FOFDM Based on Discrete Cosine Transform for Intensity-Modulated and Direct-Detected Systems

Zhou, Ji; Qiao, Yaojun; Sun, Erkun; Guo, Mengqi; Zhang, Zhenshan; Tang, Xizi; Xu, Fei

doi:10.1109/jlt.2016.2586526

Cited by 35 publications

(31 citation statements)

References 27 publications

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“…If arbitrary constellation size can be chosen on each layer, the spectral efficiency gap can be eliminated with only small number of layers. Taking practical implementation into consideration, large number of layers introduce more computational complexity, so we utilize 2-layer ACO-FOFDM system with proper [19] selection of constellation sizes on different layers. The average signal power applied to each layer is proportion to the number of bits transmitted in each layer.…”

Section: Simulation Results and Discussionmentioning

confidence: 99%

“…In recent years, fast OFDM (FOFDM) based on discrete cosine transform (DCT) has been investigated in the IM/DD optical communication systems to reduce the computational complexity [16,17,18,19]. If the inputs of DCT or inverse DCT (IDCT) are real values, the outputs are also real values.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the real transformation does not need Hermitian symmetry any more, and the one-dimensional modulation has lower computational complexity. For FOFDM system, the interval between subcarriers decreases to half of that in OFDM system, but signal on the positive frequency of FOFDM system has corresponding image on negative frequency, so the M-PAM FOFDM system has the same spectral efficiency and BER performance as M 2 -QAM OFDM system [18,19]. Consequently, it is not difficult to find DCT is also very suitable for replacing FFT in multilayered schemes to reduce the computational complexity without any influence on BER performance [20].…”

Section: Introductionmentioning

confidence: 99%

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An improved diversity combining receiver for layered ACO-FOFDM in IM/DD systems

Guo¹,

Zhou²,

Tang³

et al. 2017

Photon Netw Commun

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In this paper, an improved receiver based on diversity combining is proposed to improve the bit error rate (BER) performance of layered asymmetrically clipped optical fast orthogonal frequency division multiplexing (ACO-FOFDM) for intensity-modulated and direct-detected (IM/DD) optical transmission systems. Layered ACO-FOFDM can compensate the weakness of traditional ACO-FOFDM in low spectral efficiency, the utilization of discrete cosine transform in FOFDM system instead of fast Fourier transform in OFDM system can reduce the computational complexity without any influence on BER performance. The BER performances of layered ACO-FOFDM system with improved receiver based on diversity combining and DC-offset FOFDM (DCO-FOFDM) system with optimal DC-bias are compared at the same spectral efficiency. Simulation results show that under different optical bit en- ergy to noise power ratios, layered ACO-FOFDM system with improved receiver has 2.86dB, 5.26dB and 5.72dB BER performance advantages at forward error correction limit over DCO-FOFDM system when the spectral efficiencies are 1 bit/s/Hz, 2 bits/s/Hz and 3 bits/s/Hz, respectively. Layered ACO-FOFDM system with improved receiver based on diversity combining is suitable for application in the adaptive IM/DD systems with zero DC-bias.

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Section: Simulation Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An improved diversity combining receiver for layered ACO-FOFDM in IM/DD systems

Guo¹,

Zhou²,

Tang³

et al. 2017

Photon Netw Commun

Self Cite

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“…For a general IM/DD system, the instantaneous output optical power is proportional to the input electrical current and the data information is modulated onto the input current intensity. The input electrical current signal has to be real-valued and nonnegative [1]- [8]. At the receiver, to convert the optical signal to electrical signal, direct detection is employed, in which a photo-diode (PD) is used to produce a current proportional to the received instantaneous optical power.…”

Section: Introductionmentioning

confidence: 99%

Asymmetrically Clipped Absolute Value Optical OFDM for Intensity-Modulated Direct-Detection Systems

