Link Stability Study And Application In Ad Hoc Networks

As a new wireless communication technology, Ad Hoc networks are coming into people’s life. Comparing with traditional networks, Ad Hoc networks are more flexible since they don’t rely on pre-existing infrastructure. Each node in the Ad Hoc network acts as both transmitter and receiver. Due to the limit of communication range and mobility, Ad Hoc is a multi-hop autonomous systemThe links of Ad Hoc networks can easily break due to the mobility of nodes. When link-broken occurs, the affected nodes have to rebuild a route which increases the overhead and reduces the network performance.This paper proposes a link stability evaluation model, i.e. SEM model, which is based on the received signal strength. This model evaluates the link stability from the view of monitoring node and the view of monitored node. The direct stability value is computed by the monitoring node while the indirect stability value is measured by the monitored node which indicates the surrounding of the monitored node. SEM model synthesizes the direct and indirect stability value and is suitable for most network applications. Subsequently, we analyze the details of the SEM model. Considering the unsuitable applications of SEM model, we introduce two auxiliary models to correct the SEM model.In order to reduce the number of link-broken, we introduce the methods to compute the link remaining time with which we can repair the link before the disconnection. The use of link remaining time reduces the packet loss and delay caused by the link-broken.We analyze the application of stability model in unicast routing protocols. Subsequently, the SEM model and the method of computing the link remaining time are applied to the AODV protocol. We present specific details of the protocol. Simulation results show the advantages of the SUR over the AODV.In addition, we apply the stability evaluation model to the multicast routing protocols. We studied the SEM model in the tree-based strategy routing protocol (MAODV) and the MESH strategy routing protocol (ODMRP). We analyze the performance of the SMR and the S-ODMRP from various aspects.At the end of this paper, we give the conclusions of this work along with extensions and directions for future research.