Modeling wireless channel for ad-hoc network routing protocol

Enabling transmission over ad-hoc networks is more challenging than over conventional mobile networks because a connection path in an ad-hoc network is highly error-prone and the path can go down frequently. Although it is well-known that wireless channels are time varying because of user mobility and multi-path propagation effects, experiments for various types of channels show that the basic channel parameters can be stable for short time intervals. Therefore, a wireless channel can be adequately represented by a set of stationary channel models. There are number of wireless channel models proposed in literature. For simplicity, we used a two state Markov model known as a Gilbert-Elliot model and then in order to model more appropriately a real communication channel, a three state Markov model is analyzed here. We demonstrate our concept by applying it to the dynamic source routing protocol (DSR). In our proposed modified DSR, both the route discovery and route selection are based on physical layer parameter and the link monitoring function located at each node. Since routing selection based on the link quality is implemented, the minimum transfer delay from source to destination and the maximal throughput may be obtained. Simulation results show that according to the channel quality, the delay and throughput performance show remarkable performance when compared to traditional DSR.