Abstract
The need to achieve high data rates in modern telecommunication systems, such as 5G standard, motivates the study and development of large antenna and multiple-input multiple-output (MIMO) systems. This study introduces a large antenna-order design of MIMO quasi-orthogonal space-time block code (QO-STBC) system that achieves better signal-to-noise ratio (SNR) and bit-error ratio (BER) performances than the conventional QO-STBCs with the potential for massive MIMO (mMIMO) configurations. Although some earlier MIMO standards were built on orthogonal space-time block codes (O-STBCs), which are limited to two transmit antennas and data rates, the need for higher data rates motivates the exploration of higher antenna configurations using different QO-STBC schemes. The standard QO-STBC offers a higher number of antennas than the O-STBC with the full spatial rate. Unfortunately, also, the standard QO-STBCs are not able to achieve full diversity due to self-interference within their detection matrices; this diminishes the BER performance of the QO-STBC scheme. The detection also involves nonlinear processing, which further complicates the system. To solve these problems, we propose a linear processing design technique (which eliminates the system complexity) for constructing interference-free QO-STBCs and that also achieves full diversity using Hadamard modal matrices with the potential for mMIMO design. Since the modal matrices that orthogonalize QO-STBC are not sparse, our proposal also supports O-STBCs with a well-behaved peak-to-average power ratio (PAPR) and better BER. The results of the proposed QO-STBC outperform other full diversity techniques including Givens-rotation and the eigenvalue decomposition (EVD) techniques by 15 dB for both MIMO and multiple-input single-output (MISO) antenna configurations at 10 − 3 BER. The proposed interference-free QO-STBC is also implemented for 16 × N R and 32 × N R MIMO systems, where N R ≤ 2 . We demonstrate 8, 16 and 32 transmit antenna-enabled MIMO systems with the potential for mMIMO design applications with attractive BER and PAPR performance characteristics.
Highlights
The need for higher data rates at the user end is the major motivation for new multiple-input multiple output (MIMO) schemes in modern communication systems
In [34], a zero-forcing detection was discussed for the quasi-orthogonal space-time block code (QO-Space-time block coding (STBC)) design; this is similar to the eigenvalue method proposed in [18]
This study implements the standard QO-STBC code system described in Section 2 in the transmitter and an maximum likelihood (ML) detection dispensing with maximal ratio combining (MRC) in the receiver to construct a 8 × NR, 16 × NR
Summary
The need for higher data rates at the user end is the major motivation for new multiple-input multiple output (MIMO) schemes in modern communication systems These modern techniques dispensing with the large number of antennas enable spectral efficiency and increased transmit-energy efficiency, all antennas do not contribute [1,2,3,4]. We apply modal matrices from the eigenvalues of the QO-STBCs provided by the Hadamard matrices to orthogonalize the detection matrix and enable linear processing This is achieved by deriving an equivalent virtual channel matrix (EVCM) first, which can be used to reduce the complexity of decoupling the space-time transmitted messages at the receiver.
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