Network Coding Based Protocol For Data Broadcasting In Wireless Ad Hoc Networks

As an emerging technology, network coding has a profound impact on the theory and practical research of wireless networks. Network coding adopts a new strategy of store–code-forward mode instead of the traditional store-forward mode. It can achieve the theoretical network capacity and enhance network robustness by the way of combining packets before transmission. Wireless transmission medium is broadcast in nature, therefore network coding can be designed and implemented easily in such scenario. Network coding can also improve the reliability of wireless networks. Therefore, network coding has attracted lots of research interests and has been applied widely in wireless networks.In this thesis, we design a data broadcasting protocol ENCBP: Efficient Network Coding-Based Broadcasting Protocol. ENCBP performs well when broadcasting data in nodes randomly distributed wireless Ad Hoc Networks. ENCBP combines Network Coding and Probabilistic Flooding and improves performance further with a variety of optimization methods. ENCBP uses progressive linear network coding to increase decoding ratio at destination nodes. Multiple forwarding strategies, including probability fixed strategy, neighbor based strategy, distance based strategy and integrated forwarding strategy are proposed for nodes randomly distributed networks. To better handle IEEE 802.11 broadcast, ENCBP introduces pseudo-broadcast mechanism to further increase delivery ratio. What's more, delayed broadcast mechanism is proposed in this thesis. This mechanism requires all nodes to wait a random time slot before broadcasting.At last, ENCBP is implemented using NS2 simulator. The performance of ENCBP is evaluated through extensive simulations. Compared with traditional probabilistic flooding and network coding based flooding without optimization, ENCBP outperforms in terms of delivery ratio, average delay and protocol overhead.