This article proposes an analytical model of a multi-service hierarchical system with multi-service overflow traffic. To model the primary and secondary resources of this system, the state-dependent queue service discipline was used. In order to model the secondary resources with the dedicated queue for overflow traffic, the Hayward’s approach was generalized and applied. To evaluate its accuracy, the results of analytical modeling were compared with the data obtained during the simulation experiments carried out in the study. Both the data presented in the article and the results obtained by the present authors in numerous comparative studies clearly indicate that the proposed model makes it possible to evaluate the values of the blocking probability with the accuracy that provides its reliable practical application at the stage of network dimensioning. The overflow mechanism has particular significance in networks with limited resources, such as mobile networks.

In this article, we present a new analytical model of one-sided (unilateral) multiservice switching structures. Structures of this type are more and more frequently implemented in network layout solutions in data centres as the so-called fat-tree topologies. The analytical model developed in the article enables the possibility of determining the blocking probability in switching structures composed of leaf/edge, aggregation, and spine/core switches. The results of the analytical model for a number of selected switching structures are compared in the article with corresponding results obtained for a simulation model. The study confirms high accuracy of the proposed model. This model can be used to evaluate traffic effectiveness in data centre structures that deploy fat-tree topologies.

The article proposes a new method of determining traffic characteristics of multiservice overflow systems that carry adaptive traffic. When the total offered load in primary resources exceeds a certain value, this type of traffic is admitted for service with lower bitrate. A particular attention is given in the article to a method for a determination of the parameters of traffic that overflows to secondary resources as well as to the way adaptive traffic is serviced. The method takes into consideration three possible types of traffic: Erlang, Engset, and Pascal traffic. It is based on a generalization of Hayward’s concept and its application to model systems with adaptive traffic with threshold compression. The method can be used for optimal dimensioning of logical networks (slices) in modern mobile systems due to possibility of analytical determination of grade of service parameters (blocking probability, carried traffic, and network load). To verify the accuracy of the proposed model the results of analytical calculations, obtained on the basis of the proposed model, are then compared with the results of simulation experiments for a number of selected structures of overflow systems that service adaptive traffic. The results of the study demonstrate high accuracy of the proposed theoretical model.

This article describes an approximate model of a group of cells in the LTE network with implemented load balancing mechanism. An appropriately modified model of Er-lang's Ideal Grading is used to model this group of cells. The model makes it possible to take into account limited availability of resources of individual cells to multi-rate traffic streams. The developed solution allows the basic traffic characteristics in the considered system to be determined, i.e. the occupancy distribution and the blocking/loss probability. Because of the approximate nature of the proposed model, the results obtained based on the model were compared with the results of a digital simulation. The present study validates the proposed model both in terms of the adopted assumptions and in terms of the simulation techniques.

The aim of this paper is the elaboration of a new analytical calculation method of the occupancy distribution and the blocking probability in multi-service switching networks with multi-service sources. The considered multi-stage switching networks operates according to point-to-group selection. The analytical results of the blocking probability in the switching networks with multi-service sources are compared with simulation data.

The present article proposes a new method for modelling multi-service packet networks with implemented traffic overflow mechanisms. The basis for the proposed method is a special convolution algorithm that enables to determine the occupancy distribution and the blocking probability in network systems in which packet streams (calls) of individual traffic classes can be serviced by both direct and alternative resources. The algorithm worked out by the authors makes it possible to model systems with any type of traffic offered to direct groups. The methods that are to be found and are described in the literature of the subject permit the researcher to model systems in which direct groups are offered either Erlang or Engset streams.

In this paper, a new packet switch architecture with multiple output queuing (MOQ) is proposed. In this architecture, the nonblocking switch fabric, which has a capacity of N/spl times/N/sup 2/, and output buffers arranged into N separate queues for each output, are applied. Both switch fabric and buffers can operate at the same speed as input and output ports. This solution does not need any speedup in the switch fabric as well as arbitration logic for taking decisions which packets from inputs are to be transferred to outputs. The mean cell delay and cell loss probability, as performance measures for the proposed switch architecture, are evaluated and compared with the performance of the OQ architecture and VOQ architecture. The hardware complexity of the proposed switch is very similar to the VOQ switch but its performance is comparable to the OQ switch.