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• EVOLUTION OF RADIO OVER FREE SPACE OPTICAL COMMUNICATION UTILIZING SUBCARRIER MULTIPLEXING / AMPLITUDE SHIFT KEYING

  Hussein Ahmed Mahmood, Al-Karawi Hussein Shookor, K. Y. Rumyantsev

  2021-01-19

  Abstract ▼

  The high demand for increased bandwidth, data rate and quality in optical communication
  systems in modern applications. Radio over free space optics (RoFSO) is deemed a new design
  methodology over wireless systems and networks. This technique has to ensure data rates like ones
  presented by means optical fiber communication techniques in keeping with a portion of its arrangement
  cost. Such systems are implemented by combined radio signal (RF) with optical signal,
  which containing various wireless administrations and Free Space Optics (FSO) link. In this paper,
  the simulation and evaluation system of Subcarrier Multiplexing/Amplitude Shift Keying
  (SCM/ASK) transmitter for Free Space Optical Communication is proposed. 1Gb/s data Rate given
  to the system. Whilst 10 GHz radio frequency signal setting in electrical amplitude modulator.
  Thereafter, radio signal is added with 100 subcarrier channels of 10 MHz spacing channel at
  operated first channel frequency of 60 MHz. These subcarrier channels with 900 combined with
  10 GHz sin wave signal ( radio frequency ) at hybrid coupler, the combination of each subcarriers
  and radio signal are modulated by LiNb Mach-Zehnder optical modulator with 1550 nm wavelength
  continues wave laser signal at 10 dBm input power. The optical modulated signal (after
  optical modulator) is transmitted over a various free space optical link from 300m to 1km under
  the Atmospheric turbulence effect (the structure feature of the refractive index). The system is
  evaluated utilizing Opti system software with Q-factor and BER terminology. It is shown that the
  maximum optical distance for weak turbulence (
  at BER equal to 10-9 is
  950m, while the maximum optical distance for strong turbulence
  is 850m.

• TRANSPORT FLOW FORECASTING MODEL BASED ON NEURAL NETWORKS FOR TRAFFIC PREDICTION ON ROADS

  Alamir Haider Sagban Hussein, Е.V. Zargaryan, Y. А. Zargaryan

  124-132

  2021-08-11

  Abstract ▼

  In connection with the industrialization of modern society, the growth of the transport sys-tems of our country, an increase in certain necessary for the development of the needs of the citi-zens of our country, the number of vehicles of various types continues to increase every year very fast, causing huge traffic jams on transport roads, especially in large cities and megacities. Thus, forecasting traffic flows is an important and necessary component of optimal traffic control in modern conditions of transport network development. As a solution to this problem, this article aims to analyze and describe the application of artificial intelligence methods, in particular neural networks, which represent a modern approach to modeling in complex and nonlinear situations that arise when predicting a traffic flow model. The shown accuracy method is based on the devel-opment of a neural network to predict the daily traffic flow. The expected traffic flow is then com-pared with the actual dataset recorded on the road section and provided by the infrastructure manager. In fact, neural networks are able to learn from past situations and predict future situa-tions on the transport network. In this study, various neural network structures were examined,and the simulation results showed that the best predictions were obtained using the multilayer perceptron architecture, which has a good generalization system with a root mean square error of 0.00927 with the current set of vehicles. The first part of the article is devoted to defining various concepts related to the current research area, including a review of the literature on traffic predic-tion and neural networks. The second part is devoted to describing the problem of traffic conges-tion using forecasting problems and presenting the proposed solution method with an emphasis on artificial neural networks as a means of forecasting demand and its various structures. Then, nu-merical experiments are illustrated by analyzing the forecast results after the formation and test-ing of various neural network architectures.

