Abstract
In this paper, a linearly approximate signal detection scheme is proposed in multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. The huge MIMO-OFDM system, which uses many transmit antennas and high order modulation, requires a detection scheme at the receiver with very low complexity for practical implementation. In the proposed detection scheme, one N × N MIMO-OFDM system is divided into N / 2 2 × 2 MIMO-OFDM systems for linear increase of complexity. After the partial zero-forcing (ZF), decision feedback equalizer (DFE) and QR decomposition-M algorithm (QRD-M) are applied to each 2 × 2 MIMO-OFDM system. Despite nonlinear detection schemes, the overall complexity of the proposed algorithm increases almost linearly because the DFE and the QRD-M are applied to 2 × 2 MIMO-OFDM systems. Also, the value of M in the QRD-M is fixed according to position of the center point in constellation for efficient signal detection. In simulation results, the proposed detection scheme has higher error performance and lower complexity than the conventional ZF. Also, the proposed detection scheme has very lower complexity than the conventional DFE, with slight loss of error performance.
Highlights
Multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM)system, which is a combination of the MIMO and OFDM, is a core technology for high speed mobile communication systems
The method for candidate selections constellation (a): center is in the middle of the constellation; (b): center point is in the edge of the constellation; (c): center point is the middle of the constellation; (b): center point is in the edge of the constellation; (c): center point is the nearest point from the edge point (QAM: quadrature amplitude modulation)
signal-to-noise ratio (SNR) for the proposed detection scheme is increased according to the increased number of transmit antennas because the noise enhancement is very severe in the partial ZF stage
Summary
Multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM). Among several nonlinear detection schemes, the DFE and the QRD-M use QR receiver for low complexity. The complexity for the nonlinear detection scheme increases exponentially as the number of transmit antennas increases, and these algorithms cannot. In [19,20,21], the proposed algorithms are based on sphere decoding (SD) and K-best decoding These algorithms have a very lower complexity than the conventional detection scheme and the ML, with similar error performance. Linearly approximate signal detection scheme is proposed for easy implementation in the huge MIMO-OFDM system. The DFE and the QRD-M are applied to 2 × 2 MIMO-OFDM systems, and it does not require high complexity. Due to the partial ZF, the whole complexity for the proposed algorithm increases linearly according to the increased number of transmit antennas
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