The IEEE 802.22 standard for a Wireless Regional Area Network (WRAN) system is considered as the first wireless standard based on CR technology. Specifically, SUs should have a cognitive capability to sense the RF environment, a self-organizing capability to analyze and learn from the sensed information and a reconfigurable capability to adapt their operating parameters according to the surrounding RF environment, ,,. ![]() To enable efficient coexistence, SUs must perform spectrum sensing to determine idle channels, spectrum decision to select the best idle channel/channels, spectrum sharing to coordinate access among SUs, and spectrum mobility to vacate the occupied channel/channels when a licensed user appears. CR provides unlicensed Secondary Users (SUs) with the ability to coexist with licensed Primary Radio (PR) users in a non-interfering mode. Compared to reference spectrum allocation schemes, simulation results indicate that the proposed scheme effectively exploits the available spectrum opportunities by increasing the total number of served SU transmissions, which consequently results in a significant enhancement in the overall WRAN system performance.Ĭognitive Radio (CR) technology has been considered a promising means for addressing the spectrum scarcity problem through efficient dynamic spectrum access. Simulation results indicate that our scheme is quite robust to traffic estimation error. The expected traffic load is accurately estimated using a sample mean estimator based on previously monitored traffic in each cell. Our scheme dynamically allocates the available spectrum (idle channels) to the WRAN cells based on their expected traffic loads such that the total number of simultaneously admitted SU transmissions in the WRAN system is maximized. The proposed scheme is based on a centralized sensing mechanism that identifies the available spectrum opportunities for the WRAN cells. Specifically, we present an adaptive channel allocation scheme based on a cooperative max–min weighted fair allocation strategy. ![]() In this paper, we investigate the self-coexistence problem in a multi-cell WRAN system that adopts an exclusive spectrum sharing policy. To enable efficient WRAN communications, the operation of a WRAN system should address two types of coexistence problem: incumbent co-existence and self-coexistence. ![]() WRAN is designed to offer wireless access services in a large coverage area by allowing Secondary Users (SUs) to opportunistically exploit the under-utilized licensed portion of spectrum that is primarily allocated for TV services. The emerging IEEE 802.22-based Wireless Regional Area Network (WRAN) is the first wireless standard based on the Cognitive Radio (CR) technology.
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