Experimental study of rate-aware scheduling for 802.11n Wi-Fi network with legacy devices

In this paper, we investigate the scheduling issue in the coexistence scenarios of 802.11n devices and legacy devices. To guarantee compatibility with legacy devices such as 802.11b/g devices in the ISM bands, IEEE 802.11n protocols allow low-rate devices access wireless medium with the equal priority. However, the network system capacity decreases and user-experience of 802.11n clients degrades significantly with the introduction of legacy devices. In this paper, our aim is to improve user-experience and network capacity of 802.11n devices in case of the negative impact brought by the 802.11 legacy devices in low rate transmission mode. The main contribution in this paper is our proposed scheduling algorithm for a mixed Wi-Fi networking scenario provided with the method of identifying low-rate and high-rate packets. We implement this method on Atheros 9340 chipset with its Software Development Kit(SDK). We evaluate the performance with the Chariot testing tool to show the gains on our experimental prototype system.