"Неэнергетический" прием ультракоротких импульсных сигналов

Предложены метод приема импульсных сигналов сверхмалой длительности (IR-UWB) и реализующий его приемник, использующий не накопление энергии этих импульсов, а селекцию их временного положения. Вероятность ошибки при приеме оценивается отношением количества импульсов, сгенерированных одновибратором и соответствующих коду сигнала, к количеству импульсов, вызванных шумами и помехами. Исследованы вероятность правильной селекции импульсов кода и вероятность обнаружения импульсов шума. Проведено моделирование приема ультракоротких импульсных сигналов, подтвердившее реализуемость предложенного приемника и правильность результатов теоретических исследований.

Homodyne and autodyne configurations of short-range radar systems

The processes of useful signal formation in the short-range radar systems constructed on the heterodyne, homodyne and autodyne principles are considered. The mathematical fundamentals of the fulfilled analysis are described in brief. It is shown that the autodyne configuration is much more complicated for the examination compared to the heterodyne and homodyne configurations due to the necessity of taking into account its own re-reflected signal. To simplify the theoretical analysis, the examination of the autodyne effect is performed under an assumption of reflected signal smallness. The comparison results of the considered configurations, which show that the homodyne and autodyne signal processing in the usual Doppler short-range radar turns out similar, are given. However, the autodyne short-range radar configuration itself has its own specific peculiarities, which should be taken into consideration in practice. It is proved that in the autodyne configuration one can meet the accompanying frequency modulation of the probing oscillation. It appears even at the absence of the forced frequency modulation, which is widely used to improve the short-range radar noise immunity. It is found out that this accompanying frequency modulation at weak reflected signals does not affect noticeably on the autodyne converter operation. The main theoretical conclusions of this paper are in the good conformity with the published results.

Fairness for optimization in cooperative wireless cellular networks

Cooperative communication can improve the performance of cellular mobile networks. The optimization techniques based on duality theory, decomposition and subgradient method were applied for such wireless cellular cooperative systems. It was shown that the joint optimization and resource allocation problem can be solved efficiently within a network utility maximization framework. A concept of proportional fairness was used to achieve fair distribution of quality of service among users. Simulation results confirm the validity of the theoretical work.

Оптимальное размещение базовых станций

На основании генетического подхода решена задача оптимального размещения базовых станций при создании беспроводной широкополосной сети передачи информации. Сформирована математическая модель генетического подхода применительно к решению рассматриваемой задачи. Данная модель реализована в виде генетического алгоритма и соответствующего программного обеспечения, позволяющего эффективно решать задачи размещения большой размерности. Корректность теоретического анализа подтверждена данными, полученными методом полного перебора. Проведена оценка времени счета в зависимости от параметров задачи. Показано, что для задач малой и средней размерности разработанный алгоритм обеспечивает минимальное время счета. Результаты решения задачи для конкретного примера продемонстрировали неоспоримое преимущество генетического подхода. Полученные результаты можно успешно применять для создания муравьиных алгоритмов оптимизации размещения базовых станций.

Design principles of mobile railway networks

The basic principles of GSM railway network planning are examined. The method of the frequency channels distribution between cells is described. The development of frequency channel reuse scheme is performed. The procedure of an operational planning is proposed. The principles of even radio coverage are considered for cells with mainly free radio propagation and for urban areas.

Координация агентов в модели договорных сетей

Проведено исследование многоагентной системы управления телекоммуникационной сетью. Рассмотрен процесс кооперации агентов на основе модели договорных сетей применительно к решению задачи оптимальной загрузки телекоммуникационной системы. Приведены математические соотношения, описывающие взаимодействие агентов в кооперации. Изложена методика расчета стоимости системы в зависимости от ее технических параметров. Описан предложенный метод выбора одного реального агента-исполнителя из множества агентов-исполнителей по результатам оценки стоимости одной и той же сети в условиях влияния на результат решения задачи других агентов.

Wideband volume horn array antenna with switchable polarization capability

This paper presents the most valuable theoretical results that confirm the possibility of practical realization of a wideband volume horn array antenna with the switchable polarization capability. Among key features of the proposed antennas are their high stability of switchable linear polarization tilt angle of radiated electromagnetic wave, radiation pattern of sector type and wide operating frequency band. The paper focuses on characteristics of linear horn antenna subarrays as key components of the described volume array antenna. Subarrays fully comprise double-ridge waveguide sections. The cutoff wavenumbers calculation algorithm is developed for the symmetrical double-ridge waveguides to estimate frequency bandwidth of power dividers in their different cross sections. The problem is solved numerically by partial regions method taking into account field singularity on rectangular metal ridges.

Electromechanically tunable dielectric microwave devices

High-tunable low-loss microwave dielectric devices are designed by electromechanical alteration in the configuration of device components. Specifically, this device consists of dielectric and metallic parts with an air gap between them. The gap location provides the largest perturbation in the electromagnetic field and a mini-actuator controls the device. Through experiments conducted, we test and apply the high-tunable dielectric resonators and filters as well as wide-band low-loss phase shifters.

