Quality of service in ad hoc networks by priority queuing

The increasing usage of information technology in military affairs raises the need for robust high capacity radio networks that will be used to provide several different types of services, such as group calls and situation awareness services. As all services have specific demands on packet delays and packet losses in order to be fully functional, there is a need for a qualityof-service (QoS) mechanism in the network. In this report we examine the possibility of providing a QoS mechanism in ad hoc networks by using priority queues. The study includes two different queuing schemes, namely fixed priority queuing and weighted fair queuing. The performance of the two queuing schemes is evaluated and compared with respect to their ability to provide differentiation in network delay, i.e. provide high-priority traffic with lower delays than low-priority traffic. The study is mainly done by simulations, but for fixed priority queuing we also derive an analytical approximation of the network delay. Our simulations show that fixed priority queuing provides a sharp delay differentiation between service classes, whereas weighted fair queuing provides the ability to control the delay differentiation. One of those queuing schemes alone might not be the best solution for providing QoS. Instead we suggest that a combination of them be used.