In this paper, we propose a novel multi-symbol unitary constellation structure for non-coherent single-input multiple-output (SIMO) communications over block Rayleigh fading channels. To facilitate the design and the detection of large unitary constellations at reduced complexity, the proposed constellations are constructed as the Cartesian product of independent amplitude and phase-shift-keying (PSK) vectors, and hence, can be iteratively detected. The amplitude vector can be detected by exhaustive search, whose complexity is still sufficiently low in short packet transmissions. For detection of the PSK vector, we adopt a maximum-A-posteriori (MAP) criterion to improve the reliability of the sorted decision-feedback differential detection (sort-DFDD), which results in near-optimal error performance in the case of the same modulation order of the transmit PSK symbols at different time slots. This detector is called MAP-based-reliability-sort-DFDD (MAP-R-sort-DFDD) and has polynomial complexity. For the case of different modulation orders at different time slots, we observe that undetected symbols with lower modulation orders have a significant impact on the detection of PSK symbols with higher modulation orders. We exploit this observation and propose an improved detector called improved-MAP-R-sort-DFDD, which approaches the optimal error performance with polynomial time complexity. Simulation results show the merits of our proposed multi-symbol unitary constellation when compared to competing low-complexity unitary constellations.

翻译：本文针对块瑞利衰落信道上的非相干单输入多输出（SIMO）通信，提出一种新型多符号酉星座结构。为降低大规模酉星座的设计与检测复杂度，所提星座通过独立幅度向量与相移键控（PSK）向量的笛卡尔积构建，从而支持迭代检测。其中幅度向量可采用穷举搜索检测，在短包传输中复杂度仍足够低。对于PSK向量检测，我们采用最大后验（MAP）准则改进排序判决反馈差分检测（sort-DFDD）的可靠性，当各时隙发射PSK符号采用相同调制阶数时，该方案可获得近似最优的误码性能。该检测器称为基于MAP可靠性排序的DFDD（MAP-R-sort-DFDD），具有多项式复杂度。针对各时隙采用不同调制阶数的场景，我们发现低阶调制中未检测符号对高阶PSK符号检测存在显著影响。基于此现象，我们提出改进型检测器improved-MAP-R-sort-DFDD，可在多项式时间复杂度下逼近最优误码性能。仿真结果表明，与现有低复杂度酉星座相比，所提多符号酉星座具有显著优势。