-stage allocation.

[0094] For Tx UE120a-120c of Rel.18 that transmit two-stage allocations, subchannel resource allocation may follow the conventional resource allocation procedure, i.e., Mode 1 or Mode 2. Furthermore, resource allocation for SL-PRS may also be based on Mode 1 and Mode 2 procedures adapted for SL-PRS, which are described in more detail below.

[0095] In one embodiment, the priority of a reserved SL-PRS resource may be transmitted in the SCI (e.g., the second-stage SCI) or in the PSSCH within a subchannel carrying the two-stage reservation.

[0096] In one embodiment, the first and second stage allocations 210a, 210b may be transmitted by UE120a-120c within an allocated set of subchannels. This means that the first and second stage allocations are transmitted within a semi-dedicated resource containing the SL-PRS resource indicated by the two-stage allocation. The first and second stage allocations are then transmitted in the same slot as the SL-PRS. This has the advantage that UE120a-120c can receive the SL-PRS and the associated first and second stage allocations in the same slot. In addition, the source and destination IDs of the SL-PRS may also be transmitted within an allocated set of subchannels. Transmitting an SL-PRS with associated first and second stage allocations in the same slot, i.e., within an allocated subchannel, can be considered for both shared and dedicated resource pools.

[0097] In one embodiment, a set of sub-channels reserved by the first-stage allocation 210a may correspond to a semi-dedicated resource 260 for SL-PRS. As used herein, the semi-dedicated resource 260 for SL-PRS may correspond to a set of sub-channels in a (pre-configured) slot in a resource pool, as shown in Figure 3. Multiple SL-PRS resources may be (pre-configured) within the semi-dedicated resource 260, as shown in Figure 3. Figure 3 shows an example of an SL-PRS resource in a single symbol. The SL-PRS resources within the semi-dedicated resource 260 may spread across multiple symbols and then spread across a set of sub-channels in a comb pattern or structure. Multiple SL-PRS resources may be multiplexed within the semi-dedicated resource 260. Multiple semi-dedicated resources 260 for SL-PRS may be (pre-configured) within a resource pool. The advantage of (pre-configuring) the semi-dedicated resource 260 is that it allows Rel.18 UE120a-120c to have a common understanding of the SL-PRS resource. In particular, this allows UE120a-120c, i.e., Rel.18 UEs, to know the set of subchannels on which SL-PRS can be transmitted, and also to know the configuration of the SL-PRS resource within the set of subchannels, i.e., within the semi-dedicated resource 260 (i.e., the time / frequency allocation of the SL-PRS resource). In particular, the semi-dedicated resource 260 can be (pre-configured) within a shared resource pool. This has the advantage that subchannels within the semi-dedicated resource can be taken into consideration for SL-PRS in the shared resource pool.

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

[0099] In one embodiment, the semi-dedicated resource 260 may be configured by network 110, i.e., base station 110, for example, when UE120a-120c are within network coverage, or when they can be pre-configured for use outside network coverage. Configuration by network 110, i.e., base station 110, has the advantage that the configuration of the semi-dedicated resource 260 can be adapted by network 110, i.e., base station 110, in response to traffic load and SL-PRS resource requirements, for example. Pre-configuration has the advantage that the semi-dedicated resource 260 can be used in situations outside network coverage. In one embodiment, the semi-dedicated resource 260 may also be configured dynamically, i.e., among groups of UE120a-120c. This allows UE120a-120c within a group to have a common understanding of the SL-PRS resources within the group.

[0100] In one embodiment, the semi-dedicated resource 260 needs to be configured (pre-configured) only for UE120a-120c of Rel.18, because only UE120a-120c of Rel.18 needs to be aware of the semi-dedicated resource 260 for SL-PRS. For UE120d of Rel.16 / 17, the semi-dedicated resource 260 is transparent and corresponds to a normal subchannel, 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, the network 110, i.e., the base station 110, can allocate resources from the semi-dedicated resource 26 for SL-PRS or for data transmission, for example, on request. When a resource is allocated for SL-PRS, the network 110, i.e., the base station 110, can indicate which SL-PRS resources can be used by a given Tx UE120a-120c. In Mode 2, a Tx UE120d of Rel.16 / 17 can use a subchannel within the semi-dedicated resource 260 if it senses that it is free. In Mode 2, a Tx UE120a-120c of Rel.18 can use an SL-PR within the semi-dedicated resource 260 if it senses that 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 the selection of SL-PRS resources in the context of different, more detailed embodiments, as will be described in more detail below.

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

[0102] Multiple first-stage allocations, i.e., reservations, can also be transmitted to indicate the allocation of multiple semi-dedicated resources 260. Two first-stage allocations 210a, 210a' can be indicated using two allocations in a first-stage SCI that can be used in legacy systems for resource allocation for two retransmissions of TB. Multiple first-stage allocations can also be indicated by allocating periods to multiple semi-dedicated resources 260. Multiple first-stage allocations 210a, 210a' of multiple semi-dedicated resources 260 with periods can be indicated using RRIs transmitted in a first-stage SCI carried in a PSCCH, which can be used in legacy systems for periodic reserved resource indication for future TB transmissions. Furthermore, a second-stage allocation 210b can also indicate multiple SL-PRS resources in different reserved semi-dedicated resources 260. An example of a two-stage allocation for multiple semi-dedicated resources is shown in Figure 4. For each first-stage allocation 210a, 210a', the second-stage allocations 210b, 210b' may or may not be the same. For example, for a reserved semi-dedicated resource 260 with a certain period of time, the second-stage allocations 210b, 210b' may be the same. That is, the reserved SL-PRS resources within the semi-dedicated resource 260 are the same (see the example in Figure 4). For each first-stage allocation 210a, 210a', there may be second-stage allocations 210b, 210b'. That is, when a reserved semi-dedicated resource 260 is spread across a different number of subchannels, different second-stage allocations 210b, 210b' may be required to indicate different reserved SL-PRS resources within each semi-dedicated resource 260.

