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This paper presents a pre-coding scheme for recently proposed differential spatial modulation (DSM) systems. It employs a lattice reduction (LR) aided pre-coding approach. An approximated upper bound on average bit error rate (BER) is semi-analytically derived. It is analytically shown that it can achieve a full diversity gain. That is, the performance analysis demonstrates that the LR-aided pre-coding DSM (LR-PDSM) systems with $ {N_T} $ N T transmit antennas and $ {N_R} $ N R receive antennas can achieve the maximum transmit diversity order of $ {N_T} $ N T . Meanwhile, it is well-known that the diversity order attained by the conventional zero-forcing (ZF) pre-coding is given as $ {N_T} - {N_R} + 1 $ N T − N R + 1. Simulation results verify the approximated theoretical analysis and show that LR-aided ZF pre-coding is capable of improving the BER performance of the conventional ZF pre-coding based DSM systems under the same spectral efficiency. [ABSTRACT FROM AUTHOR]

In this paper, a new receive antenna subset (RAS) selection scheme is proposed for precoding-aided spatial modulation (PSM). First, a lattice reduction (LR)-based precoder is employed instead of a conventional zero-forcing (ZF) precoder. It is analytically shown that a full diversity gain can be achieved by the LR-based ZF precoder without RAS selection. Then, an optimal LR-based RAS selection criterion is derived for the over-determined LR-based PSM systems, and a suboptimal selection algorithm is additionally presented. It is also shown that optimal and suboptimal RAS selection algorithms based on LR improve the BER performance of the LR-based PSM system. Further, the overall diversity order of the over-determined LR-based PSM systems with optimal LR-based RAS selection is analyzed. Finally, diversity analysis and simulation results show that the LR-ZF-based PSM system with optimal LR-based RAS selection outperforms the conventional ZF-based PSM system with conventional optimal RAS selection. [ABSTRACT FROM AUTHOR]

We consider the problem of the efficient transmit antenna subset (TAS) selection for maximizing the signal-to-interference-plus-noise ratio (SINR) of multiuser space–time line code (MU–STLC) systems. The exhaustive search for optimal TAS selection is impractical since the total number of transmit antennas increases. We propose two efficient TAS selection schemes based on the Woodbury formula. The first is to incrementally select N S active transmit antennas among the available N T transmit antennas. To reduce the complexity of the incremental selection scheme, the Woodbury formula is employed in the optimization process. The second is to perform the decremental strategy in which the Woodbury formula is also applied to develop the low-complexity TAS selection procedure for the MU–STLC systems. Simulation results show that the proposed incremental and decremental TAS selection algorithms offer better alternatives than the existing greedy TAS selection algorithm for the MU–STLC systems. Furthermore, in terms of bit error rate, the proposed minimum mean square error decremental TAS selection algorithm turns out to outperform the existing greedy algorithm with significantly lower computational complexity. Finally, we analyze the detection SINR penalty experienced from TAS selection and the analytical quantity is shown to be well matched with simulation results. [ABSTRACT FROM AUTHOR]