The impact of the fiber Kerr effect on error statistics in the nonlinear (high power) transmission of the OFDM 16-QAM signal over a 2000 km EDFA-based link is examined. We observed and quantified the difference in the error statistics for constellation points located at three power-defined rings. Theoretical analysis of a trade-off between redundancy and error rate reduction using probabilistic coding of three constellation power rings decreasing the symbol-error rate of OFDM 16-QAM signal is presented. Based on this analysis, we propose to mitigate the nonlinear impairments using the adaptive modulation technique applied to the OFDM 16-QAM signal. We demonstrate through numerical modelling the system performance improvement by the adaptive modulation for the large number of OFDM subcarriers (more than 100). We also show that a similar technique can be applied to single carrier transmission.
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http://dx.doi.org/10.1364/OE.24.030296 | DOI Listing |
Direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) is widely used in blue light-emitting diode (LED)-based underwater optical wireless communication (UOWC), but the limited LED bandwidth leads to nonlinear distortions at higher frequencies. Using experiments, this paper proposes and validates a differential pre-emphasis (DPE) scheme for OFDM signal transmission in underwater channels to mitigate LED modulation bandwidth-induced nonlinearity, therefore improving transmission system performance. It is shown that the optimum DPE value leads to shorter rise time and fall time of the received signal and also avoids over- and under-shoots.
View Article and Find Full Text PDFIn cost-sensitive application scenarios, increasing the data rate per channel under a limited receiver bandwidth is critical, and thus, the transceivers with low costs and high electrical spectral efficiencies (ESEs) are highly desirable. In this Letter, we demonstrate a modified silicon photonic (SiP) carrier-assisted differential detection (CADD) receiver with a record ESE for single polarization. The ESE of the conventional CADD is mainly limited by the transfer function that originated from the optical delay and hybrid.
View Article and Find Full Text PDFWith the development of 6 G network, the issue of information security is becoming more and more significant. In this paper, a secure RoF system based on key nested polar code and feedback neural network (FNN) is proposed. For the nested polar code, the original key is randomly selected from the constructed codebook and the index of key is encoded by inner polar code which is placed at the location with better channel quality bit of the frozen bit of outer polar code, for the other part of outer polar code, information bits are encrypted by chaotic sequence generated by 4-D cellular neural network.
View Article and Find Full Text PDFThe emergence of the millimeter wave (mm-Wave; 30 GHz to 300 GHz) frequency band holds a lot of promise for addressing the congestion at low frequency in future mobile networks. Among many mm-Wave generation schemes, optical heterodyning is considered one of the most promising approaches due to its scalability and potential for integration on chip. Employing optical frequency combs (OFC) for optical heterodyning alleviates the significant phase distortions/noise introduced by the optical sources.
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