Queue Scheduling And Performace Analysis Based On Network Coding In Wireless Networks

Nowadays, wireless network has been widely used due to its flexibility and scalability. However, compared with wired networks, wireless networks have such shortcomings as low link rate, high packet loss rate, prone to eavesdropping, large transmission delay and battery-powered nodes. Network coding, which can overcome the above problems to a certain extend because of its full taking advantage of the physical-layer broadcast property of wireless link, has soon been used in wireless networks. Recently, as a new research area in network coding field, queue scheduling has arttracted more and more attention of scholars at home and abroad. As a result, how to combine network coding and design an effective queue scheduling policy to improve the performance of the wireless networks (such as throughput, etc.) has been of great importance.This paper first described the basic principle of network coding and its relavant techniques. Then we surveyed and analysed some classic queue scheduling schems based on wireless network coding. For the practical two-top wireless networks, featured by various packet sizes in different data flows and various data rates in different links, a Markov model is adopted to analyze the throughput and throughput gain achieved by network coding and opportunistic scheduling scheme. Finally, we vadidated our model with simulation and analyzed the effect of packet size, link rate, and buffer size on the throughput of network.Moreover, we presented a novel queue scheduling policy named One-To-Multiple Network Coding (OTM-NC) for the multi-hop wireless network. Taking into account of the effect of packet size on the network coding performace, OTM-NC is able to overcome the shortcoming of low throughput existing in the traditional One-To-One Coding scheme that does not consider the difference of packet size. The proposed OTM-NC, which adoptes one-to-multiple coding, is characterized by that multiple packets in a flow with shorter packet size are combined to form a new packet for coding when the packet sizes differ in multiple flows. In addition, the OTM-NC considers the impact of link rate on the network coding performace and includes the rule used in judging whether a flow taking part in network coding or not. Simulation results indicate that the proposed OTM-NC can significantly improve the throughput.