Research Of Bandwidth Estimation And Cross-layer Routing Protocol For Ad Hoc Networks With Directional Antennas

The wireless ad-hoc network based on directional antenna has many advantages,such as high spatial multiplexing,high total network throughput and strong anti-interference ability,and has received extensive attention in recent years.Link available bandwidth is the maximum transmission bandwidth that can be obtained by the receiving and sending nodes of the link without affecting the quality of service(QoS)of existing flow in the network.In this paper,we propose an estimation method of link available bandwidth that is suit for directional MAC protocol,which is based on the characteristics of directional transmission.Based on the prediction results,we propose a cross-layer routing protocol which provides QoS guarantees for multimedia services in directional ad hoc networks.The research of this paper focus on the key issues above and the main innovation content are summarized as follows:(1)In the framework of typical directional media access protocol(D-MAC),we propose a new method to estimate the available bandwidth of directional link.Firstly,the node acquires the available time information of channel in each antenna beam direction by listening to the channel.Then,we adopt the distributed method to analyze the probability of the unsynchronized available time of the receiving and sending nodes.Finally,based on the analysis of the available bandwidth estimation difficulties in directional media access protocol,we consider seven different factors that affect the actual available bandwidth of the directional link.We modify the preliminary estimation to obtain the final estimation of the available bandwidth of the link.The results of simulation experiments under various scenarios show that the method of directional available bandwidth estimation proposed above is effective.(2)Based on the available bandwidth estimation of the directional link,this paper design a cross-layer routing protocol which can guarantee the QoS of multimedia services.This protocol takes the available bandwidth estimation of the MAC layer as the upper limit of the link transmission throughput and regards the available bandwidth of the MAC layer and the number of route hops as the basis for route selection in the network layer to realize the directional channel access and route control for new incoming network service,guarantee the QoS of existing services in the network.At the same time,when we predict the actual bandwidth consumption of the directional multi-hop link service,the protocol also fully considers the ?intra-flow contention? problem of directional transmission,and points out that the actual bandwidth consumption of a node in a directional multi-hop link should be contention count of nodes times required bandwidth of business flow.Simulation results show that the performance of the protocol is superior to a typical directional dynamic source routing protocol in wireless ad hoc network.