A Contention-aware Load Balancing Routing Protocol For Wireless Ad Hoc Networks

The decentralized nature of wireless ad hoc networks makes them suitable for a variety of applications where there are no central nodes to be relied on. However, while using traditional minimum-hops routing protocols, network traffic load can be unbalanced and centered on some hot areas. When load balancing in wired networks is merely about traffic load on individual nodes, it is more related to the contention between nearby nodes in wireless ad hoc networks. That is because a communication between two wireless nodes can affect the transmission of other nodes nearby. Thus contention as an important factor needs to be included in balancing load over the network.In this thesis, we propose a Contention-Aware Load Balancing Routing protocol, CALBR, which is based on DSR. In our proposed routing protocol, we introduce a routing metric combined by two metrics of a node: Contention Metric (CM) and Load Metric (LM). Channel contention is studied by analyzing the transmission in 802.11 MAC and then a contention evaluating metric, CM, is proposed accordingly. Besides regional contention level between nodes, local traffic also plays an essential part of the whole load of a node. Here, the LM of a node, which is defined as the average sending data rate of the node over a period, is used to represent the local part of traffic load. Based on the two, we then use the integrated routing metric to find better routes to distribute traffic load and improve resource utility. The simulation on ns2 shows that the proposed routing scheme achieves significant improvement of network performance in terms of network throughput, end-to-end delay and packet delivery ratio.