lls, support for semi-static resource allocation; The uplink transport channels are classified as follows (see Figure 7-20): Uplink Shared Channel (UL-SCH) characterized by the possibility to use beamforming, support for dynamic link adaptation by varying the transmit power and modulation and coding schemes, support for HARQ, support for both dynamic and semi-static resource allocation; Random Access Channel (RACH) characterized by limited control information and collision risk. The mapping of the logical channels to the transport channels in the downlink and uplink is shown in Figure 7-21. As shown in Figures 7-16 and 7-17, the main services and functions provided by the RLC sub-layer include transfer of upper layer PDUs supporting AM or UM, TM data transfer, error Uplink Downlink Logical Logical channels channels Uplink Downlink Transport Transport UL-SCH channels DL-SCH channels FIGURE 7-21 Mapping of logical to transport channels in the downlink and uplink [9] 7.4 3GPP LTE radio link control and medium access control sub-layers correction through ARQ (since CRC check is provided by the physical layer, no CRC is needed at RLC level), segmentation according to the size of the transport block, re-segmentation of PDUs that need to be re-transmitted, concatenation of SDUs for the same radio bearer, in-sequence delivery of upper layer PDUs except during handover, duplicate detection, and protocol error detection and recovery. The users in the 3GPP LTE system are assigned temporary identifiers to protect user privacy and confidentiality. Depending on the state of the UE, different types of temporary identifiers are used. Table 7-1 summarizes the Radio Network Temporary Identifiers (RNTI) and their usage in 3GPP LTE. For example, the Random Access RNTI (RA-RNTI) is used on the PDCCH when random access response messages are transmitted. It unambiguously identifies which time-frequency resource was utilized by the UE to transmit the random access preamble. The Msg3 acronym in Table 7-1 denotes the message transmitted o