Research On QoS Routing Algorithms In Ad Hoc Networks

Along with the popularity of multimedia applications, the QoS routing has already became an important topic in Ad Hoc networks research area. In this paper we have researched on QoS Routing Algorithms in Ad Hoc Networks.The existing QoS routing algorithms are mainly based on two methods, one is to design a new QoS routing according to the QoS constraints, the other is to add the QoS constraints to the existing"Best-Efforts"QoS routing protocols. This paper has analyzed the QoS routing algorithms based on the two methods, as well as the QoS constraints in each routing algorithm and its calculation method, then pointed out the respective limitation. This paper used the second method for research.This paper has studied DSR and AODV routing protocol algorithms, and carried on modeling based on the OPNET software, including network model,node model and process model separately, then to simulate in the two different scenes, with one being static and the other being prescribed trajectory. Through the comparison we knew that using DSR there were less route discovery time, less average Ftp download response time and average Ftp upload response time, and more total traffic sent/received in the whole network, and relatively the network performance was better, so this paper studied QoS routing based on DSR protocol.This paper added bandwidth and delay QoS constraints to DSR protocol. It calculated the available bandwidth through node's maximum transmission bandwidth, observation interval time, channel idle time in observation interval time, channel busy time in observation interval time, and the sliding window with its length of 5 as well as its weights. It calculated the dynamic delay constraint with the previous delay, the predictive future delay and the current delay variation. After a detailed description of the routing discovery process and routing maintenance process, it described message format of various parts. At last it simulated the new protocol based on OPNET. comparing with DSR protocol the new one reduced network route discovery time, increased network throughput, reduced network delay and optimized network performance.