Ilya Pyatin

The article investigates the operations of identifying a cellular network and searching for a cell at various signal-to-noise ratios. The estimation of frequency and time displacement, criteria for detecting the primary synchronization signal are presented. The main contribution of this article is the consideration of the step-by-step execution of the 5G cell search procedure in a complex interference environment. The decoding steps of the primary and secondary synchronization signals are being investigated. This is achieved by analyzing the signals at each step of the correlation algorithm for different signal-to-noise ratios. In order to verify the adequacy of the proposed models, a sequence operation for synchronizing 5G mobile networks with base station signals is considered. The dependence the magnitude of the error vector modulus on the signal-to-noise ratio of a physical broadcasting channel is investigated for three different channel profiles without line of sight. As a result of the experiment, the error vector of the physical broadcast channel changes from 55% to 10%, when the signal-to-noise ratio changes from 0 to 20 dB. In the multiple-input multiple-output (MIMO) mode, we received a 3 dB increase in communication energy efficiency. The findings will be useful for 5G system designers to troubleshoot synchronization problems.

В запропонованій роботі розглянуто схемотехнічні аспекти забезпечення умов синхронізації  в системах зв’язку з OFDM. Наведено дослідження оцінок міжканальних та міжсимвольних завад в системах синхронізації. Описано та алгоритмізовано можливі сценарії оцінки завад в каналах з OFDM за навчальними послідовностями та пілот-сигналами. Наведено експериментальні результати оцінки спотворення OFDM-сигналів в умовах міжканальних завад на основі сигналів типу 16QAM. Здійснено порівняльний аналіз середньоквадратичної оцінки міжканальних завад для трьох методів синхронізації які досліджувались у статті. Розглянуто конструкції OFDМ-сигналів з пілот-сигналами. Досліджено концепції схемотехнічної реалізації систем тактової синхронізації в каналі зв’язку з OFDM. Проілюстровано процес спрацювання системи синхронізації з метою компенсації спотворень на основі сформованої сітки ресурсів в каналі зв’язку з OFDM.

In a digital communication system, the transmitter and receiver have several generators for modulation and demodulation; increasing and decreasing the sampling frequency; synchronization of symbols and bit streams. The causes of phase and carrier frequency errors are the instability of the frequency of the local generators of the transmitter and receiver; presence of Doppler frequency shift; signal propagation delay from the transmitter to the receiver. Synchronization circuits of modern digital communication systems are built on the basis of phase-locked loop (PLL). The purpose of the work is: research of various characteristics of the digital PLL (locking time; established error; transient behavior) for various types of input action; study of the bit error rate of a coherent digital communication system. The PLL consists of the following components: a phase detector that generates a signal that varies in proportion to the phase difference between the input signal and a locally gen...

The development of mobile telecommunications proceeds by increasing the productivity of communication systems, increasing the speed of information transmission, expanding the frequency band, and reducing delays. A software defined radio (SDR) is a programmable transceiver that supports various wireless technologies without the need for hardware upgrades. The best development environment for SDR devices is field-programmable gate arrays (FPGAs) because they provide parallel data processing. The signal in the communication channel is distorted under the influence of many factors: conversion of the signal sampling frequency in the transmitter and receiver, frequency and phase shift of the signal in the communication channel, signal delay, effect of white noise, etc. To reduce the impact of these effects, the receiver includes a synchronization circuit. The receiver contains the following units: automatic gain adjustment; frequency offset correction; recovery of symbol synchronization; ...

The article describes modern concepts for the development of Software-defined Radio (SDR) technology. A functional diagram of a software-defined radio station using the method of transmitting information with modulation based on Orthogonal Frequency Division Multiplexing (OFDM) is proposed. The conditions for ensuring symbol synchronization of OFDM signals are investigated. It is determined that the disruption of the orthogonality of OFDM symbols is accompanied by such phenomena as the occurrence of inter-symbol interference and inter-channel interference. The method of constellation diagrams was used to study the effect of errors caused by interference on the quality of processing of multiposition signals. The effect of interference in a channel from OFDM on the phase of signals during their processing is estimated. Mathematical models of signals with OFDM in the presence of interference effects are obtained. Two types of errors are considered, which are caused by carrier distortio...

