Tjänstekvalitet i ad hoc nät med köprioritering

The increasing usage of information technology in military affairs raises the need for robust high capacity radio networks. The network will be used to provide several different types of services, for example group calls and situation awareness services. All services have specific demands on packet delays and packet losses in order to be fully functional, and therefore there is a need for a Quality of Service (QoS) mechanism in the network. In this master thesis we examine the possibility to provide 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 are evaluated and compared with respect to the 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 a analytical approximation of the network delay. Our simulations show that fixed priority queuing provides a sharp delay differentiation between service classes, while weighted fair queuing gives 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 is used