FFT based Spectrum Sensing over Rayleigh Frequency Selective Fading Channel in In-band SIMO Full-Duplex CRNs

Abstract

This paper presents fast Fourier transform (FFT) based multiband spectrum sensing over multipath Rayleigh frequency selective fading channel for single input multiple output (SIMO) full duplex (FD) cognitive radio networks (CRNs) under residual self-interference (RSI) that affirms a more realistic scenario in heterogeneous networks for future wireless applications. In in-band FD mode, secondary users (SUs) can sense and transmit simultaneously using the same channel, doubling the spectrum efficiency of the FD enabled CRNs [1]. Researchers have extensively worked on multiband spectrum sensing in single input single output half-duplex CRNs under additive white Gaussian noise scenario [2], but fading environment is another limiting factor that results in additional detection performance degradation. In this work, we address this issue and carried out the evaluations under multipath fading scenario and to alleviate the degradation in detection performance due to fading, we use multiple antennas at SU. The SIMO sensing architecture of the proposed energy detector is shown in Fig. 1. The Proposed sensing algorithm first calculates the energy of the received $k^{th}$ subband of $m^{th}$ orthogonal-frequency-division-multiplexing (OFDM) symbol. Next, two dimensional windowing operation followed by hypothesis detection of the presence and absence of PU signal is performed on the calculated energy value. The block schematic diagram of the proposed ED is shown in Fig. 2, in which LRT statistic could be formed as: