Vol 7, No 2 (2009)

We present algorithm for optical fiber chromatic dispersion method calculation based on full-vector mixed finite element method. Algorithm potentialities are demonstrated on the samples of calculations for microstructured fibers. Correctness of estimations is confirmed by comparing to known solutions and experimental data.

In the suggested cipher each symbol (the letter, a punctuation mark, number) is replaced with two real numbers. These two numbers are top and bottom limits of the determined integral. Value of integral is used that under the table of replacements to define, to what symbol of a open text there corresponds the calculated value of integral. It is supposed, that the kind of sub-integral function and a configuration of the table of replacements are known only to authorized representatives on the transmitting and reception sides. In each session of communication the table of replacements and sub-integral function are defined by a confidential key.

Outage probability provides a fundamental performance measure of the grade of service for cellular mobile radio systems. Now effective techniques to determine outage probability are based on the Nakagami distributions. However the most general model of signals fading in a cellular mobile radio system is model with quadriparametrical distribution of amplitudes. In this paper, a new technique is presented, which is based on the quadriparametrical descriptions of signal and interferers fading. Exact precise formula for probability of outage.

The article deals with the problems of work quality control of communication networks under conditions of TDM and NGN equipment availability. There has been made an analysis of the existing and possible work quality indices of the communication networks. The method of selection of the most meaningful indices from the position of how to control the communication network work quality has been suggested.

We present results of experimental investigations of optical fiber attenuation increasing due to optical cable tight buffer deformations. Empirical ratios for calculation of tight buffer acceptable deformation via an additional loss criterion were obtained, and experimentally verified.

Distributed information system (IS) is considered with main (central) database (MDB) and collection of local databases (LDBs) at remote user workstations. With the help of asynchronous replication mechanisms a copy of certain part of MDB is maintained in each LDB. Mathematical model for analyzed system is presented and by means of this model it is demonstrated that under certain conditions the presence of local data decreases the mean duration of query processing and reduces as well expenses for data transmission between separate elements of IS.

In operation process of cloning of system operation of queuing of general view GI/G/m/k, its program implementation on the basis of digital-event the approach, and also verification of this program system are considered. Results of calculations of its main characteristics depending on the value of loading, coefficients of a variation of allocation of a holding time and arrival for a wide range of change of parameters of the traffic are resulted.

Article discusses methods for creating a steganographic system in a TCP/IP network.

The article highlights the ways of improving the quality of digital audio signals compression. The author focuses on the question how to range bits while coding the coefficients of discrete orthogonal transformations. The process of bits rate ranging is presented as necessary and sufficient for providing high-quality perception of the decoded audio signals. The work focuses on the process of bits ranging for different audio signals bands.