A Rotated Constellation Aided OFDM System for Wireless Communication

摘要

The most common way to improve spectral efficiency of the orthogonal frequency-division multiplexing (OFDM) communication system is to increase the modulation orders. However, studies have shown that this method will increase the bit error rate and symbol error rate simultaneously. In order to improve the spectral efficiency of OFDM system without reducing its reliability, this paper proposes a rotated four leaves clover (R-FLC) constellation. In this scheme, each symbol can carry additional bits through alternately employing two rotated constellations with different phases. A general rotated constellation aided OFDM system for wireless communication is also proposed. The bit error rate and effective spectral efficiency performances of this system under additional white Gaussian noise and multipath Rayleigh fading channel are evaluated in detail. Compared with the traditional Quadrature Amplitude Modulation (QAM) aided OFDM system, simulation results show that the proposed system is capable of improving the spectral efficiency without sacrificing signal-tonoise ratio under additional white Gaussian noise channel and multipath Rayleigh fading channel. The proposed system can effectively overcome the Inter Symbol Interference (ISI). The system architecture has a certain reference and practical value for the development of OFDM modulation technology.