Research On Network Coding Technology In Lte

In order to respond to the challenges of WIMAX, LTE (Long Term Evolution) isproposed by3GPP in2004. Based on OFDM/SC-FDMA and MIMO, LTE is the3.9Gtechnology whose target peak data rates for uplink and downlink are50Mbps and100Mbps. Although LTE can achieve data transmission with low-latency andhigh-data-rate, with the growth of mobile users and new applications which requirewider bandwidth and data rate, LTE cannot meet the needs of future user. Thereforeincreasing the resource utilization of LTE seems imperative.In order to improve the resource utilization of LTE, using network coding in theuplink transmission of Relay and the E-MBMS single cell retransmission is proposed inthe dissertation. And a system-level simulation platform which can simulate LTE-Auplink algorithm is developed. The main results and contributions are summarized asfollows:1. Based on LTE FDD downlink system-level simulation platform which isdeveloped by Vienna University of Technology, the author of the dissertation developsLTE-A TDD uplink system-level simulation platform. The characteristics of theplatform are analyzed. And then the basic principles of the platform are introducedbriefly and Relay-enhanced simulation modules are described particularly.2. In order to solve the bottleneck problem of backhaul link, applying networkcoding in the Relay uplink transmission is proposed. This scheme includes networkcoding scenarios, basic coding units, specific algorithms and control signals design.Through overhearing uplink data, sharing uplink control information and overhearingresults between eNB and Relay, network coding can be applied in the uplinktransmission of Relay. The network coding scheme is simulated on LTE–A TDD uplinksystem-level platform. The simulation results show that the scheme can improve thebackhaul link resource utilization and system performance effectively.3. Aiming at E-MBMS single cell retransmission issue, the effect of channelchanging and network coding on data transmission is considered. A network codingmechanism based on CQI feedback (NCCQI) is proposed. According to several MBMS UEs’ CQI which includes NAK and channel quality information, eNB selects data fornetwork coding retransmission and adjusts dynamically the MCS of data transmission inorder to improve the efficiency of retransmission. This is the fundamental idea ofNCCQI. The mechanism is simulated on LTE FDD downlink system-level simulationplatform. The simulation result demonstrates that NCCQI could improve theperformance significantly while the retransmission mechanism without network codingor based on ACK feedback could not reach.