Research And Simulation Implementation Of Fault Tolerance Mechanism Based On Network Coding In Wireless Mesh Networks

As a new kind of network, Wireless Mesh Network (WMN) is very useful and it can be applied in many fileds such as military, environment, medical, family, and so on. Since WMN is limited by power, computation capability, channel attenuation and bandwidth, how to guarantee the reliable data transmission is a significant problem.Accordingly, fault tolerance in WMN means that when some nodes or links fail, the network has the ability to recover the lost data or start self-healing mechanism to reduce the performance degradation. However, tranditional fault-tolerant technology based on redundancy resources allocation didn’t comprehensively consider the delay, energy, throughput and other characteristics, and thus it is difficult to apply the tranditional technology to the wireless network.Based on these problems we study the fault tolerance in WMN, and propose two fault tolerance algorithms based on the network coding. Firstly, in chapter three, this thesis firstly presents a fault tolerance algorithm based Tree coding. Then, this thesis presents a greedy clustering algorithm to divide the network topology into some small logical topologies, so that NCT can be extended to the general network topology. In chapter four, this thesis proposes a new Random Network Coding based on Multipath (RNCM) algorithm for the WMN. The algorithm improves the encoding node selection method of tranditional RNCM, as well as combines with multipath routing. Therefore, RNCM can reduce the resources redundancy ratio and end-to-end delay, as well as has good fault tolerance ability.In order to evaluate the algorithm performances, this thesis develops the simulation platform based on VC++to test the proposed algorithms NCT and RNCM in the performances of packet delivery ratio, resources redundancy ratio and end to end delay. Simulation results show that, comparing with the tranditional fault tolerance algorithm, NCT has the advantages in packet delivery ratio, resources redundancy ratio and end to end delay, while RNCM also has the advantages in packet delivery ratio, resources redundancy ratio and useful throughput ratio.