WO2024148154A1 - Licensed assisted sidelink communications - Google Patents

Abstract

A method of sidelink communication includes receiving, by a first user equipment (UE), configuration parameters of a plurality of carriers for sidelink communications; and communicating with a second UE via the plurality of carriers and using the configuration parameters. In the method, at least one first carrier, in the plurality of carriers, operates in a licensed spectrum; at least one second carrier, in the plurality of carriers, operates in unlicensed spectrum; and at least one type of control information is transmitted via the at least one first carrier.

Description

LICENSED ASSISTED SIDELINK COMMUNICATIONS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority under 35 USC §119(e) from U.S. Provisional Patent Application No. 63/437,307, filed on January 5, 2023, (“the provisional application”); the content of the provisional patent application is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] The present invention is directed to 5G, which is the 5^th generation mobile network. It is a new global wireless standard after 1G, 2G, 3G, and 4G networks. 5G enables networks designed to connect machines, objects and devices.

[0003] The invention is more specifically directed to systems and/or methods for enhancing existing processes for control signaling when the user equipments (UEs) operate according to unlicensed/ shared spectrum (SL-U) processes. Example embodiments enhance the existing processes for control signaling when the UEs operate according to SL-U processes.

[0004] In an embodiment, the invention provides a method of sidelink communication includes receiving, by a first user equipment (UE), configuration parameters of a plurality of carriers for sidelink communications; and communicating with a second UE via the plurality of carriers and using the configuration parameters. In the method, at least one first carrier, in the plurality of carriers, operates in a licensed spectrum; at least one second carrier, in the plurality of carriers, operates in unlicensed spectrum; and at least one type of control information is transmitted via the at least one first carrier. The carriers of the plurality of carriers may be configured for sidelink carrier aggregation. Preferably, the carriers of the plurality of carriers comprise a sidelink primary carrier and a sidelink secondary carrier. P0079PCT BABAEI, Alireza

[0005] The at least one first carrier may comprise the sidelink primary carrier. The at least one second carrier may comprise the sidelink secondary carrier. In one form, the at least one type of control information may only be only transmitted via the at least one first carrier. The at least one type of control information is preferably only transmitted via a licensed carrier. Communicating over the at least one second carrier may rely upon a channel access mechanism. The channel access mechanism may be based on a listen-before-talk process. Communicating over the at least one second carrier can be based on the listen-before-talk process indicating a clear channel. The configuration parameters may comprise one or more listen-before-talk parameters, and wherein the listen-before-talk process may be based on the one or more listen-before-talk parameters. The one or more listen-before-talk parameters may indicate a duration of clear channel assessment for an unlicensed channel.

[0006] Preferably, configuration parameters can indicate a plurality of resources pools for sidelink communications via the plurality of carriers. The configuration parameters can indicate a first resource pool for the at least one first carrier. The first resource pool is for transmission of sidelink control signaling. The first resource pool is preferably not utilized for transmission of sidelink data. The first configuration parameters of the first resource pool may comprise at least one first parameter indicating that the first resource pool is for transmission of sidelink control signaling. The at least one parameter further indicates that the first resource pool is not for transmission of sidelink data. The plurality of resource pools may comprise an exceptional resource pool. The exceptional resource pool can be configured for handover.

[0007] The exceptional resource pool may be configured for sidelink radio failure recovery. The configuration of the exceptional resource pool can be for improving reliability of sidelink communications when user equipments (UEs) in network coverage do not have stable network conditions. The exceptional resource pool can be configured for a first resource pool in the at least one first carrier. In one form, the exceptional resource pool can only be configured for a licensed carrier. The exceptional resource pool may be configured only for a sidelink primary⁷ carrier. The at least one type of control information may comprise control information used in sidelink synchronization. The control information used for sidelink synchronization may comprise a sidelink synchronization signal block (S-SSB). The sidelink synchronization signal block (S-SSB) may comprise a physical sidelink broadcast channel (PSBCCH), a sidelink primary synchronization signal (S-PSS) and a sidelink secondary synchronization signal (S-SSS).

[0008] In the method, one or more user equipments (UEs) may use the sidelink synchronization signal block (S-SSB), transmitted by the first UE, to synchronize to the first UE. The first user equipment (UE) may be a reference UE for synchronization. The one or more user equipments (UEs) may operate out of network coverage. The sidelink synchronization signal block (S-SSB) may be transmitted via a sidelink primaiy carrier. The at least one type of control information comprises hybrid automatic repeat request (HARQ) feedback. Transmission of the HARQ feedback may be implemented via a physical sidelink feedback channel (PSFCH). Transmission of the physical sidelink feedback channel (PSFCH) may be via a sidelink primaiy carrier. Hybrid automatic repeat request (HARQ) feedback may be transmitted via a physical sidelink shared channel (PSSCH) of the at least one second carrier provided that transmission of the HARQ feedback is within a channel occupancy time (COT) obtained for transmission of a sidelink packet. The hybrid automatic repeat request (HARQ) feedback may be transmitted via the same bandwidth part (BWP) or resource pool used for transmission of the sidelink packet.

[0009] In an embodiment, the invention provides a method of sidelink communication that includes receiving, by a first user equipment (UE), configuration parameters of a first carrier and a second carrier for sidelink communications, wherein the first carrier operates in a licensed spectrum and the second carrier operates in an unlicensed spectrum; and transmitting two-stage sidelink control information (SCI) comprising first SCI and second SCI, wherein transmitting the first SCI is via the first carrier. The transmitting of the first sidelink control information (SCI) may be implemented via the first carrier only. The transmitting of the first sidelink control information (SCI) may also be only via a licensed carrier. The transmitting the second sidelink control information (SCI) may be via the first carrier or via the second carrier. The first carrier and the second carrier can be configured for sidelink carrier aggregation.

[0010] The first carrier preferably is a primary sidelink carrier and the second carrier is preferably a secondary sidelink carrier. The first sidelink control information (SCI) may be transmitted via the primary sidelink carrier. The first sidelink control information (SCI) may be transmitted only via the primary sidelink carrier. The method can also include receiving first configuration parameters of a first control resource set (CORESET) of the primary sidelink carrier that is used for transmission of the first sidelink control information (SCI). The method may further include receiving second configuration parameters of a second control resource set (CORESET) of the primary sidelink carrier that is used for transmission of the second sidelink control information (SCI).

[0011 ] The method also can include receiving second configuration parameters of a second control resource set (CORESET) of the secondary sidelink carrier that is used for transmission of the second sidelink control information (SCI); and additionally, transmitting sidelink data by the first user equipment (UE) to a second UE. A two-stage sidelink control information (SCI) may be associated with the sidelink data. The first sidelink control information (SCI) of the two-stage SCI may be associated with transmission of the sidelink data via a physical sidelink shared channel (PSSCH). The first sidelink control information (SCI) of the two-stage SCI may comprise scheduling information associated with the sidelink data. The first sidelink control information (SCI) of the two- stage SCI may comprise resource reservation period. The first sidelink control information (SCI) of the two-stage SCI may comprise a demodulation reference signal (DMRS) pattern. The first sidelink control information (SCI) of the two-stage SCI may comprise a modulation and coding scheme. Transmitting the second sidelink control information (SCI) of the two-stage SCI may be implemented via the physical sidelink shared channel (PSSCH).

[0012] The second sidelink control information (SCI) of the two-stage SCI may comprise hybrid automatic repeat request (HARQ) information. The hybrid automatic repeat request (HARQ) information may comprise a HARQ process number. The hybrid automatic repeat request (HARQ) information may comprise a new data indicator. In the method, the second sidelink control information (SCI) of the two-stage SCI may comprise a source identifier associate with the first user equipment (UE). The second sidelink control information (SCI) of the two-stage SCI may comprise a destination identifier associated with the second user equipment (UE). The second sidelink control information (SCI) of the two- stage SCI may comprise a channel state information (CSI) request. The second sidelink control information (SCI) of the two-stage SCI may comprise one or more parameters related to channel access. The one or more parameters related to channel access may comprise a first parameter indicating a channel occupancy time (COT) value; the channel access can be based on a listen-before-talk (LBT) process. The method can include transmitting sidelink data by the first user equipment (UE) to a second UE in response to the before-talk (LBT) process indicating a clear channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 shows an example of a system of mobile communications according to some aspects of some of various exemplary embodiments of the present disclosure.

[0014] FIG. 2A and FIG. 2B show examples of radio protocol stacks for user plane and control plane, respectively, according to some aspects of some of various exemplary embodiments of the present disclosure.

[0015] FIG. 3A, FIG. 3B and FIG. 3C show example mappings between logical channels and transport channels in downlink, uplink and sidelink, respectively, according to some aspects of some of various exemplary embodiments of the present disclosure.

[0016] FIG. 4A, FIG. 4B and FIG. 4C show example mappings between transport channels and physical channels in downlink, uplink and sidelink, respectively, according to some aspects of some of various exemplary embodiments of the present disclosure.

[0017] FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D show examples of radio protocol stacks for NR sidelink communication according to some aspects of some of various exemplary embodiments of the present disclosure.

[0018] FIG. 6 shows example physical signals in downlink, uplink and sidelink according to some aspects of some of various exemplary embodiments of the present disclosure.

[0019] FIG. 7 shows examples of Radio Resource Control (RRC) states and transitioning between different RRC states according to some aspects of some of various exemplary embodiments of the present disclosure.

[0020] FIG. 8 shows example frame structure and physical resources according to some aspects of some of various exemplary embodiments of the present disclosure. [0021] FIG. 9 shows example component carrier configurations in different carrier aggregation scenarios according to some aspects of some of various exemplary embodiments of the present disclosure.

[0022] FIG. 10 shows example bandwidth part configuration and switching according to some aspects of some of various exemplary embodiments of the present disclosure.

[0023] FIG. 11 shows example four-step contention-based and contention-free random access processes according to some aspects of some of various exemplary embodiments of the present disclosure.

[0024] FIG. 12 shows example two-step contention-based and contention- free random access processes according to some aspects of some of various exemplary embodiments of the present disclosure.

[0025] FIG. 13 shows example time and frequency structure of Synchronization Signal and Physical Broadcast Channel (PBCH) Block (SSB) according to some aspects of some of various exemplary embodiments of the present disclosure.

[0026] FIG. 14 shows example SSB burst transmissions according to some aspects of some of various exemplary embodiments of the present disclosure.

[0027] FIG. 15 shows example components of a user equipment and a base station for transmission and/or reception according to some aspects of some of various exemplary embodiments of the present disclosure.

[0028] FIG. 16 shows an example process of using sidelink primary carrier for sidelink synchronization signa block (S-SSB) and exceptional resource pool (RP) configuration and transmission according to some aspects of some of various exemplary embodiments of the present disclosure.

[0029] FIG. 17 shows an example process of using sidelink primary carrier for physical sidelink feedback channel (PSFCH) according to some aspects of some of various exemplary embodiments of the present disclosure.

[0030] FIG. 18 shows an example process of using sidelink primary carrier for 1^st stage sidelink control information (SCI) transmission according to some aspects of some of various exemplary embodiments of the present disclosure.

[0031] FIG. 19 shows an example process according to some aspects of some of various exemplary embodiments of the present disclosure.

[0032] FIG. 20 shows an example process according to some aspects of some of various exemplary embodiments of the present disclosure.

DETAILED DESCRIPTION

[0033] FIG. 1 shows an example of a system of mobile communications 100 according to some aspects of some of various exemplary embodiments of the present disclosure. The system of mobile communication 100 may be operated by a wireless communications system operator such as a Mobile Network Operator (MNO), a private network operator, a Multiple System Operator (MSO), an Internet of Things (IOT) network operator, etc., and may offer services such as voice, data (e.g., wireless Internet access), messaging, vehicular communications services such as Vehicle to Everything (V2X) communications services, safety services, mission critical service, services in residential, commercial or industrial settings such as loT, industrial IOT (IIOT), etc.

[0034] The system of mobile communications 100 may enable various types of applications with different requirements in terms of latency, reliability, throughput, etc. Example supported applications include enhanced Mobile Broadband (eMBB), Ultra- Reliable Low- Latency Communications (URLLC), and massive Machine Type Communications (mMTC). eMBB may support stable connections with high peak data rates, as well as moderate rates for cell-edge users. URLLC may support applications with strict requirements in terms of latency and reliability and moderate requirements in terms of data rate. Example mMTC application includes a network of a massive number of loT devices, which are only sporadically active and send small data payloads.

[0035] The system of mobile communications 100 may include a Radio Access Network (RAN) portion and a core network portion. The example shown in FIG. 1 illustrates a Next Generation RAN (NG-RAN) 105 and a 5G Core Network (5GC) 110 as examples of the RAN and core network, respectively. Other examples of RAN and core network may be implemented without departing from the scope of this disclosure. Other examples of RAN include Evolved Universal Terrestrial Radio Access Network (EUTRAN), Universal Terrestrial Radio Access Network (UTRAN), etc. Other examples of core network include Evolved Packet Core (EPC), UMTS Core Network (UCN), etc. The RAN implements a Radio Access Technology (RAT) and resides between User Equipments (UEs) 125 and the core network. Examples of such RATs include New Radio (NR), Long Term Evolution (LTE) also known as Evolved Universal Terrestrial Radio Access (EUTRA), Universal Mobile Telecommunication System (UMTS), etc. The RAT of the example system of mobile communications 100 may be NR. The core network resides between the RAN and one or more external networks (e.g., data networks) and is responsible for functions such as mobility management, authentication, session management, setting up bearers and application of different Quality of Services (QoSs). The functional layer between the UE 125 and the RAN (e.g., the NG-RAN 105) may be referred to as Access Stratum (AS) and the functional layer between the UE 125 and the core network (e.g., the 5GC 110) may be referred to as Non-access Stratum (NAS).

