Abstract: In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a UE. The UE obtains a number (N) of transmissions of a sidelink synchronization signal block (S-SSB) with repetitions in a frequency domain. The UE obtains a gap in the frequency domain between two adjacent transmissions of the N transmissions. The UE maps the N S-SSBs into N sets of resources in which two adjacent sets are separated by the gap. The N sets of resources overlap in time domain. The UE performs the N transmissions of the S-SSB using the N sets of resources.

Abstract: Apparatus and methods are provided for sidelink (SL) transmission in SL unlicensed frequency bands (SL-U). In one novel aspect, one and/or multiple starting symbols within a slot is supported for SL-U to start a transmission. In one embodiment, the physical sidelink control channel (PSCCH) is configured to be transmitted on each starting symbol within a slot. In another embodiment, only physical sidelink shared channel (PSSCH) is transmitted on the starting symbols other than the first starting symbol within a slot. In one novel aspect, PSCCH is transmitted within one sub-channel. In one embodiment, the PSCCH is transmitted on a fixed subchannel of each RB set of the occupied BWP. In another embodiment, the PSCCH is transmitted on a fixed subchannel of one preconfigured RB set. In another novel aspect, the UE sets the CAPC value to be one for the physical sidelink feedback channel (PSFCH).

Abstract: Apparatus and methods are provided RLF detection for SL-U transceiving. In one novel aspect, HARQ-based RLF detection and/or LBT-based RLF detection is performed for SL-U RLF. HARQ based SL-U RLF procedure increases DTX for each PSSCH or PSCCH and disregards detected DTX on PSFCH or increases DTX for each PSFCH absence. In one embodiment, a DTX threshold value is modified. In one embodiment, the LBT based RLF procedure detects and reports an LBT failure for an RB set by the PHY layer; determines a consistent LBT (C-LBT) for the RB set based on a C-LBT threshold at the MAC layer and determines an RLF when all configured RB sets for the SL connection is determined to be C-LBT. In another novel aspect, multiple PSFCH occasions are configured for one PSSCH/PSCCH at a consecutive symbol level, a non-consecutive symbol level, a consecutive slot level or a non-consecutive slot level.

Abstract: Apparatus and methods are provided for SL-U resource allocation and usage. In one novel aspect, one or two candidate starting symbols are configured. In one embodiment, the candidate starting symbols are preconfigured for AGC or a repetition of PSCCH/PSSCH data. In one embodiment, CAPC value is mapped from a PQI with a bitmap or a mapping table. The CAPC value is mapped from the PQI based on one or more elements comprising a resource type, a default priority level, a packet delay budget (PDB) requirement, and packet data error rate. In one novel aspect, multi-consecutive-slot (MCSt) resources are reserved for SL-U by applying one or more resource selection rules, comprising selecting, by a MAC layer, resources excluded by a PHY layer in an exclusion step, increasing one or more selection thresholds comprising a resource exclusion RSRP threshold, a remaining resource portion after resource exclusion threshold, and a RSRP threshold.

Abstract: Various solutions for enhancements on sidelink (SL) over unlicensed spectrum (SL-U) communication are described. An apparatus may operate in a first transmission mode for an SL-U communication with a peer apparatus. The apparatus may determine that a condition associated with the SL-U communication is met. The apparatus may stay in the first transmission mode or switch from the first transmission mode to a second transmission mode for the SL-U communication responsive to the determining.

Abstract: Apparatus and methods are provided for sidelink synchronization signal pattern in the unlicensed frequency bands (SL-U). In one novel aspect, the UE, configured one or more SL resource pools, determines an applicability of the occupied channel bandwidth (OCB), and configures OCB-compliance SL synchronization signal block (S-SSB) based on the OCB requirement, wherein the OCB-compliance S-SSB is included in or excluded from the one or more SL resource pools to the meet the OCB requirements. In one embodiment, the S-SSB is excluded from the SL resource pool and the S-SSB is transmitted repeatedly in the frequency domain multiple times or transmitted interlaced in frequency domain based on the OCB requirement. In one embodiment, the SL synchronization signal blocks are included in the SL resource pool and are multiplexed with other transmissions in the frequency domain multiplexed (FDM) mode or time domain multiplexed (TDM) mode.

Abstract: Examples pertaining to power control of sidelink (SL) on unlicensed spectrum (SL-U) in mobile communications are described. A user equipment (UE) communicates in a SL-U. The UE performs a transmit power control (TPC) such that a power spectral density (PSD) limit is not exceeded in communicating in the SL-U.

