KNN-based Demodulation in gridless Nyquist-WDM Systems affected by Interchannel Interference

2019 ◽  
Author(s):  
Alejandro Escobar Pérez ◽  
Jhon J. Granada Torres ◽  
Neil Guerrero González
Keyword(s):  
Interchannel Interference

scholarly journals A Modified KNN Algorithm for High-Performance Computing on FPGA of Real-Time m-QAM Demodulators

Electronics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 627
Author(s):  
David Marquez-Viloria ◽  
Luis Castano-Londono ◽  
Neil Guerrero-Gonzalez
Keyword(s):  
Real Time ◽  
High Performance ◽  
Interference Mitigation ◽  
Parallel Implementation ◽  
Computational Time ◽  
Successful Implementation ◽  
Interchannel Interference ◽  
The Difference ◽  
High Level ◽  
Performance Computing

A methodology for scalable and concurrent real-time implementation of highly recurrent algorithms is presented and experimentally validated using the AWS-FPGA. This paper presents a parallel implementation of a KNN algorithm focused on the m-QAM demodulators using high-level synthesis for fast prototyping, parameterization, and scalability of the design. The proposed design shows the successful implementation of the KNN algorithm for interchannel interference mitigation in a 3 × 16 Gbaud 16-QAM Nyquist WDM system. Additionally, we present a modified version of the KNN algorithm in which comparisons among data symbols are reduced by identifying the closest neighbor using the rule of the 8-connected clusters used for image processing. Real-time implementation of the modified KNN on a Xilinx Virtex UltraScale+ VU9P AWS-FPGA board was compared with the results obtained in previous work using the same data from the same experimental setup but offline DSP using Matlab. The results show that the difference is negligible below FEC limit. Additionally, the modified KNN shows a reduction of operations from 43 percent to 75 percent, depending on the symbol’s position in the constellation, achieving a reduction 47.25% reduction in total computational time for 100 K input symbols processed on 20 parallel cores compared to the KNN algorithm.

scholarly journals Features of the construction of information transfer system which using two-dimensional signals

2019 ◽  
Vol 30 ◽  
pp. 04008
Author(s):  
Andrey Degtyaryov ◽  
Vera Miryanova
Keyword(s):  
Linear Systems ◽  
Information Transfer ◽  
Transfer System ◽  
Two Dimensional ◽  
Orthogonal Functions ◽  
Prototype Filter ◽  
Interchannel Interference ◽  
Low Pass ◽  
Impulse Characteristics ◽  
Coordinate Basis

The article deals with analysis of the causes of intersymbol interference and interchannel interference. It is indicated that physically unrealizable orthogonal bases are used to describe systems and signals. The considered interference occurs due to the loss of orthogonality by the coordinate signals of the bases. Known methods for obtaining systems of orthogonal functions do not allow the formation of a coordinate basis corresponding to physically feasible systems and signals. It is proposed to use equidistant biased impulse characteristics of physically realizable linear systems as basic signals. An orthogonalization method based on determining the weight of orthogonality is described. It is shown that the resulting basis is quasi-orthogonal. It is determined that the conversion of the standart low-pass prototype filter into the filters of channel-forming equipment does not change the conditions of orthogonality. Structural schemes of a modulator and a demodulator of two-dimensional signals are proposed, based on the developed method of orthogonalization.

scholarly journals The criterion for the existence of the weight of the orthogonality of equidistant elementary signals

2019 ◽  
Vol 30 ◽  
pp. 04015
Author(s):  
Andrey Degtyaryov
Keyword(s):  
Linear Systems ◽  
Intersymbol Interference ◽  
Basis Functions ◽  
Multiple Time ◽  
Impulse Responses ◽  
Time Intervals ◽  
Interchannel Interference

To reduce the level of intersymbol interference and interchannel interference, it is proposed to form the transmitted signals using the basis functions obtained by shifting the impulse responses of linear systems by multiple time intervals. An algorithm for calculating the weight of the orthogonality of basis functions is proposed. A criterion for the existence of the indicated weight of orthogonality is formulated.

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