[0036] The UEs 125 may include wireless transmission and reception means for communications with one or more nodes in the RAN, one or more relay nodes, or one or more other UEs, etc. Examples of UEs include, but are not limited to, smartphones, tablets, laptops, computers, wireless transmission and/or reception units in a vehicle, V2X or Vehicle to Vehicle (V2V) devices, wireless sensors, loT devices, HOT devices, etc. Other names may be used for UEs such as a Mobile Station (MS), terminal equipment, terminal node, client device, mobile device, etc.

[0037] The RAN may include nodes (e.g., base stations) for communications with the UEs. For example, the NG-RAN 105 of the system of mobile communications 100 may comprise nodes for communications with the UEs 125. Different names for the RAN nodes may be used, for example depending on the RAT used for the RAN. A RAN node may be referred to as Node B (NB) in a RAN that uses the UMTS RAT. A RAN node may be referred to as an evolved Node B (eNB) in a RAN that uses LTE/EUTRA RAT. For the illustrative example of the system of mobile communications 100 in FIG. 1, the nodes of an NG-RAN 105 may be either a next generation Node B (gNB) 115 or a next generation evolved Node B (ng-eNB) 120. In this specification, the terms base station, RAN node, gNB and ng-eNB may be used interchangeably. The gNB 115 may provide NR user plane and control plane protocol terminations towards the UE 125. The ng-eNB 120 may provide E-UTRA user plane and control plane protocol terminations towards the UE 125. An interface between the gNB 115 and the UE 125 or between the ng- eNB 120 and the UE 125 may be referred to as a Uu interface. The Uu interface may be established with a user plane protocol stack and a control plane protocol stack. For a Uu interface, the direction from the base station (e.g., the gNB 115 or the ng-eNB 120) to the UE 125 may be referred to as downlink and the direction from the UE 125 to the base station (e.g., gNB 115 or ng-eNB 120) may be referred to as uplink.

[0038] The gNBs 115 and ng-eNBs 120 may be interconnected with each other by means of an Xn interface. The Xn interface may comprise an Xn User plane (Xn-U) interface and an Xn Control plane (Xn-C) interface. The transport network layer of the Xn-U interface may be built on Internet Protocol (IP) transport and GPRS Tunneling Protocol (GTP) may be used on top of User Datagram Protocol (UDP)/IP to cariy the user plane protocol data units (PDUs). Xn-U may provide non-guaranteed delivery of user plane PDUs and may support data forwarding and flow control. The transport network layer of the Xn-C interface may be built on Stream Control Transport Protocol (SCTP) on top of IP. The application layer signaling protocol may be referred to as XnAP (Xn Application Protocol). The SCTP layer may provide the guaranteed delivery of application layer messages. In the transport IP layer, point-to- point transmission may be used to deliver the signaling PDUs. The Xn-C interface may support Xn interface management, UE mobility management, including context transfer and RAN paging, and dual connectivity.

[0039] The gNBs 115 and ng-eNBs 120 may also be connected to the 5GC 1 10 by means of the NG interfaces, more specifically to an Access and Mobility Management Function (AMF) 130 of the 5GC 110 by means of the NG-C interface and to a User Plane Function (UPF) 135 of the 5GC 110 by means of the NG-U interface. The transport network layer of the NG-U interface may be built on IP transport and GTP protocol may be used on top of UDP/IP to carry the user plane PDUs between the NG- RAN node (e.g., gNB 1 15 or ng-eNB 120 ) and the UPF 135. NG-U may provide non-guaranteed delivery of user plane PDUs between the NG- RAN node and the UPF. The transport network layer of the NG-C interface may be built on IP transport. For the reliable transport of signaling messages, SCTP may be added on top of IP. The application layer signaling protocol may be referred to as NGAP (NG Application Protocol). The SCTP layer may provide guaranteed delivery of application layer messages. In the transport, IP layer point-to-point transmission may be used to deliver the signaling PDUs. The NG-C interface may provide the following functions: NG interface management; UE context management; UE mobility management; transport of NAS messages; paging; PDU Session Management; configuration transfer; and warning message transmission.

[0040] The gNB 115 or the ng-eNB 120 may host one or more of the following functions: Radio Resource Management functions such as Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (e.g., scheduling); IP and Ethernet header compression, encryption and integrity protection of data; Selection of an AMF at UE attachment when no routing to an AMF can be determined from the information provided by the UE; Routing of User Plane data towards UPF(s): Routing of Control Plane information towards AMF; Connection setup and release; Scheduling and transmission of paging messages; Scheduling and transmission of system broadcast information (e.g., originated from the AMF); Measurement and measurement reporting configuration for mobility and scheduling; Transport level packet marking in the uplink; Session Management; Support of Network Slicing; QoS Flow management and mapping to data radio bearers; Support of UEs in RRC Inactive state; Distribution function for NAS messages; Radio access network sharing; Dual Connectivity; Tight interworking between NR and E-UTRA; and Maintaining security and radio configuration for User Plane 5G system (5GS) Cellular loT (CIoT) Optimization.

[0041] The AMF 130 may host one or more of the following functions: NAS signaling termination; NAS signaling security; AS Security control; Inter CN node signaling for mobility between 3GPP access networks; Idle mode UE Reachability (including control and execution of paging retransmission); Registration Area management; Support of intra-system and inter-system mobility; Access Authentication; Access Authorization including check of roaming rights; Mobility management control (subscription and policies); Support of Network Slicing; Session Management Function (SMF) selection; Selection of 5GS CIoT optimizations.

[0042] The UPF 135 may host one or more of the following functions: Anchor point for Intra-/ Inter- RAT mobility (when applicable); External PDU session point of interconnect to Data Network; Packet routing & forwarding; Packet inspection and User plane part of Policy rule enforcement; Traffic usage reporting; Uplink classifier to support routing traffic flows to a data network; Branching point to support multi-homed PDU session; QoS handling for user plane, e.g. packet filtering, gating, UL/DL rate enforcement; Uplink Traffic verification (Service Data Flow (SDF) to QoS flow mapping); Downlink packet buffering and downlink data notification triggering.

[0043] As shown in FIG. 1, the NG-RAN 105 may support the PC5 interface between two UEs 125 (e.g., UE 125A and UE125B). In the PC5 interface, the direction of communications between two UEs (e.g., from UE 125A to UE 125B or vice versa) may be referred to as sidelink. Sidelink transmission and reception over the PC5 interface may be supported when the UE 125 is inside NG-RAN 105 coverage, irrespective of which RRC state the UE is in, and when the UE 125 is outside NG- RAN 105 coverage. Support of V2X services via the PC5 interface may be provided by NR sidelink communication and/or V2X sidelink communication .

[0044] PC5-S signaling may be used for unicast link establishment with Direct Communication Request/ Accept message. A UE may self-assign its source Layer-2 ID for the PC5 unicast link for example based on the V2X service type. During unicast link establishment procedure, the UE may send its source Layer-2 ID for the PC5 unicast link to the peer UE, e.g., the UE for which a destination ID has been received from the upper layers. A pair of source Layer-2 ID and destination Layer-2 ID may uniquely identify a unicast link. The receiving UE may verify that the said destination ID belongs to it and may accept the Unicast link establishment request from the source UE. During the PC5 unicast link establishment procedure, a PC5-RRC procedure on the Access Stratum may be invoked for the purpose of UE sidelink context establishment as well as for AS layer configurations, capability exchange etc. PC5-RRC signaling may enable exchanging UE capabilities and AS layer configurations such as Sidelink Radio Bearer configurations between pair of UEs for which a PC5 unicast link is established.

[0045] NR sidelink communication may support one of three types of transmission modes (e.g., Unicast transmission, Groupcast transmission, and Broadcast transmission) for a pair of a Source Layer-2 ID and a Destination Layer-2 ID in the AS. The Unicast transmission mode may be characterized by: Support of one PC5-RRC connection between peer UEs for the pair; Transmission and reception of control information and user traffic between peer UEs in sidelink; Support of sidelink HARQ feedback; Support of sidelink transmit power control; Support of RLC Acknowledged Mode (AM); and Detection of radio link failure for the PC5-RRC connection. The Groupcast transmission may be characterized by: Transmission and reception of user traffic among UEs belonging to a group in sidelink; and Support of sidelink HARQ feedback. The Broadcast transmission may be characterized by: Transmission and reception of user traffic among UEs in sidelink.

[0046] A Source Layer-2 ID, a Destination Layer-2 ID and a PC5 Link Identifier may be used for NR sidelink communication. The Source Layer- 2 ID may be a link-layer identity that identifies a device or a group of devices that are recipients of sidelink communication frames. The Destination Layer- 2 ID may be a link-layer identity that identifies a device that originates sidelink communication frames. In some examples, the Source Layer-2 ID and the Destination Layer-2 ID may be assigned by a management function in the Core Network. The Source Layer-2 ID may identify the sender of the data in NR sidelink communication. The Source Layer-2 ID may be 24 bits long and may be split in the MAC layer into two bit strings: One bit string may be the LSB part (8 bits) of Source Layer-2 ID and forwarded to physical layer of the sender. This may identify the source of the intended data in sidelink control information and may be used for filtering of packets at the physical layer of the receiver; and the Second bit string may be the MSB part (16 bits) of the Source Layer-2 ID and may be carried within the Medium Access Control (MAC) header. This may be used for filtering packets at the MAC layer of the receiver. The Destination Layer-2 ID may identify the target of the data in NR sidelink communication. For NR sidelink communication, the Destination Layer- 2 ID may be 24 bits long and may be split in the MAC layer into two bit strings: One bit string may be the LSB part (16 bits) of Destination Layer-2 ID and forwarded to physical layer of the sender. This may identify the target of the intended data in sidelink control information and may be used for filtering of packets at the physical layer of the receiver; and the Second bit string may be the MSB part (8 bits) of the Destination Layer-2 ID and may be carried within the MAC header. This may be used for filtering packets at the MAC layer of the receiver. The PC5 Link Identifier may uniquely identify the PC5 unicast link in a UE for the lifetime of the PC 5 unicast link. The PC 5 Link Identifier may be used to indicate the PC5 unicast link whose sidelink Radio Link failure (RLF) declaration was made and PC5-RRC connection was released.

[0047] FIG. 2A and FIG. 2B show examples of radio protocol stacks for user plane and control plane, respectively, according to some aspects of some of various exemplary⁷ embodiments of the present disclosure. As shown in FIG. 2A, the protocol stack for the user plane of the Uu interface (between the UE 125 and the gNB 115) includes Service Data Adaptation Protocol (SDAP) 201 and SDAP 211, Packet Data Convergence Protocol (PDCP) 202 and PDCP 212, Radio Link Control (RLC) 203 and RLC 213, MAC 204 and MAC 214 sublayers of layer 2 and Physical (PHY) 205 and PHY 215 layer (layer 1 also referred to as LI). [0048] The PHY 205 and PHY 215 offer transport channels 244 to the MAC 204 and MAC 214 sublayer. The MAC 204 and MAC 214 sublayer offer logical channels 243 to the RLC 203 and RLC 213 sublayer. The RLC 203 and RLC 213 sublayer offer RLC channels 242 to the PDCP 202 and PCP 212 sublayer. The PDCP 202 and PDCP 212 sublayer offer radio bearers 241 to the SDAP 201 and SDAP 211 sublayer. Radio bearers may be categorized into two groups: Data Radio Bearers (DRBs) for user plane data and Signaling Radio Bearers (SRBs) for control plane data. The SDAP 201 and SDAP 211 sublayer offers QoS flows 240 to 5GC.

[0049] The main services and functions of the MAC 204 or MAC 214 sublayer include: mapping between logical channels and transport channels; Multiplexing/ demultiplexing of MAC Service Data Units (SDUs) belonging to one or different logical channels into / from Transport Blocks (TB) delivered to/from the physical layer on transport channels;

Scheduling information reporting; Error correction through Hybrid Automatic Repeat Request (HARQ) (one HARQ entity per cell in case of carrier aggregation (CA)); Priority handling between UEs by means of dynamic scheduling; Priority handling between logical channels of one UE by means of Logical Channel Prioritization (LCP); Priority handling between overlapping resources of one UE; and Padding. A single MAC entity may support multiple numerologies, transmission timings and cells. Mapping restrictions in logical channel prioritization control which numerology(ies), cell(s), and transmission timing(s) a logical channel may use.

[0050] The HARQ functionality may ensure delivery between peer entities at Layer 1. A single HARQ process may support one TB when the physical layer is not configured for downlink/uplink spatial multiplexing, and when the physical layer is configured for downlink/uplink spatial multiplexing, a single HARQ process may support one or multiple TBs.

[0051] The RLC 203 or RLC 213 sublayer may support three transmission modes: Transparent Mode (TM); Unacknowledged Mode (UM); and Acknowledged Mode (AM). The RLC configuration may be per logical channel with no dependency on numerologies and/or transmission durations, and Automatic Repeat Request (ARQ) may operate on any of the numerologies and/or transmission durations the logical channel is configured with.

[0052] The main services and functions of the RLC 203 or RLC 213 sublayer depend on the transmission mode (e.g., TM, UM or AM) and may include: Transfer of upper layer PDUs; Sequence numbering independent of the one in PDCP (UM and AM); Error Correction through ARQ (AM only); Segmentation (AM and UM) and re-segmentation (AM only) of RLC SDUs; Reassembly of SDU (AM and UM); Duplicate Detection (AM only); RLC SDU discard (AM and UM); RLC reestablishment; and Protocol error detection (AM only).