[0103] When multiple Rel.18 Tx UE120a-120c allocate, i.e., reserve, different SL-PRS resources within the semi-dedicated resource 260, the Rel.18 Tx UE120a-120c may send first-stage allocations 210a, 210a' for the same semi-dedicated resource 260, as shown in Figure 5. More specifically, as shown in Figure 5, the first and second-stage allocations 210a, 210b relating to the first two-stage allocation may allocate the first and second resources 220, 230. On the other hand, the first and second-stage allocations 210a', 210b' relating to a further two-stage allocation may allocate the first and second resources 220', 230'. Since multiple allocations may be transmitted for the same set of sub-channels, this increases the likelihood that the semi-dedicated resource 260 is used for SL-PRS transmissions and not for data transmissions. If one or more sub-channels in the semi-dedicated resource 260 are allocated by another UE 120b, 120c, Tx UE 120a of Rel. 18 may preempt one or more sub-channels using one or more SL-PRS allocations in the semi-dedicated resource 260. In this case, the priority of SL-PRS transmissions may be configured (in advance) to be higher than data transmissions by other UEs in order to enable the preemption mechanism, as detailed in the embodiments.

[0104] A set of subchannels can be used for both data transmission and SL-PRS transmission, and is therefore referred to as a semi-dedicated resource; that is, they are not entirely dedicated to SL-PRS. However, embodiments disclosed herein enable the use of these resources for SL-PRS transmission. In addition, embodiments disclosed herein enable UE120a-120c to have a common understanding of the SL-PRS resources within the semi-dedicated resources.

[0105] Furthermore, according to embodiments disclosed herein, the source ID and destination ID of an SL-PRS transmission may be transmitted within the same subchannel carrying the first and second stage allocations 210a, 210b, as illustrated in Figure 6a. More specifically, the source ID / destination ID may be carried within the second stage SCI within the subchannel carrying the two-stage allocation. 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 IDs are checked by Rx UE120a-120c of Rel. 18 to determine whether they are the target recipients of the allocated SL-PRS resource to be transmitted within the semi-dedicated resource 260. Sending the source ID and destination ID within the subchannel to which the two-stage assignment is transmitted allows Rx UE120a-120c of Rel.18 to know in advance whether it is the target Rx UE of SL-PRS in semi-dedicated resource 260.

[0106] In the case of multiple first-stage and second-stage allocations, a destination ID and source ID may be provided for each first-stage and second-stage allocation. In the case of multiple first-stage and second-stage allocations, the destination ID and source ID may be the same. In addition, the UE120a-120c that transmits a two-stage allocation for an SL-PRS resource may or may not be the same UE120a-120c that transmits the SL-PRS resource. Therefore, the destination ID may be an identifier for a UE120a-120c different from the UE120a-120c that transmits the two-stage allocation. This has the advantage that a UE120a-120c can transmit a reservation for an SL-PRS resource that should be transmitted by another UE120a-120c.

[0107] A modified version of the embodiment shown in Figure 6a is illustrated in Figure 6b. Here, the first UE120a transmits a two-stage reservation for SL-PRS resources to be transmitted by the second UE120b and the third UE120c. More specifically, through the two-stage allocation shown in Figure 6b, the first UE120a reserves the second resource 230' for the second UE120b and the second resource 230'' for the third UE120c. In this embodiment, UE120a-120c may be part of a group of UEs. The first UE120a is the group leader and may acquire resources for SL-PRS transmissions by UE120a-120c in the group.

[0108] As already described above, the UE120a-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. Furthermore, as already described above, one object of this disclosure is to enable the sharing of resources in a resource pool for data transmission and SL-PRS transmission with different granularities.

[0109] A first main embodiment is shown in Figure 7a, and includes (pre)configuration of UE120a-120c for a semi-dedicated SL-PRS resource 260 and for transmitting a two-stage allocation related to the SL-PRS resource. The configuration may be provided by the network 110, i.e., the base station 110, or by another UE120a-120c, or may be pre-configured within the UE120a-120c. The (pre)configuration of the semi-dedicated resource 260 may include the (pre)configuration and instruction of slots in the resource pool with the semi-dedicated resource 260, as well as the frequency resource location for each of the semi-dedicated resources 260, i.e., the starting subchannel index and the number of consecutive subchannels. In addition, the (pre)configuration may include the periodicity of the semi-dedicated resource 260. Furthermore, the (pre)configuration may include the (pre)configuration of the 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 for 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 the SL-PRS (e.g., Zaduff-Chu sequence, Gold sequence, etc.), sequence identification information, parameters for initial sequence setup, SL-PRS periodicity, resource repetition, comb size, staggering pattern, pseudo-collocation information, and parameters for power control of SL-PRS transmission. The (pre)configuration of the semi-dedicated resources enables UE120a-120c, i.e., UEs of Rel.18, to have a common understanding of the SL-PRS resources in the shared resource pool. In particular, the (pre)configuration of the semi-dedicated resources 260 enables the UE120a-120c to recognize resources that can transmit SL-PRS. The (pre)configured semi-dedicated resources 260 can consist of all subchannels in the slots within the resource pool. In particular, all (pre)configured semi-dedicated resources 260 can each spread across all subchannels of the resource pool.

[0110] Figure 7a further shows the (pre)configuration for two-stage assignment transmission. This (pre)configuration is UE120 a - 120 This indicates to c how the first stage 210a and second stage 210b allocations of the SL-PRS resource should be transmitted. The (pre)configuration of the two-stage allocation may consist of instructions 240 of where and how the first stage allocation 210a and second stage allocation 210b should be transmitted, i.e., their location within the subchannel. The (pre)configuration may indicate that UE120a-120c transmit the first stage allocation 210a in the first stage SCI carried within the PSCCH. The (pre)configuration may include instructions 240 that UE120a-120c reserving the SL-PRS resource may transmit only the first stage allocation 210a of one or more semi-dedicated resources 260. The (pre)configuration may consist of instruction 240 indicating that UE120a-120c, which allocate SL-PRS resources, indicate the existence of a second-stage allocation 210b of SL-PRS resources using one of the reserved bits in the first-stage SCI. The (pre)configuration may consist of instruction 240 indicating that UE120a-120c, which allocate SL-PRS resources, indicate the existence of a second-stage allocation 210b of SL-PRS resources using instructions in the first-stage SCI of a second-stage SCI format associated with SL-PRS. The (pre)configuration may indicate that UE120a-120c transmit a second-stage allocation in the second-stage SCI. The second-stage SCI may be associated with the first-stage SCI that carries the first-stage allocation 210a. The (pre)configuration may indicate that the UE120a-120c transmit the first and second stage allocations 210a and 210b together on a single subchannel. Based on the (pre)configuration for transmitting the two-stage allocation, the UE120a-120c then recognizes how to transmit the two-stage allocation for the SL-PRS resource.

