Section: 5.14.1.3.1 Logical channel prioritization
Content: The Logical Channel Prioritization procedure is applied when a new transmission is performed. Each sidelink logical channel has an associated priority which is the PPPP and optionally an associated PPPR. Multiple sidelink logical channels may have the same associated priority. The mapping between priority and LCID is left for UE implementation. If duplication is activated as specified in TS 36.323[ Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification ]  [4], the MAC entity shall map different sidelink logical channels which correspond to the same PDCP entity onto different carriers in accordance with clause 5.14.1.5, or onto different carriers of different carrier sets (if configured in allowedCarrierFreqList for the corresponding destination). For a given sidelink logical channel, it is up to UE implementation which carrier set to select among the carrier sets configured in allowedCarrierFreqList (if configured) for the corresponding destination. The MAC entity shall perform the following Logical Channel Prioritization procedure either for each SCI transmitted in an SC period in sidelink communication, or for each SCI corresponding to a new transmission in V2X sidelink communication: - The MAC entity shall allocate resources to the sidelink logical channels in the following steps: - Only consider sidelink logical channels not previously selected for this SC period and the SC periods (if any) which are overlapping with this SC period, to have data available for transmission in sidelink communication; - Only consider sidelink logical channels which meet the following conditions: - allowed on the carrier where the SCI is transmitted for V2X sidelink communication, if the carrier is configured by upper layers according to TS 36.331[ Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification ]  [8] and TS 24.386[ User Equipment (UE) to V2X control function; protocol aspects; Stage 3 ]  [15]; - having a priority whose associated threshCBR-FreqReselection is no lower than the CBR of the carrier when the carrier is (re-)selected in accordance with 5.14.1.5; - Only consider one sidelink logical channel among sidelink logical channels corresponding to same PDCP entity, if duplication is activated as specified in TS 36.323[ Evolved Universal Terrestrial Radio Access (E-UTRA); Packet Data Convergence Protocol (PDCP) specification ]  [4]. - Step 0: Select a ProSe Destination, having the sidelink logical channel with the highest priority, among the sidelink logical channels having data available for transmission and having the same transmission format as the one selected corresponding to the ProSe Destination; NOTE: The sidelink logical channels belonging to the same ProSe Destination have the same transmission format. - For each MAC PDU associated to the SCI: - Step 1: Among the sidelink logical channels belonging to the selected ProSe Destination and having data available for transmission, allocate resources to the sidelink logical channel with the highest priority; - Step 2: if any resources remain, sidelink logical channels belonging to the selected ProSe Destination are served in decreasing order of priority until either the data for the sidelink logical channel(s) or the SL grant is exhausted, whichever comes first. Sidelink logical channels configured with equal priority should be served equally. - The UE shall also follow the rules below during the scheduling procedures above: - the UE should not segment an RLC SDU (or partially transmitted SDU) if the whole SDU (or partially transmitted SDU) fits into the remaining resources; - if the UE segments an RLC SDU from the sidelink logical channel, it shall maximize the size of the segment to fill the grant as much as possible; - the UE should maximise the transmission of data; - if the MAC entity is given a sidelink grant size that is equal to or larger than 10 bytes (for sidelink communication) or 11 bytes (for V2X sidelink communication) while having data available for transmission, the MAC entity shall not transmit only padding.