[0053] The automatic repeat request within the RLC 203 or RLC 213 sublayer may have the following characteristics: ARQ retransmits RLC SDUs or RLC SDU segments based on RLC status reports; Polling for RLC status report may be used when needed by RLC; RLC receiver may also trigger RLC status report after detecting a missing RLC SDU or RLC SDU segment.

[0054] The main services and functions of the PDCP 202 or PDCP 212 sublayer may include: Transfer of data (user plane or control plane); Maintenance of PDCP Sequence Numbers (SNs); Header compression and decompression using the Robust Header Compression (ROHC) protocol; Header compression and decompression using EHC protocol; Ciphering and deciphering; Integrity protection and integrity verification; Timer based SDU discard; Routing for split bearers; Duplication; Reordering and in-order delivery; Out-of-order delivery; and Duplicate discarding.

[0055] The main services and functions of SDAP 201 or SDAP 211 include: Mapping between a QoS flow and a data radio bearer; and Marking QoS Flow ID (QFI) in both downlink and uplink packets. A single protocol entity of SDAP may be configured for each individual PDU session.

[0056] As shown in FIG. 2B, the protocol stack of the control plane of the Uu interface (between the UE 125 and the gNB 1 15) includes PHY layer (layer 1), and MAC, RLC and PDCP sublayers of layer 2 as described above and in addition, the RRC 206 sublayer and RRC 216 sublayer. The main services and functions of the RRC 206 sublayer and the RRC 216 sublayer over the Uu interface include: Broadcast of System Information related to AS and NAS; Paging initiated by 5GC or NG-RAN;

Establishment, maintenance and release of an RRC connection between the UE and NG-RAN (including Addition, modification and release of carrier aggregation; and Addition, modification and release of Dual Connectivity in NR or between E-UTRA and NR); Security functions including key management; Establishment, configuration, maintenance and release of SRBs and DRBs; Mobility functions (including Handover and context transfer; UE cell selection and reselection and control of cell selection and reselection; and Inter-RAT mobility); QoS management functions; UE measurement reporting and control of the reporting;

Detection of and recoveiy from radio link failure; and NAS message transfer to/from NAS from/to UE. The NAS 207 and NAS 227 layer is a control protocol (terminated in AMF on the network side) that performs the functions such as authentication, mobility management, security control, etc.

[0057] The sidelink specific services and functions of the RRC sublayer over the Uu interface include: Configuration of sidelink resource allocation via system information or dedicated signaling; Reporting of UE sidelink information; Measurement configuration and reporting related to sidelink; and Reporting of UE assistance information for SL traffic pattern (s).

[0058] FIG. 3A, FIG. 3B and FIG. 3C show example mappings between logical channels and transport channels in downlink, uplink and sidelink, respectively, according to some aspects of some of various exemplary embodiments of the present disclosure. Different kinds of data transfer services may be offered by MAC. Each logical channel type may be defined by what type of information is transferred. Logical channels may be classified into two groups: Control Channels and Traffic Channels. Control channels may be used for the transfer of control plane information only. The Broadcast Control Channel (BCCH) is a downlink channel for broadcasting system control information. The Paging Control Channel (PCCH) is a downlink channel that carries paging messages. The Common Control Channel (CCCH) is channel for transmitting control information between UEs and networks. This channel may be used for UEs having no RRC connection with the network. The Dedicated Control Channel (DCCH) is a point-to-point bi-directional channel that transmits dedicated control information between a UE and the network and may be used by UEs having an RRC connection. Traffic channels may be used for the transfer of user plane information only. The Dedicated Traffic Channel (DTCH) is a point-to-point channel, dedicated to one UE, for the transfer of user information. A DTCH may exist in both uplink and downlink. Sidelink Control Channel (SCCH) is a sidelink channel for transmitting control information (e.g., PC5-RRC and PC5-S messages) from one UE to other UE(s). Sidelink Traffic Channel (STCH) is a sidelink channel for transmitting user information from one UE to other UE(s).

Sidelink Broadcast Control Channel (SBCCH) is a sidelink channel for broadcasting sidelink system information from one UE to other UE(s).

[0059] The downlink transport channel types include Broadcast Channel (BCH), Downlink Shared Channel (DL-SCH), and Paging Channel (PCH). The BCH may be characterized by: fixed, pre-defined transport format; and requirement to be broadcast in the entire coverage area of the cell, either as a single message or by beamforming different BCH instances. The DL-SCH may be characterized by: support for HARQ; support for dynamic link adaptation by vaiying the modulation, coding and transmit power; possibility to be broadcast in the entire cell; possibility to use beamforming; support for both dynamic and semi- static resource allocation; and the support for UE Discontinuous Reception (DRX) to enable UE power saving. The DL-SCH may be characterized by: support for HARQ; support for dynamic link adaptation by varying the modulation, coding and transmit power; possibility to be broadcast in the entire cell; possibility to use beamforming; support for both dynamic and semi-static resource allocation; support for UE discontinuous reception (DRX) to enable UE power saving. The PCH may be characterized by: support for UE discontinuous reception (DRX) to enable UE power saving (DRX cycle is indicated by the network to the UE); requirement to be broadcast in the entire coverage area of the cell, either as a single message or by beamforming different BCH instances; mapped to physical resources which can be used dynamically also for traffic/ other control channels.

[0060] In downlink, the following connections between logical channels and transport channels may exist: BCCH may be mapped to BCH; BCCH may be mapped to DL-SCH; PCCH may be mapped to PCH; CCCH may be mapped to DL-SCH; DCCH may be mapped to DL-SCH; and DTCH may be mapped to DL-SCH.

[0061] The uplink transport channel types include Uplink Shared Channel (UL-SCH) and Random Access Channel(s) (RACH). The UL-SCH may be characterized by possibility to use beamforming; support for dynamic link adaptation by varying the transmit power and potentially modulation and coding; support for HARQ; support for both dynamic and semi- static resource allocation. The RACH may be characterized by limited control information; and collision risk.

[0062] In Uplink, the following connections between logical channels and transport channels may exist: CCCH may be mapped to UL-SCH; DCCH may be mapped to UL- SCH; and DTCH may be mapped to UL-SCH. [0063] The sidelink transport channel types include: Sidelink broadcast channel (SL-BCH) and Sidelink shared channel (SL-SCH). The SL-BCH may be characterized by pre-defined transport format. The SL-SCH may be characterized by support for unicast transmission, groupcast transmission and broadcast transmission; support for both UE autonomous resource selection and scheduled resource allocation by NG-RAN; support for both dynamic and semi-static resource allocation when UE is allocated resources by the NG-RAN; support for HARQ; and support for dynamic link adaptation by varying the transmit power, modulation and coding.

[0064] In the sidelink, the following connections between logical channels and transport channels may exist: SCCH may be mapped to SL-SCH; STCH may be mapped to SL-SCH; and SBCCH may be mapped to SL- BCH.

[0065] FIG. 4A, FIG. 4B and FIG. 4C show example mappings between transport channels and physical channels in downlink, uplink and sidelink, respectively, according to some aspects of some of various exemplary embodiments of the present disclosure. The physical channels in downlink include Physical Downlink Shared Channel (PDSCH), Physical Downlink Control Channel (PDCCH) and Physical Broadcast Channel (PBCH). The PCH and DL-SCH transport channels are mapped to the PDSCH. The BCH transport channel is mapped to the PBCH. A transport channel is not mapped to the PDCCH but Downlink Control Information (DCI) is transmitted via the PDCCH.

[0066] The physical channels in the uplink include Physical Uplink Shared Channel (PUSCH), Physical Uplink Control Channel (PUCCH) and Physical Random Access Channel (PRACH). The UL-SCH transport channel may be mapped to the PUSCH and the RACH transport channel may be mapped to the PRACH. A transport channel is not mapped to the PUCCH but Uplink Control Information (UCI) is transmitted via the PUCCH. [0067] The physical channels in the sidelink include Physical Sidelink Shared Channel (PSSCH), Physical Sidelink Control Channel (PSCCH), Physical Sidelink Feedback Channel (PSFCH) and Physical Sidelink Broadcast Channel (PSBCH). The Physical Sidelink Control Channel (PSCCH) may indicate resource and other transmission parameters used by a UE for PSSCH. The Physical Sidelink Shared Channel (PSSCH) may transmit the TBs of data themselves, and control information for HARQ procedures and CSI feedback triggers, etc. At least 6 OFDM symbols within a slot may be used for PSSCH transmission. Physical Sidelink Feedback Channel (PSFCH) may carry the HARQ feedback over the sidelink from a UE which is an intended recipient of a PSSCH transmission to the UE which performed the transmission. PSFCH sequence may be transmitted in one PRB repeated over two OFDM symbols near the end of the sidelink resource in a slot. The SL-SCH transport channel may be mapped to the PSSCH. The SL-BCH may be mapped to PSBCH. No transport channel is mapped to the PSFCH but Sidelink Feedback Control Information (SFCI) may be mapped to the PSFCH. No transport channel is mapped to PSCCH but Sidelink Control Information (SCI) may be mapped to the PSCCH.

[0068] FIG. 5A, FIG. 5B, FIG. 5C and FIG. 5D show examples of radio protocol stacks for NR sidelink communication according to some aspects of some of various exemplary embodiments of the present disclosure. The AS protocol stack for user plane in the PC5 interface (i.e., for STCH) may consist of SDAP, PDCP, RLC and MAC sublayers, and the physical layer. The protocol stack of user plane is shown in FIG. 5A. The AS protocol stack for SBCCH in the PC5 interface may consist of RRC, RLC, MAC sublayers, and the physical layer as shown below in FIG. 5B. For support of PC5-S protocol, PC5-S is located on top of PDCP, RLC and MAC sublayers, and the physical layer in the control plane protocol stack for SCCH for PC5-S, as shown in FIG. 5C. The AS protocol stack for the control plane for SCCH for RRC in the PC5 interface consists of RRC, PDCP, RLC and MAC sublayers, and the physical layer. The protocol stack of control plane for SCCH for RRC is shown in FIG. 5D.

[0069] The Sidelink Radio Bearers (SLRBs) may be categorized into two groups: Sidelink Data Radio Bearers (SL DRB) for user plane data and Sidelink Signaling Radio Bearers (SL SRB) for control plane data. Separate SL SRBs using different SCCHs may be configured for PC5-RRC and PC5-S signaling, respectively.

[0070] The MAC sublayer may provide the following services and functions over the PC5 interface: Radio resource selection; Packet filtering; Priority handling between uplink and sidelink transmissions for a given UE; and Sidelink CSI reporting. With logical channel prioritization restrictions in MAC, only sidelink logical channels belonging to the same destination may be multiplexed into a MAC PDU for every unicast, groupcast and broadcast transmission which may be associated to the destination. For packet filtering, a SL-SCH MAC header including portions of both Source Layer-2 ID and a Destination Layer-2 ID may be added to a MAC PDU. The Logical Channel Identifier (LCID) included within a MAC subheader may uniquely identify a logical channel within the scope of the Source Layer-2 ID and Destination Layer-2 ID combination.

[0071] The services and functions of the RLC sublayer may be supported for sidelink. Both RLC Unacknowledged Mode (UM) and Acknowledged Mode (AM) may be used in unicast transmission while only UM may be used in groupcast or broadcast transmission. For UM, only unidirectional transmission may be supported for groupcast and broadcast.

[0072] The services and functions of the PDCP sublayer for the Uu interface may be supported for sidelink with some restrictions: Out-of- order delivery may be supported only for unicast transmission; and Duplication may not be supported over the PC5 interface. [0073] The SDAP sublayer may provide the following service and function over the PC5 interface: Mapping between a QoS flow and a sidelink data radio bearer. There may be one SDAP entity per destination for one of unicast, groupcast and broadcast which is associated to the destination.

[0074] The RRC sublayer may provide the following services and functions over the PC5 interface: Transfer of a PC5-RRC message between peer UEs; Maintenance and release of a PC5-RRC connection between two UEs; and Detection of sidelink radio link failure for a PC5-RRC connection based on indication from MAC or RLC. A PC5-RRC connection may be a logical connection between two UEs for a pair of Source and Destination Layer-2 IDs which may be considered to be established after a corresponding PC5 unicast link is established. There may be one-to-one correspondence between the PC5-RRC connection and the PC5 unicast link. A UE may have multiple PC5-RRC connections with one or more UEs for different pairs of Source and Destination Layer-2 IDs. Separate PC5-RRC procedures and messages may be used for a UE to transfer UE capability and sidelink configuration including SL-DRB configuration to the peer UE. Both peer UEs may exchange their own UE capability and sidelink configuration using separate bi-directional procedures in both sidelink directions.