[0111] A second main embodiment is shown in Figure 7b, and includes (pre)configuration of UE120a-120c for a semi-dedicated resource 260 and for receiving a two-stage allocation related to SL-PRS resources. The configuration is provided by network 110 or can be pre-configured within UE120a-120c. The (pre)configuration of the semi-dedicated resource 260 corresponds to the (pre)configuration of the semi-dedicated resource 260 described above in the contest of the first main embodiment. The (pre)configuration of the semi-dedicated resource 260 enables UE120a-120c to have a common understanding of SL-PRS resources in the shared resource pool. In particular, the (pre)configuration of the semi-dedicated resource 260 enables UE120a-120c to recognize resources that can receive SL-PRS.

[0112] Figure 7b further shows a (pre)configuration for receiving two-stage allocations. This (pre)configuration indicates to UE120a-120c where to find and how to determine the first-stage 210a and second-stage 210b allocations of SL-PRS resources, i.e., their location within the subchannels. The (pre)configuration may indicate that the first-stage 210a and second-stage 210b allocations are transmitted together, for example, in a single subchannel. The (pre)configuration may indicate that the first-stage allocation 210a may be located in the first-stage SCI carried in the PSCCH. The (pre)configuration may indicate that the allocation of one or more semi-dedicated resources 260 corresponds to the first-stage allocation 210a of SL-PRS. The (pre)configuration may consist of instructions that UE120a-120c interpret the resource allocation in the first stage SCI as the first stage allocation 210a of the SL-PRS resource, based on the presence of the second stage allocation 210b of the SL-PRS resource. The (pre)configuration may also indicate that the presence of the second stage allocation 210b of the SL-PRS can be indicated by one of the reserved bits in the first stage SCI, or by instructions in the first stage SCI for the second stage SCI format associated with the SL-PRS. The (pre)configuration may also indicate that the presence of the second stage allocation 210b can be indicated by allocations in the first stage SCI for a given number of subchannels, or by allocations in the first stage SCI for a semi-dedicated resource 260. In this case, in one embodiment, it may be configured that only UE120a-120c of Rel.18 are capable of allocating a given number of consecutive subchannels, for example, all subchannels in the RP, for the purpose of allocating SL-PRS resources. The legacy UE120d is then configured not to allocate more than a given number of subchannels for data transmission. The (pre)configuration may also indicate that the second stage allocation 210b is located in the second stage SCI. In particular, the second stage SCI may be associated with the first stage SCI that carries the first stage allocation 210a.Based on the (pre)configuration for receiving two-stage allocations, the UE120a-120c then recognize how to receive two-stage allocations for SL-PRS resources and, therefore, where to receive SL-PRS.

[0113] Regarding the network coverage scenario, a third main embodiment is shown in Figure 8, where the base station or gNB 110 provides UE120a-120d with configurations for SL-PRS and semi-dedicated resources 260 for two-stage allocation. In one embodiment, both configurations are not recognized by Rel.18 UE120a-120c, i.e., legacy UE120d, regarding the configuration related to SL-PRS. This means that the configurations may be release-specific. In Figure 8, the first UE120a (UE1) and the second UE120b (UE2) are assumed to be Rel.18 UEs. The configurations for SL-PRS and semi-dedicated resources 260 for two-stage allocation may be included in an information element that specifies configuration information for a resource pool (e.g., SL-ResourcePool), which is signaled to UE120a and 120b by the network.

[0114] When gNB 110 configures a resource pool for sidelink communication, i.e., for data transmission over a sidelink, gNB 110 may also configure a resource pool for SL-PRS transmission. The resource pool becomes a shared pool for sidelink communication and SL-PRS transmission. The configuration in which the resource pool is a shared resource pool is only possible for UE120a-120c of Rel.18. The configuration in which the resource pool is a shared resource pool may correspond to the configuration of a semi-dedicated resource 260 for SL-PRS and / or for two-stage allocation. Therefore, when UE120a-120c of Rel.18 is given the configuration of a semi-dedicated resource 260 for SL-PRS and / or for two-stage allocation, it recognizes that the resource pool is a shared resource pool. The configuration of a semi-dedicated resource 260 for SL-PRS and for two-stage allocation may be provided for UE120a-120c of Rel.18. Furthermore, the subsequent gNB 110 may provide additional configuration for configuring the resource pool to become a shared resource pool. The legacy UE120d does not recognize shared resource pools.

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

[0116] In addition, gNB 110 provides a two-stage allocation configuration for UE120a-120c of Rel.18 (step 803 in Figure 8). This configuration includes configurations for transmitting and receiving two-stage allocations. This configuration indicates to the Tx UE, e.g., UE120a, where and how to transmit the SL-PRS resources, i.e., the first and second stage allocations 210a and 210b in the subchannel, and to the Rx UE, e.g., UE120b, where and how to find and determine the first and second stage allocations 210a and 210b of the SL-PRS resources. The two-stage allocation configurations correspond to the two-stage allocation configurations for transmitting and receiving described above, respectively, in the context of the first and second main embodiments. In particular, only the Rel.18 UE120a-120c are allowed to reserve a given number of consecutive subchannels, for example, all subchannels in the RP, in order to reserve SL-PRS resources. The legacy UE120d may be configured to reserve up to a given number of subchannels minus one. That is, the legacy UE120d is not permitted to reserve a given number of subchannels for transmission. The Rel.18 UE120a-120c may also be configured to interpret the reservation of a given number of subchannels as a first-stage reservation 210a of SL-PRS, and then to search for a second-stage reservation 210b within the same subchannel to determine the reserved SL-PRS resources within the reserved number of subchannels.

[0117] In the exemplary embodiment shown in Figure 8, it is assumed that UE120a and 120b are configured to transmit / receive first-stage reservations 210a and second-stage reservations 210b in the first-stage SCI and second-stage SCI, respectively. UE120a and 120b are also configured so that the presence of second-stage reservation 20b is indicated using a second-stage SCI format associated with SL-PRS. Based on the presence of the second-stage SCI associated with SL-PRS, UE120a and 120b recognize that the reservation carried in the first-stage SCI corresponds to first-stage reservation 210a of the SL-PRS resource.

