S2-GI: Intelligent Selection of Guard Interval in High Throughput WLANs

Short guard interval (SGI) is a new feature of the physical (PHY) layer in High Throughput Wireless Local Area Networks (HT-WLANs), like IEEE 802.11n/ac, where the value of the guard interval is set to 400ns instead of general 800ns. By reducing the overhead of extra idle time between transmissions of two successive symbols, SGI helps to enhance the average system throughput, compared to the guard interval of 800ns. However, the signal quality of the channel and high data traffic can affect the performance of SGI in a network. In a congested network scenario, channel interference and load of data transmission are increased; and consequently, inter-symbol interference becomes higher, which increases the rate of packet losses and thus, reduces average throughput in the case of SGI. In this paper, we design Thompson sampling based online learning mechanism, Smart Selector of Guard Interval (S2-GI), to select guard interval dynamically by considering the present channel condition. We analyze the performance of S2-GI through a thorough simulation in IEEE 802.11ac WLAN and we observe that S2-GI can enhance the network performance.