Soft decoding based Fuzzy Logic for processing of elementary signals within data transmission channels of distributed control systems

Abstract

Subject. Decoding and decision making models, methods and algorithms for elementary signals of receiving devices of distributed control systems elements. Purpose. Development, research and realization of soft decoding and decision making method for elementary signals (channel symbols) within receiving devices of distributed control systems elements based on the fuzzy logic fundamentals and methods. Methodology of research. The analysis of signals distortions by noise of different sources and forms is carried out in this paper. The «quasioptimum» receiving methods for taking account of distortions are analyzed. A condition of uncertainty often occurs at reception so it is difficult to correlate the distorted signal with any of the possible basic (transmitted) signals. The probability of the error at the same time considerably increases. The application of fuzzy sets and fuzzy logic math fundamentals for taking into account and the subsequent removal of uncertainty when decision making is offered. The elementary signals soft decoding (decision making) method based on the fuzzy sets theory and fuzzy logic methods is developed. The decision making device model with Fuzzy Logic Toolbox (MathWorks MatLab) for the offered decoding method application is developed and researched. The common block circuit of the elementary signals quasioptimum receiver is released and the algorithm of it's functioning is described. Research results. The formal description of elementary signals distortions is executed, the variables for decision making are entered. The decision making method of received symbol based fuzzy logic fundamentals is developed; input and output variables and their membership functions are defined; productional rules are formulated; defuzzyfication algorithm is offered. The common block circuit of receiving device is developed used offered decision making method for conclusion formations about received symbol. The simulation and research of the offered circuit is executed; the quantitative assessments of their functioning are received. Application. The offered decision making method based on fuzzy logic fundamentals is planned to be used within elementary signals decision making device. This device is the general node at the common block circuit of receiving device within distributed control systems elements. Conclusions. The researching of the developed receiving device model has shown that the decision making method provides a preset reliability indicators, assumes the computing complexity decreasing due to the arithmetic operations using and the possibility of decision making model parameters adaptation to the change of external conditions (change of error model parameters in a communication channel, increase in requirements to reliability, etc.). It allows to increase the efficiency and reliability of soft decoding applied algorithms.