[0118] Due to the availability of network coverage, resource selection for SL-PRS resources may be performed using Mode 1 resource allocation. Resource selection can also be performed using Mode 2 resource allocation when within network coverage. In the embodiment shown in Figure 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 in Figure 8). The first UE 120a may also acquire resources based on autonomous resource selection, for example in Mode 2. The first UE 120a may also provide further relevant information that enables the gNB 110 to determine appropriate resources for SL-PRS, i.e., positioning requirements, SL-PRS bandwidth requirements, etc. The gNB 110 provides the first UE 120a with the configuration of the resources (i.e., one subchannel) for the first UE 120a to transmit a two-stage reservation on those resources (step 807 in Figure 8). This configuration may include time and frequency allocation of resources. The gNB 110 provides resources for SL-PRS to the first UE 120a (step 809 in Figure 8) and indicates to the first UE 120a which SL-PRS resource on which semi-dedicated resource 260 should be used for its SL-PRS transmission.

[0119] After gNB 110 provides the configuration of the resources for the two-stage reservation and the associated SL-PRS, the first UE 120a transmits the first and second-stage reservations 210a and 210b together in the configured resources (steps 811 and 813 in Figure 8). More specifically, the first UE 120a transmits the first-stage reservation 210a in the first-stage SCI and the second-stage reservation 210b in the associated second-stage SCI, where the format of the second-stage SCI is associated with the SL-PRS. In the second-stage SCI being 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 in Figure 8). The second UE 120b receives the two-stage reservation and the source ID and destination ID of the SL-PRS. The second UE102b is configured to interpret the two-stage reservation of SL-PRS based on the configuration provided by gNB 110. The second UE120b is also aware of the SL-PRS resource in the semi-dedicated resource 260, where it receives an SL-PRS. Subsequently, the first UE120a transmits an SL-PRS on the configured SL-PRS resource (step 817 in Figure 8). The second UE120b receives the SL-PRS transmitted by the first UE120a. The other UE120c may be configured to transmit an SL-PRS on another SL-PRS resource in the semi-dedicated resource from which the first UE120a transmits an 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 selecting an SL-PRS resource based on a Mode 2 sensing procedure with a two-stage reservation. The complete procedure is provided only for UE120a-120c in Rel. 18, as the legacy UE120d does not recognize SL-PRS in the resource pool.

[0121] The UE120a-120c first searches for the PSCCH (step 901 in Figure 9). Similar to legacy mode 2 sensing, i.e., mode 2 sensing in Rel.16 and Rel.17, the UE120a-120c can search for the PSCCH at all potential locations of the PSCCH in each subchannel within a slot in the resource pool, for example, within a slot in the sensing window. The presence of the PSCCH can be detected based on the PSCCH DMRS. If the PSCCH is found (step 903 in Figure 9), the UE120a-120c decodes the first stage SCI carried by the PSCCH and determines the resource reservation indicated by the first stage SCI (step 905 in Figure 9). The UE120a-120c then needs to determine whether the indicated resource reservation is for data transmission or for SL-PRS transmission. UE120a-120c check whether the resource reservation indicated by the first-stage SCI corresponds to the first-stage reservation 210a of the SL-PRS resource (step 907 in Figure 9). This may be determined in different ways. UE120a-120c may determine that the resource reservation for a given number of sub-channels corresponds to the first-stage reservation 210a of the SL-PRS resource. UE120a-120c may also determine that the resource reservation for the semi-dedicated resource 260 corresponds to the first-stage reservation 210a of the SL-PRS. UE120a-120c may also determine that the resource reservation is the first-stage reservation 210a based on the presence of the second-stage reservation 210b. The presence of the second-stage reservation 210b may be indicated using one of the reserved bits in the first-stage SCI or using an indication in the second-stage SCI format associated with the SL-PRS.

[0122] If UE120a-120c detects a first-stage reservation 210a for an SL-PRS resource, it proceeds to decode the second-stage reservation 210b for the SL-PRS resource (step 913 in Figure 9). Based on its (pre)configuration, UE120a-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 a first-stage SCI. After decoding the second-stage reservation 210b, UE120a-120c determines the reserved SL-PRS resource (step 915 in Figure 9).

[0123] If the resource reservation indicated by the first stage SCI does not correspond to the first stage reservation 210a, UE120a-120c then check whether the resource reservation indicates a reservation for a subchannel within the semi-dedicated resource 260 for SL-PRS (step 909 in Figure 9). The resource reservation may also be based on the periodicity of the reserved resource, i.e., on the RRI. In this way, UE120a-120c can determine the reserved subchannel within the semi-dedicated resource.

[0124] Based on resource reservations within the semi-dedicated resource 260, i.e., the SL-PRS resource, or a subchannel within the semi-dedicated resource, UE120a-120c can then perform resource selection for the SL-PRS resource (step 911 in Figure 9). For this purpose, it can perform resource exclusion based on resource reservations within the semi-dedicated resource 260.

[0125] Figure 10 shows the Mode 2 sensing procedure in UE120a-120c, namely, for selecting a resource for SL-PRS for UE Rel.18. As shown in step 1001 of Figure 10, UE120a-120c may determine the reservation of a subchannel within a semi-dedicated resource, for example, based on the procedure previously described in the context of the fourth primary embodiment. The reserved subchannel may be indicated in the first stage SCI carried in the PSCCH received by UE120a-120c. UE120a-120c also determines the RSRP associated with the reserved subchannel. The RSRP may be measured based on the DMRS in the PSCCH carrying the first stage SCI indicating the reserved subchannel. This RSRP should be considered for resource exclusion in the Mode 2 sensing procedure. UE120a-120c are (pre-configured) to measure the RSRP associated with resource reservations based on the PSCCH DMRS of the PSCCH, which carries the first-stage SCI indicating resource reservations. In particular, the (pre-configuration) for measuring RSRP based on the PSCCH DMRS for resource selection may be part of the (pre-configuration) of the resource pool. In this case, all UE120a-120c using the resource pool can measure the 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, namely sl-RS-ForSensing. The (pre-configuration) may be indicated within the (pre-configuration) of the SL-ResourcePool information element, i.e., by setting the parameter sl-RS-ForSensing-r16 to pscch. In addition, UE120a-120c may determine the priority associated with transmission in reserved subchannels. The priority may be indicated in the first-stage SCI indicating resource reservations for subchannels.

