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摘要
An energy detection-based active spectrum sensing scheme is proposed to carry out spectrum sensing and secondary transmissions simultaneously. It successfully avoids the widely used quiet periods, which have at least two shortcomings. First, periodical interruptions of secondary transmissions degrade the quality of service of secondary networks (e.g. decreasing the system capacity and increasing end-to-end packet delay). Second, frequent tight synchronisation is necessary but very difficult to implement in the distributed networks. With the assistance of the geolocations, the proposed sensing scheme is able to decompose the received power into the primary signal power, secondary signal power, and the device noise power. The power decomposition is formulated into a problem of solving a homogeneous linear equation set with a coefficient matrix involving only the distances among the primary users, secondary users, and the sensors. Through the decomposition, the primary signal power can be differentiated from the secondary signal power, which is generally treated as interference in spectrum sensing. When constructing the test statistic, such interference can be cancelled from the collected energy. As a result, the noise uncertainty problem, which significantly compromises the performance of the energy detection, can be greatly alleviated by noticing the fact that the interference dominates the noise uncertainty problem. Because the achieved signal-to-interference ratio can be improved by cancelling the interference, the detection errors in terms of the probability of false alarm and missed detection can be significantly reduced. Simulations verify the feasibility and efficiency of the proposed scheme.
- 出版日期2015-5
