Access Disparity Mitigation in Multi-hop Wireless Networks

In Multi-hop Wireless Networks (MWNs), the end-to-end performance degrades exponentially with hop counts and the degree of traffic aggregation at each hop. Fair allocation of bandwidth among nodes is one of the challenging problems in MWNs. The IEEE 802.11 distributed coordination function standard stipulates long-term equalization of throughput among stations by giving the same number of transmission opportunities regardless of their individual bit rates. In this paper, we propose a bandwidth allocation scheme for MWNs that uses the underlying hop contention graph, along with hop counts and traffic aggregates in order to achieve a long-term equalization of the end-to-end throughput. The proposed scheme first determines direct and indirect (hidden) contentions among nodes, it then finds the end-to-end upstream and downstream access probabilities, and finally allocates access opportunities accordingly. The scheme significantly improves fairness among nodes. The performance, in terms of throughput, delay, and fairness, has been studied under various traffic sources, traffic loads, and different network topologies.