[0126] As illustrated in step 1003 of Figure 10, UEs 120a-120c may determine the reservation of an SL-PRS resource, for example, based on a procedure previously described in the context of the fourth primary embodiment. The reserved SL-PRS resource may be determined using a two-stage reservation, i.e., a first-stage reservation 210a carried in the first-stage SCI and a second-stage reservation 210b carried in the second-stage SCI. UEs 120a-120c may also determine the RSRP associated with the reserved SL-PRS resource. The RSRP associated with the reserved SL-PRS resource may be measured based on the SL-PRS transmitted in the reserved SL-PRS resource. 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 carrying 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. UE120a-120c may be (pre-configured) to measure the RSRP associated with the first-stage reservation 210a of an SL-PRS resource based on the PSCCH DMRS of the PSCCH, which carries the first-stage SCI indicating the first-stage reservation 210a. In particular, the (pre-configuration) for measuring RSRP based on the PSCCH DMRS for resource selection may be part of the (pre-configuration) of the resource pool for UE120a-120c in Rel. 18. The (pre-configuration) may be shown using higher-level parameters. It may be shown within the (pre-configuration) of the SL-ResourcePool information element. In addition, UE120a-120c may determine the priority associated with the reserved SL-PRS resource. The priority may be shown in the first-stage SCI, or in the second-stage SCI associated with the first-stage SCI carrying the first-stage reservation 210a.

[0127] As explained in step 1005 of Figure 10 、UE120a-120c then performs resource selection for SL-PRS resources based on reserved subchannels in the semi-dedicated resource 260, the RSRP associated with the reserved subchannels, the priority associated with transmissions on the reserved subchannels, reserved SL-PRS resources, the RSRP associated with the reserved SL-PRS resources, and optionally, the priority associated with the reserved SL-PRS resources. UE120a-120c first determines candidate SL-PRS resources. To determine candidate resources, UE120a-120c can exclude resources based on reserved resources in the semi-dedicated resource 260, as well as the associated RSRP and priority of the reserved resources. For example, if more than X subchannels are reserved in the semi-dedicated resource 260, UE120a-120c can exclude all SL-PRS resources in the semi-dedicated resource 260. For resource exclusion, UE120a-120c may be configured (in advance) to exclude resources based on the relevant RSRP and priority of the reserved subchannels. For example, if more than X subchannels are reserved in a semi-dedicated resource 260 having an RSRP above the RSRP threshold RSRP1, UE120a-120c may then exclude all SL-PRS resources in the semi-dedicated resource 260. Furthermore, if more than X subchannels are reserved in a semi-dedicated resource 260 having a priority higher than the priority of the SL-PRS that UE120a-120c wishes to transmit, UE120a-120c may then exclude all SL-PRS resources in the semi-dedicated resource 260. Exclusion of the semi-dedicated resource 260 may be based on both the conditions for the relevant RSRP and the priority of the reserved resources.

[0128] UE120a-120c may also exclude SL-PRS resources based on reserved SL-PRS resources. That is, if an SL-PRS resource in semi-dedicated resource 260 is reserved, UE120a-120c will exclude this SL-PRS resource. For resource exclusion, UE120a-120c may consider the RSRP and priority of reserved SL-PRS resources. For example, UE120a-120c may exclude an SL-PRS resource in semi-dedicated resource 260 if it has an associated RSRP that exceeds the RSRP threshold RSRP2. Furthermore, UE120a-120c may exclude an SL-PRS resource in semi-dedicated resource 260 if it has an associated priority that exceeds the priority of the SL-PRS that UE120a-120c wishes to transmit. Exclusion of semi-SL-PRS resources may be based on both the conditions for the associated RSRP and the priority of the reserved SL-PRS resource.

[0129] UE120a-120c can also exclude resources based on half-duplex constraints similar to those in the legacy mode 2 sensing procedure. SL-PRS resources remaining after resource exclusion, i.e., within the selection window, are considered candidate SL-PRS resources. UE120a-120c can then select SL-PRS resources from among the candidate SL-PRS resources, for example, randomly. If the proportion of candidate resources in half-duplex mode falls below a (pre-configured) threshold, UE120a-120c can increase the RSRP threshold used to exclude resources by a given amount, e.g., 3dB, and repeat the procedure for resource exclusion. The values ​​of X, RSRP1, and RSRP2 can be (pre-configured) for the UE, as shown in Figure 10.

[0130] Figure 11 shows a flowchart illustrating another embodiment. Here, only the reservation of SL-PRS resources for resource selection using Mode 2 is considered. That is, resources are excluded based on reserved SL-PRS resources, but not based on reserved subchannels within the dedicated resource. The following description relating to steps 1101 and 1103 in Figure 11 is similar to the description of the previous embodiment, but does not consider reserved subchannels within the semi-dedicated resource. In the embodiment shown in Figure 11, UE120a-120c of Rel. 18 may reserve a resource for SL-PRS in the semi-dedicated resource 260 even if one or more subchannels within the semi-dedicated resource 260 are reserved by another UE120a-120d for data transmission. UE120a-120c of Rel. 18 may ignore the reservation of subchannels within the semi-dedicated resource 260 (i.e., for data transmission). UE120a-120c of Rel. 18 does not need to be aware of the reservation of subchannels within the semi-dedicated resource 260. If one or more subchannels are reserved within the semi-dedicated resource 260, UE120a-120c of Rel.18 may wish to transmit SL-PRS resources there, which could lead to a collision, i.e., a collision between the SL-PRS transmission of UE120a-120c of Rel.18 and the data transmission of other UE120a-120d. To avoid this, a preemption mechanism may be considered, where SL-PRS transmission takes precedence over data transmission. For this purpose, the priority of SL-PRS is configured (in advance) to be higher than the priority of data transmission, i.e., different traffic types. For this purpose, the preemption mechanism may be enabled in the resource pool. Preemption in the resource pool can be enabled using parameters in the SL-ResourcePool information element, e.g., sl-PreemptionEnable-r16, which provides the (pre)configuration of the resource pool.