[0075] FIG. 6 shows example physical signals in downlink, uplink and sidelink according to some aspects of some of various exemplary embodiments of the present disclosure. The Demodulation Reference Signal (DM-RS) may be used in downlink, uplink and sidelink and may be used for channel estimation. DM-RS is a UE-specific reference signal and may be transmitted together with a physical channel in downlink, uplink or sidelink and may be used for channel estimation and coherent detection of the physical channel. The Phase Tracking Reference Signal (PT-RS) may be used in downlink, uplink and sidelink and may be used for tracking the phase and mitigating the performance loss due to phase noise. The PT-RS may be used mainly to estimate and minimize the effect of Common Phase Error (CPE) on system performance. Due to the phase noise properties, PT-RS signal may have a low density in the frequency domain and a high density in the time domain. PT-RS may occur in combination with DM-RS and when the network has configured PT-RS to be present. The Positioning Reference Signal (PRS) may be used in downlink for positioning using different positioning techniques. PRS may be used to measure the delays of the downlink transmissions by correlating the received signal from the base station with a local replica in the receiver. The Channel State Information Reference Signal (CSI-RS) may be used in downlink and sidelink. CSI-RS may be used for channel state estimation, Reference Signal Received Power (RSRP) measurement for mobility and beam management, time /frequency tracking for demodulation among other uses. CSI-RS may be configured UE- specifically but multiple users may share the same CSI-RS resource. The UE may determine CSI reports and transit them in the uplink to the base station using PUCCH or PUSCH. The CSI report may be carried in a sidelink MAC CE. The Primary Synchronization Signal (PSS) and the Secondary Synchronization Signal (SSS) may be used for radio fame synchronization. The PSS and SSS may be used for the cell search procedure during the initial attachment or for mobility purposes. The Sounding Reference Signal (SRS) may be used in uplink for uplink channel estimation. Similar to CSI-RS, the SRS may serve as QCL reference for other physical channels such that they can be configured and transmitted quasi-collocated with SRS. The Sidelink PSS (S-PSS) and Sidelink SSS (S-SSS) may be used in sidelink for sidelink synchronization .

[0076] FIG. 7 shows examples of Radio Resource Control (RRC) states and transitioning between different RRC states according to some aspects of some of various exemplary embodiments of the present disclosure. A UE may be in one of three RRC states: RRC Connected State 710, RRC Idle State 720 and RRC Inactive state 730. After power up, the UE may be in RRC Idle state 720 and the UE may establish connection with the network using initial access and via an RRC connection establishment procedure to perform data transfer and/or to make/receive voice calls. Once RRC connection is established, the UE may be in RRC Connected State 710. The UE may transition from the RRC Idle state 720 to the RRC connected state 710 or from the RRC Connected State 710 to the RRC Idle state 720 using the RRC connection Establishment/ Release procedures 740.

[0077] To reduce the signaling load and the latency resulting from frequent transitioning from the RRC Connected State 710 to the RRC Idle State 720 when the UE transmits frequent small data, the RRC Inactive State 730 may be used. In the RRC Inactive State 730, the AS context may be stored by both UE and gNB. This may result in faster state transition from the RRC Inactive State 730 to RRC Connected State 710. The UE may transition from the RRC Inactive State 730 to the RRC Connected State 710 or from the RRC Connected State 710 to the RRC Inactive State 730 using the RRC Connection Resume/ Inactivation procedures 760. The UE may transition from the RRC Inactive State 730 to RRC Idle State 720 using an RRC Connection Release procedure 750.

[0078] FIG. 8 shows example frame structure and physical resources according to some aspects of some of various exemplary embodiments of the present disclosure. The downlink or uplink or sidelink transmissions may be organized into frames with 10 ms duration, consisting of ten 1 ms subframes. Each subframe may consist of 1, 2, 4, ... slots, wherein the number of slots per subframe may depend on the subcarrier spacing of the carrier on which the transmission takes place. The slot duration may be 14 symbols with Normal Cyclic Prefix (CP) and 12 symbols with Extended CP and may scale in time as a function of the used sub-carrier spacing so that there is an integer number of slots in a subframe. FIG. 8 shows a resource grid in time and frequency domain. Each element of the resource grid, comprising one symbol in time and one subcarrier in frequency, is referred to as a Resource Element (RE). A Resource Block (RB) may be defined as 12 consecutive subcarriers in the frequency domain.

[0079] In some examples and with non-slot-based scheduling, the transmission of a packet may occur over a portion of a slot, for example during 2, 4 or 7 OFDM symbols which may also be referred to as minislots. The mini- slots may be used for low latency applications such as URLLC and operation in unlicensed bands. In some embodiments, the mini-slots may also be used for fast flexible scheduling of services (e.g., pre-emption of URLLC over eMBB).

[0080] FIG. 9 shows example component carrier configurations in different carrier aggregation scenarios according to some aspects of some of various exemplary embodiments of the present disclosure. In Carrier Aggregation (CA), two or more Component Carriers (CCs) may be aggregated. A UE may simultaneously receive or transmit on one or multiple CCs depending on its capabilities. CA may be supported for both contiguous and non-contiguous CCs in the same band or on different bands as shown in FIG. 9. A gNB and the UE may communicate using a serving cell. A serving cell may be associated at least one downlink CC (e.g., may be associated only with one downlink CC or may be associated with a downlink CC and an uplink CC). A serving cell may be a Primary Cell (PCell) or a Secondary cCell (SCell).

[0081] A UE may adjust the timing of its uplink transmissions using an uplink timing control procedure. A Timing Advance (TA) may be used to adjust the uplink frame timing relative to the downlink frame timing. The gNB may determine the desired Timing Advance setting and provides that to the UE. The UE may use the provided TA to determine its uplink transmit timing relative to the UE's observed downlink receive timing.

[0082] In the RRC Connected state, the gNB may be responsible for maintaining the timing advance to keep the LI synchronized. Serving cells having uplink to which the same timing advance applies and using the same timing reference cell are grouped in a Timing Advance Group (TAG) . A TAG may contain at least one serving cell with configured uplink. The mapping of a serving cell to a TAG may be configured by RRC. For the primary TAG, the UE may use the PCell as timing reference cell, except with shared spectrum channel access where an SCell may also be used as timing reference cell in certain cases. In a secondary TAG, the UE may use any of the activated SCells of this TAG as a timing reference cell and may not change it unless necessary.

[0083] Timing advance updates may be signaled by the gNB to the UE via MAC CE commands. Such commands may restart a TAG-specific timer which may indicate whether the LI can be synchronized or not: when the timer is running, the LI may be considered synchronized, otherwise, the LI may be considered non-synchronized (in which case uplink transmission may only take place on PRACH).

[0084] A UE with single timing advance capability for CA may simultaneously receive and / or transmit multiple CCs corresponding to multiple serving cells sharing the same timing advance (multiple serving cells grouped in one TAG). A UE with multiple timing advance capability for CA may simultaneously receive and/or transmit on multiple CCs corresponding to multiple serving cells with different timing advances (multiple serving cells grouped in multiple TAGs). The NG-RAN may ensure that each TAG contains at least one serving cell. A non-CA capable UE may receive on a single CC and may transmit on a single CC corresponding to one serving cell only (one serving cell in one TAG).

[0085] The multi-carrier nature of the physical layer in case of CA may be exposed to the MAC layer and one HARQ entity may be required per serving cell. When CA is configured, the UE may have one RRC connection with the network. At RRC connection establishment/ reestablishment/ handover, one serving cell (e.g., the PCell) may provide the NAS mobility information. Depending on UE capabilities, SCells may be configured to form together with the PCell a set of serving cells. The configured set of serving cells for a UE may consist of one PCell and one or more SCells. The reconfiguration, addition and removal of SCells may be performed by RRC.

[0086] In a dual connectivity scenario, a UE may be configured with a plurality of cells comprising a Master Cell Group (MCG) for communications with a master base station, a Secondary Cell Group (SCG) for communications with a secondary base station, and two MAC entities: one MAC entity and for the MCG for communications with the master base station and one MAC entity for the SCG for communications with the secondary base station.

[0087] FIG. 10 shows example bandwidth part configuration and switching according to some aspects of some of various exemplary embodiments of the present disclosure. The UE may be configured with one or more Bandwidth Parts (BWPs) 1010 on a given component carrier. In some examples, one of the one or more bandwidth parts may be active at a time. The active bandwidth part may define the UE's operating bandwidth within the cell's operating bandwidth. For initial access, and until the UE's configuration in a cell is received, initial bandwidth part 1020 determined from system information may be used. With Bandwidth Adaptation (BA), for example through BWP switching 1040, the receive and transmit bandwidth of a UE may not be as large as the bandwidth of the cell and may be adjusted. For example, the width may be ordered to change (e.g., to shrink during period of low activity to save power); the location may move in the frequency domain (e.g., to increase scheduling flexibility); and the subcarrier spacing may be ordered to change (e.g., to allow different services). The first active BWP 1020 may be the active BWP upon RRC (re-) configuration for a PCell or activation of an SCell.

[0088] For a downlink BWP or uplink BWP in a set of downlink BWPs or uplink BWPs, respectively, the UE may be provided the following configuration parameters: a Subcarrier Spacing (SCS); a cyclic prefix; a common RB and a number of contiguous RBs; an index in the set of downlink BWPs or uplink BWPs by respective BWP-Id; a set of BWP- common and a set of BWP-dedicated parameters. A BWP may be associated with an OFDM numerology according to the configured subcarrier spacing and cyclic prefix for the BWP. For a serving cell, a UE may be provided by a default downlink BWP among the configured downlink BWPs. If a UE is not provided a default downlink BWP, the default downlink BWP may be the initial downlink BWP.

[0089] A downlink BWP may be associated with a BWP inactivity timer. If the BWP inactivity timer associated with the active downlink BWP expires and if the default downlink BWP is configured, the UE may perform BWP switching to the default BWP. If the BWP inactivity timer associated with the active downlink BWP expires and if the default downlink BWP is not configured, the UE may perform BWP switching to the initial downlink BWP.

[0090] FIG. 11 shows example four-step contention-based and contention-free random access processes according to some aspects of some of various exemplary embodiments of the present disclosure. FIG. 12 shows example two-step contention-based and contention-free random access processes according to some aspects of some of various exemplary embodiments of the present disclosure. The random access procedure may be triggered by a number of events, for example: Initial access from RRC Idle State; RRC Connection Re-establishment procedure; downlink or uplink data arrival during RRC Connected State when uplink synchronization status is "non-synchronized"; uplink data arrival during RRC Connected State when there are no PUCCH resources for Scheduling Request (SR) available; SR failure; Request by RRC upon synchronous reconfiguration (e.g. handover); Transition from RRC Inactive State; to establish time alignment for a secondary TAG; Request for Other System Information (SI); Beam Failure Recoveiy (BFR);

Consistent uplink Listen-Before -Talk (LBT) failure on PCell. [0091] Two types of Random Access (RA) procedure may be supported: 4- step RA type with MSG1 and 2-step RA type with MSGA. Both types of RA procedure may support Contention-Based Random Access (CBRA) and Contention- Free Random Access (CFRA) as shown in FIG. 11 and FIG. 12.

[0092] The UE may select the type of random access at initiation of the random access procedure based on network configuration. When CFRA resources are not configured, an RSRP threshold may be used by the UE to select between 2-step RA type and 4-step RA type. When CFRA resources for 4-step RA type are configured, UE may perform random access with 4-step RA type. When CFRA resources for 2-step RA type are configured, UE may perform random access with 2-step RA type.

[0093] The MSG1 of the 4-step RA type may consist of a preamble on PRACH. After MSG1 transmission, the UE may monitor for a response from the network within a configured window. For CFRA, dedicated preamble for MSG 1 transmission may be assigned by the network and upon receiving Random Access Response (RAR) from the network, the UE may end the random access procedure as shown in FIG. 11. For CBRA, upon reception of the random access response, the UE may send MSG3 using the uplink grant scheduled in the random access response and may monitor contention resolution as shown in FIG. 11. If contention resolution is not successful after MSG3 (re)transmission(s), the UE may go back to MSG1 transmission.

[0094] The MSGA of the 2-step RA type may include a preamble on PRACH and a payload on PUSCH. After MSGA transmission, the UE may monitor for a response from the network within a configured window. For CFRA, dedicated preamble and PUSCH resource may be configured for MSGA transmission and upon receiving the network response, the UE may end the random access procedure as shown in FIG. 12. For CBRA, if contention resolution is successful upon receiving the network response, the UE may end the random access procedure as shown in FIG. 12; while if fallback indication is received in MSGB, the UE may perform MSG3 transmission using the uplink grant scheduled in the fallback indication and may monitor contention resolution. If contention resolution is not successful after MSG3 (re)transmission(s), the UE may go back to MSGA transmission.

[0095] FIG. 13 shows example time and frequency structure of Synchronization Signal and Physical Broadcast Channel (PBCH) Block (SSB) according to some aspects of some of various exemplary embodiments of the present disclosure. The SS/PBCH Block (SSB) may consist of Primary and Secondary Synchronization Signals (PSS, SSS), each occupying 1 symbol and 127 subcarriers (e.g., subcarrier numbers 56 to 182 in FIG. 13), and PBCH spanning across 3 OFDM symbols and 240 subcarriers, but on one symbol leaving an unused part in the middle for SSS as show in FIG. 13. The possible time locations of SSBs within a half-frame may be determined by sub-carrier spacing and the periodicity of the half-frames, where SSBs are transmitted, may be configured by the network. During a half-frame, different SSBs may be transmitted in different spatial directions (i.e., using different beams, spanning the coverage area of a cell).

[0096] The PBCH may be used to carry Master Information Block (MIB) used by a UE during cell search and initial access procedures. The UE may first decode PBCH /MIB to receive other system information. The MIB may provide the UE with parameters required to acquire System Information Block 1 (SIB1), more specifically, information required for monitoring of PDCCH for scheduling PDSCH that carries SIB 1. In addition, MIB may indicate cell barred status information. The MIB and SIB 1 may be collectively referred to as the minimum system information (SI) and SIB1 may be referred to as remaining minimum system information (RMSI). The other system information blocks (SIBs) (e.g., SIB2, SIB3, ..., SIB 10 and SIBpos) may be referred to as Other SI. The Other SI may be periodically broadcast on DL-SCH, broadcast on- demand on DL-SCH (e.g., upon request from UEs in RRC Idle State, RRC Inactive State, or RRC connected State), or sent in a dedicated manner on DL-SCH to UEs in RRC Connected State (e.g., upon request, if configured by the network, from UEs in RRC Connected State or when the UE has an active BWP with no common search space configured).

