WLC07-3: Packet and Flow Level Performance of Wireless Multihop Data Networks

We consider wireless multihop data networks with random multi-access mechanisms at the MAC layer. Our aim is to study the performance as perceived by users in a dynamic setting where data flows are generated randomly by users and cease upon completion. This task comprises two major difficulties: first, the behavior of random multi-access algorithms at slot- level in a multi-hop network is even more complex than in the case of a single hop hotspot. Second, in order to study user-level performance accounting for a dynamic population of flows, one has to first characterize the so-called rate region when the population is fixed. The rate region is defined by the set of rates at which the different active users can generate packets without inducing any instabilities in the network. Since links interact with each other through interference, characterizing the rate region is as difficult as studying the behavior of a set of interacting queues. In addition, the behavior of the congestion control algorithm must be taken into account since it impacts the set of active links and then interference. We propose a model, based on the so-called mean field approach, that circumvents both difficulties and allows the derivation of explicit expressions for the rate region. Finally, using these expressions we analyze the flow-level performance of the network.