Research On Opportunistic Routing In Wireless Mesh Network

Wireless Mesh Network (WMN) is a high-capacity, high-speed, multi-point to multi-point distributed network with dynamic self-organizing, self-healing which has emerged as a key technology for next-generation wireless networking as it can solve the "last mile" bottleneck. WMN is undergoing rapid progress and inspiring numerous commercial applications in recent years. However, the key issue in WMN design is to provide high-quality and high-efficient routing protocols. Despite the availability of many routing protocols for Ad-hoc networks, the design of routing protocols for WMN is still an active research area without uniform standards. Traditional routing protocols follow the same design principle from wired network that chooses the next-hop before transmitting a packet, and the routing algorithm is responsible for picking the best path through the nodes to destination, it conceals the underlying broadcast medium of wireless multi-hop network behind a point-to-point abstraction.Opportunistic routing is a recent technique which allows any node that overhears the transmission and is closer to the destination to participate in forwarding the packet. However, it introduces a difficult challenge that multiple nodes may hear a packet broadcast and unnecessarily forward the same packet. The current opportunistic routing protocols impose a strict schedule on routers'access to the medium to ensure routers that hear the same transmissions do not forward spurious packets. This coordination between routers increases the network overhead and impacts the robustness and flexibilities of the routing which makes it been less practical applied.To address above issues, Opportunistic Routing based-on Random Coding in Wireless Mesh Network (ORRC) integrated the network coding technique with opportunistic routing technique to improve transmission performance in WMN. Each router makes an opportunistic routing strategic independently, avoids the communication overhead between routers. Distributed multi-path transmission makes full use of the idle nodes as well as keeps the network load balancing. ORRC randomly mixes packets before forwarding them and needs no special scheduler to coordinate routers. This randomness ensures that routers that hear the same transmission do not forward the same packets, reducing the probability of repeat transmission as well as requirements of coordination between routers, thus brings down the overhead of opportunistic routing. ORRC chooses the best routing ways according to data flows'type, combines opportunistic routing with best-path routing to ensure that transmissions between source and destination can make full use of network bandwidth, maximize network throughput and improve network performance. Testing showed that ORRC increases network throughput to a certain degree and keeps load balancing in variety of wireless Mesh topology.