Scalable Quadrature Spatial Modulation

• Published in: IEEE transactions on wireless communications Vol. 21; no. 11; pp. 9293 - 9311
• Main Authors: Rou, Hyeon Seok, de Abreu, Giuseppe Thadeu Freitas, Iimori, Hiroki, G., David Gonzalez, Gonsa, Osvaldo
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.11.2022; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Bit error rate; Complexity theory; Design optimization; Dispersion; Iterative methods; low-complexity; massive MIMO; Modulation; optimality; Parameterization; Quadrature spatial modulation; Quadratures; Receivers; scalablility; space-time coding; Symbols; Transmitters; Wireless communication
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2022.3175579

We consider quadrature spatial modulation (QSM) schemes, which achieve high spectral efficiency (SE) via the dispersion of a relatively small number <inline-formula> <tex-math notation="LaTeX">P </tex-math></inline-formula> of <inline-formula> <tex-math notation="LaTeX">M </tex-math></inline-formula>-ary modulated symbols over a large number of combinations of <inline-formula> <tex-math notation="LaTeX">n_{T} </tex-math></inline-formula> transmit antennas and <inline-formula> <tex-math notation="LaTeX">T </tex-math></inline-formula> transmit instances. In particular, we design a new space-time block code (STBC)-based scalable QSM scheme combining high SE with maximum diversity and optimum coding gains. Deriving a closed-form expression for the optimum SE, we show that scaling the size <inline-formula> <tex-math notation="LaTeX">T </tex-math></inline-formula> with <inline-formula> <tex-math notation="LaTeX">n_{T} </tex-math></inline-formula> not only is required to achieve SE optimality, but also results in further gains in bit error rate (BER) performance. Building on the latter optimal parameterization, a fully optimized scalable QSM (OS-QSM) transmitter design is then obtained by introducing a new dispersion matrix index selection algorithm that ensures even utilization of spatial-temporal resources. Finally, a new greedy boxed iterative shrinkage thresholding algorithm (GB-ISTA) QSM receiver is proposed, which exploits the inherent sparsity of QSM signals and while detecting spatially and digitally modulated bits in a greedy fashion. The resulting low complexity of the new receiver, which is linear on <inline-formula> <tex-math notation="LaTeX">n_{T} </tex-math></inline-formula>, enables the utilization of OS-QSM in systems of previously prohibitive dimensions.