Time-Offset Generalized Frequency Division Multiplexing Communication in Doubly-selective Channels

The performance of Generalized Frequency Division Multiplexing ( GFDM) systems significantly degrades over time-frequency doubly selective channels due to the severe inter-carrier interference and intersubsymbol interference. To this end, a Time-Offset GFDM (TO-GFDM) is proposed, which can improve the performance of GFDM systems under doubly selective channel environment by introducing a time-offset to the prototype filter of conventional GFDM systems. The average signal-to-interference ratio of GFDM systems in doubly selective channels is analytically derived, and a pilot-aided joint iterative channel estimation and symbol detection algorithm is proposed. The proposed algorithm can progressively decrease the interference signal and improve the performance of channel estimation and symbol detection with the information exchanging between the channel estimation unit and the successive interference cancellation based symbol detection unit. The results of theoretical analysis and simulation demonstrate that in doubly selective channels, the time-offset GFDM outperforms the conventional GFDM in terms of average signal-to-interference ratio and bit error rate, and the joint iterative channel estimation and symbol detection algorithm can reduce the bit error rate effectively.