e 3GPP LTE-Advanced is similar to that of 3GPP LTE Rel-8, except for the addition of the multi-carrier functionality; however, the multi-carrier nature of the physical layer is only exposed to the MAC layer through transport channels, where one HARQ entity is required per component carrier [34]. Reports Packets Packets Header Header Compression Decompression Ciphering Deciphering Segmentation and Payload Selection Reassembly and ARQ Priority Handling UE Multiplexing UE Demultiplexing Re-transmission Control Redundancy Redundancy Version Version Channel Coding Channel Decoding Modulation Data Modulation Data Demodulation Scheme MIMO Mode MIMO Encoding MIMO Decoding Selection Resource/Power Resource Mapping Resource Demapping Assignment Antenna Antenna Mapping Antenna Demapping Mapping FIGURE 3-24 User data processing and signaling protocols in 3GPP LTE eNB and UE 3.3 3GPP LTE/LTE-advanced protocol structure The main difference between MAC and RRC control lies in the signaling reliability. The signaling corresponding to state transitions and radio bearer configurations should be performed by RRC sub- layer due to signaling reliability. The different characteristics of MAC and RRC control are summarized in Table 3-1. The physical layer provides information transfer services to MAC and higher layers. The physical layer transport services are described by how and with what characteristics data is transferred over the radio interface. This should be clearly separated from the classification of what is transported, which relates to the concept of logical channels at MAC sub-layer. Figure 3-24 illustrates the IP packet processing in the eNB and UE transmitter and receiver sides, respectively. The main functions of each protocol layer and their interconnections have been identified. One of the noticeable differences with IEEE 802.16m data processing is the location of encryption or ciphering of the user payload. Unlike the IEEE 802.16m, 3GPP LTE encrypts the packets in the PDCP layer before delivering the service data uni