[0131] Furthermore, a legacy UE120d intended to transmit data may be configured (in advance) to check whether another UE120a-120d has reserved the same subchannel for a higher-priority transmit. In other words, a preemption mechanism is enabled. With the preemption mechanism enabled, collisions can be avoided because a UE120a-120d will drop its subchannel reservation within a semi-dedicated resource if it receives a reservation for a transmit with a higher priority than the intended transmit of the UE120a-120d (from a Rel.18 UE120a-120c wishing to transmit SL-PRS).

[0132] Furthermore, the Rel.18 UE120a-120c units intended to transmit data may be configured (in advance) to exclude all resources from the semi-dedicated resource 260 during resource selection in Mode 2. The Rel.18 UE120a-120c units may recognize the semi-dedicated resource 260. In this way, the Rel.18 UE120a-120c units do not select subchannels within the semi-dedicated resource 260 for data transmission.

[0133] Figure 12 shows a flowchart illustrating processing steps for a further embodiment that considers resource selection for SL-PRS and for resources carrying two-stage reservations. After UE120a-120c are triggered to send SL-PRS, for example, by the UE's own upper layer or by another UE120a-120c, UE120a-120c select an SL-PRS resource (step 1201 in Figure 12). Resource selection for the SL-PRS resource may be performed using mode 1 resource allocation or mode 2 resource allocation. UE120a-120c also select a resource for sending a two-stage reservation (step 1203 in Figure 12). The resource for sending a two-stage reservation may consist of a single subchannel. Resource selection for this resource may be performed using mode 1 resource allocation or mode 2 resource allocation. After selecting the SL-PRS resource and the resource that will carry the two-stage reservation, UE120a-120c transmit the two-stage reservation on the selected resource and the SL-PRS on the selected SL-PRS resource (step 1205 in Figure 12). UE120a-120c can transmit the two-stage reservation using a higher transmit power compared to the transmit power of the data transmission, i.e., the PSSCH. In this exemplary embodiment, the UE120a-120c transmitting the two-stage reservation for the SL-PRS resource may be the same UE120a-120c transmitting the SL-PRS resource (step 1207 in Figure 12). However, as already mentioned, this is not always the case.

[0134] Figure 13 shows a further embodiment relating to the transmission of a two-stage reservation in a selected subchannel. The first-stage reservation for SL-PRS is transmitted in a first-stage SCI carried by a PSCCH in the selected subchannel. In NR V2X Rel. 16 / 17, the first-stage SCI may indicate a reservation for the initial transmission of TB (i.e., the current transmission), as well as reservations for one or two subsequent resources, for example, for retransmission of TB. The reservation includes indications for the frequency resource location of the transmission (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). According to embodiments disclosed herein, a two-stage reservation relating to an SL-PRS resource may be transmitted in a single subchannel. The first-stage reservation 210a is transmitted in a first-stage SCI carried by a PSCCH transmitted in the subchannel, as shown in Figure 13. The first-stage reservation 210a indicates a reservation for a semi-dedicated resource 260, which in this example occupies all subchannels in the resource pool. Since a two-stage reservation transmission occupies one subchannel, the reservation for the current transmission of the two-stage reservation (i.e., the initial transmission) only needs to indicate that one subchannel is occupied. On the other hand, the first-stage reservation 210a reserves all subchannels in the semi-dedicated area, i.e., all subchannels in the resource pool, for the transmission of SL-PRS. In NR V2X of Rel. 16 / 17, 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, a 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 a resource reservation carried by the first-stage SCI, which is usually used to indicate a resource reservation for a retransmission. This means that the current transmission of the two-stage reservation also occupies the same number of channels as the reserved semi-dedicated resources.For this purpose, according to embodiments disclosed herein, UE120a-120c of Rel. 18 are configured (pre-configured) to ignore larger implicit reservations for the transmission of a two-stage reservation. After UE120a-120c has determined that a first-stage reservation 210a exists (i.e., has detected the presence of a second-stage reservation 210b), it knows that the reservation indicated in the first-stage SCI is associated with SL-PRS (i.e., the first-stage reservation 210a), and therefore can ignore larger "dummy" reservations relating to the current transmission of the two-stage reservation. It only decodes the information in the subchannel having PSCCH that carries the first-stage SCI associated with the SL-PRS reservation. Thus, the larger reservation relating to the current transmission of the two-stage reservation is a dummy reservation. The UE120a-120c in Rel.18 can also be configured (pre-configured) to ignore this larger "dummy" reservation for their Mode 2 sensing procedures.

[0135] Figure 14 shows a flowchart illustrating one embodiment of SL-PRS reception. UE120a-120c first check whether they are (pre-configured) to receive SL-PRS (step 1401 in Figure 14). This (pre-configuration) may be per UE120a-120c or per resource pool. UE120a-120c may be (pre-configured) not to receive SL-PRS to avoid a two-stage reservation search and to reduce their power consumption. If UE120a-120c is (pre-configured) to receive SL-PRS, UE120a-120c then searches for PSCCH (step 1403 in Figure 14). Similar to the legacy procedures in Rel. 16 and Rel. 17, UE120a-120c may search for PSCCH at all potential locations of PSCCH in each subchannel within the resource pool slot. The presence of a PSCCH can be detected based on the PSCCH DMRS. If a PSCCH is found (step 1405 in Figure 14), UE120a-120c decode the first-stage SCI carried by the PSCCH and determine the resource reservation indicated by the first-stage SCI (step 1407 in Figure 14). UE120a-120c then determine whether the indicated resource reservation is for data transmission or for SL-PRS transmission (step 1409 in Figure 14). UE120a-120c check whether the resource reservation indicated by the first-stage SCI corresponds to the first-stage reservation 210a of the SL-PRS resource (step 1409 in Figure 14). This can be determined in different ways. UE120a-120c may determine that resource reservations for a given number of sub-channels correspond to the first-stage reservation 210a of the SL-PRS resource. UE120a-120c may also determine that the resource reservation for the semi-dedicated resource 260 corresponds to the first-stage reservation 210a of SL-PRS. UE120a-120c may also determine that the resource reservation is the first-stage reservation 210a based on the existence of the second-stage reservation 210b.The presence of the second-stage reservation 210b may be indicated using one of the reserved bits in the first-stage SCI, or using the indication of the second-stage SCI format associated with SL-PRS.