: Software-defined radio (SDR) allows using software to set or modify working radio frequency parameters: communication standard, frequency range, modulation type, output power, etc. An interpolator is an integral part of the transmitter, which increases the sampling frequency of the modulated signal. Interpolators are built on the basis of integrated cascaded integral-comb (CIC) non-multiplier filters. CIC interpolation filters have uneven amplitude-frequency characteristic (AFC), so the CIC compensator filter is turned on for its alignment. The eye-diagrams of signals with different interpolation coefficients are investigated in the paper. The quality of the signal in the transmitter can be evaluated by the eye-diagram. Interpolation is accompanied by the effect of amplifying the signal, reducing the time of increase in pulse, reducing the signal quality factor. The jitter in the transmitter decreases when the interpolation factor is a multiple of the sampling rate of the information sequence of symbols. If the signal quality factor is Q>7, the bit error rate has a BER<10-9 value for practice. Ref. 11, pic. 16Технология программно-управляемого радио (SDR) позволяет с помощью программного обеспечения устанавливать или изменять рабочие радиочастотные параметры стандарта связи, диапазон частот, тип модуляции, выходную мощность и тому подобное. Составной частью передатчика является интерполятор, который повышает частоту дискретизации модулированного сигнала. Интерполятор строят на основе интегральных Сascaded Integral-Comb (CIC) фильтров, не содержащих умножителей. Фильтры CIC-Interpolation имеют неравномерную АЧХ, поэтому для ее выравнивания предложено фильтр CIC-Compensator. В статье исследованы глазковые диаграммы сигналов с различными коэффициентами интерполяции. По глазковым диаграммам проведена оценка качества сигнала в передатчике. Интерполяция сопровождается эффектом усиления сигнала, уменьшением времени нарастания импульса, уменьшением коэффициента качества сигнала. Джиттер в передатчике уменьшается, если коэффициент интерполяции кратный частоте дискретизации информационной последовательности символов. Если коэффициент качества сигнала Q> 7, то коэффициент битовых ошибок имеет допустимое для практики значение BER <10-9.Библ. 11, ил. 16Технологія програмно-керованого радіо (SDR) дозволяє за допомогою програмного забезпечення встановлювати або змінювати робочі радіочастотні параметри: стандарт зв’язку, діапазон частот, тип модуляції, вихідну потужність, тощо. Складовою частиною передавача є інтерполятор, який підвищує частоту дискретизації модульованого сигналу. Інтерполятори будують на основі інтегральних Сascaded Integral-Comb (CIC) фільтрів, що не містять помножувачів. Фільтри CIC-Interpolation мають нерівномірну АЧХ, тому для її вирівнювання запропоновано фільтр CIC-Compensator. У статті досліджені око-діаграми сигналів з різними коефіцієнтами інтерполяції. За око-діаграмою проведено оцінювання якісті сигналу у передавачі. Інтерполяція супроводжується ефектом підсилення сигналу, зменшенням часу наростання імпульсу, зменшенням коефіцієнту якості сигналу. Джиттер у передавачі зменшується, якщо коефіцієнт інтерполяції кратний частоті дискретизації інформаційної послідовності символів. Якщо коефіцієнт якості сигналу Q>7, то коефіцієнт бітових помилок має припустиме для практики значення BER<10-9.Бібл. 11, іл. 1

The transmission of the information signal through the communication channel is accompanied by the addition of additive white Gaussian noise (AWGN), industrial interference, atmospheric noise, etc. In addition, the signal may have an additional frequency and phase shift caused by the movement of the receiver concerning the transmitter. The article is devoted to the study of the effect of the listed conditions on the errors number dependence in the communication channel on the signal-to-noise ratio (SNR). It also explores the possibilities of reducing the effect of signal propagation conditions in a communication channel by using symbolic synchronization, which is based on a phase-locked loop (PLL). The early-late-time and Gardner synchronization error detectors are investigated. The early-late-time synchronization error detector is 1.5 dB more efficient than the Gardner detector at low SNR and has a simpler implementation scheme. An energy efficiency study of a coherent digital communication system with quadrature phase-shift keying (QPSK) modulation at the phase shift in the propagation medium is performed. The energy efficiency of a non-coherent digital QPSK modulation system is reduced by 10 dB at the phase shift of 30° in the propagation medium. Frequency shifting has a significant impact on the energy efficiency of the communication system. The energy efficiency of the digital communication system decreases by 10 dB when 0.1 Hz frequency offset occurs and symbolic synchronization is missing. Symbol synchronization circuit increases the energy efficiency by 7 dB with a frequency shift of 0.1 Hz. When the value of frequency offset increases, the energy efficiency of coherent communication expands. The efficiency of coherent digital communication is increased by 24 dB with the introduction of frequency shift at 2 Hz.