Bai

Wang

Hanzo

2017

J. Lightwave Technol.

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Abstract-Orthogonal frequency division multiplexing (OFD-M) is attracting increasing attention in optical communication systems thanks to the inherent benefits such as high spectral efficiency and resistance to frequency-selective channels. In this paper, a novel energy and spectrally efficient scheme called asymmetrically clipped absolute value optical OFDM (AAO-OFDM) is proposed for intensity-modulated direct-detection (IM/DD) systems. In AAO-OFDM, absolute value optical OFDM (AVO-OFDM) signals on the even subcarriers and asymmetrically clipped optical OFDM (ACO-OFDM) signals on the odd subcarriers are combined for simultaneous transmission, which employs all the subcarriers requiring no DC biases. For AVO-OFDM scheme, the frequency symbols are firstly modulated on the even subcarriers, which are then fed into an inverse fast Fourier transform block. Afterwards, the absolute values of the bipolar time-domain signals are taken to guarantee nonnegativity, while their signs are mapped to the complex-valued symbols and modulated on the odd subcarriers. Since there remain unused odd subcarriers, other useful symbols can be modulated on them, which leads to the conventional ACO-OFDM scheme. At the receiver, the ACO-OFDM symbols on the odd subcarriers are demodulated firstly, which are reconstructed and removed from the received signals. Afterwards, the remaining signals are utilized to detect the AVO-OFDM symbols with the aid of the demodulated sign symbols on the odd subcarriers. Theoretical analysis and simulation results show that AAO-OFDM has lower peak-to-average power ratio than other optical OFDM schemes, which makes it less sensitive to the nonlinearity of the optical devices. Furthermore, it achieves better bit error rate performance compared to its counterparts for the same spectral efficiency.Index Terms-Intensity modulation with direct detection, orthogonal frequency division multiplexing, energy efficiency, spectral efficiency.

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“…In IM/DD OWC systems, the transmitted electrical signal is modulated onto the instantaneous power of an optical emitter such as LED (Light-Emitting Diode) or LD (Laser Diode). Thus the time-domain signals should be real-valued and nonnegative [1,2,6] .…”

Section: Introductionmentioning

confidence: 99%

Enhanced asymmetrically clipped DC biased optical OFDM for intensity-modulated direct-detection systems

Bai

Chen

Mao

et al. 2017

J. Commun. Inf. Netw.

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In this paper, we propose an EADO-OFDM (Enhanced Asymmetrically Clipped DC Biased Optical Orthogonal Frequency Division Multiplexing) method for IM/DD (Intensity-Modulated DirectDetection) optical systems, in which the AV-DCO-OFDM (Absolute Valued DC Biased Optical OFDM) symbols on the even subcarriers and ACO-OFDM (Asymmetrically Clipped Optical OFDM) symbols on the odd subcarriers are combined for simultaneous transmission. Moreover, we discuss the PDF (Probability Density Function) and electrical SNR (Signal to Noise Ratio) of the symbols, which are utilized to estimate the BER (Bit Error Ratio) performance and overall performance of EADO-OFDM. The Monte Carlo simulation results have validated the theoretical analysis and have also confirmed the EADO-OFDM is attractive considering the following benefits. Firstly, EADO-OFDM is more energy efficient compared to the power-efficient DCO-OFDM (DC Biased Optical OFDM), since the required DC bias is smaller when appropriate constellation size combinations are chosen. In addition, EADO-OFDM performs better than the conventional ADO-OFDM (Asymmetrically Clipped DC Biased Optical OFDM), because the absolute value operation causes no clipping distortion.

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FOFDM Based on Discrete Cosine Transform for Intensity-Modulated and Direct-Detected Systems

Cited by 35 publications

References 27 publications

An improved diversity combining receiver for layered ACO-FOFDM in IM/DD systems

An improved diversity combining receiver for layered ACO-FOFDM in IM/DD systems

Asymmetrically Clipped Absolute Value Optical OFDM for Intensity-Modulated Direct-Detection Systems

Enhanced asymmetrically clipped DC biased optical OFDM for intensity-modulated direct-detection systems

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