IEEE 802.11 Delay Analysis for Multirate Variable Frame Length

The strong research on the performance of the IEEE 802.11 standard seen lately contributes to a better understanding of the network and as a starting point for the design of future networks (specially in the ad-hoc area). Oliveira et al. proposed a model to study the IEEE 802.11 DCF delay assuming saturated or non-saturated broadcast and unicast traffic. Oliveira et al. assumes that all nodes generate frames having the same length. This paper extends Oliveira et al. supporting variable frame´s length and both unicast basic and RTS/CTS multirate transmission schemes. The 802.11 MAC average time overhead per frame is deduced. Several simulations scenarios are described to validate the theoretical analysis. The validation results confirm that the MAC transmission delay is strongly dependent on the amount of broadcast traffic in the network. For high transmission data rates the MAC delay increases when the broadcast traffic also increases. However when high data rates are not possible the broadcast traffic increase can have the reverse effect.