Abstract
The QR decomposition-M algorithm (QRD-M) is a popular signal detector which has similar error performance with maximum likelihood (ML) in multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. The QRD-M uses M candidates at each layer, unlike the ML. However, the complexity of the QRD-M is high in huge MIMO-OFDM systems due to unnecessary survival paths at each layer. In this paper, a low-complexity QRD-M with variable number of survival paths at each layer is proposed. In the conventional QRD-M, path eliminations at the previous layer reduce the number of calculations for accumulated squared Euclidean distance (ASED) in subsequent layers. The proposed QRD-M eliminates unnecessary survival paths by comparing the ASED and the calculated threshold at each layer. The simulation results show that the proposed QRD-M maintains the error performance for the conventional QRD-M and has a very low complexity.
Highlights
Multiple input multiple output (MIMO) systems have been used to increase spectral efficiency and channel capacity without high transmit power or wide bandwidth in a rich scattering wireless channel [1,2]
The QR decomposition-M algorithm (QRD-M) is the simplified maximum likelihood (ML) detection based on tree search
The average number of metric operations for the conventional QRD-M is shown with M = 1, 4, 8, 16, and all results are not changed with respect to the signal-to-noise ratio (SNR) because the number of survival paths at all layers is M
Summary
Multiple input multiple output (MIMO) systems have been used to increase spectral efficiency and channel capacity without high transmit power or wide bandwidth in a rich scattering wireless channel [1,2]. In [10,11,12], adaptive path eliminations were used at each layer for low complexity These proposed detections still have high complexity since thedeveloped average number of [10,11,12], unnecessary survival and a lattice reduction (LR)-aided adaptive. Modified tree structure has eliminations were used at each layer for low complexity These proposed detectionshigh still complexity when the number of transmit antennas is high because the conventional is have high complexity since the average number of unnecessary survival paths is high despite the path applied from the. O denotes modulation order.isTherefore, thisthe paper proposes very transmit positive antennasinfinity is high and because the conventional applied from to d Nt /O e-th layer low complexity hasrounding the same function error performance as ML.positive. The complexity of value the proposed is much lower than that of other QRD-M detection schemes in [10,11,12] because of the efficient threshold value considering the modulation order
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