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In this paper, the PWM encoding of an optical OFDM transmission is studied and simulated. Traditional optical OFDM schemes make use of linear drivers, but the inherent nonlinear behavior of the optical emitters produce a harmful effect on the demodulated signal. PWM allows the use of nonlinear drivers, avoiding this harmful effects and increasing the efficiency of the transmission. Furthermore, synchronization...
In this paper, a system based on time-hopping spread spectrum techniques for indoor visible light communications is studied via simulation. A 2-PPM modulation scheme is selected because it yields good results in wireless optical communications. Furthermore, the system allows for selecting the number of pulses per symbol to be transmitted and makes use of an optimum maximum-likelihood receiver for...
There are physical spaces and infrastructure environments in which conventional radio-frequency (RF) wireless systems can result in hazardous conditions due to the intrinsic risk of producing high levels of electromagnetic interference (EMI), which can affect sensitive electronic equipment placed in proximity of such high energy RF sources. Two good examples of infrastructures where the levels of...
In this paper, the use of visible light communications (VLC) technologies for providing data networking for passengers during flight is explored. An uplink channel based on infrared is also studied. The potential capabilities of this optical access technique are examined.
This work presents the use of white LED (WLED) lamps as broadcast emitters in an optical wireless system. The proposed system allows the data transmission at medium data rate (500 kb/s). The level of illumination can be changed without any degradation of the transmission performances. If a pulse width modulation (PWM) driver is used to apply the electrical power to the WLED, the transmission capabilities...
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