逼近信道容量的非等概幅度相移键控星座映射

为解决格雷编码的幅度相移键控( APSK: Amplitude Phase Shift Keying) 映射方式在非迭代的独立解映射情况下互信息与信道容量仍存在差距的问题，提出一种非等概的APSK 映射方式，通过减少内环对应的星座点数，变换为低价的Gray-PSK，从而提高其限制下的互信息。仿真结果表明，针对2 /3 码率设计的64NE-APSK 较64Gray-QAM 星座映射有0． 6 dB 的性能优势，比64Gray-APSK 的系统有约0． 1 dB 的优势。从而，在接收端独立解映射的情况下，该设计能比格雷编码的APSK 映射更逼近信道容量，且无需增加系统实现的复杂度。

Non-Equiprobable Amplitude Phase Shift Keying Design for Near-Capacity Constellation Mapping

The gap between the mutual information of the Gray-coded amplitude phase shift keying ( APSK) and the channel capacity can not be narrowed sufficiently，especially with non-iterative independent demapping at the receiver，in order to solve the problem，a non-equiprobable APSK constellation is proposed． The mutual information under the restriction is improved by reducing the number of constellation points corresponding to the inner loop and transforming it into a low-order Gray-PSK． Simulation shows that the 64NE-APSK designed for 2 /3 code rate has a performance advantage of 0． 6 dB compared to the 64Gray-QAM constellation，having an advantage of about 0． 1 dB over the 64Gray-APSK． Therefore，in the case of independent de-mapping at the receiver，the design helps approaching the channel capacity without increasing the complexity of the system implementation．