Research On Probabilistic-priority Based Qos Model In Ad Hoc Networks

With the growing needs of transmitting multimedia traffic in mobile Ad Hoc networks, how to provide quality of service (QoS) guarantees in Ad Hoc networks becomes a hotspot. Mobile multi-hop wireless networks differ from traditional wired Internet infrastructures. The differences introduce unique issues and difficulties for supporting QoS in Ad Hoc environments. The difficulties include unpredictable link properties, node mobility, and limited battery life and so on, all of which make the QoS supporting in Ad Hoc networks challengeable. In recent years, researchers have laid more and more emphasis on the research of QoS support in Ad Hoc networks. It encompasses issues of QoS model, QoS MAC protocols, QoS routing and so on, of which QoS model is the essential part, since it achieves QoS on the system level. Thus, QoS model should be the first matter to consider for the QoS support in Ad Hoc networks.This paper introduces SWAN--a simple but available QoS model for Ad Hoc networks. After analyzing its principle, working background and drawbacks, a probabilistic-priority-based PSWAN model is proposed in this paper. By combining the Probabilistic Priority scheduling algorithm with SWAN, PSWAN solves the problem of resource contention. Hence, PSWAN performs well in end-to-end delay and packet loss rate. Besides, PSWAN model is capable of service differentiation, which can dramatically provide distinguished quality of service for different priority levels of traffic: the real-time traffic receive lower delay and packet loss rate, while the performance of the other three traffic are distinct. Moreover, by improving the rate control algorithm of SWAN, PSWAN possesses the advantage of simple implementation.The performance of PSWAN is evaluated via simulations. Simulation results show that PSWAN model can satisfy the different QoS demands of different class of traffic; it performs well in end-to-end delay and packet loss rate under various conditions.