双选择信道中的时间偏移广义频分复用通信

当信道存在时间-频率双选择性时,严重的子载波间干扰和子符号间干扰将导致广义频分复用(GFDM)系统性能显著下降.为此,该文提出一种时间偏移GFDM系统(TO-GFDM),通过对传统GFDM系统的原型滤波器进行时间偏移,来提高双选择信道下GFDM系统的性能.该文推导了GFDM信号在双选择信道中的平均信干比公式,并提出基于离散导频的联合迭代信道估计与符号检测算法,该算法利用信道估计器与串行干扰消除符号检测器之间的信息交换,逐步减小干扰信号,提高信道估计与符号检测的精度.理论分析与仿真实验结果表明,在双选择信道条件下,时间偏移GFDM比传统的GFDM具有更高的平均信干比和误码率性能;并且,联合迭代信道估计与符号检测算法能有效降低系统误码率.

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 inter-subsymbol 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.