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In this paper, minimum shift keying (MSK) scheme and Gaussian minimum shift keying (GMSK) scheme used in Short-Range visible light communication(VLC) is presented. The light-emitting diode (LED) model in short-range VLC is introduced, the bit error rate (BER) performance of MSK is compared with GMSK by Monte Carlo simulations and experiments. The results are shown and MSK has the better BER performance...
This paper investigate the performance of a proposed optical orthogonal frequency-division multiplexing (OFDM) in a short-range intensity-modulated, direct-detected (IM/DD) optical channel. Because of the high peak-to-average power ratio (PAPR) problem of the OFDM modulation scheme, the beneficial clipping method has been proposed to improve the performance of communication system. In the optical...
The existing clipping researches in direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) systems generally originate from insufficient DC bias and the nonlinear transmission characteristics of physical devices which will distort the system performances. In contrast to conventional clipping theories, the beneficial clipping method demonstrated in this paper aims to improve...
In visible light communication (VLC) systems, the employing of orthogonal frequency division multiplexing (OFDM) may produce nonlinear distortion, due to the nonlinear characteristics of LEDs and the high peak to average power ratio (PAPR) of OFDM. Moreover, the clipping block deteriorates the distortion. In this paper, an advanced A-law algorithm for alleviating such distortion in VLC-OFDM systems...
This paper proposes a novel four phase-shifted sinusoid symbol (PSS-4) signaling technique to relief high-speed wireline backplane transceiver to reduce large intersymbol interference. The four-level pulse amplitude modulation (PAM-4) and other existing amplitude modulation techniques have been widely used to simplify transceiver equalization design for highly dispersive channels. Unfortunately, PAM-4...
This paper analyzes the impact of tracking errors on the time diversity structure in relation to beam tracking over free-space optics (FSO) links. The paper proposes a time-diversity scheme with beam tracking introducing a powerfading model for an FSO system that utilizes beam tracking through atmospheric turbulence. Further, the paper derives a closed-form bit error rate (BER) for no-diversity and...
In this paper, we develop a simple closed-form generalized likelihood ratio test (GLRT) detector for a multi-relay amplify-and-forward (AF) cooperative network employing noncoherent M-ary frequency-shift keying (M-FSK). The proposed detector is robust in the sense that it does not require any prior knowledge about the channels such as the variance of the additive white Gaussian noise, the fading model,...
Free space optical(FSO) communication can provide high bandwidth, high security communication services. it is attractive for its convenient establish the communication link and low power consuming. As the active received area of optical fiber is very small, when using optical fiber technology in FSO system, we must consider the effects of angle of arrival. Tracking subsystem is an effective method...
When we use the free space optical(FSO) communication in the near-ground, it will be great influenced by the atmospheric turbulence. There are many studies on the effects of atmospheric turbulence in FSO. Recently gamma-gamma is a widely accepted model for the optical propagating through the atmosphere in normal and strong turbulence. In order to enhance bit error rate(BER) performance influenced...
Abstract-We investigate the exact error performance of hard minimum mean-squared error (MMSE) detection in multipleinput multiple-output (MIMO) systems. To facilitate the analysis, we first conduct error analysis for a general system with decision statistic, z = ax + u, where a >; 0, x is the transmitted signal, and u is the arbitrarily distributed noise component which is independent of x. For...
In this paper, we propose a new scheme of time-diversity system using Optical Code Division Multiple Access (OCDMA) in free space optical (FSO) communication. Our design is a fully-optical communication system which facilitates synthesizing the time-diversity signals. We found that it can effectively minimize the influence of scintillation caused by atmospheric turbulence. We analyze the bit error...
A 2.4 GHz on-off keying (OOK) transmitter with high data rate up to 136 Mb/s for biotelemetry applications has been designed in a 0.18 μm CMOS process. Power consumption of the transmitter is reduced by 38 percent with the proposed mechanism of switching an oscillator on and off to generate an OOK modulated signal. The TX for 136 Mb/s OOK data has a DC power consumption of 3 mW and an output power...
We study the optimum maximum-likelihood (ML) detection and sub-optimum detection with limited channel state information (CSI) for a multi-branch dual-hop cooperative diversity network which consists of a source, multiple relays, and a destination without a direct source-destination path. With the limited CSI, the signalling overhead at each relay is reduced by 50%. We first derive the optimum ML detection...
Practical and low complexity implementation of receivers is of vital importance for the successful penetration of the ultra-wideband (UWB) technology. The role of a synchronization technique is essentially to determine the relative delay of the received signal with respect to a template signal in the receiver, and it is difficult to implement due to the ultra-fine time-resolvability of the UWB signal...
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