Study On The Application Of Network Coding In Wireless Multi-hop Network

Network coding is a major breakthrough in the field of communication in the 21st century, which incorporates the concept of routing and coding, processes the information from different link, making the intermediate nodes to have functions of encoding and routing. Within the network coding structure, network performance can reach the theoretical maximum flow limit of transmission. Network coding can increase the throughput of the multicast network, improve network load balancing, and increase network link robustnessMulti-hop wireless network is a new type of network which has some typical kinds such as wireless Ad Hoc networks, wireless sensor networks and wireless mesh network. It is an important branch of mobile communications, without center support, networks expediently. It has broad prospects and value in military, medical, scientific, business and many other areas. But the energy, computing power, transmission bandwidth and storage capacity are still limited in this kind of wireless network node. How to improve network throughput and reliability of data transmission, to extend the lifetime of wireless networks with limited resources is an important problem.This paper introduces the basic principles of network coding, and then summarizes the domestic and international research progress of network coding in wireless multi-hop network from main aspects of increasing throughput, energy efficiency and increasing network robustness and safety. Second, by using network coding when wireless base station releases monitor tasks, the cluster head nodes can successfully recover the original data when received a sufficient number of linearly independent encoded packets without need to receive the whole packets. Network coding reduces the dependency of cluster head nodes on single data and effectively improves tolerance of network packet loss fault. Then we propose a physical layer network coding (PNC-DPSK) scheme which based on differential phase shift keying modulation and be extended to M-ary differential phase shift keying (MDPSK).The new scheme addresses the PSK's "downπphenomenon" and even "0" with "1" problem. In fact, realizing the network coding in physical layer can shorten the time slot of information exchange between nodes. Finally, since traditional routing protocols are designed to minimize or avoid the interference of signal transmission, does not really exploit the advantages of the physical layer network coding, then network throughput can not be promoted. To address the problem we proposed a wireless network routing protocols based on the physical layer network coding, which through the cross-layer collaboration between network layer and physical layer to enhance the interactive capabilities between nodes. The simulation results show that the proposed protocol can more effectively improve the network throughput, compared with non-coding or forward-directly network coding.