A Survey On The Performance Of Network Coding Techniques In Multi-Hop Wirless MESH Networks

In the recent years wireless mesh networks become famous in the field of networking because of their advantages in providing cheap accessing to the internet and efficient scaling as the size of the network expand, however these networks suffer from limited throughput and low reliability, hence they can not meet the demands of applications like high definition videos, file sharing and gaming.Network coding was introduced as a solution to throughput problems in WMNs, since its inception; it has been used by many techniques to achieve the goal of improving the throughput. Whether these mechanisms are theoretical based on mathematical calculations or practical test-beds, they all have utilized the broadcast nature of the wireless medium to mix the data from multiple sources and thus bandwidth saving will obtained. However along these years, these works on throughput optimization using wireless network coding has taken two branches, the first one depends on traditional routing protocol to determine the path from the source to the sink, while the mixing can be done along this path if there is a possible chance to code, this way is called the coding oblivious routing ,while the other branch called coding aware routing, which is mean the path between the source can be established according to where these chances form.This thesis is a survey between these two branches, here we are investigating and comparing between two different techniques, the first one is coding oblivious routing, and so called COPE, it is a technique that modifies the node's layer stacks by inserting a coding layer between the IP and MAC layers, thus the node will be able to mix the data when it find the chance to code along the path from the source to the sink. While the other one is coding aware-routing method, which specifies two types of headers for the received packets (encoded and native) that utilized by along with information obtained from the routing table, to proactively search the broadcast for the available coding chances and then draw the path from the source to the sink based on these chances, known by BEND.We are subjecting these two mechanisms to several topologies of WMNs to provide a full understanding of both behaviors. We are studying their ability to mix multiple packet in single transmission, their capability to share the resources and to prevent congestions in the network and their performance in multi hop multiple unicast flow of WMNs.The experiments has showed that BEND can offer a promising performance for the first hop forwarding, however COPE comparing to BEND show more stability performance with increasing the number of the node while the data travel more than 2 hop to is its sink.