Digital communication system with QPSK modulation and symbolic synchronization has been investigated. Amplitude-frequency characteristic (AFC) of Farrow interpolator affects the signal more than the upper frequency of the signal spectrum is higher, that is the less the counts on the symbol. For a linear interpolator, the AFC unevenness in the low frequency region is higher, so this interpolator will distort the signal more strongly. The bit error rate is analyzed depending on the signal-to-noise ratio (SNR). A coherent communication network with QPSK modulation using an interpolation filter based on Farrow structure with FIR filters is more efficient at low signal-to-noise ratios (Eb/N0). Energy gain of 3 dB can be achieved by using the Farrow structure with FIR filters compared to linear interpolation.

The article studies the efficiency of channel codes coding. The study covered issues related to determining the energy gain of coding. For this purpose, turbo codes, LDPC codes, polar codes were compared. The work contains the developed schemes of encoders and decoders of channel codes for those developed using a hardware description language (HDL). The results of comparing the resources used for the implementation of encoders and decoders and comparing their performance are obtained. Research indicates a high efficiency of turbo codes in coding schemes. The results of comparing the productivity of different channel codes can be used to design practical coding and decoding schemes in information channels.

Traditional mobile networks have bandwidth and infrastructure limitations. Each base station has a limited number of users and data capacity. 5G technology uses advanced technologies, such as massive MIMO and beamforming, to increase data rates and spectrum efficiency. These features, and the large number of small cells, allow many 5G users to receive low latency and high traffic without overloading the base station. Small cells work the same way as regular cells, but use new technology and millimetre waves (5G New Radio). Low-power base stations can be easily deployed. Cell search is a procedure by which the user equipment (UE) obtains time and frequency synchronization with the base station and decodes the cell ID of the mobile device. System information is broadcast information that is periodically transmitted by the base station on the downlink. This is very important information for the mobile device (UE) needed to connect to the base station (gNB). The UE reads system informat...

This paper discusses the polar code is applied to the downlink control information and uplink control information to enhanced mobile broadband, as well as to broadcast channel. Channel coding contains a set of procedures for error detection, error correction, rate matching, bit interleaving and mapping of information to physical control channels or transport layer. The downlink control information model with polar coding and modulation types provided by the standard (QPSK, 16-QAM, 64-QAM, 256-QAM) for the transmission channel with additive white Gaussian noise is investigated in the article. This model presents the results of bit error rate for coding scheme with different code rates. The structural scheme of the decision model on the modulation mode of the digital communication system is analyzed in the paper. Dependencies of bit error rate on the effective rate of the polar code with different types of modulation are explored. The modulation mode selection algorithm for code rate R=0.5 is developed on the basis of the obtained dependencies.

This paper is devoted to research of the urgent problem of developing models of efficient coding in telecommunication networks on the basis of low-density parity-check codes. The solution of the problem is carried out taking into account the code rate and the number of iterations decoding for envisaging the defined noise immunity indices. The noise immunity of signal-code constructions based on low-density codes has been increased by combining them with multi position digital modulation. This solution eventually allowed to develop a strategy for decoder designing of such codes and to optimize the code structure for a specific information network. The paper presents experimental studies of low-density codes for different types of channels. The maximum noise immunity is determined. The possibility of combining low-density codes with differential modulation is estimated. The research results of productivity of information transmission channels with defined codes at different values of redundancy, transport block size, code rate are given.

The methodology description of the adaptive multi-threshold decoding of self-orthogonal codes in the telecommunication channels of information transfer is shown in this paper. The method of multi-threshold decoder modification is described on the basis of adaptive filtration algorithms. Principles of adaptive algorithms application provide for necessary data transmission validity in the case of the multi-threshold decoding are explored. The graphic charts of multi-threshold decoders noise immunity of self-orthogonal block and convolutional codes are presented. It is determined the coding gain (CG) for multi-threshold decoding schemes. The result of research conducted in the course of the paper is to develop a set of scientifically grounded theoretical positions and practical recommendations and proposals for the development of mechanisms of formalization of description of method of increasing of noise immunity of telecommunication systems transmitting information to the synthesis an...

The methodology description of the adaptive multi-threshold decoding of self-orthogonal codes in the telecommunication channels of information transfer is shown in this paper. The method of multi-threshold decoder modification is described on the basis of adaptive filtration algorithms. Principles of adaptive algorithms application provide for necessary data transmission validity in the case of the multi-threshold decoding are explored. The graphic charts of multi-threshold decoders noise immunity of self-orthogonal block and convolutional codes are presented. It is determined the coding gain (CG) for multi-threshold decoding schemes. The result of research conducted in the course of the paper is to develop a set of scientifically grounded theoretical positions and practical recommendations and proposals for the development of mechanisms of formalization of description of method of increasing of noise immunity of telecommunication systems transmitting information to the synthesis an...