Abstract: A method can include determining a resource allocation framework for sidelink communication, allocating resources in a resource grid for PSCCH, PSSCH, or PSFCH based on the framework, and transmitting a sub-channel index and an RB set index to indicate resource allocation information of the PSCCH, the PSSCH, or the PSFCH over an SL-U spectrum, wherein the resource allocation framework comprising at least one SL-U CC including an SL-U BWP including X indexed RBs, the SL-U BWP being divided into Y indexed RPs and at least one inter-RP GB when to Y being an integer greater than 1, each RP being divided into N indexed RB sets and at least one intra-cell GB when N being an integer greater than 1, K indexed interlaces configured to map the RBs cyclically per RP, and sub-channels configured to map the interlaces per RB set and cyclically across different RB set per RP.

Abstract: A method can include determining a resource allocation framework for sidelink communication, allocating resources in a resource grid for PSCCH, PSSCH, or PSFCH based on the framework, and transmitting at least one sub-channel index and at least one RB set index to indicate resource allocation information of PSCCH, PSSCH, or PSFCH over an SL-U spectrum, wherein the resource allocation framework comprising at least one SL-U CC including an SL-U BWP including X indexed RBs, the SL-U BWP being divided into Y indexed RPs and at least one inter-RP GB when Y being an integer greater than 1, each RP being divided into N indexed RB sets and at least one intra-cell GB when N being an integer greater than 1, K indexed interlaces configured to map the RBs cyclically per BWP, and sub-channels configured to map the interlaces per RB set and cyclically across different RB set per RP.

Abstract: A method for performing sidelink transmission over an unlicensed band is provided. The method includes performing a first-type listen-before-talk (LBT) process on the unlicensed band to obtain a channel occupancy time (COT) for the sidelink transmission. The first-type LBT process includes a random backoff process. Duration of the random backoff process is determined by a randomly generated LBT counter. The method further includes determining, based on a result from a sensing operation performed on the unlicensed band within a sensing window, a plurality of candidate sidelink resources on the unlicensed band within a sidelink resource selection window. The method also includes selecting, based on a completion time point of the first-type LBT process, a sidelink resource from the plurality of candidate sidelink resources. The method also includes performing the sidelink transmission within the obtained COT on the selected sidelink resource.

Abstract: A method can include determining candidate sidelink resources by a user equipment (UE) for sidelink transmission on an unlicensed band from a sidelink resource selection window based on results of a sensing operation on the unlicensed band during a sidelink sensing window, selecting a sidelink resource from the candidate sidelink resources, performing a listen-before-talk (LBT) process on the unlicensed band to obtain a channel occupancy time (COT), and performing a sidelink transmission within the COT using the first sidelink resource. The selection of the sidelink resource can be based on an LBT time that is a predicted duration of a random backoff process of the first LBT process. Also, the first sidelink resource can be selected from the candidate sidelink resources without randomization.

Abstract: A method can include determining candidate sidelink resources by a user equipment (UE) for sidelink transmission on an unlicensed band from a sidelink resource selection window based on results of a sensing operation on the unlicensed band during a sidelink sensing window, selecting a sidelink resource from the candidate sidelink resources, performing a listen-before-talk (LBT) process on the unlicensed band to obtain a channel occupancy time (COT), and performing a sidelink transmission within the COT using the first sidelink resource. The selection of the sidelink resource can be based on an LBT time that is a predicted duration of a random backoff process of the first LBT process. Also, the first sidelink resource can be selected from the candidate sidelink resources without randomization.

Abstract: Apparatus and methods are provided for sidelink resource selection in unlicensed frequency bands. In one novel aspect, a combination of SL resource selection procedure and a listen-before-talk (LBT) procedure are used for resource selection in unlicensed frequency bands. In one embodiment, the LBT procedure is performed after the SL resource selection procedure. In one embodiment, the candidate resource selected by the SL resource selection procedure has an overbooking resource size larger than or equal to a resource size required for the SL data transceiving. In another embodiment, the overbooking resource size is dynamically determined based on one or more preconfigured conditions comprising an LBT failure probability, channel loading status information, and channel congestion control information. In yet another embodiment, the candidate resources are multi-consecutive-slot (MCSt) resources with configured multiple consecutive resource blocks.