l, dedicated to one UE, for the transfer of user information. A DTCH can exist in both uplink and downlink. Multicast Traffic Channel (MTCH): MTCH is a point-to-multipoint downlink channel for transmitting traffic data from the network to the UE. This channel is only used by UEs that receive MBMS. MAC provides the control and traffic channels as listed in Table 3.7. Table 3.6 Transport channels used by MAC Transport channel name Acronym Downlink Uplink Broadcast Channel Downlink Shared Channel DL-SCH Paging Channel Uplink Shared Channel UL-SCH Random Access Channel Source: 2009 3GPP [16] Next Generation Mobile Communications Ecosystem Table 3.7 Logical channels provided by MAC Logical channel name Acronym Control channel Traffic channel Broadcast Control Channel Paging Control Channel Common Control Channel Dedicated Control Channel Dedicated Traffic Channel Source: 2009 3GPP [16] 3.6.1.3 Mapping Between Transport and Logical Channels The MAC entity is responsible for mapping logical channels for the uplink onto uplink transport channels (Figure 3.15) and responsible for mapping the downlink logical channels to downlink transport channels (Figure 3.16). 3.6.2 RLC Sublayer The functions of the RLC sublayer are performed by RLC entities. For a RLC entity configured at the eNB, there is a peer RLC entity configured at the UE and vice versa. The RRC (Radio Resource Control) is generally in control of the RLC configuration [14, 17]. 3.6.2.1 RLC Architecture Figure 3.17 illustrates the overview model of the RLC sublayer which shows three RLC entities namely Transparent Mode (TM), Unacknowledged Mode (UM) or Acknowledged Mode (AM). An RLC entity can be configured to perform data transfer in one of these three modes: A TM RLC entity is configured either as a transmitting TM RLC entity or a receiving TM RLC entity. The transmitting TM RLC entity receives RLC SDUs (service data unit) 12 from upper layer and sends RLC PDUs to its peer receiving TM RLC entity via lower layers. The receiving TM RLC entity delivers RLC SDUs to