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We have proposed a novel hybrid software and hardware equalization scheme based on digital zero-padding pre-equalization and differential reception. We have experimental demonstrated a red LED based visible light communication system over 1-meter free space transmission with the measured BER below 7% FEC threshold. The signal is QAM-DMT modulated and the modulation level is varying from 32QAM to 128QAM...
Turbulent environment can highly affect the performance of free space optical (FSO) communication links. Therefore, how to obtain the turbulence intensity is a very important issue. The paper has shown the detailed analysis to calculate the log irradiance variance (σ2R) along with the experimental verification under an indoor laboratory controlled turbulence condition. This paper verifies the consistency...
To solve the phase deviation problem caused by antenna orientation centre deviation during the phase calibration of Monopulse tracking receiver on ship-borne sitcom station, a phase compensation method is proposed to enhance the phase calibration precision. The working principle of monopulse tracking receiver is discussed, the demodulation process of sum and difference signal, and the cause of phase...
Visible light communication (VLC) using light emitted diodes (LEDs) has been considered as the most attractive solution for indoor positioning. In this paper, an indoor visible light positioning system taking account of multiple reflections is investigated. Based on received signal strength indication (RSSI) algorithm, the positioning error distributions are simulated and show that the reflections...
The long-distance ultraviolet communication has to take the influence of atmosphere turbulence into consideration. This paper proposed a new turbulent channel combined with single scattering model for ultraviolet communication, where the variation of refractive-index structure parameter is introduced. The calculating results of new model is closer to the experimental results compared to that of the...
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...
This paper proposes a two-dimension encryption orthogonal frequency division multiplexing passive optical network (OFDM-PON) based on dynamic chaos-iteration. The correlation monitoring method is adopted to achieve dynamic key distribution between OLT and ONUs. It is shown that key space can be larger than 1086, which would be against exhaustive attack effectively. We experimentally demonstrate a...
Inter-symbol interference (ISI) in visible light communication (VLC) systems has been considered as a major problem which seriously deteriorates system performance. Constant modulus algorithm (CMA) is a widely adopted blind equalization scheme to eliminate ISI in practice due to its computational simplicity and effectiveness. This paper proposed an initialization scheme for CMA based on received signal...
The cognitive radio (CR) have been proposed to improve spectral efficiency and to meet growing demands for higher data rates in mobile communications and satellite communications. In this paper, we propose a blind estimation algorithm for a secondary user to estimate transmission parameters of the primary signal in an OFDM overlay system, using only the available fast Fourier transform (FFT) component...
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...
Visible light communication has drawn much attention due to the extensive use of light emitting diodes (LED). For ultra-dense small cell deployment, visible light communication has to define the position of users for providing services and switch policies, and deal with the superposition of the light. In this paper, we propose an indoor intelligent visible light system based on Triple-Domain-Cooperation...
A method of adding squared signals of three polarization diversity receiver to overcome the polarization induced fading (PIF) in the optical fibre hydrophone is proposed and experimentally verified. This triple polarization diversity receiver (tri-PDR) is first analysed and theoretically demonstrated. Then, a Mach-Zehnder interferometric sensor with polarization rotator in the reference arm is fabricated...
The standard core protocol of Narrow Band Internet of Things (NB-IOT) was approved by the RAN plenary session in June 16, 2016. Global operators have a standardized IOT proprietary protocol. The successful completion of the standardization work also marks that the NB-IOT has entered the commercial stage. Modern wireless communication equipment must accommodate high power transmitter and high sensitivity...
This paper proposes an adaptive method to modify network delay caused by clock skew. First, we introduce the concept of end-to-end network delay, and then we propose a method which aims at eliminate the effect cause by the difference clock frequency. The method first denoises the data set to remove error points, and then uses Least Square Method to estimate the clock skew in distributed network. Finally,...
Analytical model is proposed to estimate EVM under the case of nonlinear noise for coherent optical fiber communications with digital receivers. Theoretical formula is obtained, which is validated by numerical simulations.
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