EVALUATION OF FREQUENCY-PHASE DISTORTIONS IN OPTICAL TELECOMMUNICATIONS USING OFDM

Abstract

The article proposes a method for monitoring the peak-to-average power ratio (PAPR), and also discusses the results of assessing the sensitivity of optical-OFDM systems to phase-frequency distortions. The results of a study of the noise immunity of an optical-OFDM system for frequency shift relative to the spacing of optical subcarriers are presented. A description of the factors causing interference and frequency-phase distortions caused by chromatic dispersion (CD) and polarization mode dispersion (PMD) on the performance of optical multiplexing systems with orthogonal frequency division is carried out. Monitoring the PAPR in OFDM systems is relevant, in particular, in the context of fiber optic communication problems that are caused by the nonlinearity of the optical fiber. It is shown that when directly deploying optical networks, the presence of frequency distortions and sensitivity to phase noise are the two main disadvantages of OFDM. Both frequency distortion and phase noise lead to interchannel interference (ICI). Due to the relatively large symbol length compared to a single carrier, OFDM is susceptible to both frequency distortion and phase noise. An additional cumulative distribution function is used for a visual description of PARP. The effect of the oversampling coefficient on the PARP value is determined. It is proposed to use the oversampled signal to obtain a more accurate PARP value. The results of the study show that the effect of phase noise on a signal in optical OFDM channels is due to the existing long symbol period compared to signal transmission on a single carrier. In addition, with an increase in the modulation order, optical OFDM becomes more sensitive to phase noise, which encourages an increase in the signal-to-noise ratio to counteract this. The results of the research showed that for coherent OFDM optical systems, the line width of the optical quantum generator is a critical parameter, especially when switching to high-order modulation. The paper discusses a diagram describing the process of convergence of radio and optical technologies in the context of the use of OFDM modulation. This technique allows for the correct choice of channel multiplexing strategy in optical OFDM telecommunications with multi-position signals.