[0136] When UE120a-120c detects a first-stage reservation for an SL-PRS resource, it proceeds to determine the destination ID of the reserved SL-PRS resource (step 1411 in Figure 14). Based on its (pre)configuration, UE120a-120c knows where and how to find the destination ID. 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, UE120a-120c checks whether it is the target Rx UE for SL-PRS (step 1413 in Figure 14), i.e., whether UE120a-120c is the intended receiver for SL-PRS. If UE120a-120c is the target Rx UE for the reserved SL-PRS resource, it proceeds to determine the second-stage reservation 210b for the SL-PRS resource (step 1415 in Figure 14). Based on its (pre)configuration, UE120a-120c knows where and how to find the second-stage reservation 210b. The second-stage reservation 210b may be carried on the same subchannel that carries the first-stage reservation 210a. In particular, the second-stage reservation 210b may be carried on the second-stage SCI associated with the first-stage SCI. After decoding the second-stage reservation 210b, UE120a-120c determine the reserved SL-PRS resources.

[0138] After UE120a-120c has determined the first and second stage reservations 210a and b for the SL-PRS resource, it knows which semi-dedicated resource 260 and which SL-PRS resource should receive the SL-PRS. (Step 1417 in Figure 14).

[0139] Figure 15 shows one embodiment relating to the time and frequency allocation of several SL-PRS resources within a semi-dedicated resource. In the example shown in Figure 15, eight SL-PRS resources are depicted, each SL-PRS resource spread across four symbols, and all subchannels within the semi-dedicated resource are arranged in a comb pattern. For simplicity, only the frequency chunks within the semi-dedicated resource are shown, but the comb pattern may be repeated in the rest of the semi-dedicated resource. Figure 15 also shows automatic gain control (AGC) symbols and gap or guard symbols. The AGC symbol allows the Rx UE to adjust the dynamic range based on the received signal. The guard symbol allows switching from transmit to receive or receive to transmit. Due to the half-duplex constraint, UE120a-120c do not need to receive SL-PRS when it is transmitting SL-PRS simultaneously, i.e., in the same symbol. Therefore, UE120a-120c transmitting SL-PRS resource 1 cannot receive SL-PRS resource 2. However, a UE120a-120c transmitting SL-PRS resource 1 can receive SL-PRS resource 5. The illustrated example allows a UE120a-120c to transmit SL-PRS on SL-PRS resources 1, 2, 3, or 4, and to receive SL-PRS on SL-PRS resources 5, 6, 7, or 8. This allows a UE120a-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 a semi-dedicated resource, i.e., by having 12 SL-PRS resources followed by one AGC symbol (e.g., in a comb pattern), and finally a guard symbol among 14 symbols in the slot.

[0140] Figure 16 shows a further embodiment for a group of UE120a-120c in a scenario outside network coverage. Figure 16 shows a signaling diagram in which the configuration of a semi-dedicated resource (step 1601 in Figure 16) is performed dynamically among the group of UE120a-120c. This allows the UE120a-120c in the group to have a common understanding of the SL-PRS resource within the group. This configuration may be provided by one UE120a to the other UE120b, 120c, or the UE120a-120c may agree together on the configuration. A preconfiguration for sending and receiving two-stage reservations is also shown (step 1603 in Figure 16). The preconfiguration may be performed as in the embodiments described above. The first UE120a (UE1) may instruct the second UE120b (UE2) to select an SL-PRS resource for the first UE120a (step 1605 in Figure 16). The second UE 102b selects resources for transmitting a two-stage reservation, as well as SL-PRS resources for the first UE and the second UEs 120a and 120b (steps 1607 and 1609 in Figure 16). For example, the second UE 120b selects two SL-PRS resources within one semi-dedicated resource 260 for two SL-PRS transmissions, namely 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 one semi-dedicated resource, as described in a previous embodiment. Resource selection may be performed using mode 2 resource allocation, i.e., as described in a previous embodiment. UEs 120a-120c may also be within network coverage and may select resources based on mode 2 resource allocation. Second UE102b selects a subchannel to transmit a two-stage reservation, as well as the source IDs and destination IDs of two SL-PRS resources. The two selected SL-PRS resources are indicated as SL-PRS1 and SL-PRS2, respectively, to be transmitted by first UE120a and second UE120b.Subsequently, the second UE120b transmits a two-stage reservation (steps 1611a, 1611b and 1613a, 1613b in Figure 16) as well as the source IDs and destination IDs for SL-PRS1 and SL-PRS2 on the selected subchannel (steps 1615a, 1615b in Figure 16), which is received by the first UE120a and the third UE120c (UE3). The first UE120a and the third UE120c determine that a first-stage reservation 210a for the SL-PRS resource exists. The third UE120c also determines, based on the destination ID, that it is the target receiver for the two SL-PRS resources. The first UE120a determines, based on the source ID of SL-PRS1, that the second UE120b has reserved an SL-PRS resource for the first UE120a. The first UE120a then transmits SL-PRS1 on the selected SL-PRS resource (step 1619 in Figure 16). The second UE120b then transmits SL-PRS2 on the selected SL-PRS resource (step 1617 in Figure 16). The third UE120c 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 UE120a is configured to check the two-stage reservation transmitted by the second UE120b.

[0141] Figure 17 is a flowchart illustrating a method 1700 according to one embodiment for transmitting a two-stage allocation relating to time and frequency resources for transmitting one or more sidelink positioning reference signals. The method 1700 comprises transmitting an allocation using the two-stage allocation of step 1701, which includes a first-stage allocation 210a relating to one or more first time and frequency resources 220 from a plurality of time and frequency resources 200 having a first granularity, and a second-stage allocation 210b relating to one or more second time and frequency resources 230 from a plurality of time and frequency resources 200 having a second granularity, where one or more second time and frequency resources 230 are subsets of one or more first time and frequency resources 220.

[0142] Figure 18 is an explanatory flowchart illustrating a method 1800 according to one embodiment for receiving a two-stage allocation of time and frequency resources for transmitting one or more sidelink positioning reference signals. The method 1800 includes step 1801 of receiving an allocation using a two-stage allocation, which includes a first-stage allocation 210a relating to one or more first time and frequency resources 220 out of a plurality of time and frequency resources 200 having a first granularity, and a second-stage allocation 210b relating to one or more second time and frequency resources 230 out of a plurality of time and frequency resources 200 having a second granularity, where one or more second time and frequency resources 230 are subsets of one or more first time and frequency resources 220.

