Abstract
In this paper, we present an efficient transmission scheme for multiple-input multiple-output (MIMO) systems, i.e., coded spatial modulation (SM) systems with soft-decision aided detector. To exploit the powerful error correction of channel coding, the key challenge of coded SM systems is on designing a reliable but low-complexity soft-output detector. Fighting against this problem, we first propose two soft-output detection algorithms by exploiting the features of M-phase-shift keying (PSK) and M-quadrature amplitude modulation (QAM) constellations, namely, PSK-based soft-output detector (PBSD) and QAM-based soft-output detector (QBSD). Furthermore, to further enhance the performance of the two algorithms, we propose another two soft-output detection algorithms taking into account of counterpart maximum-likelihood (ML) estimate, namely, improved PSK-based soft-output detector (IPBSD) and improved QAM-based soft-output detector (IQBSD). The findings of this paper demonstrate that: (1) The computational complexity of PBSD and QBSD algorithms are much lower than that of Max-Log-LLR algorithm at the expense of error performance. (2) Both the IPBSD and IQBSD algorithms achieve the same performance as Max-Log-LLR algorithm with reduced computational complexity. In addition, a comprehensive performance and computational complexity comparison between the proposed algorithms and the Max-Log-LLR algorithm is provided to verify our proposed low-complexity soft-output detectors.
Highlights
Spatial modulation (SM) has been identified as a new efficient multiple-input multiple-output (MIMO) technique, which was first proposed in [1]
For coded SM-MIMO systems with Gray-labeled phase-shift keying (PSK), we first design a new calculation of log-likelihood ratio (LLR) method based on the hard-decision detector in [6], denoted as PSK-based soft-output detector (PBSD) algorithm
For coded SM-MIMO systems with Gray-labeled quadrature amplitude modulation (QAM) modulation, we propose a low-complexity soft-output detector based on hard-limiter-based ML method proposed in [7], labeled as QAM-based softoutput detector (QBSD) algorithm
Summary
Spatial modulation (SM) has been identified as a new efficient multiple-input multiple-output (MIMO) technique, which was first proposed in [1]. It is urgent to design low-complexity soft-output detectors for coded SM-MIMO systems. For coded SM-MIMO systems with Gray-labeled phase-shift keying (PSK), we first design a new calculation of log-likelihood ratio (LLR) method based on the hard-decision detector in [6], denoted as PSK-based soft-output detector (PBSD) algorithm. N is a zero-mean additive white Gaussian noise vector with E nnH = σ 2INr×Nr. At the receiver, to achieve the advantage of channel coding, a soft-output detector is employed, where the soft information for each coded bits is calculated based on the received signal.
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