Twenty International Crimean Conferences "Microwave & Telecommunication Technology" (CriMiCo)

The International Crimean Microwave Conference (CriMiCo) is convened in Sevastopol since 1991. 20 years saw this conference become the flagship venue for far reaching research into theoretical, experimental, manufacturing, applied and historical aspects of microwave engineering and telecommunication technology. Solely in 2010 over 500 reports were delivered by scientists and experts from 208 universities and 17 countries: Belarus, Belgium, Bosnia and Herzegovina, Germany, Israel, Iran, Kazakhstan, Canada, China, Korea, Lithuania, Moldova, Poland, Russia, USA, Ukraine and the Republic of South Africa.

Capacity increasing of sensor telecommunication networks

A method of capacity increasing of sensor telecommunication networks has been proposed and investigated. The method proposed is based on a placement control of unmanned aerial vehicles in view of the rapid and unpredictable movement of mobile subscribers. A distinctive feature of developed method is combining mathematical models of connectivity estimation taking into account a quality of service of mobile subscribers and an advanced search algorithm of quasi-optimal placement of unmanned aerial vehicles in a single computational procedure. An application of the method proposed allows increasing the throughput of telecommunication networks to 15 — 20 percent in comparison with existing methods. Deviations of obtained sub-optimal solutions from optimal ones received by exhaustive method do not exceed 5 — 7 percent.

A concept for modern virtual telecommunication engineering office

High-performance modern Internet allows internal delivery and complement of attractive (mobile) services in the same way and QoS that are in the LANs. The world economics is widely characterized nowadays via the stable trends that the large and mid-range companies and authorities let in ever greater extent to outsource own engineering services via external smaller service providers. A concept for a modern virtual telecommunication engineering office under use of Service-Oriented Architectures and Cloud Computing technologies has been offered. Multiple use cases for virtual telecommunication engineering office have been discussed. As a significant example, the CANDY Framework and Online Platform have been examined. The important development trends for the CAD for network planning regarding to the tool integration and effective access optimization have been discussed. The CANDY system has been represented as an exhibit at CeBIT 2007, 2008, 2011 in Hannover.

Multiroute cross-layer transport protocol with reliable data delivery

A multiroute cross-layer transport protocol with data delivery capabilities for mobile networks is proposed. Protocol combines routing functionality with reliable data delivery. It is shown that finding multiple routes to the destination can be successfully combined with a connection establishment for connection-oriented protocols such as TCP. Establishing a connection over multiple routes can significantly decrease the time of the connection recovery when some routes become unavailable thus increasing total throughput of transport protocol in mobile networks environment. Performance analysis of the proposed protocol indicated that in mobile sensor networks with 5 - 10 % of packet losses its throughput is approximately 60 % higher than throughput of TCP-Reno2 flowing over shortest path.

Analysis of microstrip structures by numerical conformal transformations technique

Computer aided microstrip structures modeling has been performed by conformal mapping technique. A new approach to reduce the connectivity order of the original cross-section geometry of the structure is proposed. The multiply connected domain is reduced to simply connected ones by implementation of magnetic slits concept. The microstrip structures analysis is carried out by numerical conformal transformations technique realized in Schwarz - Christoffel toolbox for MATLAB. This technique is applied to the quasi-static analysis of coupled microstrip lines taking into account the conductor thickness. Described approach ensures high numerical efficiency and can be used for accurate analysis of complex microstrip structures.

Determination of autodyne oscillator parameters by the beating method

The research results of oscillator internal parameters influence the features of dynamic autodyne characteristics formation in the case of external oscillator signal influence are presented. The equivalent circuit with a single-circuit oscillating system is considered as a model of the autodyne oscillator. Abbreviated equations are obtained by an averaging method and then they are linearized for small disturbances in a vicinity of the steady-state mode. The obtained characteristics for the beating mode are compared with characteristics of autodynes for short-range radar technology. The essential differences in behavior of the oscillator with acting the external oscillator and the oscillator with acting the own reflected signal have been found. The physical sense of the frequency dispersion phenomenon for the autodyne frequency deviation in the vicinity of hypothetical "zero" beating is discovered. The research results of dynamic autodyne characteristics in the frequency conversion mode of signals modulated on amplitude or frequency are given. It is shown that to suppress the spurious harmonics of the beating frequency, it is advisable to take additional measures for generated frequency stabilization in autodyne frequency converters, for instance, using the external feedback in the oscillator or using the external high-Q resonator. The adequacy of theoretical conclusions is confirmed by results of experimental investigations of the hybrid-integrated module of 8 mm-range made on the basis of the planar two-meza Gunn diode. Oscillator characteristics obtained by the beating method are compared with results of investigation fulfilled with the help of modulation characteristics. It is shown that errors in experimental determination of dynamic characteristics of autodyne oscillators caused by frequency limitations of a pin-diode typical for the modulation characteristic method can be eliminated. Problems of practical application of obtained results in real radar systems using autodyne oscillators are discussed.

