Section: 8.4 NR sidelink communication and V2X sidelink communication related identities
Content: The following identities are used for NR sidelink communication: - Source Layer-2 ID: Identifies the sender of the data in NR sidelink communication. The Source Layer-2 ID is 24 bits long and is split in the MAC layer into two bit strings: - One bit string is the LSB part (8 bits) of Source Layer-2 ID and forwarded to physical layer of the sender. This identifies the source of the intended data in sidelink control information and is used for filtering of packets at the physical layer of the receiver; - Second bit string is the MSB part (16 bits) of the Source Layer-2 ID and is carried within the MAC header. This is used for filtering of packets at the MAC layer of the receiver. - Destination Layer-2 ID: Identifies the target of the data in NR sidelink communication. For NR sidelink communication, the Destination Layer-2 ID is 24 bits long and is split in the MAC layer into two bit strings: - One bit string is the LSB part (16 bits) of Destination Layer-2 ID and forwarded to physical layer of the sender. This identifies the target of the intended data in sidelink control information and is used for filtering of packets at the physical layer of the receiver; - Second bit string is the MSB part (8 bits) of the Destination Layer-2 ID and is carried within the MAC header. This is used for filtering of packets at the MAC layer of the receiver. - PC5 Link Identifier: Uniquely identifies the PC5 unicast link in a UE for the lifetime of the PC5 unicast link as specified in TS 23.287[ Architecture enhancements for 5G System (5GS) to support Vehicle-to-Everything (V2X) services ]  [40]. The PC5 Link Identifier is used to indicate to upper layers the PC5 unicast link in which sidelink RLF was declared and corresponding PC5-RRC connection was released. V2X sidelink communication related identities are specified in clause 8.3 of TS 36.300[ Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 ]  [2].