Study Of Tandem Queuing Models In Wireless Multi-hop Networks And Applications To QoS Routing

Recently, research on providing QoS support and guaranteeing QoS requirements in wireless multi-hop networks has received much attention.QoS routing can make significant contributions to the provision of QoS, and to the improvement of traffic performance. The key component of any QoS routing algorithm is the route discovery task, which essentially involves the link or path metrics calculation. Furthermore, QoS metrics depend on many factors, including the physical and link layer designs. For this reason, study on a kind of tandem queuing model with cross-layer design is essential, which can help to solve the problem of link QoS metrics calculation.The paper focuses on designing a kind of tandem queuing model with more accurate calculation and widespread use.Based on the one-dimensional tandem queuing model,the paper derives modified one-dimensional and two-dimensional tandem queuing models separately.The modified models exploit the traffic arrival process, multi-rate transmission in the physical layer and truncated automatic repeat request (ARQ) mechanism in the link layer with cross-layer design.They build one-dimensional and two-dimensional Finite State Markov Chain (FSMC) separately based on the queue state and the union of queue and service states.Among them, the former has relatively lower computation complexity,whereas the latter has better analytic character of the system,and can make more accurate calculation. A model based QoS routing algorithm is then proposed, which can better support the end-to-end QoS requirements on bandwidth, lossrate and delay.Firstly, the paper outlines the system model and key technologies, which lay the foundation for modeling. Secondly, the one-dimensional tandem queuing model is discussed with tests and analysis. Thirdly, the paper derives a modified one-dimensional tandem queuing model in order to improve the applicability, and also does some tests and estimates. At last, in order to better analyze the system behavior, the paper proposes a modified two-dimensional tandem queuing model, which can calculate the QoS metrics more accurately, especially the end-to-end delay. On applying the modified two-dimensional tandem queuing model to QoS routing algorithm, simulation results indicate that the algorithm can find routs with better QoS performance compairing with the Minimal Hop Routing (MHR) algorithm, and so can better satisfy the QoS requirements.