THE ANALYTICAL MODEL OF NOISE IMMUNITY CALCULATION OF COMMUNICATION SYSTEMS WITH MULTI-POSITION TYPES OF MODULATION AND CONVOLUTIONAL CODING

Author(s):  
Э.Б. ЛИПКОВИЧ ◽  
А.А. СЕРЧЕНЯ

Получены математические модели расчета отношений сигнал/шум и несущая/шум, требуемые для обеспечения заданной вероятности ошибки на выходе декодера с «мягким» решением, без необходимости вычисления коэффициентов спектра сверточного кода и выполнения процедур компьютерного моделирования характеристик помехоустойчивости. Приведены расчетные выражения для определения исправляющей способности декодера, энергетического выигрыша от кодирования и информационной эффективности систем связи в зависимости от параметров многопозиционных видов модуляции, сверточного кодирования и вероятности ошибки в информационном бите. По полученным аналитическим моделям построены зависимости и дана оценка результатов исследований. Mathematical models are obtained for calculating signal-to-noise and carrier-to-noise ratios required to provide a given error probability at the decoder output with a “soft” solution and without calculating the convolutional code spectrum coefficients and performing computer simulations of noise immunity characteristics. Calculation expressions are given to determine the correcting ability of the decoder, the energy gain from coding, and the information efficiency of communication systems depending on the parameters of multi-position types of modulation, convolutional coding, and the probability of error in the information bit. Dependencies are constructed according to the obtained analytical models and the research results are evaluated.

Author(s):  
A. A. Paramonov ◽  
Van Zung Hoang

In the context of continuous improvement of radio prospecting and active radio jamming technics along with introduction of automated active countermeasures systems (ACS), the frequency-hopping spread spectrum (FHSS) radio communication systems (RCS) are widely used in order to improve reliability and noise immunity of data transmission. The noise immunity of the RCS affected by unintentional or deliberate interference can be significantly perfected by the combined use of frequency-time division and antinoise coding. This paper explores the case when the interference created by an ACS system with a limited transmitter power covers a part of the RCS frequency range. The receiver gets input mix of the wanted signal, the receiver noise, and probably a deliberate interference also considered as a noise. The article analyzes the noise immunity of signals reception with FHSS in the low-speed radio systems with joint use of frequency-time division of information subsymbols and noise combating codes when the deliberate interference destructively impacts a part of the RCS working band. Dependence of the bit error probability on the signal-to-noise ratio is calculated for the joint use of frequency division of information subsymbols and noise combating codes. It is shown that due to effective use of the frequency-energy resource of a radio line, considering the use of correction codes, a quite high noise immunity of RCS under the influence of deliberate interference can be assured. The indicated dependences of the error probability on the signal-to-noise ratio confirm that the reliability of data transmission can be significantly increased by the proper combination of signal spectrum spreading, applying of correction codes, and frequency division of subsymbols followed by their weight processing.


Radiotekhnika ◽  
2020 ◽  
pp. 133-140
Author(s):  
S.G. Rassomakhin ◽  
A.A. Zamula ◽  
I.D. Gorbenko ◽  
Ho Tri Luc

The article shows that the solution to the problem of increasing the noise immunity (noise immunity and secrecy of functioning) of the ICS can be achieved using systems of nonlinear signals with improved ensemble, structural and correlation properties. Two classes of nonlinear complex discrete signals are considered: characteristic discrete signals (CDS) and cryptographic signals (CS). Methods for the synthesis of these signals are presented. The paper gives a statistical simulation model for studying the noise immunity of various classes of signals in the Gaussian channel. Using this model, estimates of the dependence of the error probability on the signal-to-noise ratio were obtained for various classes of signals, namely: CDS, KS and standard BPSK AFM-16 signals. It is shown that for the signal-to-noise ratio – 10 the error probability for the CDR is 4.6875e-06, for the CS is 3.515625e-06, and for the AFM-16 is 0.002025. Thus, the use of nonlinear complex discrete signals, in particular, CDS and KS, can significantly increase the noise immunity of signal reception in modern ICS. At the same time, taking into account the improved ensemble and structural properties of these nonlinear signals, it is possible to improve significantly the indicators of crypto- and imitation security of the systems functioning.