[0097] FIG. 14 shows example SSB burst transmissions according to some aspects of some of various exemplary embodiments of the present disclosure. An SSB burst may include N SSBs and each SSB of the N SSBs may correspond to a beam. The SSB bursts may be transmitted according to a periodicity (e.g., SSB burst period). During a contentionbased random access process, a UE may perform a random access resource selection process, wherein the UE first selects an SSB before selecting a RA preamble. The UE may select an SSB with an RSRP above a configured threshold value. In some embodiments, the UE may select any SSB if no SSB with RSRP above the configured threshold is available. A set of random access preambles may be associated with an SSB. After selecting an SSB, the UE may select a random access preamble from the set of random access preambles associated with the SSB and may transmit the selected random access preamble to start the random access process.

[0098] In some embodiments, a beam of the N beams may be associated with a CSI-RS resource. A UE may measure CSI-RS resources and may select a CSI-RS with RSRP above a configured threshold value. The UE may select a random access preamble corresponding to the selected CSI- RS and may transmit the selected random access process to start the random access process. If there is no random access preamble associated with the selected CSI-RS, the UE may select a random access preamble corresponding to an SSB which is Quasi-Collocated with the selected CSI-RS.

[0099] In some embodiments, based on the UE measurements of the CSI-

RS resources and the UE CSI reporting, the base station may determine a Transmission Configuration Indication (TCI) state and may indicate the TCI state to the UE, wherein the UE may use the indicated TCI state for reception of downlink control information (e.g., via PDCCH) or data (e.g., via PDSCH). The UE may use the indicated TCI state for using the appropriate beam for reception of data or control information. The indication of the TCI states may be using RRC configuration or in combination of RRC signaling and dynamic signaling (e.g., via a MAC Control element (MAC CE) and/or based on a value of field in the downlink control information that schedules the downlink transmission). The TCI state may indicate a Quasi-Colocation (QCL) relationship between a downlink reference signal such as CSI-RS and the DM-RS associated with the downlink control or data channels (e.g., PDCCH or PDSCH, respectively).

[0100] In some embodiments, the UE may be configured with a list of up to M TCI-State configurations, using Physical Downlink Shared Channel (PDSCH) configuration parameters, to decode PDSCH according to a detected PDCCH with DCI intended for the UE and the given serving cell, where M may depend on the UE capability. Each TCI-State may contain parameters for configuring a QCL relationship between one or two downlink reference signals and the DM-RS ports of the PDSCH, the DM- RS port of PDCCH or the CSI-RS port(s) of a CSI-RS resource. The quasi co-location relationship may be configured by one or more RRC parameters. The quasi co-location types corresponding to each DL RS may take one of the following values: 'QCL-TypeA': {Doppler shift, Doppler spread, average delay, delay spread}; ’QCL-TypeB': {Doppler shift, Doppler spread}; 'QCL-TypeC: {Doppler shift, average delay}; 'QCL- TypeD': {Spatial Rx parameter}. The UE may receive an activation command (e.g., a MAC CE), used to map TCI states to the codepoints of a DCI field.

[0101] FIG. 15 shows example components of a user equipment and a base station for transmission and/or reception according to some aspects of some of various exemplary embodiments of the present disclosure. All or a subset of blocks and functions in FIG. 15 may be in the base station 1505 and the user equipment 1500 and may be performed by the user equipment 1500 and by the base station 1505. The Antenna 1510 may be used for transmission or reception of electromagnetic signals. The Antenna 1510 may comprise one or more antenna elements and may enable different input-output antenna configurations including Multiple-Input Multiple Output (MIMO) configuration, Multiple- Input Single-Output (MISO) configuration and Single-Input Multiple-Output (SIMO) configuration. In some embodiments, the Antenna 150 may enable a massive MIMO configuration with tens or hundreds of antenna elements. The Antenna 1510 may enable other multi-antenna techniques such as beamforming. In some examples, depending on the UE 1500 capabilities or the type of UE 1500 (e.g., a low-complexity UE), the UE 1500 may support a single antenna only.

[0102] The transceiver 1520 may communicate bi-directionally, via the Antenna 1510, wireless links as described herein. For example, the transceiver 1520 may represent a wireless transceiver at the UE and may communicate bi-directionally with the wireless transceiver at the base station or vice versa. The transceiver 1520 may include a modem to modulate the packets and provide the modulated packets to the Antennas 1510 for transmission, and to demodulate packets received from the Antennas 1510.

[0103] The memory 1530 may include RAM and ROM. The memory 1530 may store computer-readable, computer-executable code 1535 including instructions that, when executed, cause the processor to perform various functions described herein. In some examples, the memory 1530 may contain, among other things, a Basic Input/output System (BIOS) which may control basic hardware or software operation such as the interaction with peripheral components or devices. [0104] The processor 1540 may include a hardware device with processing capability (e.g., a general purpose processor, a DSP, a CPU, a microcontroller, an ASIC, an FPGA, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some examples, the processor 1540 may be configured to operate a memory using a memory controller. In other examples, a memory controller may be integrated into the processor 1540. The processor 1540 may be configured to execute computer-readable instructions stored in a memory (e.g., the memory 1530) to cause the UE 1500 or the base station 1505 to perform various functions.

[0105] The Central Processing Unit (CPU) 1550 may perform basic arithmetic, logic, controlling, and Input/ output (I/O) operations specified by the computer instructions in the Memory 1530. The user equipment 1500 and/or the base station 1505 may include additional peripheral components such as a graphics processing unit (GPU) 1560 and a Global Positioning System (GPS) 1570. The GPU 1560 is a specialized circuitry for rapid manipulation and altering of the Memory 1530 for accelerating the processing performance of the user equipment 1500 and/or the base station 1505. The GPS 1570 may be used for enabling location-based services or other services for example based on geographical position of the user equipment 1500.

[0106] In some examples, for NR sidelink communication, the UE may operate in two modes for resource allocation in sidelink: Scheduled resource allocation and UE autonomous resource selection. Scheduled resource allocation may be characterized by: The UE needs to be RRC CONNECTED in order to transmit data; and NG-RAN schedules transmission resources. UE autonomous resource selection may be characterized by: The UE may transmit data when inside NG-RAN coverage, irrespective of which RRC state the UE is in, and when outside NG-RAN coverage; and The UE autonomously selects transmission resources from resource pool(s). In some examples, for NR sidelink communication, the UE may perform sidelink transmissions only on a single carrier.

[0107] In some examples, NG-RAN may dynamically allocate resources to the UE via the SL-RNTI on PDCCH(s) for NR sidelink communication.

[0108] In some examples, in addition, NG-RAN may allocate sidelink resources to a UE with two types of configured sidelink grants: With type 1 , RRC may directly provide the configured sidelink grant only for NR sidelink communication; With type 2, RRC may define the periodicity of the configured sidelink grant while PDCCH can either signal and activate the configured sidelink grant or deactivate it. The PDCCH may be addressed to SL-CS-RNTI for NR sidelink communication.

[0109] In some examples, NG-RAN may semi-persistently allocate sidelink resources to the UE via the SL Semi-Persistent Scheduling V-RNTI on PDCCH(s) for V2X sidelink communication.

[0110] In some examples, for the UE performing NR sidelink communication, there may be more than one configured sidelink grant activated at a time on the carrier configured for sidelink transmission.

[0111] In some examples, when beam failure or physical layer problem occurs on MCG, the UE may continue using the configured sidelink grant Type 1 until initiation of the RRC connection re-establishment procedure. During handover, the UE may be provided with configured sidelink grants via handover command, regardless of the type. If provided, the UE may activate the configured sidelink grant Type 1 upon reception of the handover command or execution of CHO.

[0112] In some examples, the UE may send sidelink buffer status report to support scheduler operation in NG-RAN. For NR sidelink communication, the sidelink buffer status reports may refer to the data that is buffered in for a group of logical channels (LCG) per destination in the UE. Eight LCGs may be used for reporting of the sidelink buffer status reports. Two formats, which may be SL BSR and truncated SL BSR, may be used.

[0113] In some examples, the UE may autonomously select sidelink resource(s) from resource pool(s) provided by broadcast system information or dedicated signalling while inside NG-RAN coverage or by pre-configuration while outside NG-RAN coverage.

[0114] In some examples, for NR sidelink communication, the resource pool(s) may be provided for a given validity area where the UE does not need to acquire a new pool of resources while moving within the validity area, at least when this pool is provided by SIB. The NR SIB area scope mechanism may be reused to enable validity area for SL resource pool configured via broadcasted system information.

[0115] In some examples, the UE may be allowed to temporarily use UE autonomous resource selection with random selection for sidelink transmission based on configuration of the exceptional transmission resource pool.

[0116] In some examples, when a UE is inside NG-RAN coverage, NR sidelink communication and/or V2X sidelink communication may be configured and controlled by NG-RAN via dedicated signalling or system information: The UE may support and may be authorized to perform NR sidelink communication and/or V2X sidelink communication in NG-RAN; If configured, the UE may perform V2X sidelink communication unless otherwise specified, with the restriction that the dynamic scheduling for V2X sidelink communication (i.e. based on SL-V-RNTI) may not be supported; NG-RAN may provide the UE with intra-carrier sidelink configuration, inter-carrier sidelink configuration and anchor carrier(s) which may provide sidelink configuration via a Uu carrier for NR sidelink communication and/or V2X sidelink communication; When the UE cannot simultaneously perform both NR sidelink transmission and NR uplink transmission in time domain, prioritization between both transmissions may be done based on their priorities and thresholds configured by the NG-RAN or pre-configured. When the UE cannot simultaneously perform both V2X sidelink transmission and NR uplink transmission in time domain, prioritization between both transmissions may be done based on the priorities (i.e., PPPP) of V2X sidelink communication and a threshold configured by the NG-RAN or preconfigured.

[0117] In some examples, when a UE is outside NG-RAN coverage, SL DRB configuration(s) may be preconfigured to the UE for NR sidelink communication. If UE changes the RRC state but has not received the SL DRB configuration(s) for the new RRC state, UE may continue using the configuration obtained in the previous RRC state to perform sidelink data transmissions and receptions until the configuration for the new RRC state is received.

[0118] In some examples, the UE in RRC_CONNECTED may perform NR sidelink communication and/or V2X sidelink communication, as configured by the upper layers. The UE may send Sidelink UE Information to NG-RAN in order to request or release sidelink resources and report QoS information for each destination.

[0119] In some examples, NG-RAN may provide RRCReconfiguration to the UE in order to provide the UE with dedicated sidelink configuration. The RRCReconfiguration may include SL DRB configuration (s) for NR sidelink communication as well as mode 1 resource configuration and/or mode 2 resource configuration. If UE has received SL DRB configuration via system information, UE may continue using the configuration to perform sidelink data transmissions and receptions until a new configuration is received via the RRCReconfiguration.

[0120] In some examples, NG-RAN may configure measurement and reporting of CBR for NR sidelink communication and V2X sidelink communication and reporting of location information for V2X sidelink communication to the UE via RRCReconfiguration. [0121] In some examples, during handover, the UE may perform sidelink transmission and reception based on configuration of the exceptional transmission resource pool or configured sidelink grant Type 1 (for NR sidelink communication only) and reception resource pool of the target cell as provided in the handover command.

[0122] In some examples, the UE in RRC_IDLE or RRC_INACTIVE may perform NR sidelink communication and/or V2X sidelink communication, as configured by the upper layers. NG-RAN may provide common sidelink configuration to the UE in RRC_IDLE or RRC_INACTIVE via system information for NR sidelink communication and/or V2X sidelink communication. UE may receive resource pool configuration and SL DRB configuration via SIB 12 for NR sidelink communication, and/or resource pool configuration via SIB 13 and SIB 14 for V2X sidelink communication.

[0123] In some examples, when the UE performs cell reselection, the UE interested in V2X service(s) may consider at least whether NR sidelink communication and/or V2X sidelink communication are supported by the cell. The UE may consider the following carrier frequency as the highest priority frequency, except for the carrier only providing the anchor carrier: the frequency providing both NR sidelink communication configuration and V2X sidelink communication configuration, if configured to perform both NR sidelink communication and V2X sidelink communication; the frequency providing NR sidelink communication configuration, if configured to perform only NR sidelink communication; the frequency providing V2X sidelink communication configuration, if configured to perform only V2X sidelink communication.

[0124] In some examples, the UE may perform NR sidelink discoven- while in-coverage or out-of-coverage for non-relay operation. In some examples, the Relay discovery mechanism (except the U2N Relay specific threshold based discovery message transmission) may be applied to sidelink discovery. [0125] In some examples, Sidelink may support SL DRX for unicast, groupcast, and broadcast. Similar parameters as defined for Uu (on- duration, inactivity-timer, retransmission-timer, cycle) may be defined for SL to determine the SL active time for SL DRX. During the SL active time, the UE may perform SCI monitoring for data reception (i.e., PSCCH and 2nd stage SCI on PSSCH). The UE may skip monitoring of SCI for data reception during SL DRX inactive time.

[0125] In some examples, the SL active time of the RX UE may include the time in which any of its applicable SL on-duration timer(s), SL inactivity - timer(s) or SL retransmission timer(s) (for any of unicast, groupcast, or broadcast) are running. In some examples, the slots associated with announced periodic transmissions by the TX UE and the time in which a UE is expecting CSI report following a CSI request (for unicast) may be considered as SL active time of the RX UE.