Dual frequency circularly polarized microstrip antenna array

Paper contains the most valuable results of experimental and theoretical investigations of dual frequency circularly polarized microstrip antenna array for smart antenna applications with adaptive space-time processing capability. Geometry of the proposed antenna array was optimized for the operation in two frequency bands located inside IEEE L band. Presented array structure is composed from ten microstrip radiators independently excited via separate coaxial input ports. Two central radiating elements for two frequency bands have circular shapes with slits and are stacked to provide compact sizes and convergence of their phase centers. Peripheral radiators have annular ring with slits topology. Their geometric centers are superposed with the corners of virtual quadrats with the sides equal to the half of the wavelength for the appropriate band to eliminate the appearance of grating lobes and additional nulls in equivalent radiation patterns. The main feature of the array is its compact packaging that causes significant levels of electromagnetic mutual coupling. Last influences and noticeably deteriorates the shapes of radiation patterns, purity of polarization characteristics and reflection characteristics of planar radiators. The geometric parameters of presented array were selected via multi parametric particle swarm optimization method to provide optimum performance of each radiator in compact array packaging. Moreover, several circularly polarized radiators of the described array assembly were rotated around their centers to improve their characteristics and to increase the quality and effectiveness of latter space-time processing of adaptive antenna system. Novel design of the dual frequency circularly polarized array and imperfectness of obtained characteristics are experimentally validated.

Active integrated antennas and arrays with field-effect transistors

Electromagnetic wave generation processes in the hybrid log-periodic microstripe antenna on the dielectric substrate integrated with field-effect transistor are experimentally studied in the frequency range of 6 — 20 GHz. The possibility of synchronization and power combining in the array consisting of antenna-coupled oscillators placed on the common dielectric substrate is investigated. It is shown that the considerable increasing the generation efficiency and power combining can be obtained by using the external synchronization signal or quasi-optical design of the array.

Antenna on microstrip line with orthogonally placed dielectric resonator

Single-element antenna that uses microstrip line as a feeder and cylindrical dielectric resonator orthogonally oriented relative to the line as a radiating element has been investigated. The complete mathematical model of proposed design consisting of a number of analytical expressions for main antenna characteristics is obtained and verified. The analytical relation for antenna return loss versus stub length and coupling coefficients of dielectric resonator with the feeding line and open space is derived. The assessment of the potential possibility and conditions of perfect antenna matching with feeding line is carried out. The influence of main parameters of a dielectric resonator antenna on its characteristics is examined. The numerical analysis of different antenna parameters proving the obtained analytical expressions is performed. The results of theoretical analysis are in good agreement with experimental data.

Efficiency of spatial signal processing in wireless communications

The mathematical modeling of amplitude and phase distribution of the electromagnetic fields at the aperture of the receiving antenna system has been performed. The possibility of frequency reuse in radio relay link under condition when two transmitters operate simultaneously on the same frequency and with same polarization is substantially investigated by using the phenomenon of phase front curvature of electromagnetic wave. An effective approach to optimal spatial processing of two radio signals from two transmitters at the receiving side of radio relay link is developed. The mathematical expressions allowing the theoretical analysis of spatial processing of radio relay link signals are obtained. The results of theoretical investigations are extensively discussed. The references for practical application of obtained results at the development of microwave link equipment are given.

Homomorphic suppression of noises in transients based on wavelet decomposition

The new procedure of sequential noise suppression in transient signals has been developed. The additive, convolutional and multiplicative noises are reduced to the additive forms by appropriate homomorphic transformation. In the decomposition of the signal by wavelets, the additive noise component is identified with the detailizing parts of this expansion. It is found that the Daubechies wavelets would be used as the basis functions. The specific features of the thresholds choice for noise suppression are discussed. According to the results of numerical simulations, it is ascertained that in certain cases the main role in the forming of transients belongs to convolutional noise.

Complex approach to service development

Modern companies including telecommunication companies and mobile operators working in the global environment should guarantee technological effectiveness and innovation, renewing their technologies and services. Operation Support System/Business Support System is used in telecommunication companies. In current state-of-the-art approaches, several iterations involving analysts and system architects are necessary, methodologies allow modeling non-functional or functional requirements but they do not take into account the interaction between functional and non-functional requirements as well as collaboration between services. Web Services Agreement is a convenient way to contain QoS parameters but state-of-the-art SLA-aware methods cannot support all classes of non-functional parameters and provide run-time support and dynamic reconfiguration at the same time. The approach proposed in this paper fills this gap. It employs a well-defined workflow and analysis model for developing and adapting complex software systems including support of all classes of non-functional parameters and providing run-time support and dynamic reconfiguration of provided services.