Key Technologies For Synchronous Relaying In Next Generation Of Wireless Cellular Communication

When implementing the relay technique into a wireless cellular system, the resultant relay cellular network can achieve dramatically higher system capacity and spectrum efficiency through multi-hop transmission and cooperative diversity. This research focuses on investigating some of the key technologies for synchronous relaying in next generation systems of wireless cellular communication.First a synchronization strategy is presented for the OFDM system which covers both the downlink physical and MAC layer synchronization. Based on our proposed training sequence structure, the symbol-wise timing and frequency synchronization algorithms are studied. The optimized downlink cell search protocol is shown to enable the frame synchronization and base station information detection.Next an adaptive cooperative coding (ACC) protocol is proposed, where the source transmits the coded bit sequence to the destination through two independent links in two steps, each with rates adapted to the current channel condition. Numerical analysis demonstrates that the strict and asymptotic upper bounds of theoretical performance for the ACC protocol are attained under various channel conditions. The optimal power allocation algorithm is also studied to further enhance the system performance.Then three different bi-directional relaying protocols are examined and their theoretical throughputs are predicted by the Shannon theory. The bi-directional amplification of throughput (BAT) protocols utilizing the network coding overperforms the conventional one due to their higher transmit efficiency. The optimal power allocation algorithms for these protocols are shown to improve the throughputs as well as robustness to asymmetric channel conditions. The Markov chain is used to model the bi-directional protocols for analyzing throughputs under adverse channel conditions.Finally an interference cancellation (IC) based BAT protocol is proposed and its throughput is evaluated via the Markov chain model. The simultaneity in transmission and receiving enabled by the macro relay group structure in combination with the 1C algorithm improves the system transmit efficiency. In the meanwhile, each node only needs the channel state information of the links connecting to its neighboring nodes, thus reduces the signaling overhead.