Four-Level Pulse Width Modulation for Fiber Optic Communications

The performance of a digital fiber optical system employing four-level pulse width modulation (PWM) is considered. It is shown that PWM may be an attractive alternative to pulse amplitude modulation (PAM), especially if a wide band channel is used. The probability density function (pdf) of the timin...

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Bibliographic Details
Published inIEEE transactions on communications Vol. 30; no. 8; pp. 1958 - 1963
Main Authors Dai Xianda, Englefield, C., Goud, P., Razdan, R.
Format Journal Article
LanguageEnglish
Published IEEE 01.08.1982
Subjects
Bit error rate
Noise level
Optical fiber communication
Optical modulation
Optical noise
Optical pulses
Optical receivers
Pulse amplifiers
Pulse width modulation
Space vector pulse width modulation
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Summary:The performance of a digital fiber optical system employing four-level pulse width modulation (PWM) is considered. It is shown that PWM may be an attractive alternative to pulse amplitude modulation (PAM), especially if a wide band channel is used. The probability density function (pdf) of the timing error is obtained in terms of the pdf of the noise amplitude, taking into account the thermal noise of the amplifier and the signal-dependent shot noise introduced by the photodiode detector. Near-Gaussian optical pulse edges at the receiver are assumed. Using typical system parameters, the variation of bit error rate (BER) with power level, and the effects of different bit rates, mean photodetector gain, and system bandwidths are calculated. It is observed that minimum BER's are achieved at moderate values of mean photodetector gain and that increased system bandwidth results in increased receiver sensitivity.
ISSN:0090-6778
1558-0857
DOI:10.1109/TCOM.1982.1095677