An Analysis of Joint Aggregation, Bursting, Routing, and Rate Adaptation for Increasing VoIP Capacity in Multi-Hop 802.11 Networks

Due to the low cost and ease of deployment, single- hop and multi-hop 802.11 networks have become attractive solutions for providing last-mile broadband (wireless) access in urban environments. However, a critical issue in using such networks to support applications such as Voice over IP is the widely known overheads in the Medium Access Control (MAC) layer and Physical (PHY) layer for each transmission. The effect of these overheads can be more severe in multi-hop deployments, and can limit the number of VoIP calls per Gateway Access Point (GAP) in a multi-hop system to be no greater than that of a single-hop single-GAP system. In this paper, we build upon our previous work that showed that a multi-hop network, with one GAP using a single channel, can in fact support more users than a single-hop network. To do so functions such as aggregation have to be intelligently used at relays in the network. We build on this prior work giving a theoretical framework that considers the joint tradeoff of aggregation, bursting, and PHY rate adaptation given a set of admission and routing decisions. We compare call-capacity estimates from the theory to those derived from simulations, and illustrate through examples the advantages of considering routing/admission decisions jointly with bursting and aggregation.