ADAPTIVE TECHNIQUE FOR HIGH SPEED MOBILE ENVIRONMENT USING TFT-OFDM?

Orthogonal frequency division multiplexing (OFDM) is widely recognized as the key technology for the next generation broadband wireless communication (BWC) systems. The high spectral efficiency, reliable performance over fast fading channels is becoming more and more important for OFDM-based Broadband Wireless Communication systems. The time domain synchronous OFDM (TDS-OFDM) has higher spectral efficiency than the standard cyclic prefix OFDM (CP-OFDM), but suffers from severe performance loss over high speed mobile channels since the required iterative interference cancellation between the training sequence (TS) and the OFDM data block, for the application of compressed sensing (CS) to the estimation of doubly selective channels within pulse-shaping multicarrier systems (which include orthogonal frequency- division multiplexing (OFDM) systems as a special case. Thus, the fundamentally distinct OFDM-based transmission scheme called time-frequency training OFDM (TFT-OFDM) is proposed, whereby every TFT-OFDM symbol has training information both in the time and frequency domains. The grouped pilots in TFT-OFDM occupy only about 3% of the signal bandwidth with high spectral efficiency as well as good performance over fast time-varying channels. The efficiency of the proposed approach is illustrated in a simulation environment that allows for a flexible, structured, and comparative performance evaluation.