| Wireless communication networks have been incorporated into our daily life and provide convenience anytime and anywhere. However, the wireless medium is unreliable and unpredictable. Current wireless networks suffer from low throughput, low reliability, etc. Network coding, an alternative approach, has attracted more interests and has emerged as an important technology in wireless networks. It can provide significant potential throughput improvements and a high degree of robustness.;This dissertation is built on the theory of network coding. In this dissertation, different network coding protocols are designed in varied wireless networks. The first part of this dissertation proposes a novel coding-ware routing protocol in wireless mesh networks. In particular, a generalized coding condition is formally established to identify the coding opportunities. Based on general coding conditions analysis, a novel routing metric FORM (Free-ride Optimal Routing Metric) and the corresponding routing protocol are developed with the objective to exploit the coding opportunities and maximize the benefit of "free-ride" in order to reduce the total number of transmissions and consequently to increase the network throughput. The results show the proposed protocol achieves significant throughput gain than existing approaches.;The second part of this dissertation exploits network coding in wireless cooperative networks. Firstly, a Decode-and-Forward Network Coded (DFNC) protocol is proposed for multi-user cooperative communication system. In particular, DFNC develops an efficient construction method for coding coefficients and a novel decoding algorithm that combines network coding and channel coding. DFNC exploits both temporal and spatial diversities through multiple channels by allowing all the users to generate redundant network-coded packets in a distributed manner and it helps fully explore the redundancy provided by network coding to realize error correction. Theoretical analysis and simulation results demonstrate that DFNC outperforms other transmission schemes in terms of Symbol Error Rate (SER) and achieves higher diversity order. Secondly, the idea of DFNC is extended and Modified-DFNC (M-DFNC) is introduced for a more practical scenario: not all the users will be able to dedicate their resources to provide assistance for others. The throughput analysis shows that M-DFNC outperforms the conventional cooperative protocol in the low-SNR regime and it implies that an adaptive cooperation system should be adopted to optimize the performance. The simulation results validate the theoretical analysis. |
