Research On Network Coding Aware Routing In Wireless Mesh Networks

Wireless Mesh Networks(WMN) are multi-hop networks with wide range of applications, large network capacity, high access speed, while the deployment cost is low. It is a new way to solve bottleneck problem of the last kilometer in network. WMN can provide efficient bandwidth and flexible networking to meet the people’s growing demand for network access. WMN has attracted industry and academic attention for its outstanding advantage.Due to the characteristics of wireless medium in WMN, it will be subject to random radio interference, serious channel fading and other effects. These effects can cause severe packet loss, end to end delay and network throughput drops in network, thus resulting in a decline in network performance. With the introduction of information theory, network coding attracted much research interest as a new data processing method with effective network throughput improvement. Network coding can reduce the number of data packets transmission, the network has been proven to reach maximum capacity. Network coding-aware routing can detect coding opportunities actively, but existing coding-aware routing mostly only consider to increase opportunities for coding, ignore the problem of data stream gathering in coding region, which would degrade the network performance. So the study considered interference, load balancing, coding-aware routing has important significance.Firstly, the status of Network Coding and relative routes were introduced; subsequently WMN traditional routing and coding-aware routing are classified; finally discuss the problem that current network coding-aware routing easily lead to traffic aggregation, resulting in hot spots in depth. The main work is as follows:(1) To address the above problem of the current network coding-aware routing, a coding aware routing metric which comprehensively considered coding gain, load, interference factors(Interference avoiding Load balance and Coding Aware, ILCA) was proposed, then a routing protocol ILCAR based on the metric was proposed in this paper. ILCAR calculate the path cost according to the metric, in order to select the optimal routing path. ILCAR can actively seek coding opportunities, taking into account the trade-off between gains from coding and network load, interference conditions. ILCAR considering coding gains in Wireless Mesh Network, the degree of competition that each interference links within the neighborhood has on the current communication link, the number of data packets in node cache, the current transmission rate of link factors, to overcome the current coding-aware routing can cause traffic convergence, and the problem of uneven load.(2) Since the link throughput depends on the current traffic load, the measurements of packet loss rate index have great fluctuations over time. Consider high dynamic range of the received signal strength in Wireless Mesh Network, this paper based on the ILCA routing metric which combining coding gain and load balancing, to capture the fast-changing of link status and improving the existing routing metric, a coding-aware routing metric considered received power(Power Interference avoiding Load balance and coding aware, PILCA) was proposed, and PILCAR routing protocol based on the metric was proposed. PILCAR using the received signal level to improve ILCAR, link cost captures coding opportunity while reflects the link state of any time, thus enhance network performance.The two network coding-aware routing proposed in this paper were simulated respectively in NS3 simulation, building network coding layer into the wireless node model. The simulation results show that the proposed algorithm can effectively improve network throughput when compared to classical COPE and DCAR protocol, and reduce average end to end delay and packet loss rate.