Towards sensitive link quality prediction in ad hoc routing protocol based on grey theory

A mobile ad hoc network (MANET) is a self-organizing network of mobile nodes which can form a dynamic topology. All the nodes generally have a limited transmission range and move freely throughout the network. So implementing a good routing protocol to react the link state changing is a critical issue in current research. From now on, a popular method is introducing a link quality evaluation (LQE) mechanism in routing algorithm. In this paper, we study the link quality evaluation scheme based on traffic-based metrics, such as packet reception ratio (PRR), and find two flaws (one is the assessment lagging and the other is the sample bias) which result in large handoff delay in routing protocols, especially when the PRR-like scheme is used in mobile environments. Therefore, we propose a link quality prediction (LQP) model to sense the link state by analyzing the Signal to Noise ratio of the neighbor link, and using grey theory to tackle the small sample size problem. Finally we set up mobile nodes test-bed to validate the scheme. Based on comparison of previous schemes, the LQP's performance is far better in handoff delay and packet loss rate.