Multiple Antennas-Based Improved Sensing Detector

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RESEARCH ARTICLE

Multiple Antennas-Based Improved Sensing Detector Ashish Bagwari1 • Jyotshana Kanti1 • Geetam Singh Tomar1

Received: 15 November 2016 / Revised: 2 November 2018 / Accepted: 19 December 2018 Ó The National Academy of Sciences, India 2019

Abstract In this paper, we present multiple antennasbased improved sensing detector (MA_ISD). The proposed scheme reduces sensing failure problem and improves reliability by using adaptive threshold and multiple antennas patterns. The presented scheme uses two detectors concept, detectors imply multiple antennas, follows selection combination to select best signals. The proposed model enhances the detection performance and takes less sensing or detection time. Out of the two detectors, the first one is energy detector with a single adaptive threshold (ED-SAT) and the second one is energy detector with two adaptive thresholds (ED-TAT). The thresholds are adaptive as they are dependent on noise variance (r2x ), and the value of this noise variance changes according to the noise signal. Both the detectors work simultaneously, and their output is then fed to a decision device which takes the decision using OR-rule. In the proposed scheme, more than one antenna has been used and is compared with existing sensing techniques. Results show that the proposed multiple antennas-based improved sensing detector (MA_ISD) technique while number of antennas (Nr) = 2, improves the detection performance by 24.6%, 53.4%, 37.9%, and 49.6%, as compared to existing schemes (i.e., EDT-ASS2015 scheme, ED and cyclo-2010, adaptive SS-2012, and conventional-ED) scheme at - 12 dB SNR, respectively. Meanwhile, proposed technique also decreases sensing time in the order of 47.0 ms, 49.0 ms, and 53.2 ms as compared to existing schemes (EDT-ASS-2015, Adaptive SS-2012, and ED and Cyclo-2010) scheme at - 20 dB SNR, respectively. & Ashish Bagwari [email protected] 1

Keywords Cognitive radio networks  Single adaptive threshold  Two adaptive thresholds  Signal-to-noise ratio

1 Introduction In the present scenario, day-by-day technology is growing as 5-G technology is the example of this. 5-G technology is also known as CRNs, in which spectrum detection plays a key role. Therefore, various detection techniques have been proposed to sense licensed signal. Maleki et al. [1] introduced two-stage detectors: energy detector in the first stage and the second stage is a cyclostationary detector, but detector has limitations, computationally more complex and required longer sensing time. Moreover, to minimize sensing time, Ejaz et al. [2] presented adaptive spectrum sensing scheme, in which out of two stages only one stage’s detector performed sensing operation at a time, and minimized sensing time, but system complexity was there. Furthermore, Sobron et al. [3] presented adaptive sensing technique using energy detector (EDT-ASS) and discussed on cost function and concluded about the PU’s absence or presence. In this paper, we optimize detection performance using multiple antennas with two detecto