Head of Laboratory – Dr.Sc. (Technology) Sergei Stepanov

Tel.: (095) 299-94-15; E-mail: stepanov@iitp.ru

The leading researchers of the laboratory include:

The laboratory deals with the development of teletraffic theory and its applications in telecommunications and computer systems. The following problem areas and models are studied at the laboratory in 2000:

• the construction of numerically optimized algorithms of calculation the performance measures of queueing models described by multi-dimensional Markovian processes.
• the development and analysis of teletraffic models for performance evaluation of new cost-effective telecommunication systems.
• the development of the software tools based on the efficient algorithms to support the performance modelling of the teletraffic models.
• the construction of the asymptotically optimal procedures for the sequential design of experiments for statistical problems related to telecommunication networks.
• the analysis of switching systems and interconnection networks for telecommunication and multiprocessing systems.

The approximate algorithm of estimation the performance measures of multiflow model of digital line in overload condition in situation when blocked message has the possibility for finite number of retrials is derived. The algorithm is based on the poissonian assumption for arriving of retrials. It allows to use for estimation the performance measures of model with retrials the corresponding model with losses having effective calculation algorithms. (S. N. Stepanov.)

For the model of digital channel with large number of input flows and access control the algorithm of calculation of main performance measures based on the convolution scheme is derived. The effectiveness of the suggested approach for channels having high speed is shown. (S. N. Stepanov, E. O. Naumova, M. Yu. Zozulinskiy.)

Estimations of the second term of the asymptotical expansion for a risk function of hypothesizes testing for a non-parametric set of distributions when the maximal probability of error tends to zero were found. Applications of this procedure for change-point detection and homogeneity testing were investigated in the IID case. (I. I. Tsitovich.)

The selection of comparable methods of effectivness estimation for microcell structure was made. (A. D. Charkevich.)

A class of rearrangeable interconnection systems with added looping paths was described. It was shown that such topology made more reliable interconnection system. The fault characteristics were investigated. (V. A. Garmash.)

Laplace's transformation domain models of superinductance and supercapacitance have been made. For this case a general method for designing operator equivalent circuits was used. It allows for non-zero initial values of voltages, currents and their time derivatives. The method used has been developed in application to linear two-terminal networks with operator resistances of arbitrary finite orders. (A. A. Vitkova.)

A method of asymptotic expansion of stationary distribution of queue lengths for node into series of the power of the small parameter for a characteristics estimation of nonproduct form queueing network with blocking at multiserver channel is suggested. An effective recurrence algorithm of calculation the coefficients of the asymptotic expansion for an arbitrary number of expansion terms is constructed. For a special case of considered model the necessary and sufficient conditions of product form distribution of queue lengths for nodes of the networks are suggested. (O. V. Ivnitskiy.)

The architecture of renewal the Internet services for mobile subscribers is derived. (V. A. Naumov.)

The method for estimating the B-ISDN link capacity with reserving of bandwidth for different user classes has been developed. The constructed method allows calculate ATM link capacity in multiservice systems. The method is based on the theory of multidimensional markov processes and new achievements of the networks resources reservation theory. (V. A. Ershov, O. F. Sergeeva.)