Research And Implementation Of QoS Routing Protocol For Ad Hoc Networks

With the popularity of wireless mobile devices, various types of multimedia applications have been used more widely. Streaming multimedia has higher requirements on data transmission, for example, real-time voice traffic has proposed a very high demand on delay and jitter. Thus, it is very necessary that the mobile Ad Hoc networks offer a certain quality of service (Quality of Service, QoS) guarantee.Wireless networks are vulnerable to the surrounding environment, and have a poor channel quality, which has bit error rate and packet loss rate. Furthermore, the mobile nodes in Ad Hoc network could move in any way, topology changes dynamically, it is not conducive to provide adequate resources for the applications by the resource reservation mechanism. Energy and the processing capability of the mobile nodes are limited, and the loss of energy nodes will lead to the change of topology. In addition, the emitted power of wireless node is low, so inter-node communication requires relay by other nodes, which needs some incentive policies to encourage nodes to transit the information for other nodes. To provide QoS control in the network involves admission control, resource reservation, transmission scheduling, traffic policing of the complex mechanisms on data plane and control plane, so it is difficult to provide QoS guarantee in wired network. Because of the particularity of the network and link, providing QoS guarantee in Ad Hoc network is more difficult. Given that the routing mechanism has a very important role to provide quality of service control for application, this paper will focus on the design and implementation of Ad Hoc routing protocols to support QoS.This paper is based on OLSR (Optimized Link State Routing, OLSR) to carry out related work, through the expansion from the single path routing to multipath routing, we propose a multipath routing protocol MOLSR (Multipath OSLR). Making the network resources used as much as possible, improving quality of service and meeting customer requirements. MOLSR mainly involves three aspects:multipath searching, multipath maintenance and transmission multipath scheduling. The main problems include quality evaluation of the multipath, the degree of cross-multipath, efficient reconstruction of routing table, balance network traffic, etc.. In addition, MPR (Multi-Point Relays) generation algorithm of OLSR is improved, which could optimize the MPR set size, reduce the number of topology control messages, and reduce the overhead of routing maintenance, save the limited resources in Ad Hoc network.In this paper, we firstly introduce the mobile Ad Hoc network and existing routing protocols, routing algorithm; then, give a detailed introduction about the multipath routing; after, describe the design and implementation of MOLSR; Finally, MOLSR is simulated using NS2.In different scenarios, through the analysis and comparison about the number of MPR nodes, the number of control messages, the number of paths, end to end delay, throughput, delay jitter and other performance indicators, show that the MOLSR can provide a certain QoS guarantee for applications, and can effectively improve the network performance.