Single Carrier Frequency Domain Equalization For PN-based Systems

Single carrier (SC) modulation and demodulation have been applied widely in wireless digital communication system, and it is an important research aspect. The time domain equalization based on the traditional single carrier modulation is complex, especially when single-carrier and multi-carrier mode are compatible in communication system. How to make it less complex for frequency domain equalization in single carrier modulation is studied in this thesis. PN-based HDFE (Hybrid Decision Feedback Equalization) method is also proposed. This method can simplify the calculation based on the LMS algorithms and PN extension is used to initialize the DFE, which have advantages in convergence speed of equalizer. According to the frame structure in the Chinese national standard on DTTB (digital television terrestrial broadcasting), this method is improved, where 4375-point FFT operation is applied without using cyclic restoration. The simulation results show that the proposed methods can reduce the error floor at high SNR, and give about 2dB improvements over the conventional FDE (Frequency Domain Equlization). Another way, the scheme with hybrid equalization based on the 4QAM-NR modulation is presented, which combines the quadrature demodulation and the soft/hard decision.Finally, it validates the effectiveness of frequency domain equalization algorithm and can reject more serious ISI (InterSignal Interference).