Doklady BGUIR ◽  
2020 ◽  
pp. 35-42
Author(s):  
E. B. Lipkovich ◽  
V. A. Kovshik ◽  
A. A. Serchenya

The aim of this article is to create analytical models that estimate the continuity and effectiveness of digital radio communication systems using multipositional types of modulation (CAM-M, PM-M, FM-M, AM-M) and block coding according to the Reed–Solomon algorithm (RS) with hard decoding. In contrast to the well-known approaches to determining the noise immunity of systems that require computation model, new estimating models are presented that do not require knowledge of the spectrum coefficients, computer simulation training methods and graphical construction of interference curves for various types of modulation and coding parameters. The calculated ratios presented in the article include only the main parameters of the code (free distance, codeword length, relative code speed) and of the modulation type (modulation order, squared noise immunity). They make it possible to directly determine the theoretically required values of signalto-noise ratios (SNR) for input devices from given probabilistic errors based on RS signals, as well as to study the energy gain from coding (EGC), accessible and frequency-efficient systems. Based on the proposed rations, the calculations of the main characteristics of the communication channels for various parameters of the RS codes, the reliability of reception, types and orders of modulation are performed. Comparison of the results of calculation of noise immunity and system effectiveness given in the article with known similar characteristics obtained as a result of computer modeling confirms the correctness of the presented analytical models. The error of the constructed noise immunity curves does not exceed 0.1 dB in the operating range of the SNR. The materials presented in this article are original and can be used in the design, calculation and development of terrestrial and satellite systems.


Author(s):  
E.A. Trubachev ◽  
A.I. Senin

In this paper, there is noise immunity research of one version of construction multi-frequency information transmission system with code division of user's channels. An engineering method for noise immunity estimate is developed. Error probability dependences on average signal-to-noise ratio are calculated for the cases of uniform multipath intensity profile. Researchable system comparison of noise immunity with single-frequency system of CDMA standard is made.


Author(s):  
B. G. Shadrin ◽  
◽  
D. E. Zachateyskiy ◽  
V. A. Dvoryanchikov Dvoryanchikov ◽  
◽  
...  

2017 ◽  
Vol 2 (3) ◽  
pp. 235
Author(s):  
Massimiliano Laddomada ◽  
Bartolo Scanavino

The aim of this paper is twofold. On one hand, it presents the results of the search for good punctured systematicrecursive convolutional encoders suitable for application in serially concatenated convolutional codes (SCCCs) operating in two different target regions: at low-to moderate signal-to-noise ratios (SNRs), i.e., in the so called waterfall region, and at high SNRs. On the other hand, it provides some useful design guidelines for choosing the constituent encoders in an SCCC. The results of the search for good SCCCs operating in the waterfall region rely upon an effective algorithm, based on density evolution technique, first proposed in a companion paper. Good punctured SCCCs were obtained through considerationsdeduced by the behaviour of the bit error probability of an SCCC for high values of both SNR and interleaver length, i.e., through asymptotic considerations. The mother codes in the serial concatenation are rate 1/2 recursive convolutional encoders (RCC) found by an exhaustive search for encoders tailored to SCCC schemes, using two different selection criteria. Extensive tables of optimized puncturing patterns for various mother codes and SCCCs are presented along with sample simulation results.


2018 ◽  
Vol 42 (1) ◽  
pp. 167-174 ◽  
Author(s):  
V. I. Parfenov ◽  
D. Y. Golovanov

An algorithm for estimating time positions and amplitudes of a periodic pulse sequence from a small number of samples was proposed. The number of these samples was determined only by the number of pulses. The performance of this algorithm was considered on the assumption that the spectrum of the original signal is limited with an ideal low-pass filter or the Nyquist filter, and conditions for the conversion from one filter to the other were determined. The efficiency of the proposed algorithm was investigated through analyzing in which way the dispersion of estimates of time positions and amplitudes depends on the signal-to-noise ratio and on the number of pulses in the sequence. It was shown that, from this point of view, the efficiency of the algorithm decreases with increasing number of sequence pulses. Besides, the efficiency of the proposed algorithm decreases with decreasing signal-to-noise ratio.It was found that, unlike the classical maximum likelihood algorithm, the proposed algorithm does not require a search for the maximum of a multivariable function, meanwhile characteristics of the estimates are practically the same for both these methods. Also, it was shown that the estimation accuracy of the proposed algorithm can be increased by an insignificant increase in the number of signal samples.The results obtained may be used in the practical design of laser communication systems, in which the multipulse pulse-position modulation is used for message transmission. 


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