• ANALYSIS OF MATLAB SYSTEM APPLICABILITY FOR SYNTHESIS OF CONTROLLED BUTTERWORTH DIGITAL RECURSIVE IIR FILTERS

  Hussein Sh. Mogheer, I. I. Turulin

  2021-08-11

  Abstract ▼

  A number of digital signal processing applications use controlled IIR digital recursive filters.
  The word " controlled " refers to filters whose structure ratios clearly depend on the cut rate or
  boundary frequencies. Controlled IIR filters can be synthesized using a variety of tools to compute
  traditional, uncontrolled IIR filters. The article dealt with the synthesis uncontrolled IIR filters and
  analyzed the suitability of the presentation of the results of synthesis for the construction of controlled
  IIR filters. The design techniques based on MATLAB (2021a) and the fundamental concepts of IIRButterworth
  digital filters were described and explained. The composited signal was processed by the
  analyzed filter to find whether it met the filtering progress criteria. To check the calculated filters, the
  Simulink prototype was used, as well as FDA tool of signal processing toolbox. Based on the results
  obtained, a conclusion was made about the applicability of the MAT LAB (2021a) system for the
  synthesis of controlled digital recursive IIR-Butterworth filters. The analyzed technique was more
  efficient, faster, decreased the tasks and found the results are satisfying.

• REDUCTION APPROACH OF TRANSIENT PROCESS OVERSHOOT IN CONTROLLED TUNABLE LOW PASS DIGITAL FILTER

  Al-Karawi Hussein Shakor Mogheer, I.I. Turulin

  2022-08-09

  Abstract ▼

  Digital signal processing is widely used in modern technology, including robotics, medical
  technology, etc. Thus, the controlled digital filters are used to eliminate the constant component of
  the output signal at the output of an analog-to-digital converter. This also reduces the low-frequency
  interference level spread out on the frequency axis to the left of the lower boundary of the signal
  spectrum. In actual situations, signals are subjected to a variety of disruptions and noises; however,
  applying a filter may suppress these noises and produce a clean signal. Controllability means the
  explicit dependence of the filter coefficients on the cutoff frequency. A transient occurrence can arise
  in a digital filter, which is indicated in the overshoot of the signal. A change in the cutoff frequency
  during filtering operation could cause this transient event. In this report, a Butterworth LPF filter is
  used to offer a compensation strategy for reducing this overshoot. A transient is an overshoot (drive)
  in the result timing chart. This drive is an after effect of the adjustment of the coefficients (boundaries)
  of the filter during filtering (this is classified "on-the-fly tuning"). By using the MATLAB program,
  the transient process resulting from the restructuring of the filter was investigated and the
  formulas were checked compensation of this transient process. It was found that the application of
  such compensation reduced the negative effects of the transition process. This decrease depends on
  the order of the filter, the adjustment coefficient (the ratio of cut frequencies before and after adjustment)
  and the moment of adjustment (for the periodic signal).

• METHOD AND ALGORITHM FOR SYNTHESIS OF CONTROLLED CHEBYSHEV DIGITAL FILTERS OF THE FIRST KIND OF LOW FREQUENCIES BASED ON THE BILINEAR TRANSFORMATION METHOD

  I.I. Turulin, S.M. Hussein

  2022-11-01

  Abstract ▼

  The article presents a technique for the synthesis of controlled digital recursive Chebyshev lowpass
  filters of the first kind with an infinite impulse response. The frequency response of such filters has
  ripples in the passband and is as flat as possible in the stopband. Controllability is understood as an
  explicit dependence of the filter coefficients on the cutoff frequency. The technique is based on the bilinear
  transformation of the transfer function of the analog low-pass filter prototype and the frequency
  transformation of the amplitude-frequency characteristics of the obtained digital filter. The main idea ofthe technique is that for an analog prototype filter with a cutoff frequency of 1 rad/s, the parameters of
  the transfer function of biquadratic or bilinear links, which have the dimension of frequency, will be
  numerically equal to the correction factors for similar parameters of a controlled filter with an arbitrary
  cutoff frequency. As an example, the synthesis of a digital Chebyshev filter of the first kind of the fifth
  order is considered. In this article, the transfer function of an arbitrary order filter is represented as a
  cascade connection of II order links if the filter is of an even order. In the case of an odd order greater
  than one, one cascaded link of the first order is added. Despite the relative simplicity of the frequency
  conversion, in its practical use for digital filters synthesized using computer-aided design of digital filters
  (or using reference books containing calculated prototype low-pass filters for various approximations
  of the frequency response of an ideal low-pass filter), a series arises non-trivial specific moments
  that complicate the engineering use of this method of synthesizing controlled digital filters. Therefore, in
  addition to the technique, a step-by-step algorithm has been developed that allows one to synthesize a
  filter without knowing these moments. The algorithm is implemented in the Mathcad environment; as
  an example, a digital recursive Chebyshev filter of the 1st kind of the 5th order is calculated.
  The example shows the calculated coefficients of a digital controlled low-pass filter, which explicitly
  depend on the cutoff frequency, the amplitude-frequency characteristics of this filter and its lowfrequency
  prototype converted into a filter with the same cutoff frequency, the amplitude-frequency
  characteristics are given in the same coordinates. Due to the good formalization of the algorithm, the
  latter is suitable for the implementation of computer-aided design systems for controlled digital
  Chebyshev low-pass filters of the first kind.

