Empirical model for improving throughput of 802.11 MAC

Abstract

Wireless devices are typically battery operated hence energy efficiency is essential for wireless networks. 802.11 is also used as the MAC protocol for wireless sensor networks. It is essential to reduce the energy consumption of sensor nodes. To achieve this, it is desirable to have a model of performance of the 802.11 protocol to study the impact of various parameters on the throughput and energy consumption. Existing research has many models for 802.11. These models show the performance measurement of an 802.11 as a function of number of competing stations sharing access point, effect of size of the packet on throughput, infrastructure and adhoc mode, speed of the vehicle(for VANET), effect of environment, etc. In our work we perform experiments with devices to emulate a WSN, using 802.11 enabled laptops, and model the performance of 802.11. We vary MTU and distance to determine the impact on throughput, in presence or absence of a simple wooden barrier. We determine a simple generic model for throughput dependent on the distance and MTU. This model will help to determine an optimal MTU for varying conditions, to achieve maximum throughput. If the throughput is high, the energy savings are expected to be higher. This model could be applied to wireless sensor networks. Our results show that simple linear equations fit the throughput data. These are single variable models for MTU and throughput, for different distances. We have also developed a two variable model for throughput as a function of MTU and distance.