Sławomir Hanczewski

Modelling of Cellular Networks with Traffic Overflow

The paper proposes a new method for modelling multiservice cellular networks with traffic overflow. The proposed method employs a model of Erlang’s Ideal Grading (EIG) with multiservice traffic and differentiated availability. The fundamental advantage of the proposed method, as compared to other relevant methods, is a major simplification in modelling systems with traffic overflow that results from the elimination of the necessity of a determination of the parameters of overflow traffic, that is, the average value and the variance. According to the proposed method, calculations in the overflow system can be reduced to calculations in a system composed of one grading only. The paper presents the method for determining availability in such a grading that models a system with traffic overflow. The results of analytical calculations were compared with the results of simulation experiments. The results of the research study confirm high accuracy of the proposed method.

Erlang's Ideal Grading in DiffServ modelling

Traffic overflow is one of the most effective mechanisms of the management of traffic distribution in telecommunications systems. The paper considers a possibility of using traffic overflow in present-day IP networks. Additionally, a new simplified method for the calculation of the blocking probability in overflow systems is proposed in the paper. The method is based on the model of Erlangs Ideal Grading (EIG) with multi-rate (multi-service) traffic and different availabilities. The method does not require calculations of the parameters of overflow traffic and its accuracy is not lower than the accuracy of other methods for the calculation of overflow systems with multi-rate traffic available in the literature of the subject. The results of the analytical calculations have been compared with the results of the simulations, which has confirmed the high accuracy of the proposed model.

Modeling Erlang's Ideal Grading with Multirate BPP Traffic

This paper presents a complete methodology for modeling gradings (also called non-full-availability groups) servicing single-service and multi-service traffic streams. The methodology worked out by the authors makes it possible to determine traffic characteristics of various types of gradings with state-dependent call arrival processes, including a new proposed structure of the Erlang’s Ideal Grading with the multirate links. The elaborated models of the gradings can be used for modeling different systems of modern networks, for example, the radio interfaces of the UMTS system, switching networks carrying a mixture of different multirate traffic streams, and video-on-demand systems. The results of the analytical calculations are compared with the results of the simulation data for selected gradings, which confirm high accuracy of the proposed methodology.

Approximation for Multi-service Systems with Reservation by Systems with Limited-Availability

The paper presents a new method for modeling systems with reservation. The method is based on the generalized ideal grading model servicing multi-rate traffic. The paper proposes an algorithm for determining such an availability value in the ideal grading that causes blocking equalization of different classes of calls. The proposed method was worked out for integer and non-integer values of the availability parameters. A comparison of the analytical results with the simulation data proves high accuracy of the proposed method.

A model of WCDMA radio interface with reservation

In the present paper we propose a new method of modeling WCDMA radio interface with reservation. The proposed method is based on the generalized Erlangs ideal grading model. The results of the analytical calculations of the blocking probability are compared with the results of the discrete events simulations. The present analytical study has confirmed the correctness of all theoretical assumptions and fair accuracy of the proposed analytical method.

The Queueing Model of a Multiservice System with Dynamic Resource Sharing for Each Class of Calls

The paper presents a new model of a multiservice queueing system with limited queue and state-dependent dynamic resource sharing of the server between individual classes of calls. The advantage of the proposed model is the possibility to evaluate the average parameters of queues for individual classes of calls. The proposed model can be taken as a basis for further research on multiservice queueing systems.

The application of the Erlang's Ideal Grading for modelling of UMTS cells

The present article proposes an analytical model of the WCDMA radio interface that is based on the concept of Erlangs Ideal Grading (EIG) with multi-rate traffic. The proposed approach is very simple and makes it possible to include in the calculations the interference influence from other cells of the UMTS network through a determination of appropriate values of the availability parameter. The results of the analytical calculations for cells of the UMTS network are compared with the data obtained in a computer simulation. The present study confirms the usability of the EIG model for the analysis of radio interfaces limited by the influence of interference.

Performance modelling of Video-on-Demand systems

Video-on-Demand (VoD) system have become increasingly popular over time. Currently constructed systems offer to their users a vast array of multimedia content spanning movies, video clips, TV programs, etc. that is made available through many video servers. One of the very important parameters at the initial stage of the system design is the blocking probability that follow the instances of unavailability of service resulting from the lack of provision of access to a given content. This parameter can be defined by means of appropriate tools, i.e. analytical models of systems, that enable to determine the level of losses in a system under design in relation to offered access demand and usage. The paper presents a new method for modelling of distributed Video-on-Demand systems. The proposed method is based on Erlangs Ideal Grading (EIG) with differentiated availability. Until now, Erlangs ideal gradings have not been used in modelling systems such as VoD.

A new model of the soft handover mechanism in the UMTS network

Mobile networks are among the fastest-developing areas of ICT. The increasing number of network users and the number of services offered by the network makes it necessary to develop new methods of network modeling and analysis. These methods also need to take into account the influence of complex traffic management mechanisms on network efficiency. An important group of traffic management mechanisms are used for the handover functionality. The paper proposes a new analytical model of a handover mechanism employed in the UMTS network.

Routing and control plane in the Parallel Internet IPv6 QoS

The article is devoted to an implementation of the Control Plane module (responsible for the routing) for the nodes of Parallel Internet IPv6 QoS network. The mentioned network is one out of three IIP System networks, built within the Future Internet Engineering project. A characteristic feature of the PI IPv6 QoS network is to provide an appropriate quality of services. This functionality is dependent on the routing as well. Therefore, the CP module must meet the numerous criteria. A way of applying the Control Plane module for the nodes of PI IPv6 QoS network, proposed by the authors of this article, has been implemented, tested and integrated with this network. The conducted tests have proved a correctness of the named assumptions.