A 5 GHz WLAN MAC performance comparison based on physical layer measurements

This paper presents a MAC performance comparison between IEEE 802.11a, 802.11e and HiperLAN/2 WLAN standards. These standards share the same OFDM physical layer at 5 GHz but offer very different medium access and retransmission mechanisms. In addition, the radio channel is very difficult to model and to predict over a long period. Therefore, some simulations of the different MAC and error control layers have been conducted in a single user environment using a binary error pattern captured with an actual OFDM modem instead of an error model. These simulations integrate a physical layer rate adaptation mechanism common to all protocols. The performance is evaluated by assessing the maximum total goodput provided by the systems in a typical radio environment. Transfer delay is also examined according to the traffic load and the channel noise. Finally, an analysis of the results establishes the conditions in which the mechanisms specific to each protocol become profitable.