An Optimized Transmission Algorithm Based On Network Coding In Wireless Network

Proposed network coding can achieve the maximum capacity of the network bounded by max flow-min cut theorem, which makes many researchers carried out extensive research on network coding.Recently, the use of network coding to improve the performance of wireless networks attracts more and more interest. With the broadcast nature of wireless channel, it is particularly advantageous for the bandwidth efficiency and encoding and decoding with network coding. In particular, how to reduce the number of retransmission to improve network utilization, in the same channel quality, has been one of targets inquiry related to academics.Firstly, how to use network coding to reduce the number of retransmission as much as possible were studied after packet loss occurs during broadcast for bulk data. Since wireless channel is not reliable, if packet loss occurs during transmission, it need to be retransmitted. In the paper, retransmission conditions of data to be encoded is expressed by matrix and vector operations. Then the graph is constructed according to corresponding correlative matrix, and an optimized algorithm to find coding opportunity is given by the optimal match in graph theory. This algorithm can not only finds all the coding opportunities, but also takes into account how to combine the packets to minimize the number of retransmission to achieve a coding optimization. The results shows that this algorithm can effectively improve the transmission performance and throughput.Next, the case of multi-hop transmission optimization problem is studied. [1] proposed Distributed Coding-Aware Routing (DCAR) for multi-hop transmission, which overcomes the dependence on the route and the restrictions on the number of hops (limited in two hops) in COPE [2]. However, the algorithm is limited to the use of a so-called best route, which may cause local congestion. In addition, when a number of flow intersect, they are combined in random, which is difficult to reach the optimal solution in general. Based on this, proposed the CAMCR which combine the minimum cost maximum flow algorithm and weighted matching algorithm to optimize the routing and coding respectively in this paper, which has significantly improved the performance.