在发送端通过能量扩展变换来改善向量近似消息传递软频域均衡算法收敛特性,均衡器迭代输出可近似认为无符号间干扰,均衡器输出符号与发送符号之间可用加性高斯白噪声信道来建模。在带宽受限的加性高斯白噪声信道下,均匀分布的调制方式距离香农容量限有一定差距。为缩小这个差距,发送端可通过星座概率成形设计,获得成形增益。接收端可利用非等概符号的先验信息改进均衡器结构,提升接收性能。理论分析和仿真结果表明,在经典的Proakis B和Proakis C多径信道下,所提算法能够大幅度提升收敛速度以及均衡性能。相比均匀分布的信号,约有0.5 dB的性能增益。
吴喜胜
,
武岩波
,
朱敏
,
李栋
,
褚润聪
. 面向星座概率成形的向量近似消息传递软频域均衡算法[J]. 中国科学院大学学报, 2023
, 40(5)
: 694
-700
.
DOI: 10.7523/j.ucas.2022.010
The convergence characteristic of the vector approximate message passing soft frequency-domain equalization algorithm is improved by the energy spreading transform at the transmitter. The output of the equalizer can be considered as free of inter-symbol interference. The relation between the output of the equalizer and the transmitted symbols can be modeled by an additive white Gaussian noise channel. Over the bandwidth-constrained additive white Gaussian noise channel, the uniform distribution modulation format has a gap to the Shannon limit. The gap can be closed by probabilistic constellation shaping. The a priori information of unequal probability symbols is used to improve the structure of the equalizer and enhance the performance at the receiver. Theoretical analysis and simulation results show that the proposed algorithm can substantially improve the convergence speed as well as the equalization performance over classical Proakis B and Proakis C multipath channels. There is about 0.5 dB performance gain compared with the uniform distribution signal.
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