Distributed channel assignment and routing in Mobile Ad Hoc Networks

Capacity of Mobile Ad Hoc Networks using a single channel and a single interface reduces due to channel interference and collision. Use of multiple non overlapping channels increases the network capacity by allowing more concurrent transmissions. A single interface together with multiple channels results in high switching delay. As a result multiple interfaces should be used to reduce the switching delay. Channel assignment and Routing are interdependent. This paper presents a channel assignment and routing algorithm for multi-channel and multi-interface mobile ad hoc networks. At each hop a channel is selected based on the value of a function f (channel interference value which is calculated for each channel) which gives a measure of interference for each channel. The channel with the lowest f value is selected. Our proposed routing algorithm is similar to the AODV routing protocol but instead of choosing the shortest path, the algorithm chooses the path with the least interference value. The algorithm simultaneously also takes care that other communications in the network are least affected. Each node has a combination of fixed and switchable interfaces. Fixed interfaces listen to fixed channels which maintain connectivity where as the switchable interfaces increase the network performance by efficiently utilizing the available channels. The algorithm allows the fixed channels of a node to be changed dynamically. The algorithm ensures that the channel selection is made on the basis of the most recent data by taking care of any loss of HELLO packets which are used for information exchange between the neighbors. Finally we evaluate the performance of the algorithm using simulations.