 for both directions of transmission; - management of the HARQ retransmission mechanism; - management of the mobile random access on reception of the Random Access Channel (RACH); - management of Discontinuous Reception (DRX); - management of Timing Advance (TA). NG-RAN and 5G-NR 8.4.1.2. UE side operation The operations at the User Equipment (UE) level are described in Figure 8.18. Logical channel PCCH BCCH CCCH DCCH DTCH MCCH MTCH CCCH DCCH DTCH Management of scheduling, of HARQ mechanism and Demultiplexing Demultiplexing Multiplexing random access PCH BCH DL-SCH UL-SCH Transport channel Figure 8.18. MAC Operation: UE side The MAC layer transfers the PCH transport channel to the PCCH logical channel. The MAC layer transfers the MIB messages of the BCH transport channel to the BCCH logical channel. The MAC layer performs multiplexing, for the uplink direction, of different logical channels to the UL-SCH transport channel. The different logical channels multiplexed for the uplink direction are as follows: - the CCCH logical channel containing the RRC common control messages; - the DCCH logical channel containing the RRC dedicated control messages; - the DTCH logical channel containing the IP packets. The MAC layer performs demultiplexing, for the downlink direction, of the DL-SCH transport channel to restore the different logical channels. The different logical channels resulting from demultiplexing for the downlink direction are as follows: - the BCH logical channel containing the SIB messages; - the CCCH logical channel containing the RRC common control messages; 5G-NR Radio Interface - Data Link Layer - the DCCH logical channel containing the RRC dedicated control messages; - the DTCH logical channel containing the IP packets. The MAC layer performs demultiplexing, for the downlink direction, of the MCH transport channel to restore the MCCH and MTCH logical channels. The MAC layer control entity performs the following functions: - management of the scheduling of different logical channels in the resource alloc