An experimental study on performance comparison of rate adaptation and fixed rate in IEEE 802.11g

IEEE 802.11 rate adaptation is a mechanism that adapts channel data rate in response to varying channel conditions. Rate adaptation has been considered a key component to achieve high performance. Indeed, many access points use rate adaptation as the default setting. However, how well rate adaptation performs in comparison with fixed rate has never been clearly identified. In this paper, we present an experimental study using commercial access points to compare the performance of rate adaptation and fixed rate in an IEEE 802.11g testbed. The comparison is conducted with various factors taken into account (e.g., UDP traffic, sending rate, power level, distance). The results show in many cases that fixed rate outperforms rate adaptation. Our findings raise questions regarding the suitability of the adopted rate adaptation algorithm in typical indoor environments and can provide useful information on the design of rate adaptation. Furthermore, our study indicates that it is not wise to simply ignore fixed rate. Fine selection of a fixed rate could be made to achieve desired performance.