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Linear frequency modulated (LFM) phase‐sensitive optical time‐domain reflectometry (φ‐OTDR) relieves the trade‐off between sensing range and spatial resolution; however, it is still limited by low sidelobe suppression ratio and signal fading. Fractional Fourier transform (FrFT) is applied to LFM φ‐OTDR for signal generation and compression. An LFM pulse is generated using the p‐order FrFT of a direct...
In this paper, a 60cm free-space optical card-to-card wavelength division multiplexing (WDM) transmission architecture using OFDM modulation and coherent detection is proposed and demonstrated, which can offer flexibility and high speed transmission simultaneously. The experimental results show that the net data rate is up to 106.9Gb/s and the receiver sensitivity is −34dBm at the BER threshold of...
We compared the performance of the asymmetric and direct current bias limiting optical orthogonal frequency division multiplexing (ADO-OFDM), asymmetric limiting optical orthogonal frequency division multiplexing (ACO-OFDM), and the direct current bias limiting optical orthogonal frequency division multiplexing (DCO-OFDM) in visible light communication (VLC) systems. We optimize the power ratio between...
We investigate and analyze the asymmetrically clipped and direct-current-biased optical orthogonal frequency division multiplexing (ADO-OFDM) in visible light communication (VLC) system. Then we propose two modified channel equalization algorithms of ADO-OFDM in VLC systems. It is shown that the algorithm combined with channel estimation for interference cancellation to recover ADO-OFDM signal is...
In orthogonal frequency division multiplexing (OFDM) systems, a number of OFDM symbols form one subframe and consecutive subframes may be allocated to different users. Automatic gain control (AGC) is commonly employed in OFDM systems because the power of receiving signals can vary over a large dynamic range. After measuring the power of cyclic prefix (CP) of the first OFDM symbol in a subframe, AGC...
A novel Brillouin optical time-domain analysis (BOTDA) system is demonstrated using intensity-modulated optical orthogonal frequency division multiplexing probe signal and direct detection (IM-DD-OOFDM) for stimulated Brillouin spectrum (SBS) measurement without frequency sweep operation. The SBS is reconstructed by channel estimation algorithm and Brillouin frequency shift (BFS) is located by curve...
Visible light communication (VLC) has been a research hotspot for broad bandwidth, high speed, and anti-interference. Power line communication (PLC) has the advantages of low cost and flexible access, which is connected and combined with VLC to be a hybrid communication system. We set up a communication system model of PLC&VLC based on orthogonal frequency division multiplexing (OFDM) modulation,...
Energy-efficient transmission is an important issue for wireless communication systems, due to the increased energy consumption and limited battery capacity. In this paper, we study the energy-efficient transmission in a single cellular downlink multi-user Orthogonal Frequency Division Multiple Access (OFDMA) system. The transmit power consumption and the circuit power consumption are both taken into...
In order to analyze the performance on the Orthogonal Frequency Division Multiplex (OFDM) physical layer (PHY) of IEEE 802.11ad, a transceiver is designed based on the draft. The impacts of hardware impairments on the Bit Error Rate (BER) performance are studied, including phase noise and power amplifier (PA) nonlinear distortion. Simulation results indicate that phase noise makes a smaller effect...
The linear minimum mean square error (LMMSE) channel estimation has better performance than the least square (LS) channel estimation. However, it requires channel statistics which are often difficult to obtain. In addition, the computational complexity of the LMMSE channel estimation is high because of the inverse matrix computation. In order to overcome these implementation issues, a vector quantization...
Spatial division multiple access can be used to boost spectrum efficiency if perfect channel information is available at the transmitter. By using equal-gain beamforming, this paper reformulates the difficult non-convex optimization problem of finding the optimal multiuser beamforming vectors into a convex one. Consequently, the Nash equilibrium solution can be reached based on a non- cooperative...
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