Towards a Complete Multi-layered Framework for IEEE-802.11e Multi-hop Ad Hoc Networks

Performance of IEEE 802.11 in multi-hop wireless networks depends on the characteristics of the protocol itself, and on those of the other layers. We are interested in this paper in modeling the IEEE 802.11e Enhanced Distributed Coordination Function. This paper investigates the intricate interactions among PHY, MAC and Network layers. For instance, we jointly incorporate the carrier sense threshold, the transmit power, the contention window size, the retransmissions retry limit, the multi rates, the routing protocols and the network topology. Then, we build a general cross-layered framework to represent multi-hop ad hoc networks with asymmetric topology and asymmetric traffic. We develop an analytical model that predicts the throughput of each connection as well as the stability of forwarding queues at intermediate nodes. To the best of our knowledge, our work is the first to consider general topology and asymmetric parameters setup in PHY/MAC/Network layers. Performance of such a system is also evaluated via simulation. We show that the performance measures of MAC layer are affected by the traffic intensity of flows to be forwarded. More precisely, attempt rate and collision probability are dependent on the traffic flows, topology and routing.