Cooperative Spectrum Sensing Using Quantized Energy Statistics in the Absence of Dedicated Reporting Channel

Reporting channels are essential for implementing cooperative spectrum sensing (CSS) in cognitive radio technology. In this paper, a novel decentralized CSS scheme capable of operating in the absence of dedicated reporting channels is presented. Existing schemes which operate in the absence of dedicated reporting channels rely on the transmission of hard decision bits from cooperating secondary users (CSUs). The proposed scheme supports a mobile spectrum sensor termed as the leading secondary sensor node (LSSN) to assist a contending secondary transmitter in spectrum sensing. Unlike existing schemes, the proposed CSS framework offers the freedom of using multiple bits for transmitting a quantized version of the test statistics between secondary user (SU) nodes. In order to reduce energy consumption and system complexity, the CSUs do not take part in sensing but only act as relays for retransmitting the quantized test statistics from LSSN to the contending SU transmitter. The proposed network protocol also assists the SU transmitters in avoiding collisions with each other. Closed form expressions for the probability of false alarm and detection have been derived. Monte-Carlo simulations are used to validate the analytical expressions. The proposed scheme can outperform the recently proposed best-selection reporting scheme when the number of CSUs is less and the contending CSUs and the SU transmitter lie in an area of poor primary signal reception.