[0127] In some examples, a TX UE may maintain a set of timers corresponding to the SL DRX timers in the RX UE(s) for each pair of source/ destination L2 ID for unicast or destination L2 ID for groupcast/ broadcast. When data is available for transmission to one or more RX UE(s) configured with SL DRX, the TX UE may select resources taking into account the active time of the RX UE(s) determined by the timers maintained at the TX UE.

[0128] In some examples, a UE may determine from SIB 12 whether the gNB supports SL DRX or not.

[0129] In some examples, a default SL DRX configuration for groupcast/ broadcast may be used for discovery message in sidelink discovery and for relay discovery messages.

[0130] In some examples, for unicast, SL DRX may be configured per pair of source L2 ID and destination L2 ID.

[0131] In some examples, the UE may maintain a set of SL DRX timers for each direction per pair of source L2 ID and destination L2 ID. The SL DRX configuration for a pair of source/ destination L2 IDs for a direction may be negotiated between the UEs in the AS layer. For SL DRX configuration of each direction, where one UE is the TX UE and the other is the RX UE: RX UE may send assistance information, which may include its desired SL on-duration timer, SL DRX start offset, and SL DRX cycle, to the TX UE and the mode 2 TX UE may use it to determine the SL DRX configuration for the RX UE; Regardless of whether assistance information is provided or not, the TX UE in RRC_IDLE/RRCJNACTIVE/OOC, or in RRC_CONNECTED and using mode 2 resource allocation, may determine the SL DRX Configuration for the RX UE. For a TX UE in RRC_CONNECTED and using mode 1 resource allocation, the SL DRX configuration for the RX UE may be determined by the serving gNB of the TX UE; TX UE may send the SL DRX configuration to be used by the RX UE to the RX UE; The RX UE may accept or reject the SL DRX configuration.

[0132] In some examples, a default SL DRX configuration for groupcast/ broadcast may be used for DCR messages.

[0133] In some examples, when the TX UE is in RRC_CONNECTED, the TX UE may report the received assistance information to its serving gNB and may send the SL DRX configuration to the RX UE upon receiving the SL DRX configuration in dedicated RRC signaling from the gNB. When the RX UE is in RRC_CONNECTED, the RX UE may report the received SL DRX configuration to its serving gNB, e.g., for alignment of the Uu and SL DRX configurations.

[0134] In some examples, SL on-duration timer, SL inactivity-timer, SL HARQ RTT timer, and SL HARQ retransmission timer may be supported in unicast. SL HARQ RTT timer and SL HARQ retransmission timer may be maintained per SL process at the RX UE. In addition to

(pre) configured values for each of these timers, SL HARQ RTT timer value may be derived from the retransmission resource timing when SCI indicates more than one transmission resource. [0135] In some examples, SL DRX MAC CE may be introduced for SL DRX operation in unicast only.

[0136] In some examples, for groupcast/broadcast, SL DRX may be configured commonly among multiple UEs based on QoS profile and Destination L2 ID. Multiple SL DRX configurations may be supported for each groupcast/broadcast.

[0137] In some examples, SL on-duration timer, SL inactivity-timer, SL HARQ RTT and SL retransmission timers may be supported for groupcast. In some examples, only SL on-duration timer may be supported for broadcast. SL DRX cycle, SL on-duration, and SL inactivity timer (only for groupcast) may be configured per QoS profile. The starting offset and slot offset of the SL DRX cycle may be determined based on the destination L2 ID. The SL HARQ RTT timer (only for groupcast) and SL HARQ retransmission timer (only for groupcast) may not be configured per QoS profile or per destination L2 ID. For groupcast, the RX UE may maintain an SL inactivity timer for each destination L2 ID, and may select the largest SL inactivity timer value if multiple SL inactivity timer values associated with different QoS profiles may be configured for that L2 ID. For groupcast and broadcast, the RX UE may maintain a single SL DRX cycle (selected as the smallest SL DRX cycle of any QoS profile of that L2 ID) and single SL on-duration (selected as the largest SL on-duration of any QoS profile of that L2 ID) for each destination L2 ID when multiple QoS profiles may be configured for that L2 ID.

[0138] In some examples, for groupcast, SL HARQ RTT timer and SL retransmission timer may be maintained per SL process at the RX UE. SL HARQ RTT timer may be set to different values to support both HARQ enabled and HARQ disabled transmissions.

[0139] In some examples, a default SL DRX configuration, common between groupcast and broadcast, may be used for a QoS profile which may not be mapped onto any non-default SL DRX configuration(s). [0140] In some examples, in-coverage TX and RX UEs in RRC_IDLE/RRC_INACTIVE may obtain their SL DRX configuration from SIB. UEs (TX or RX) in RRC_CONNECTED may obtain the SL DRX configuration from SIB, or from dedicated RRC signaling during handover. For the out of coverage case, the SL DRX configuration may be obtained from pre-configuration.

[0141] In some examples, for groupcast, the TX UE may restart its timer corresponding to the SL inactivity timer for the destination L2 ID (used for determining the allowable transmission time) upon reception of new data with the same destination L2 ID.

[0142] In some examples, TX profile may be introduced to ensure compatibility for groupcast and broadcast transmissions between UEs supporting/not-supporting SL DRX functionality. A TX profile may be provided by upper layers to AS layer and identifies one or more sidelink feature group(s). Multiple TX profiles with the support of SL DRX and without the support of SL DRX may be associated to a destination L2 ID. A TX UE may only assume SL DRX for the destination L2 IDs when all the associated TX profiles correspond to support of SL DRX. A Tx UE may assume no SL DRX for the destination L2 ID if there is no associated TX profile. An RX UE may determine that SL DRX is used if all destination L2 IDs of interest are assumed to support SL DRX. For groupcast, the UE may report each destination L2 ID and associated SL DRX on/ off indication to the gNB.

[0143] In some examples, alignment of Uu DRX and SL DRX for a UE in RRC_CONNECTED may be supported for unicast, groupcast, and broadcast. Alignment of Uu DRX and SL DRX at the same UE may be supported. In some examples, for mode 1 scheduling, the alignment of Uu DRX of the TX UE and SL DRX of the RX UE may be supported.

[0144] In some examples, alignment may comprise of either full overlap or partial overlap in time between Uu DRX and SL DRX. For SL RX UEs in RRC_CONNECTED, alignment may be achieved by the gNB. [0145] In some examples, the SL UE in Mode 2 may support partial sensing-based resource allocation and random resource selection as power saving resource allocation methods. A SL mode 2 TX resource pool may be (pre)configured to allow full sensing only, partial sensing only, random selection only, or any combination(s) thereof. A UE may decide which resource allocation scheme(s) may be used in the AS based on its capability (for a UE in RRCJDLE/RRCJNACTIVE/OOC) and the allowed resource schemes in the resource pool configuration.

[0146] In some examples, random resource selection is applicable to both periodic and aperiodic traffic.

[0147] In some examples, a UE capable for partial sensing may perform periodic-based partial sensing and/or contiguous partial sensing for resource (re)selection. Periodic-based partial sensing may only be performed if periodic resource reservation is configured in the resource pool. In periodic-based partial sensing, the UE may monitor slots in periodic sensing occasion(s) for a given resource reservation periodicity. Contiguous partial sensing may be performed by a UE capable of partial sensing when resource (re) selection is triggered by a UE in a TX pool configured with partial sensing. In contiguous partial sensing, the UE may monitor slots in a contiguous sensing window which occur prior to the selected transmission resource.

[0148] Example embodiments may enable NR side-link carrier aggregation (CA) operation. Example embodiments may enable side-link on unlicensed spectrum (SL-U) for mode 1 and/or mode 2. In some examples, Uu operation for mode 1 may be limited to licensed spectrum.

[0149] In some examples, a channel access mechanism (e.g., based on a listen-before-talk (LBT) process) may be used for side-link unlicensed operation.

[0150] In some examples, side-link resource reservation may be used for side-link unlicensed operation within the boundaries of unlicensed channel access mechanism and operation. [0151] In some examples, licensed assisted access and carrier aggregation may be for sidelink communication over unlicensed carriers. In example embodiments a carrier in carrier aggregation may be a sidelink primary component carrier and a different carrier may be a sidelink secondary carrier in for sidelink data transmission in unlicensed carriers.

[0152] In some examples, sidelink communication may be used for advanced V2X applications. In some examples, power saving solutions and inter-UE coordination may be used to improve power consumption for battery limited terminals and reliability of sidelink transmissions.

[0153] In some examples, to enhance the sidelink communications may be enhanced by expanding the applicability of NR Side-link to other commercial use cases, for which two new requirements have been identified, for examples, increased sidelink data rate and support of new carrier frequencies for sidelink. In some examples, the use of carrier aggregation (CA) over sidelink and operation of sidelink in unlicensed /shared spectrum (SL-U) may be used to enhance sidelink communications. In some examples, sidelink communications may operate in unlicensed spectrum with and without carrier aggregation (CA). Without these capabilities the deployment of V2X and Industrial IOT and some of other 5G use cases may be limited or costly.

[0154] In some examples, some operators may be reluctant to use their expensive licensed spectrum for sidelink operation. Allowing sidelink (SL) to use unlicensed spectrum may enable proliferation of V2X and other sidelink applications. On the other hand, SL operation in unlicensed band may result in lower reliability, less predictable QoS, higher latencies and power consumption due to listen-before-talk (LBT)/ clear channel assessment (CCA) failures.

[0155] In some examples, both licensed and unlicensed spectrum may be used for sidelink communications.

[0156] In some examples, sidelink operation may involve synchronization, control signaling and data communication which may be transmitted on same or different RF carriers. Control signaling may include broadcast control signaling, first and second stage sidelink control information (SCI), sidelink HARQ feedback and RRC and MAC layer signaling.

[0157] In some examples, data and higher layer, e.g., MAC/RRC, signaling may be carried on Sidelink Physical Shared Channel (PSSCH), transmitted on RAN configured or pre-configured Resource Pool (RPs). In some examples, an exceptional RP may be configured to be used exclusively in certain conditions such as SL radio link recovery, handovers, etc. to avoid conflicting such transmissions with regular SL data traffic.

[0158] In some examples, SL-U may use NR SL in licensed spectrum and some aspects of NR in unlicensed bands (NR-U).

[0159] In some examples, SL data and control/ signaling communications may be on carried unlicensed spectrum.

[0160] In some examples, the spectrum or carrier used for SL control signaling may not be the same as spectrum used for Data communications .

[0161] In some examples, SL may use a combination of resources in licensed and unlicensed spectrum to improve control signaling latency and reliability.

[0162] In some examples, application of license assisted access in SL-U may allow simpler and more efficient design of control signaling to enable more predictable, lower latency and more power efficient operation of SL. In this approach a carrier in license spectrum may be used not only for configuration of SL radio resources but also to carry some of time critical SL-U control signaling and traffic.

[0163] In some examples, SL-U radio (pre) configuration may define a licensed carrier as primary SL component carrier (SL-PCC), to be used for transmission of some or all SL-U control signaling.

[0164] In some examples, the SL-PCC may or may not include any

Resource Pools for SL data communications. [0165] In some examples, an exceptional Resource Pool may be configured to be used for UEs in specific situations such as handover or sidelink radio link failure. In some examples, exceptional pool in unlicensed band may not provide reliable and timely accessibility of resources needed for UE in such situations.

[0166] In some examples, configuration and use of exceptional transmit resource pools (RP) may be for the case when UEs in network coverage do not have a stable network connection. The exceptional RPs may be used when a UE is in a transition from idle to connected mode, when a UE experiences a link failure or a handover, or when a UE is changing between different configured transmit RPs. The use of exceptional transmit RPs in such situations may aid in improving service continuity. The rational and use cases for exceptional RP may apply to SL when operating in unlicensed spectrum. Exceptional RPs for SL-U operation if configured in the unlicensed carrier may be subject to LBT/CCA failures and may not meet the needs of UEs in the target use cases. In some examples as shown in FIG. 16, a licensed carrier may be utilized, e.g., SL-PCC for exceptional resource pool to avoid such uncertainties and complexities.

[0167] In some examples, exceptional transmit RPs may be reliable and predictable to be effective and useful for target use cases. In some examples, the exceptional RP in SL-U may be configured and used on SL- PCC.

[0168] In some examples in NR V2X, a UE may transmit information for supporting synchronization in the sidelink. In some examples, the UE may serve as a synchronization reference and may be referred to as a SyncRef UE. The synchronization information in NR V2X SL may be carried on the S-SSB that consists of the PSBCH, S-PSSS and S-SSS. Nearby UEs that may be out of network or GNSS coverage may receive S- SSB transmissions from a SyncRef UE and may synchronize to it. [0169] In some examples, transmission and reception of S-SSB on an unlicensed carrier may need to consider the uncertainty associated with LBT/CCA process. Therefore, S-SSB transmission may be configured over a discovery window. Such design may require multiple LBT attempts by RefSynch UE and longer monitoring time and less power saving by receiving UEs. LBT failures on S-SSB may complicate SL-U synchronization design and may become even more complicated if any kind of beam sweeping is used for SL-U.

[0170] In some examples, transmission of SL SSBs in unlicensed carrier may result in longer synchronization time, more processing, and less power saving by receiving UEs.

[0171] In some examples as shown in FIG. 16, to simplify the design and improve efficiency, a license carrier may be used to convey S-SSB information. This may allow predictable and consistent transmission of S-SSB on specific slots.

[0172] In some examples, the S-SSB in SL-U may be transmitted on SL- PCC.

