Items of № 5, 2010

The Electrosvyaz Magazine is one of the leading science & technical magazines in Russia.

Studying the efficiency of data channel loading strategies in the exercise of distant education


Distance education, which differs high efficiency of management of learning process nowadays, is considered in the article. Problem of formation of the dynamic organization in distance educational process consists in planning on sessions of rational loading of one or several channels (ranges), with specified resource-intensiveness, linearly ordered interrupted and uninterrupted traffic which is characterized by resource requirements and duration of completion in one session. The models of channel loading and their effectiveness are analyzed.

Key words: distance educational process, channel loading optimization, network data traffic, resource-intensiveness, conference communications.

Assessment of electromagnetic compatibility between VSAT and direct relay Ku-band stations


Assessment of electromagnetic compatibility between VSAT and direct relay stations (RRS) in Ku-band is determined. Method of statistical modeling is used by means of programme package SEAMCAT (Spectrum Engineering Advanced Monte-Carlo Analysis Tool). Interference probability from VSAT to RRS were calculated while changing principal parameters of RRS and VSAT. It is shown that interference probability is very small in most cases (does not exceed units of the percent) that stands basis for putting into operation simplified (registration) procedure of the frequency provision and VSAT installation in the 14,4−14,5 GHz frequency band.

Key words: VSAT, relay station, statistical modeling, Monte Carlo method, interference probability.

Multipath telecommunication channel’s optimal linear correction


The article presents a simple analytical method to determine key parameters of an optimal transversal filter. Additionally, analysis of the noise immunity of signal reception is presented. Key filter parameters were determined based on the measurement of the frequency characteristic of the multipath channel which transmits information signals. It was shown that if a frequency characteristic response of a real communication channel has substantial non-uniformity in a working frequency band, then an optimal linear equalizer can completely eliminate intersymbol interference given high signal-to-noise ratios, however it also increases the level of the thermal noise on the demodulator’s input. The article also contains formulas that allow to estimate the probability of an error in signal reception through the multipath communication channel and the equalizer of intersymbol interference.

The adaptive high-speed signal transmission system in a multipath fading channel


The adaptive system of the sending speediest signal in multipath channel with fading is built with use principle division of the speediest flow on flows with the following their sending on separate frequency. The influence of fading amplitude separate partial signal under adaptive sending is reduce two ways: in — first, for each partial signal is chosen optimum frequency from M available in given channel uncorrelated frequencies, in the second powers for redistribution between partial signal on sending. In article consider the system of the sending, in which is executed specified procedure of the double use the features of the channel. In article give analytical dependencies to probability of the error from relations signal/noise in channel with rayleigh fading, when use the procedure to adaptation both on frequency and on powers The calculation show that at double use the features of the channel gives the additional advantage on noise-immunity. The method of the leveling the powers on sending is an efficient way of the fight with fading without use of frequency redundancy, typical of systems with diversity acceptance.

Key words: noise-immunity, fading, multipath radio link, relative-phase keying, adaptation.

Synchronization networks based on the synchronous Ethernet technology


The Synchronous Ethernet (SyncE) as a promising technique of timing signals distribution in new generation packet networks is considered. It is shown that SyncE has inherit the main network synchronization principles successfully used in «classical» SDH/SONER networks.

Time synchronization protocols for clock-pulse alignment in packet switching networks


The base approches for time and frequency synchronization evolving from communication technology development are considered in this paper. The dynamics of frequency stability and time accuracy specifications following by standardization bodies, so long as network operators and equipment vendors were trading between performance characteristics of the transport medium and quality of service to be demonstrated.

Key words: synchronization, time synchronization accuracy, time scale, time protocols, transport technologies, carrier class paket networks, SDH, Ethernet.

Configuring and reconfiguring a clock system network taking into account a clocked telecommunication network’s topology


Paper deals with some methods of configuring and reconfiguring synchronization network avoiding synchronization loops for different topologies of synchronized telecommunication network.

Key words: Synchronization Loop, Linear Topology, Local Segment, Core Segment, Network Element.

Effectiveness increase of high-frequency communication in distribution power network


The problems connected with possibility of simultaneous work of two information networks, are considered in this article. The first network is local and is intended for data gathering on peripheral object. The second network is external and is intended for communication realization between point of management and peripheral object of system of telemetry. The author has analyzed various variants of increase of a system effectiveness of communication with use of distributive power networks as a communication channel component. The variant of increase of the efficiency, based on updating of the protocol of data exchange in an information network, is close to the best. This variant allows to double throughput of a communication channel roughly.

Key words: high-frequency communication, information network, the data exchange report, the distributed system of data gathering.

Liouville’s theorem and phase volumes method in research of the fiber-optical systems' transmission ability


In this article the phase-volumes method in research of transmission ability of the fiber-optical networks and devices (network components) is developed. The theorems of transferring of light power in fiber-optical system are formulated and proved. Also the efficiency of application of the phase-volumes method to the problems of optimization of passive optical networks is shown. This work is based on Humelton’s formalism of ray optics and the Liouville’s theorem on the incompressibility of phase volume of a bunch of light rays.

Key words: aperture, phase volume value, Fiber-Optic Communication System, fiber-optic circuit, geometrical optics, Lagrange’s invariant, transmission coefficient (Transfer factor), directional coupler, optical fiber, Passive Optical Network (PON), radiant power, beam, splitter, light guide, Liouville’s theorem, Abbe’s sine theorem (condition), phase- space, phase volume, Humelton function, Lagrange function, Numerical Aperture.

Determination of capacity in the load of a HF path containing N inhomogeneous parts


A calculation technique of power in load of HF path, containing unlimited quantity of passive devices, accounting their reflectance, phase delays and fading, is proposed.

Key words: HF path, reflectance, power.

Specifics of quasi matching devices' usage in wideband transmitters


Radio-frequency spectrum used by LTE and LTE Advanced networks


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