Fairness-oriented spectrum sharing for ODFC-based WRAN

Abstract

Wireless Regional Area Network (WRAN) is standardized by IEEE 802.22 to improve the spectrum utilization in the TV frequency spectrum. Spectrum sharing or coexistence among unlicensed users, plays a crucial role in the spectrum utilization and hence it has been identified as a critical issue in WRAN. Coexistence between unlicensed users is referred to as self-coexistence for which IEEE 802.22 designs the On Demand Frame Contention (ODFC) as a solution. The traditional 802.22 ODFC selects a contention winner in a random manner where all the contenders have a uniform winning probability distribution, without considering different frame demands from contenders. Consequently, the winner will occupy the channel for a long time if it has a larger frame demand while unsuccessful contenders may suffer from spectrum starvation, thus ODFC does not ensure a fair self-coexistence. In this paper, we investigate the fairness issue and present a novel approach termed Fairness-oriented ODFC (F-ODFC). The proposed approach considers several effects including different frame demands from contenders and previous contention failure rates among multiple users with the same frame demands. In F-ODFC, we employ a probabilistic approach rather than the traditional deterministic solution to attack the fairness problem. Extensive simulations verify that the proposed F-ODFC is able to provide a fair self-coexistence mechanism with varied frame demands and significantly enhance the fairness of ODFC-based WRAN.