New Modeling and Analysis of IEEE 802.11 Distributed Coordination Function for a Multihop Wireless Adhoc Network

Initially designed for WLAN‟s, IEEE 802.11 Medium Access Control (MAC) has also been widely used in the research of multihop wireless networks. The core MAC technique of IEEE 802.11 is called distributed coordination function (DCF). DCF is a carrier sense multiple access with collision avoidance (CSMA/CA) scheme combined with binary exponential backoff (BEB). Due to the hidden terminal problem, analytical models developed for singe-hop networks cannot be applied in multihop networks. On the other hand, although researchers have proposed several analytical models for multihop networks, they failed to capture the effect of binary exponential backoff (BEB). In this paper we present an analytical model to derive the saturation throughput of DCF in multihop wireless networks including effect of BEB with nodes randomly placed according to a two-dimensional Poisson distribution. The proposed framework applies to both packet transmission schemes employed by DCF, namely, the basic access and the RTS/CTS access mechanisms. By means of the proposed model, we evaluate throughput performance of DCF in multihop wireless networks. Our model indicates that the RTS/CTS access method with the default parameters operates in a region almost optimal in terms of saturation throughput.