An Efficient MAC Layer Access Protocol for White Space Standard IEEE 802.11af

With the rapid development of WLAN, Ultra High Frequency(UHF) spectrum gradually attracts peoples attention. Due to its low utilization and good propagation property, FCC has issued two white space standards named IEEE 802.22 and IEEE 802.11af for cognitive radio to operate in the UHF TeleVision(TV) bands. This paper aims to build an efficient and relatively simple MAC layer access protocol for white space standard 802.11af, which adopts DCF protocol as its MAC layer access protocol. To this end, channel resources are allocate by the base station, which is the common approach to improving utilization and stability in multi-user networks. Channel structure and frame structure are optimized to increase the proportion of data channel and ensure avoidance of collisions. Simulation results show that the proposed design offers significant benefits compared with DCF protocol. The channel utilization can be up to 81 percent without considering frame efficiency, and end-to-end delay decreases sharply as compared to DCF protocol. With the growth of the number of terminal users, the decrease of throughput is negligible.