• CHANNEL ANALYSIS OF OPTICAL SINGLE SIDEBAND QUADRATURE PHASE SHIFT KEYING WITH SUBCARRIER RADIO SIGNAL FOR LASER SATELLITE COMMUNICATIONS UNDER ATMOSPHERIC TURBULENCE

  Hussein Ahmed Mahmood, К. Y. Rumyantsev, A. H. S. Al-Begat

  2023-10-23

  Abstract ▼

  Compared to traditional satellite radio communication, laser communication techniques
  demonstrate greater performance in terms of available data rates, and also guarantee a reduction
  in size, weight and power of the communication subsystem. In a satellite laser communication
  system, a laser source generates a narrow beam of radiation at the transmitter. A laser beam
  propagating through the atmosphere towards an optical receiver can experience large random
  fluctuations in optical intensity due to turbulence, which can lead to loss of power in the receiver
  and degrade system performance. In a subcarrier multiplexing (SCM) system, multiple information
  is electrically modulated at different radio carrier frequencies. Analog or digital signals carrying
  information may have different modulation formats. Optical single sideband radiation (OSSB) is
  typically generated using a dual drive Mach–Zehnder modulator (MZM). In the article, the analysis
  channel for optical single-sideband quadrature phase-shift keying transmitted signal was proposed
  for different distances under atmospheric turbulence conditions. The numerical results of
  laser satellite communications are based on an atmospheric altitude model of the structural characteristic
  of Hufnagel-Valley (H-V) refractive index fluctuations. The performance analysis makes
  it possible to estimate the effect of atmospheric turbulence, pointing error, and the diameter of the
  received aperture on the received power during transmission of a laser signal between a ground
  station and a satellite for a laser communication system, where the optical wave is a collimated
  beam with a wavelength of 1550 nm.

• FORMATION OF A SINGLE SIDEBAND QUADRATURE PHASE SHIFT KEYING OF RADIO SIGNALS AT SUB-CARRIER FREQUENCIES IN A COHERENT OPTICAL COMMUNICATION SYSTEM

  А.М. Mahmood Hussein, К. Е. Rumyantsev

  2023-02-17

  Abstract ▼

  The coherent optical communication technology allows to create a transmission system over
  long distances with high bandwidth. Higher order modulation formats such as Quadrature Phase
  Shift Keying (QPSK) provide high data rates in a simple, reliable and cost-effective manner. These
  multi-bit modulation methods are transmitted as a symbol implementing simple in-phase and
  quadrature (IQ) modulation formats. To increase throughput in coherent optical systems, optical
  subcarrier multiplexing is used, when several radio signals are multiplexed on one optical carrier.
  This multiplexing is limited by double sideband, resulting in reduced received subcarrier power
  and degraded carrier-to-noise ratio. To accumulate these effects, many ways of implementing
  optical single sideband (OSSB) are proposed. The paper proposes an analysis of a coherent optical
  transmission system for generating single-sideband QPSK modulation using an optical I/Q
  modulator and M-ary RF pulse shaping. The pseudo-random bit sequence generator generates a
  10 Gb/s modulation baseband signal. Each bit sequence is converted into an M-ary sequence of
  symbols from binary signals using phase shift keying (PSK). The M-ary pulse generator generates
  a multi-level pulse shaping according to the sequence of M-ary input symbols. Electrical pulses
  are applied to the electrodes of the electro-optical modulator according to the Mach–Zehnder
  interferometer (MZM) scheme. The I/Q modulator operated at the quadrature operating point in
  both the in-phase and quadrature branches, with an extinction ratio 60 dB and 3 V switching voltage.
  The light wave is emitted by a CW laser with a wavelength of 1550 nm.