[0143] Those skilled in the art will understand that the “blocks” (“units”) in various figures (of methods and apparatus) represent or illustrate the functionality of embodiments of the present disclosure (not necessarily individual “units” in hardware or software), and therefore equally illustrate the functionality or features of embodiments of apparatus and embodiments of methods (units = steps).

[0144] It should be understood that the systems, apparatus, and methods disclosed in some embodiments provided in this application may be implemented in other ways. For example, the described embodiments of the apparatus are merely illustrative. For example, unit divisions are merely logical functional divisions and may be different divisions in actual implementations. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not performed. In addition, the mutual coupling, direct coupling, or communication connection shown or described may be implemented by using some interfaces. Indirect coupling or communication connection between apparatus or units may be implemented electronically, mechanically, or in other forms.

[0145] Units described as separate parts may or may not be physically separate, and parts shown as units may or may not be physical units, and may be located in one location or distributed across multiple network units. Some or all of the units may be selected as needed to achieve the objectives of the solution according to the embodiment.

[0146] In addition, the functional units in the embodiments of this disclosure may be integrated into a single processing unit, or each unit may exist physically independently, or two or more units may be integrated into a single unit.

Claims

1. User equipment, UE, for transmitting time and frequency resource allocations for transmitting one or more sidelink positioning reference signals, SL-PRS, The UE is configured to transmit the assignment using a two-stage assignment process. The aforementioned two-stage allocation includes a first-stage allocation relating to one or more first-order time and frequency resources among a plurality of time and frequency resources having a first-order granularity, and a second-stage allocation relating to one or more second-order time and frequency resources among the plurality of time and frequency resources having a second-order 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 aforementioned UE is configured to transmit first-stage sidelink control information, SCI, and, The first stage SCI includes the first stage allocation, The user device according to claim 1.

3. The aforementioned UE is configured to transmit second-stage sidelink control information, SCI, and, The second stage SCI includes the second stage assignment, The user device according to claim 2.

4. The first stage SCI includes information indicating the existence of the second stage assignment, The user device according to 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 stage SCI include information indicating the existence of the second stage allocation. The user device according to claim 4.

6. The aforementioned multiple time and frequency resources comprise multiple slots and multiple subchannels, The user device according to any one of claims 1 to 5.

7. The UE is configured to transmit the two-stage assignment within one or more subchannels of the plurality of slots and plurality of subchannels. The user device according to claim 6.

8. The UE is configured to transmit control information associated with one or more subchannels of the plurality of slots and one or more SL-PRS within the plurality of subchannels that carry the second stage allocation. The user device according to claim 7.

9. The UE is configured to transmit the two-stage allocation within one slot before one or more slots containing the first time and frequency resources. The user device according to claim 6.

10. The UE is configured to transmit the two-stage allocation within a single slot containing the first time and frequency resources. The user device according to claim 6.

11. The UE is configured to transmit one or more SL-PRS in the second time and frequency resources, as indicated by the second stage allocation. The user device according to any one of claims 1 to 5.

12. The UE is configured to transmit one or more SL-PRS in the second time and frequency resources, as indicated by the first stage allocation and the second stage allocation. The user device according to any one of claims 1 to 5.

13. The UE is configured to transmit time and frequency resource allocations using the two-stage allocation for one or more transmissions relating to the one or more SL-PRS by another UE. The user device according to any one of claims 1 to 5.

14. The first granularity is a subchannel of the slot, The user device according to any one of claims 1 to 5.

15. The plurality of time and frequency resources comprises one or more SL-PRS resources having the second granularity. The user device according to claim 14.

16. The aforementioned plurality of time and frequency resources include one or more SL-PRS resources, The aforementioned UE and / or another UE is configured to transmit the one or more SL-PRS in one or more SL-PRS resources of the one or more SL-PRS resources. The user device according to any one of claims 1 to 5.

17. The UE is configured to transmit the two-stage allocation in one or more of the multiple time and frequency resources that are different from the one or more SL-PRS resources. The user device according to claim 16.

18. The UE is configured to transmit data in one or more time and frequency resources among the multiple time and frequency resources, including one or more of the one or more SL-PRS resources. The user device according to 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 of the multiple time and frequency resources. The user device according to claim 17.

20. The aforementioned UE is configured to receive configuration information relating to one or more SL-PRS resources from a base station or from another UE. The user device according to claim 15.

21. The UE is configured to transmit one or more identifiers relating to one or more UEs intended to transmit one or more SL-PRS in the second time and frequency resources. The user device according to any one of claims 1 to 5.

22. The UE is configured to transmit one or more identifiers relating to one or more UEs, intended to receive the one or more SL-PRS in the second time and frequency resource. The user device according to any one of claims 1 to 5.

23. A method for transmitting time and frequency resource allocations for the transmission of one or more sidelink positioning reference signals, SL-PRS, the method being: The process includes the step of using a two-stage assignment to transmit the assignment, The aforementioned two-stage allocation includes a first-stage allocation relating to one or more first-order time and frequency resources among a plurality of time and frequency resources having a first-order granularity, and a second-stage allocation relating to one or more second-order time and frequency resources among the plurality of time and frequency resources having a second-order 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. User equipment, UE, for receiving time and frequency resource allocations for transmitting one or more sidelink positioning reference signals, SL-PRS, The UE is configured to receive the assignment using a two-stage assignment process. The aforementioned two-stage allocation includes a first-stage allocation relating to one or more first-order time and frequency resources among a plurality of time and frequency resources having a first-order granularity, and a second-stage allocation relating to one or more second-order time and frequency resources among the plurality of time and frequency resources having a second-order 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. A method for receiving time and frequency resource allocations for the transmission of one or more sidelink positioning reference signals, SL-PRS, wherein the method is The process includes the step of receiving the assignment using a two-stage assignment, The aforementioned two-stage allocation includes a first-stage allocation relating to one or more first-order time and frequency resources among a plurality of time and frequency resources having a first-order granularity, and a second-stage allocation relating to one or more second-order time and frequency resources among the plurality of time and frequency resources having a second-order granularity. The one or more second time and frequency resources are a subset of the one or more first time and frequency resources. method.

26. A computer-readable storage medium that stores program code, When the aforementioned program code is executed by a computer or processor, The method according to claim 23 or the method according to claim 25 is to be carried out by the computer or the processor. A computer-readable storage medium.

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