Abstract
Layered asymmetrically clipped optical orthogonal frequency division multiplexing (LACO-OFDM) has a high spectral efficiency. However, an iterative detection with a pair of fast Fourier transform (FFT) and inverse fast Fourier transform (IFFT) is required for LACO-OFDM, which increases the complexity for the receiver of LACO-OFDM. In this paper, the performance of the receiver with a single FFT is analyzed for LACO-OFDM in visible light communications. In the single-FFT receiver, the different layers of ACO-OFDM signals are distinguished in time domain without the FFT/IFFT pair. Because only one FFT is employed in the proposed receiver, the complexity of O( N log2 N ) can be achieved, which is much lower than the complexity of the conventional LACO-OFDM receiver. Simulation results illustrate that the proposed scheme has a signal-to-noise ratio (SNR) penalty of 1dB ∼ 3dB compared with the conventional solution in additive white Gaussian noise (AWGN) channel. However, the proposed receiver outperforms conventional LACO-OFDM solution in light emitting diode (LED) nonlinearity channel.
Highlights
O PTICAL orthogonal frequency division multiplexing (OFDM) is being considered as a candidate for visible light communications (VLC) because of many advantages such as high spectral efficiency and anti-multipath fading [1]–[4]
There are several schemes to improve the spectral efficiency for ACO-OFDM including asymmetrically clipped direct current (DC) biased optical OFDM (ADO-OFDM) [6], hybrid ACO-OFDM (HACO-OFDM) [7], spectral and energy efficient OFDM (SEE-OFDM) [8], enhanced unipolar OFDM [9], enhanced ACOOFDM [10], augmented spectral efficiency discrete multi-tone (ASE-DMT) [11] and layered ACO-OFDM (LACO-OFDM) [12]
In all these schemes, the iterative detection with the fast Fourier transform (FFT)/inverse fast Fourier transform (IFFT) pair is still required in the receiver, which increases the computational complexity for the receiver of LACO-OFDM
Summary
O PTICAL orthogonal frequency division multiplexing (OFDM) is being considered as a candidate for visible light communications (VLC) because of many advantages such as high spectral efficiency and anti-multipath fading [1]–[4]. Wang et al experimentally show that LACO-OFDM exhibits its great potential in short-haul optical transmission link [17] In all these schemes, the iterative detection with the FFT/IFFT pair is still required in the receiver, which increases the computational complexity for the receiver of LACO-OFDM. In our previous work, we proposed a diversity combining scheme via symmetry recovering for ACO-OFDM systems [18]. Symmetry recovering is a simple signal processing in time domain without the FFT/IFFT pair which can reduce the computational complexity for the receiver, which may be a great benefit for LACO-OFDM. A low-complexity receiver with only single FFT for LACO-OFDM is proposed.
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