Performance Analysis of IEEE 802.11g Multi-Rate Support for Industrial Applications

The multi-rate support is a feature made available by the IEEE 802.11 Wireless LAN to dynamically adapt its transmission rate to the underlying wireless channel state. This feature, which makes use of suitable rate adaptation (RA) techniques, allows to reach the best transmission success probability, even in the presence of noisy channels. The most popular RA technique, available for general purpose applications, is the Automatic Rate Fallback (ARF). In this paper we focus on the performance of two alternative RA techniques, namely Static retransmission rate ARF (SARF) and Fast rate reduction ARF (FARF), specifically conceived for the industrial communication scenario. In particular, we take into consideration a prototype network, typical of low levels of factory automation systems, and evaluate the behavior of these techniques by means of meaningful performance indicators obtained through numerical simulations. We also propose a comparison with results obtained, for the same network, when fixed transmission rates are used. Simulations have been carried out using both channel and devices models that reflect experimental outcomes. The analysis reveals that both SARF and FARF perform eectively since they are able to ensure short cycle times along with limited randomness.