Blind Constellation Identification for MQAM in Hybrid Satellite-Terrestrial Networks

Abstract

In hybrid satellite-terrestrial networks (HSTNs), frequency-selective fading can severely deteriorate the quality of transmitted signal by generating undesired and disordered constellation diagrams due to scatters in the mutipath channels. In this paper, we propose a low-overhead blind constellation identification method to combat frequency-selective fading in HSTNs. Specifically, a pre-equalization method is proposed based on a constant modulus algorithm to restore the contour of the constellation diagram. Moreover, the similarity measure function and the difference measure function are derived using template matching to identify the constellation of M-ary quadrature amplitude modulation (MQAM). The proposed method requires less information and no training sequences and pilots. Simulation results show that the proposed method is able to accurately identify the constellation type of MQAM signal, and these features are extremely useful in HSTNs.