Downlink performance analysis of a CSMA based WLAN under physical interference model

Abstract

A significant amount of research work has been done on throughput and energy efficiency analysis of IEEE 802.11 based wireless local area networks (WLANs) under the simplistic protocol interference model. However, very little work has been done on analytical modelling and analysing the downlink throughput and energy efficiency of WLANs under the realistic physical interference model. In this paper, we study the downlink throughput and energy efficiency of a carrier sense multiple access (CSMA) based WLAN under the physical interference model in presence of path loss, Rayleigh fading and log-normal shadowing. For this purpose, we develop analytical models to compute the downlink throughput and energy efficiency of a CSMA based WLAN under a saturation traffic condition. We then validate the analytical models via simulation. By computing throughput and energy efficiency with the developed analytical models, we demonstrate that the downlink throughput and energy efficiency obtained by the physical interference model significantly differ from those are obtained by the widely used protocol interference model. We also find that, in a CSMA MAC protocol based WLAN, RTS/CTS channel access mode provides significant benefits over the basic channel access mode in increasing downlink throughput and energy efficiency. Further, we study the effect of node transmit power, data transmission rate, data packet size, and channel access rate of the access point (AP) and the users on throughput and energy efficiency performance of WLANs and provide various engineering insights on WLAN downlink performance and better configurations of WLAN parameters.