Spectrum sensing plays an important role in spectrum sharing. Energy detection is generally used because it does not require a priori knowledge of primary user, (PU) signals; however, it is sensitive to noise uncertainty. An order statistics (OS) detector provides inherent protection against nonhomogeneous background signals. However, no analysis has been conducted yet to apply OS detection to spectrum sensing in a wireless channel to solve noise uncertainty. In this paper, we propose a robust spectrum sensing scheme based on generalized order statistics (GOS) and analyze the exact false alarm and detection probabilities under noise uncertainty. From the equation of the exact false alarm probability, the threshold value is calculated to maintain a constant false alarm rate. The detection probability is obtained from the calculated threshold under noise uncertainty. As a fusion rule for cooperative spectrum sensing, we adopt an OR rule, that is, a 1‐out‐of‐N rule, and we call the proposed scheme GOS‐OR. The analytical results show that the GOS‐OR scheme can achieve optimum performance and maintain the desired false alarm rates if the coefficients of the GOS‐OR detector can be correctly selected.

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In this paper, we discuss the spectral efficiency and coverage efficiency of WRAN(Wireless Regional Area Network) system in TV bands which are under standardization at the IEEE 802.22 WG. Instead of spectrum underlay technologies which have been used conventionally, spectrum overlay technology model will be the subject of analysis and simulations in this paper. The research results revealed that the increase of spectral reuse distance(guard distance) negatively affects the spectral and coverage efficiency. In WRAN system that uses spectrum overlay technologies and where the Tx power of TV stations and WRAN BSs are constant, decrease in both of the spectral efficiency and the coverage efficiency were observed in counter-proportion to the increasing guard distance at the size of given area(about 400 to 800 km).