[0173] In some examples, SL-U may provide timely resources for HARQ feedback on Physical Sidelink Feedback Channel (PSFCH). While some PSFCH transmission may be allowed through CoT sharing by TX UEs in many cases such feedback may need to be carried on resource allocated for PSFCH through RRC configuration and DCI signaling. Timely transmission of HARQ feedback on unlicensed spectrum for unicast may be challenging due to possible LBT conflicts and failures experienced by receiving the UEs to send its ACK/ NACK feedback. The complexity and performance challenge may be even more for multicast SL-U communications where multiple UEs need to apply LBT for their PSFCH transmission at the same time and on possibly on shared resources.

[0174] In some examples, transmission of HARQ feedback on PSFCH on unlicensed spectrum may experience longer latency and lower reliability and performance due to LBT result. [0175] In some examples as shown in FIG. 17, PSFCH resources may be configured on a licensed carrier, i.e., on the SL-PCC.

[0176] In some examples, PSFCH resources for HARQ feedback for unicast and multicast transmission may be configured and used on SL- PCC.

[0177] In some examples, the PSFCH transmission may be allowed in a COT initiated and shared by a transmitting UE. Such transmission may not be subject to excessive LBT delays and may be carried on the unlicensed carrier and on the same SL BWP/RP used by TX UE for PSSCH transmission.

[0178] In some examples, HARQ feedback on PSFCH may be carried on unlicensed carrier on the same SL BWP used for PSSCH if enabled through COT sharing by transmission UE.

[0179] Sidelink carrier aggregation (sidelink CA) and operation of sidelink carriers in unlicensed spectrum (SL-U) may be used to enhance sidelink performance. Existing processes for control signaling may result in wireless devices and wireless network performance degradation when the UEs operate according to SL-U processes. There is a need to enhance the existing processes for control signaling when the UEs operate according to SL-U processes. Example embodiments enhance the existing processes for control signaling when the UEs operate according to SL-U processes.

[0180] In some examples, Sidelink Control Information (SCI) signaling may be used for SL-U operation. Resource allocation in Mode 2 may rely on a two stage Sidelink Control Information (SCI). In some examples, the CORESET carrying first stage SCI may need to be duplicated across all RB sets to ensure that UE receive the SCI regardless of which subset of RBsets pass the LBT test and end up being used for transmission of data on PSSCH. Such duplicate configuration may result in extra overhead that may be avoided. All UEs may need to perform more stage 1 SCI monitoring across RBsets which may negatively impact their battery lives. Using the SL-PCC to carry 1st stage SCI may help avoid inefficiencies, as shown in FIG. 18.

[0181] In some examples, transmission of first stage SCI signaling, for SL- U data communication, on a licensed carrier may be beneficial from signaling overhead and UE power saving.

[0182] In some examples, the SL-U CORESET, i.e. PSCCH resources for 1st stage SCI transmission, supporting SL-U may be configured and used on SL-PCC.

[0183] In an example embodiment as shown in FIG. 19, a first user equipment (UE) may receive, from a base station, one or more messages (e.g., one or more RRC messages) comprising configuration parameters. The configuration parameters may comprise sidelink configuration parameters used by the first UE for sidelink communications with one or more UEs (e.g., for sidelink communications with a second UE). The configuration parameters may comprise configuration parameters of a plurality of carriers for sidelink communications. The first UE may utilize the configuration parameters of the plurality of carriers for sidelink communications with a second UE via the plurality of carriers. The configuration of the plurality of carriers for the first UE may enable carrier aggregation for sidelink. The plurality of carriers may comprise at least one first carrier that operates in licensed spectrum and may comprise at least one second carrier that operates in unlicensed spectrum. The plurality of carriers may comprise a sidelink primary carrier and a sidelink secondary carrier. Based on the at least one first carrier, in the plurality of carriers, operating in the licensed spectrum, the sidelink primary carrier may be one of the at least one first carrier. In some examples, the at least one second carrier may comprise at least one sidelink secondary carrier in which case the at least one sidelink secondary carrier may be unlicensed carriers. In some examples, the at least one first carrier may comprise at least one sidelink secondary carrier in which case the at least one sidelink secondaiy carrier may be licensed carriers. At least one type of control information for sidelink operations may be transmitted via the at least one first carrier. In an example, at least one type of control information for sidelink operations may only be transmitted via the at least one first carrier. In some examples, at least one type of control information for sidelink operations may be transmitted via a licensed carrier. In an example, at least one type of control information for sidelink operations may only be transmitted via a licensed carrier.

[0184] In some examples, communicating of the first UE to the second UE may be based on a channel access mechanism and in response to the channel access mechanism indicating that the first UE is allowed to transmit sidelink data/ signaling. In an example, the channel access mechanism may be based on a listen-before-talk (LET) process. The first UE may transmit sidelink data/ signaling in response to the LET process indicating a clear channel. The LBT process may be based on one or more LBT configuration parameters. The one or more LBT configuration parameters that are used for sidelink channel access may be RRC configuration parameters. The one or more LBT configuration parameters may be used by the first UE to perform the LBT process, such as a duration of the LBT/ clear channel access mechanism before determining whether channel is available or busy.

[0185] In some examples, the configuration parameters (e.g., sidelink configuration parameters) may indicate a plurality of resource pools (RPs) for the plurality of carriers for sidelink communications via the plurality of carriers. The plurality of resource pools may comprise at least one first resource pool for the at least one first carrier. In some examples, the first resource pool may be dedicated for transmission of control information. In some examples, the at least one first resource pool may not be used for sidelink data transmission. The wireless device may determine the first resource pool based on configuration parameters received associated with the first resource pool. For example, the configuration parameters of the first resource pool may comprise at least one first parameter indicating that the first resource pool is for transmission of sidelink control signaling and/or is dedicated/ only used for transmission of sidelink control signaling and/or is not used for transmission of sidelink data. In an example, the plurality of carriers configured for the UE may comprise at least one exceptional resource pool. The exceptional resource pool may be configured /used in case of handover and/or radio link failure/ radio link failure recovery and/or in scenarios that the channel conditions are not stable. The configuration of the exceptional resource pool may be for improving reliability of sidelink communications when UEs in network coverage do not have stable channel conditions. The exceptional resource pool may be configured for the at least one first carrier (i.e., the carrier(s) that operate in the licensed spectrum). In some examples, the exceptional resource pool may only be configured for a licensed carrier and may not be configured for an unlicensed carrier. In some examples, the exceptional resource pool may only be configured for the sidelink primary carrier (e.g., the sidelink primary carrier that operate in the licensed spectrum) and/or may not be configured for a sidelink secondary carrier (e.g., a sidelink secondary carrier operating in the unlicensed spectrum).

[0186] In some examples, the at least one type of control information, which may be transmitted (e.g., only transmitted) via the at least one first carrier, may comprise control information used in sidelink synchronization (e.g., the sidelink synchronization signal block (S-SSB)). The S-SSB may comprise a physical sidelink broadcast channel (PSBCCH), a sidelink primary synchronization signal (S-PSS) and a sidelink secondary synchronization signal (S-SSS). One or more UEs (e.g., one or more UEs that are outside network coverage) may synchronize to the first UE (which may be a reference UE for synchronization) based on the S-SSB transmitted by the first UE. The S- SSB may be transmitted via the at least one first carrier (e.g., a licensed carrier). In some examples, the S-SSB may only be transmitted via the at least one first carrier (e.g., only via the licensed carrier). In some examples, the S-SSB may be transmitted (e.g., may only be transmitted) via a primary sidelink carrier.

[0187] In some examples, the at least one type of control information may comprise HARQ feedback (e.g., for transmission of via a PSFCH). In some examples, the transmission of the HARQ feedback via the PSFCH may be via the at least one first carrier (e.g., only via the at least one first carrier). In some examples, the transmission of the HARQ feedback via the PSFCH may be via a licensed carrier (e.g., only via the licensed carrier). In some examples, the transmission of the HARQ feedback via the PSFCH may be via the sidelink primary carrier (e.g., only via the sidelink primary carrier) .

[0188] In some examples, HARQ feedback may be transmitted via a physical sidelink shared channel (PSSCH) of the at least one second carrier (e.g., via an unlicensed carrier, e.g., an unlicensed secondary carrier) provided that transmission of the HARQ feedback is within a channel occupancy time (COT) obtained for transmission of a sidelink packet. The HARQ feedback may be transmitted via the same BWP or resource pool used for transmission of the sidelink packet.

[0189] Sidelink carrier aggregation (sidelink CA) and operation of sidelink carriers in unlicensed spectrum (SL-U) may be used to enhance sidelink performance. Existing processes for two-stage sidelink control information (SCI) signaling may result in wireless device and wireless network performance degradation when the UEs operate according to SL- U processes. There is a need to enhance the existing processes for two- stage SCI signaling when the UEs operate according to SL-U processes. Example embodiments enhance the existing processes for two-stage SCI signaling when the UEs operate according to SL-U processes.

[0190] In an example embodiment as shown in FIG. 20, a first user equipment (UE) may receive one or more messages (e.g., one or more RRC messages) comprising configuration parameters (e.g., RRC configuration parameters) . The configuration parameters may comprise first configuration parameters of a first carrier and a second carrier for sidelink communications. In some examples, the configuration of the first carrier and the second carrier may be for configuration of sidelink carrier aggregation for the first UE. The carriers configured for sidelink communications may comprise a sidelink primary carrier and a sidelink secondary carrier. In some examples, the first carrier may be a sidelink primary carrier and the second carrier may be a sidelink secondary carrier. The first carrier (e.g., the sidelink primary carrier) may operate in licensed spectrum and the second carrier (e.g., the sidelink secondary carrier) may operate in unlicensed spectrum. The first UE may transmit two-stage sidelink control information (SCI) comprising first SCI and second SCI. The first UE may transmit the first SCI (e.g., the first stage of a multi-stage SCI) via the first carrier. In some examples, the first UE may transmit the first SCI (e.g., the first stage of a multi-stage SCI) only via the first carrier. In some examples, the first UE may transmit the first SCI (e.g., the first stage of a multi-stage SCI) via a licensed carrier. In some examples, the first UE may transmit the first SCI (e.g., the first stage of a multi-stage SCI) only via a licensed carrier. In some examples, the first UE may transmit the first SCI (e.g., the first stage of a multistage SCI) via the sidelink primary carrier. In some examples, the first UE may transmit the first SCI (e.g., the first stage of a multi-stage SCI) only via the sidelink primary carrier. In some examples, the first UE may transmit the second SCI (e.g., the second stage of a multi-stage SCI) via the first carrier or via the second carrier. In some examples, the first UE may transmit the second SCI (e.g., the second stage of a multi-stage SCI) via the sidelink primary carrier or via the sidelink secondary carrier. In some examples, the first UE may transmit the second SCI (e.g., the second stage of a multi-stage SCI) via a licensed carrier or via an unlicensed carrier. [0191] In some examples, the first UE may receive first configuration parameters of a first control resource set (CORESET). The first CORESET may be configured for the primary sidelink carrier. The first CORESET of the sidelink primary carrier may be used for transmission of the first SCI of the multi-stage SCI. In some examples, the first UE may receive second configuration parameters of a second CORESET that is used for transmission of the second SCI of the multi-stage SCI. In some examples, the second CORESET may be configured for the sidelink primary carrier. In some examples, the second CORESET may be configured for the sidelink secondary carrier. In some examples, the second configuration parameters of the second CORESET may comprise at least one parameter indicating that the second CORESET is for transmission of SCI (e.g., indicating that the second CORESET is for transmission of second SCI of a two-stage SCI).

[0192] The first UE may transmit sidelink data to a second UE. The two- stage SCI may be associated -with (e.g., may comprise information used by the first UE and / or the second UE for transmission or reception of) the sidelink data. The first SCI of the two-stage SCI may be associated with transmission of sidelink data via PSSCH. For example, the first SCI of the two-stage SCI may comprise scheduling information indicating radio resources (sidelink radio resources) used for transmission of a sidelink transport block. For example, the first SCI of the two-stage SCI may comprise information indicating a resource reservation period for reservation of sidelink resources in the reservation period. For example, the first SCI of the two-stage SCI may indicate a DMRS pattern. The DMRS pattern may be used in reception of the sidelink transport block/packet. For example, the first SCI of the two-stage SCI may comprise information associated with a modulation and coding scheme (MCS). The MCS may be used in reception of the sidelink transport block/packet. In some examples, the second SCI of the two-stage SCI may be transmitted via the PSSCH (e.g., the PSSCH that is used for transmission of the sidelink transport block/ packet). In some examples, the second SCI of the two-stage SCI may comprise HARQ information (e.g., a HARQ process number, new data indicator (NDI), redundancy version (RV), etc.). In some examples, the second SCI of the two-stage SCI may comprise a source identifier associated with the first UE (e.g., the transmitting UE). In some examples, the second SCI of the two-stage SCI may comprise a destination identifier associated with the second UE to which the sidelink transport block is transmitted. In some examples, the second SCI of the two-stage SCI may comprise a channel state information (CSI) request indicating a request for transmission of a CSI report by the second SCI. In some examples, the second SCI of the two- stage SCI may comprise one or more parameters related to channel access, e.g., a listen-before-talk process. For example, the second SCI of the two-stage SCI may comprise a channel occupancy time obtained by the first UE in response to a successful LBT process. The first UE may transmit sidelink data (e.g., a sidelink transport block) in response to performing an LBT process and the LBT process indicating a clear channel. In some examples, the LBT process may be based on one or more LBT parameters. The one or more LBT parameters may be based on one or more LBT configuration parameters indicating the one or more LBT parameters used in the LBT process. In some examples, the one or more LBT parameters may indicate a duration of clear channel assessment wherein the first UE senses the unlicensed channel for the duration of the clear channel assessment.

