Geometry Distance Estimated MAC Protocol for TV White Space

Regulatory bodies worldwide have quite recently approved the dynamic access of unlicensed networks to the TV white space (TVWS) spectrum. In TVWS, secondary users (SUs) are required to access a database periodically to acquire information on the spectrum usage of primary users (PUs). The spectrum database querying of SUs will solve the spectrum scarcity problem. A key technology in efficiently using the TVWS spectrum is designing an efficient medium access control (MAC) protocol. In this paper, we propose a geometry distance estimated medium access control (GMAC) protocol to mitigate the hidden and exposed terminal problems in TVWS. GMAC provides an efficient means of channel database querying to obtain the list of available channels to overcome interference with PUs. We develop a Markov chain model to characterize the saturation normalized throughput of our proposed GMAC protocol for the TVWS. In this study, transmitter power control is based on the geometrically estimated distance between SU communication pairs; this increases channel spatial reuse and throughput, and reduces PU outage probability. We also compare our proposed scheme with existing MAC protocols for TVWS. We show that the GMAC will improve the channel spatial reuse and normalized throughput, and reduce PU outage probability.