Throughput Analysis of Multi-Hop CSMA/CA Wireless Networks

In this paper an accurate model for the evaluation of the throughput in a CSMA/CA multi-hop wireless network with arbitrary topology is proposed. A fixed-point procedure is developed based on an extended analysis of the air-time of a link and on a decoupling procedure to estimate the air-time of a node. The intrinsic fairness of a MAC protocol e.g. the DCF of IEEE802.il in a single-hop wireless network allows for a straightforward evaluation of the (saturation) throughput. The air-time, the relative amount of time that a node can transmit, is shared by all nodes in the network. The intricacies in a multi-hop scenario makes the throughput calculation more involved. The air-time is no longer common to all nodes but the notion of a link, the sender-receiver pair, and the topology of the network are playing a major role in the throughput analysis. The iterative method proposed in this paper is illustrated by examples for which the saturation throughput of all nodes is evaluated in an IEEE802.11b network with RTS/CTS enabled access. The result fits closely the saturation throughput of an event-driven simulation with the same settings.