Blind Modulation Classification of Different Variants of QPSK and 8-PSK for Multiple-Antenna Systems with Transmission Impairments
Rahul Gupta, Sudhan Majhi, Octavia A. Dobre · 2018
This work proposes the blind modulation classification (MC) of different variants of quadrature phase-shift-keying (QPSK), i.e.,$\pi/4$-QPSK, offset QPSK (OQPSK), and minimum-shift-keying (MSK), and 8-PSK. The problem of MC for multiple antenna systems is investigated over frequency-selective fading channels with transmission impairments, i.e., phase, timing, and frequency offsets, without having prior information about channel coefficients. The MC algorithm proposed in this paper employs the cyclostationarity and higher-order statistical properties of the received baseband signal for classification. The MC is performed in three stages: at the first stage, the second-order cyclic cumulant uses the position of the cycle frequency to classify MSK and OQPSK. At the second and third stages, the fourth-order correlation function of the signals received from different antennas exhibits peaks, which are employed as discriminating features for QPSK,$\pi/4$·QPSK, and 8-PSK. Monte Carlo simulations are used to evaluate the performance of the proposed algorithm.