The Research On QoS Routing Algorithm With Two-hop Interference Model For Wireless Mesh Network

Wireless Mesh Networks (WMNs), which have a new broadband wireless network structure and a high-capacity high-speed feature, have become a research focus in the area of next generation wireless networks. Now a plenty of multi-media applications are emerging, so it has a great future that WMNs carry diverse multi-media traffic such as video and voice. However, In order to meet the requirement of multi-media traffic transmission, WMNs must provide the quality of service (QoS) support, which will guarantee per-flow bandwidth request in the network. In fact, Based on estimation of node's available bandwidth, our research group has implemented a real-time multi-media transmission testbed, which makes a series extension to standard DSR protocol and has a good effect in small scale network. Whereas, the algorithm of node's available bandwidth in the testbed oversimplifies inter-flow and intra-flow contention and has fewer theoretical results to justify itself.In view of the research on the algorithms of available bandwidth evaluation and wireless interference phenomenon in recent years, the paper revises the method of the node's available bandwidth evaluation in original testbed and then proposes a new node-based rate constraint called NABE. NABE is based on two-hop interference model and has comprehensively considered scheduling and spatial reuse. For NABE, MAC protocol must be in accord with two-hop interference model, so we modify the Ieee802.11 protocol by exploiting 802.11 multi-rate features. The paper also will compare the performance of NABE with scaled clique constraints and row constraints from the extent of restriction and the difficulty in application through theory analysis and simulation. Those results show that NABE is closer to the optimal solution and is easy to implement.Meanwhile, according to NABE, we also design a new QoS route algorithm to evaluate the performance of NABE and meet the project's requirement. In addition, based on NABE constraints, we propose a heuristic interference degree metric for selecting routing to alleviate network"hot-pots".In the end, we implement all the ideas above in NS environment. The simulation results demonstrate that QoS routing algorithm are able to utilize the network capacity effectively, prevent the network overload and guarantee most flows bandwidth request, so they can meet the requirement of multi-media traffic. It also proves that the routing metric of interference degree can select the better path with larger bandwidth and lower delay in unsaturated network and with lower delay in saturated network.