[0193] In an example embodiment, a first user equipment (UE) may receive configuration parameters of a plurality of carriers for sidelink communications. The first UE may communicate with a second UE via the plurality of carriers and using the configuration parameters. At least one first carrier, in the plurality of carriers, may operate in licensed spectrum. At least one second carrier, in the plurality of carriers, may operate in unlicensed spectrum. At least one type of control information may be transmitted via the at least one first carrier.

[0194] In some examples, configuration of the plurality of carriers may be for sidelink carrier aggregation.

[0195] In some examples, the plurality of carriers may comprise a sidelink primary carrier and a sidelink secondary" carrier. In some examples, the at least one first carrier may comprise the sidelink primary carrier. In some examples, the at least one second carrier may comprise the sidelink secondary carrier.

[0196] In some examples, the at least one type of control information may only be transmitted via the at least one first carrier.

[0197] In some examples, the at least one type of control information may only be transmitted via a licensed carrier.

[0198] In some examples, communicating over the at least one second carrier may comprise a channel access mechanism. In some examples, the channel access mechanism may be based on a listen-before-talk process. In some examples, the communicating over the at least one second carrier may be based on the listen-before-talk process indicating a clear channel. In some examples, the configuration parameters may comprise one or more listen-before-talk parameters, wherein the listen- before-talk process may be based on the one or more listen-before-talk parameters. In some examples, the one or more listen-before-talk parameters may indicate a duration of clear channel assessment for an unlicensed channel.

[0199] In some examples, the configuration parameters may indicate a plurality of resources pools for sidelink communications via the plurality of carriers. In some examples, the configuration parameters may indicate a first resource pool for the at least one first carrier. In some examples, the first resource pool may be for transmission of sidelink control signaling. In some examples, the first resource pool may not be for transmission of sidelink data. In some examples, first configuration parameters of the first resource pool may comprise at least one first parameter indicating that the first resource pool is for transmission of sidelink control signaling. In some examples, the at least one parameter may further indicate that the first resource pool is not for transmission of sidelink data. In some examples, the plurality of resource pools may comprise an exceptional resource pool. In some examples, the exceptional resource pool may be configured for handover. In some examples, the exceptional resource pool may be configured for sidelink radio failure recovery. In some examples, the configuration of the exceptional resource pool may be for improving reliability of sidelink communications when user equipments (UEs) in network coverage do not have stable network conditions. In some examples, the exceptional resource pool may be configured for a first resource pool in the at least one first carrier. In some examples, the exceptional resource pool may only be configured for a licensed carrier. In some examples, the exceptional resource pool may only be configured for a sidelink primary carrier.

[0200] In some examples, the at least one type of control information may comprise control information used in sidelink synchronization. In some examples, the control information used for sidelink synchronization may comprise sidelink synchronization signal block (S-SSB). In some examples, the sidelink synchronization signal block (S-SSB) may comprise a physical sidelink broadcast channel (PSBCCH), a sidelink primaiy synchronization signal (S-PSS) and a sidelink secondary synchronization signal (S-SSS). In some examples, one or more user equipments (UEs) may use the sidelink synchronization signal block (S- SSB), transmitted by the first UE, to synchronize to the first UE. In some examples, the first user equipment (UE) may be a reference UE for synchronization. In some examples, the one or more user equipments (UEs) may be out of network coverage. In some examples, the sidelink synchronization signal block (S-SSB) may be transmitted via a sidelink primary carrier.

[0201] In some examples, the at least one type of control information may comprise hybrid automatic repeat request (HARQ) feedback. In some examples, transmission of the HARQ feedback may be via a physical sidelink feedback channel (PSFCH). In some examples, transmission of PSFCH may be via a sidelink primary carrier.

[0202] In some examples, hybrid automatic repeat request (HARQ) feedback may be transmitted via a physical sidelink shared channel (PSSCH) of the at least one second carrier provided that transmission of the HARQ feedback is within a channel occupancy time (COT) obtained for transmission of a sidelink packet. In some examples, the hybrid automatic repeat request (HARQ) feedback may be transmitted via the same bandwidth part (BWP) or resource pool used for transmission of the sidelink packet.

[0203] In an example embodiment, a first user equipment (UE) may receive configuration parameters of a first carrier and a second carrier for sidelink communications. The first carrier may operate in licensed spectrum and the second carrier may operate in unlicensed spectrum. The first UE may transmit two-stage sidelink control information (SCI) comprising first SCI and second SCI. Transmitting the first SCI may be via the first carrier.

[0204] In some examples, the transmitting the first sidelink control information (SCI) may only be via the first carrier.

[0205] In some examples, the transmitting the first sidelink control information (SCI) may only be via a licensed carrier.

[0206] In some examples, the transmitting the second sidelink control information (SCI) may be via the first carrier or via the second carrier.

[0207] In some examples, configuration of the first carrier and the second carrier may be for sidelink carrier aggregation. In some examples, the first carrier may be a primaiy sidelink carrier and the second carrier may be a secondary sidelink carrier. In some examples, transmitting the first sidelink control information (SCI) may be via the primary sidelink carrier. In some examples, transmitting the first sidelink control information (SCI) may only be via the primary sidelink carrier.

[0208] In some examples, the first UE may receive first configuration parameters of a first control resource set (CORESET) of the primary sidelink carrier that is used for transmission of the first sidelink control information (SCI). In some examples, the first UE may receive second configuration parameters of a second control resource set (CORESET) of the primary sidelink carrier that is used for transmission of the second sidelink control information (SCI). In some examples, the first UE may receive second configuration parameters of a second control resource set (CORESET) of the secondary sidelink carrier that is used for transmission of the second sidelink control information (SCI).

[0209] In some examples, the first UE may transmit sidelink data to a second UE. In some examples, the two-stage sidelink control information (SCI) may be associated with the sidelink data. In some examples, the first sidelink control information (SCI) of the two-stage SCI may be associated with transmission of the sidelink data via a physical sidelink shared channel (PSSCH). In some examples, the first sidelink control information (SCI) of the two-stage SCI may comprise scheduling information associated with the sidelink data. In some examples, the first sidelink control information (SCI) of the two-stage SCI may comprise resource reservation period. In some examples, the first sidelink control information (SCI) of the two-stage SCI may comprise a demodulation reference signal (DMRS) pattern. In some examples, the first sidelink control information (SCI) of the two-stage SCI may comprise a modulation and coding scheme. In some examples, transmitting the second sidelink control information (SCI) of the two-stage SCI may be transmitted via the physical sidelink shared channel (PSSCH) . In some examples, the second sidelink control information (SCI) of the two-stage SCI may comprise hybrid automatic repeat request (HARQ) information. In some examples, the second sidelink control information (SCI) of the two-stage SCI may comprise hybrid automatic repeat request (HARQ) information. In some examples, the hybrid automatic repeat request (HARQ) information may comprise a HARQ process number. In some examples, the hybrid automatic repeat request (HARQ) information may comprise a new data indicator. In some examples, the second sidelink control information (SCI) of the two-stage SCI may comprise a source identifier associate with the first user equipment (UE). In some examples, the second sidelink control information (SCI) of the two-stage SCI may comprise a destination identifier associated with the second user equipment (UE). In some examples, the second sidelink control information (SCI) of the two-stage SCI may comprise a channel state information (CSI) request. In some examples, the second sidelink control information (SCI) of the two-stage SCI may comprise one or more parameters related to channel access. In some examples, the one or more parameters related to channel access may comprise first parameter indicating a channel occupancy time (COT) value. In some examples, the channel access may be based on a listen-before-talk (LBT) process. In some examples, the first UE may transmit sidelink data to a second UE in response to the before-talk (LBT) process indicating a clear channel. In some examples, the first UE may receive listen-before-talk (LBT) configuration parameters, wherein the LBT process may be based on the one or more LBT configuration parameters. In some examples, the one or more listen-before-talk (LBT) configuration parameters may indicate a duration of clear channel assessment for an unlicensed channel.

[0210] The exemplary blocks and modules described in this disclosure with respect to the various example embodiments may be implemented or performed with a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. Examples of the general-purpose processor include but are not limited to a microprocessor, any conventional processor, a controller, a microcontroller, or a state machine. In some examples, a processor may be implemented using a combination of devices (e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration) .

[0211] The functions described in this disclosure may be implemented in hardware, software executed by a processor, firmware, or any combination thereof. Instructions or code may be stored or transmitted on a computer-readable medium for implementation of the functions. Other examples for implementation of the functions disclosed herein are also within the scope of this disclosure. Implementation of the functions may be via physically co-located or distributed elements (e.g., at various positions), including being distributed such that portions of functions are implemented at different physical locations.

[0212] Computer-readable media includes but is not limited to non- transitory computer storage media. A non-transitoiy storage medium may be accessed by a general purpose or special purpose computer.

Examples of non-transitory storage media include, but are not limited to, random access memoiy (RAM), read-only memory (ROM), electrically erasable programmable ROM (EEPROM), flash memoiy, compact disk (CD) ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, etc. A non-transitory medium may be used to carry or store desired program code means (e.g., instructions and/or data structures) and may be accessed by a general-purpose or specialpurpose computer, or a general-purpose or special-purpose processor. In some examples, the software/ program code may be transmitted from a remote source (e.g., a website, a server, etc.) using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave. In such examples, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are within the scope of the definition of medium. Combinations of the above examples are also within the scope of computer-readable media.

[0213] As used in this disclosure, use of the term “or” in a list of items indicates an inclusive list. The list of items may be prefaced by a phrase such as “at least one of or “one or more of. For example, a list of at least one of A, B, or C includes A or B or C or AB (i.e., A and B) or AC or BC or ABC (i.e., A and B and C). Also, as used in this disclosure, prefacing a list of conditions with the phrase “based on” shall not be construed as “based only on” the set of conditions and rather shall be construed as “based at least in part on” the set of conditions. For example, an outcome described as “based on condition A” may be based on both a condition A and a condition B without departing from the scope of this disclosure.

[0214] In this specification the terms “comprise”, “include” or “contain” may be used interchangeably and have the same meaning and are to be construed as inclusive and open-ending. The terms “comprise”, “include” or “contain” may be used before a list of elements and indicate that at least all of the listed elements within the list exist but other elements that are not in the list may also be present. For example, if A comprises B and C, both {B, C} and {B, C, D} are within the scope of A.

[0215] The present disclosure, in connection with the accompanied drawings, describes example configurations that are not representative of all the examples that may be implemented or all configurations that are within the scope of this disclosure. The term “exemplary” should not be construed as “preferred” or “advantageous compared to other examples” but rather “an illustration, an instance or an example.” By reading this disclosure, including the description of the embodiments and the drawings, it will be appreciated by a person of ordinary skills in the art that the technology disclosed herein may be implemented using alternative embodiments. The person of ordinary skill in the art would appreciate that the embodiments, or certain features of the embodiments described herein, may be combined to arrive at yet other embodiments for practicing the technology described in the present disclosure. Thus, the disclosure is not limited to the examples and designs described herein but is to be accorded the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method of sidelink communication, comprising the steps of: receiving, by a first user equipment (UE), configuration parameters of a plurality of carriers for sidelink communications; communicating with a second UE via the plurality of carriers and using the configuration parameters; and wherein: at least one first carrier, in the plurality of carriers, operates in a licensed spectrum; at least one second carrier, in the plurality of carriers, operates in unlicensed spectrum; and at least one type of control information is transmitted via the at least one first carrier.

2. The method of claim 1 , wherein the carriers of the plurality of carriers are configured for sidelink carrier aggregation.

3. The method of claim 1, wherein the carriers of the plurality of carriers comprise a sidelink primary carrier and a sidelink secondary carrier.

4. The method of claim 3, wherein the at least one first carrier comprises the sidelink primary carrier.

5. The method of claim 3, wherein the at least one second carrier comprises the sidelink secondary carrier.

6. The method of claim 1, wherein the at least one type of control information is only transmitted via the at least one first carrier.

7. The method of claim 1, wherein the at least one type of control information is only transmitted via a licensed carrier.

8. The method of claim 1, wherein communicating over the at least one second carrier relies upon a channel access mechanism.

9. The method of claim 8, wherein the channel access mechanism is based on a listen-before-talk process.

10. The method of claim 9, wherein the communication over the at least one second carrier is based on the listen-before -talk process indicating a clear channel.

11. A method of sidelink communication, comprising the steps of: receiving, by a first user equipment (UE), configuration parameters of a first carrier and a second carrier for sidelink communications, wherein the first carrier operates in a licensed spectrum and the second carrier operates in an unlicensed spectrum; transmitting two-stage sidelink control information (SCI) comprising first SCI and second SCI, wherein transmitting the first SCI is via the first carrier.

12. The method of claim 11, wherein the transmitting of the first sidelink control information (SCI) is only via the first carrier.

13. The method of claim 11, wherein the transmitting of the first sidelink control information (SCI) is only via a licensed carrier.

14. The method of claim 11, wherein the transmitting the second sidelink control information (SCI) is via the first carrier or via the second carrier.

15. The method of claim 11, wherein the first carrier and the second carrier are configured for sidelink carrier aggregation.

16. The method of claim 15, wherein the first carrier is a primary sidelink carrier and the second carrier is a secondary sidelink carrier.

17. The method of claim 16, wherein the first sidelink control information (SCI) is transmitted via the primary sidelink carrier.

18. The method of claim 17, wherein the first sidelink control information (SCI) is transmitted only via the primary sidelink carrier.

19. The method of claim 11, further comprising receiving first configuration parameters of a first control resource set (CORESET) of the primary sidelink carrier that is used for transmission of the first sidelink control information (SCI) .

20. The method of claim 19, further comprising receiving second configuration parameters of a second control resource set (CORESET) of the primary sidelink carrier that is used for transmission of the second sidelink control information (SCI).