Access Disparity Mitigation in Multi-hop Wireless Networks Jalaa Hoblos • Hassan Peyravi Received: 29 April 2014 / Accepted: 10 February 2015 Ó Springer Science+Business Media New York 2015 Abstract 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 coordina- tion 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 through- put. 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 sig- nificantly improves fairness among nodes. The performance, in terms of throughput, delay, and fairness, has been studied under various traffic sources, traffic loads, and different net- work topologies. 1 Introduction MWNs have been studied significantly and deployed con- siderably for a variety of applications including Mobile Ad Hoc Networks (MANETs), Wireless Sensor Networks (WSN), and Wireless Mesh Networks (WMNs). These ap- plications have inspired a significant amount of research in the field. Path computation has received considerable attention that resulted in development of a number of routing protocols. However, there is a well-known access disparity prob- lem in MWNs. The end-to-end throughput between a pair of nodes in a wireless network depends on various physical and environmental factors. Physical factors include their distance, transmission power, and data rate. The environ- mental factors include noise, path loss, attenuation, user mobility and fading. This disparity problem further exas- perates in MWN, where a client traffic is forwarded via a series of relay nodes towards the destination through a series of tandem contention domains. Due to the broadcast nature of the wireless medium, the end-to-end throughput is limited not only by the data rate of the individual links along the path, but also inversely affected by the hearing range of the participating nodes and their level of activity. Multi-hop Wireless Networks (MWNs) based on Carrier Sense Multiple Access with Collision Avoidance (CSMA/ CA) are difficult to analyze due to their complex dynamics. While the performance modeling of a single-hop 802.11 Media Access Control (MAC) protocol is quite well-un- derstood [2, 4], there is little agreement among researchers for the multi-hop counter part where wireless relay nodes provide an end-to-end communication. In addition to the single-hop factors, other factor also contribute to the complexity of the analysis including tandem contention domains and multi-hop contention graph, routing and transport layer mechanism. In a single-hop Wide Area Network (WAN), aggregate throughput and the throughput of high bit rate stations are negatively affected by the channel holding time of a low bit rate station [9]. A low bit rate stations hold the channel longer than a high bit rate station. The distributed coordi- nation function (DCF), used in IEEE 802.11 networks, tends to provide equitable long-term transmission J. Hoblos (&)  H. Peyravi Kent State University, Kent, OH, USA e-mail: jhoblos@cs.kent.edu H. Peyravi e-mail: peyravi@cs.kent.edu 123 Int J Wireless Inf Networks DOI 10.1007/s10776-015-0263-2