Spatial modulation (SM) is a multiple-input multiple-output (MIMO) technique that achieves a MIMO capacity by conveying information through antenna indices, while keeping the transmitter as simple as that of a single-input system. Quadrature SM (QSM) expands the spatial dimension of the SM into in-phase and quadrature dimensions, which are used to transmit the real and imaginary parts of a signal symbol, respectively. A parallel QSM (PQSM) was recently proposed to achieve more gain in the spectral efficiency. In PQSM, transmit antennas are split into parallel groups, where QSM is performed independently in each group using the same signal symbol. In this paper, we analytically model the asymptotic pairwise error probability of the PQSM. Accordingly, the constellation design for the PQSM is formulated as an optimization problem of the sum of multivariate functions. We provide the proposed constellations for several values of constellation size, number of transmit antennas, and number of receive antennas. The simulation results show that the proposed constellation outperforms the phase-shift keying (PSK) constellation by more than 10 dB and outperforms the quadrature-amplitude modulation (QAM) schemes by approximately 5 dB for large constellations and number of transmit antennas.

中文翻译：

---

并行正交空间调制的性能分析和星座设计

空间调制 (SM) 是一种多输入多输出 (MIMO) 技术，它通过通过天线索引传达信息来实现 MIMO 容量，同时保持发射机与单输入系统一样简单。正交 SM (QSM) 将 SM 的空间维度扩展为同相和正交维度，分别用于传输信号符号的实部和虚部。最近提出了并行 QSM (PQSM) 以实现更多的频谱效率增益。在 PQSM 中，发射天线被分成并行组，其中 QSM 在每个组中使用相同的信号符号独立执行。在本文中，我们对 PQSM 的渐近成对错误概率进行了分析建模。因此，PQSM 的星座设计被表述为多元函数和的优化问题。我们为星座大小、发射天线数量和接收天线数量的几个值提供了建议的星座。仿真结果表明，对于大型星座和发射天线数量，所提出的星座比相移键控 (PSK) 星座的性能高出 10 dB 以上，并且比正交幅度调制 (QAM) 方案的性能高约 5 dB。