Fairness and QoS in multihop wireless networks

In multihop wireless networks, fair allocation of bandwidth among different nodes is one of the critical problems that affect the serviceability of the entire system. Although there is significant research on the fairness issues in single-hop wireless networks, research on multihop fairness is rarely found in the literature. We study various queuing schemes for multihop wireless networks and examine the fairness and throughput performance of each scheme. Each scheme offers a different degree of fairness. While relatively simple queuing schemes require less hardware and processing budget, they inevitably lack good fairness and performance. In contrast, the scheme that provides fairness requires per-flow (i.e., network-layer flow) queuing. Furthermore, we show that in order to achieve the optimal bandwidth utilization, the medium access control (MAC) layer should be able to support different priorities. Without such a MAC-layer QoS scheme, in the worst case, the bandwidth utilization can be degraded by O(N), where N is the number of end users. We theoretically investigate the pros and cons of different queuing schemes and verify the analytical results with detailed simulations.