Low-complexity soft ML detection for generalized spatial modulation

• Published in: Signal processing 2022-07, Vol.196, p.108509, Article 108509
• Main Authors: Ángeles Simarro, M., García-Mollá, Víctor M., Martínez-Zaldívar, F.J., Gonzalez, Alberto
• Format: Article
• Language: English
• Subjects: Generalized spatial modulation (GSM); Low-complexity; Multiple-Input multiple-Output (MIMO); Soft-output
• ISSN: 0165-1684; 1872-7557
• DOI: 10.1016/j.sigpro.2022.108509

•Maximum-Likelihood detection for soft-output in MIMO-GSM systems leads a high computational cost.•Three different algorithms that achieve Maximum-Likelihood performance are proposed to provide a reasonable computational cost in order to make a performance benchmark available.•The algorithms show reduced complexity compared to other ML algorithms, especially when the system size increases. Generalized Spatial Modulation (GSM) is a recent Multiple-Input Multiple-Output (MIMO) scheme, which achieves high spectral and energy efficiencies. Specifically, soft-output detectors have a key role in achieving the highest coding gain when an error-correcting code (ECC) is used. Nowadays, soft-output Maximum Likelihood (ML) detection in MIMO-GSM systems leads to a computational complexity that is unfeasible for real applications; however, it is important to develop low-complexity decoding algorithms that provide a reasonable computational simulation time in order to make a performance benchmark available in MIMO-GSM systems. This paper presents three algorithms that achieve ML performance. In the first algorithm, different strategies are implemented, such as a preprocessing sorting step in order to avoid an exhaustive search. In addition, clipping of the extrinsic log-likelihood ratios (LLRs) can be incorporating to this algorithm to give a lower cost version. The other two proposed algorithms can only be used with clipping and the results show a significant saving in computational cost. Furthermore clipping allows a wide-trade-off between performance and complexity by only adjusting the clipping parameter.