Cooperative Spectrum Sensing With Hard Decision Fusion Based on Modified Correlation Detection Scheme in Additive Laplacian Noise

Abstract

This paper proposes a cooperative spectrum sensing (CSS) scheme based on the modified correlation detection (MCD) in an additive Laplacian noise environment. In MCD, the received signal at the cognitive terminal correlates with the primary user (PU) signal. The received signal is then raised to an arbitrary exponent P where 0 < P ≤ 2. At all the values of P except P = 1, the MCD operates as a non-linear detection scheme. For the special case of MCD at P =1, the considered detection scheme follows linear behaviour and it is known as Matched Filter (MF) detection scheme. Using MCD and MF at the cognitive terminal, hard decisions are forwarded to the centralized controlling centre known as fusion centre (FC). Then, they are combined according to standard fusion rules of cooperative spectrum sensing (CSS) scheme such as the ‘OR’ rule, the ‘AND’ rule and the ‘majority rule’, respectively denoted as CSS:OR, CSS:AND and CSS:majority. Finally, the FC decides the presence of the PU. Here, the analytical expressions are obtained for estimating the detection probability and false alarm probability and present the same in form of receiver operating characteristics. The proposed analytical results are corroborated by a close match between simulation results and analytical findings. The proposed results are then compared with the existing detection scheme called soft-limiting PCA (SL-PCA). The proposed research study finally concludes that for a broad range of average signal-to-noise ratio (SNR) indicated by γ, i.e., −20 ≤ γ ≤ 10 dB, the detection performance of CSS:OR fusion scheme outperforms the performance of other CSS:majority and CSS:AND fusion schemes. In addition to this, this study also concludes that the performance of CSS:OR and CSS:majority fusion schemes based on MCD and MF detectors outperform the same based on SL-PCA detection scheme. Conventional schemes refer to the detection schemes in non-cooperative scenario where only one CR exists. As a result, the CSS:majority rule outperforms the conventional detection schemes MCD and MF beyond γ = −12 dB and γ = −11 dB, respectively.