Performance Analysis of π/4 DQPSK for FrFT-OFDM System with Carrier Frequency Offset

The Orthogonal Frequency Division Multiplexing (OFDM) has widely been used in broadband wireless communication due to its ability to efficiently utilize the spectrum with multicarrier communication. In this paper BER expression for π/4 DQPSK modulation has been derived from FrFT based OFDM system in the presence of carrier frequency offset (CFO) under frequency selective Rayleigh fading channel. The performance of proposed system has been evaluated and compared with the FFT based OFDM system. It is found that the FrFT based OFDM system outperforms the FFT based OFDM. BER analysis has also been done for various values of α (FrFT angle parameter) on said FrFT based OFDM system, however the system responds best at α = 0.9 as compared with other values of α . Improvement as high as up to 23 dB in SNR has been achieved with the proposed FrFT based OFDM system at α = 0.9 for said modulation with carrier frequency offset of 0.1 under frequency selective Rayleigh fading channel.