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1

Development of QoS Methods in the Information Networks with Fractal Traffic

Daradkeh Y. I., Kirichenko L., Radivilova T.

International Journal of Electronics and Telecommunications

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2018

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Vol. 64, No. 1

27--32

EN

The paper discusses actual task of ensuring the quality of services in information networks with fractal traffic. The generalized approach to traffic management and quality of service based on the account of multifractal properties of the network traffic is proposed. To describe the multifractal traffic properties, it is proposed to use the Hurst exponent, the range of generalized Hurst exponent and coefficient of variation. Methods of preventing of network overload in communication node, routing cost calculation and load balancing, which based on fractal properties of traffic are presented. The results of simulation have shown that the joint use of the proposed methods can significantly improve the quality of service network.

2

Modeling TCP/RED - approximate performance evaluation using an analytical queueing approach

Świderski J.

Systems Science

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2006

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Vol. 32, no 3

109-117

EN

This paper is concerned with the approximate performance analysis of TCP Reno connections coexisting with flows that are not TCP-friendly (i.e. flows that use more bandwidth than would any conformant TCP implementation in the same circumstances). The network model is based on two earlier models. The first model enables one to calculate the TCP send rate which is the amount of data sent by the sender in unit time. This model has been presented in [6] and captures the behavior of both the fast retransmit and time-out mechanisms. The send rate for a given TCP connection can be calculated assuming that the round trip time, the time-out and the loss probability are known for this connection. These quantities can be determined using the second model – the queueing network model that represents an IP network and has been introduced in [13]. It enables one to include the Random Early Detection (RED) queue based active queue management (AQM) scheme that can be met in today’s routers.

3

Approximate performance analysis of slotted downlink channel in a wireless CDMA system supporting integrated voice and data services

Świderski J.

Journal of Telecommunications and Information Technology

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2004

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nr 2

47-53

EN

This paper is concerned with the performance analysis of a slotted downlink channel in a wireless CDMA communication system with integrated packet voice and data transmission. The system model consists of mobile terminals (MT) and a single base station (BS). It is assumed that the voice (data) packet error rate (PER) does not exceed lO(-2) (10(-5)). With this requirement the number of simultaneous transmissions over the downlink channel is limited. Therefore, the objective of the call admission control is to restrict the maximum number of CDMA codes available to voice and E data traffic. Packets of accepted voice calls are transmitted immediately while accepted data packets are initially buffered at the BS. This station distinguishes between silence and talk-spurt periods of voice sources, so that data packets can use their own codes for transmission during silent time slots. Data packets are buffered in queues created separately for each destination. Discrete-time Markov processes are used to model the system operation. Statistical dependence between queues is the main difficulty which arises during the analysis. This dependence leads to serious computational complexity. The aim of this paper is to present an approximate analytical method based on the restricted occupancy urn model which enables to evaluate system performance despite the dependence. Numerical calculations compared with simulation results show excellent agreement for the average system throughput and the blocking probability of data packets for higher system loads. On the other hand, when the average data packet delay is considered, analytical results underestimate simulation and therefore only approximate system performance evaluation is possible.