An apparatus configured to be employed within a User Equipment, UE, comprising: a memory; and one or more processors configured to implement a protocol stack for Fifth Generation, 5G, New Radio Things Sidelink, tSL, communications between 5G New Radio Things UEs and network UEs, wherein the protocol stack implements a Higher Layer, tSL-HL, entity, interfacing with an Internet Protocol, IP, layer entity and a tSL physical layer, tSL-PHY, entity also comprised by the protocol stack, wherein the tSL-HL entity is configured to: receive one or more user plane, UP, packets from the IP layer entity as corresponding one or more tSL-HL service data units, SDUs; assign a distinct sequence number to each of one or more tSL-HL service data units; buffer the one or more tSL-HL SDUs to a UP transmission buffer; determine a physical resource assignment, PRA, and an allocated size for a tSL-HL UP protocol data unit, PDU; generate the tSL-HL UP PDU based on the one or more tSL-HL SDUs buffered to the UP transmission buffer, the PRA, and the allocated size for the tSL-HL UP PDU; where generating the tSL-HL UP PDU includes adding a tSL-HL header; provide the tSL-HL UP PDU to the tSL-PHY entity for transmission based on the PRA; generate the tSL-HL UP PDU based at least in part on a UP retransmission buffer; determine distinct priorities for both of the UP transmission buffer and the UP retransmission buffer; and generate the tSL-HL UP PDU based at least in part on the distinct priorities. a memory; and one or more processors configured to implement a protocol stack for Fifth Generation, 5G, New Radio Things Sidelink, tSL, communications between 5G New Radio Things UEs and network UEs, wherein the protocol stack implements a Higher Layer, tSL-HL, entity, interfacing with an Internet Protocol, IP, layer entity and a tSL physical layer, tSL-PHY, entity also comprised by the protocol stack, wherein the tSL-HL entity is configured to: receive one or more user plane, UP, packets from the IP layer entity as corresponding one or more tSL-HL service data units, SDUs; assign a distinct sequence number to each of one or more tSL-HL service data units; buffer the one or more tSL-HL SDUs to a UP transmission buffer; determine a physical resource assignment, PRA, and an allocated size for a tSL-HL UP protocol data unit, PDU; generate the tSL-HL UP PDU based on the one or more tSL-HL SDUs buffered to the UP transmission buffer, the PRA, and the allocated size for the tSL-HL UP PDU; where generating the tSL-HL UP PDU includes adding a tSL-HL header; provide the tSL-HL UP PDU to the tSL-PHY entity for transmission based on the PRA; generate the tSL-HL UP PDU based at least in part on a UP retransmission buffer; determine distinct priorities for both of the UP transmission buffer and the UP retransmission buffer; and generate the tSL-HL UP PDU based at least in part on the distinct priorities. receive one or more user plane, UP, packets from the IP layer entity as corresponding one or more tSL-HL service data units, SDUs; assign a distinct sequence number to each of one or more tSL-HL service data units; buffer the one or more tSL-HL SDUs to a UP transmission buffer; determine a physical resource assignment, PRA, and an allocated size for a tSL-HL UP protocol data unit, PDU; generate the tSL-HL UP PDU based on the one or more tSL-HL SDUs buffered to the UP transmission buffer, the PRA, and the allocated size for the tSL-HL UP PDU; where generating the tSL-HL UP PDU includes adding a tSL-HL header; provide the tSL-HL UP PDU to the tSL-PHY entity for transmission based on the PRA; generate the tSL-HL UP PDU based at least in part on a UP retransmission buffer; determine distinct priorities for both of the UP transmission buffer and the UP retransmission buffer; and generate the tSL-HL UP PDU based at least in part on the distinct priorities.