Spatial modulation (SM) is a promising multiple-input multiple-output system used to increase spectral efficiency. The maximum likelihood (ML) decoder jointly detects the transmitted SM symbol, which is of high complexity. In this paper, a novel reliable sphere decoder (RSD) algorithm based on tree-search is proposed for the SM system. The basic idea of the proposed RSD algorithm is to reduce the size of the tree-search, and then, a smart searching method inside the reduced tree-search is performed to find the solution. The proposed RSD algorithm provides a significant reduction in decoding complexity compared to the ML decoder and existent decoders as well. Moreover, the RSD algorithm provides a flexible trade-off between the bit error rate (BER) performance and decoding complexity, so as to be reliable for a wide range of practical hardware implementations. The BER performance and decoding complexity analysis for the RSD algorithm are studied, and Monte Carlo simulations are then provided to demonstrate the findings.

中文翻译：

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空间调制系统的可靠检测

空间调制 (SM) 是一种很有前途的多输入多输出系统，用于提高频谱效率。最大似然(ML)解码器联合检测传输的SM符号，其复杂度高。在本文中，针对SM 系统提出了一种基于树搜索的新型可靠球体解码器(RSD) 算法。所提出的RSD算法的基本思想是减小树搜索的大小，然后在缩小的树搜索内部执行智能搜索方法来找到解决方案。与 ML 解码器和现有解码器相比，所提出的 RSD 算法显着降低了解码复杂度。此外，RSD 算法在误码率 (BER) 性能和解码复杂度之间提供了灵活的权衡，以便在广泛的实际硬件实现中可靠。研究了 RSD 算法的 BER 性能和解码复杂度分析，然后提供蒙特卡罗模拟来证明结果。