Performance analysis of a pre-FFT equalizer design for DVB-T

Conventional OFDM systems employ a guard interval to combat delay spread di stortion of transmitted data. This reduces the efficiency of the OFDM trans mission. A combined OFDM-Equalization reception strategy is presented in th is paper. This strategy employs an Adaptive Equalizer to combat delay sprea d distortion instead of a guard interval. This facilitates the use of very short guard intervals and thus the transmission efficiency of the OFDM modu lation scheme is improved. This paper presents the combined OFDM-equalizati on receiver and the pre-FFT equalizer designs. The efficiency of both the c onventional OFDM and combined OFDM-equalization strategies is considered an d it is demonstrated that combined OFDM-equalization offers a significant i mprovement in transmission efficiency. The transmission of OFDM signals in Single Frequency Networks is considered and it is shown that the combined O FDM-Equalization technique is particularly effective for such applications, offering an improvement in bandwidth efficiency of 14% under severe delay spread conditions. The limitations of the combined OFDM-equalization strate gy to operate effectively under both additive noise and time variant condit ions are considered. Performance is simulated and the sensitivity to this i mpairment analyzed.