Stoyan Poryazov

Some General Terminal and Network Teletraffic Equations for Virtual Circuit Switching Systems

A virtual circuit is a connection between two users, devices, or terminals that Junctions as if it were a direct connection. Forwarding, switching, and/or routing over directly-connected circuits takes place at intermediate devices within the virtual circuit, but the details are hidden from the end points. Virtual circuits are widely used in many telecommunications and networking architectures; viz.: in wireline (PSTN, ISDN, BISDN) and wireless (GSM) telephony; in packet-switched networks at various layers (e.g., transport layer connections); in Multiprotocol Label Switched (MPLS) networks where tunnels are a type of virtual circuit; in Asynchronous Transfer Mode (ATM) networks where permanent and switched virtual circuits are fundamental components; in optical networks where wavelength routing and burst switching are abstract forms of provisioned virtual circuits; and in emerging multi-service networks where managed Ethernet virtual circuits are used to bridge legacy technologies like frame relay and ATM.

On the Minimal Traffic Measurements for Determining the Number of Used Terminals in Telecommunication Systems with Channel Switching

In this paper a telecommunication system with (virtual) channel switching, heterogeneous users and with Poisson input flow is studied in stationary state. It is assumed that unsuccessful calling attempts resulting from abandoned dialing, abandoned ringing, blocked and abandoned conversation situations are not repeated. A model for such a telecommunication system has been proposed that requires the measurement of minimum number of parameters for the determination of the number of terminals in use, and various other characteristics of the system state.

Conceptual and analytical models for predicting the quality of service of overall telecommunication systems

This chapter presents scalable conceptual and analytical performance models of overall telecommunication systems, allowing the prediction of multiple Quality of Service (QoS) indicators as functions of the user- and network behavior. Two structures of the conceptual presentation are considered and an analytical method for converting the presentations, along with corresponding additive and multiplicative metrics, is proposed. A corresponding analytical model is elaborated, which allows the prediction of flow-, time-, and traffic characteristics of terminals and users, as well as the overall network performance. In accordance with recommendations of the International Telecommunications Union’s Telecommunication Standardization Sector (ITU-T), analytical expressions are proposed for predicting four QoS indicators. Differentiated QoS indicators for each subservice, as well as analytical expressions for their prediction, are proposed. Overall pie characteristics and their causal aggregations are proposed as causal-oriented QoS indicators. The results demonstrate the ability of the model to facilitate a more precise dynamic QoS management as well as to serve as a source for predicting some Quality of Experience (QoE) indicators.

Scalable Traffic Quality and System Efficiency Indicators Towards Overall Telecommunication System’s QoE Management

Conceptual and analytical models of an overall telecommunication system are utilized in this chapter for the definition of scalable indicators towards Quality of Service (QoS) monitoring, prediction, and management. The telecommunication system is considered on different levels – service phase, service stage, network, and overall system. The network itself is presented in seven service stages – A-user, A-terminal, Dialing, Switching, B-terminal Seizure, B-terminal, and B-user, each having its own characteristics and specifics. Traffic quality indicators are proposed on each level. Two network cost/quality ratios are proposed – mean and instantaneous – along with illustrative numerical predictions of the latter, which could be useful for dynamic pricing policy execution, depending on the network load. All defined indicators could be considered as sources for Quality of Experience (QoE) prediction.

Comparison of Conceptual Models of Overall Telecommunication Systems with QoS Guarantees

Different approaches to conceptual modeling of overall telecommunication systems with QoS guarantees are discussed. Generalized Nets (GNs) are used as an alternative to the already existing conceptual models based on the Service Networks Theory. Two GN representations of a part of the Switching stage are proposed and their advantages and disadvantages are discussed.

Problems with quality enabling of information functions composition in smart buildings

The aim of this paper is to point out and summarise existing problems and research trends that arise when assessing and ensuring quality of information services. On the focus of this work are smart buildings. Basic information functions that are composed in different services are described. The sets and structures of the composition form various scenarios. Problems in determination the quality of these scenarios, and their implementation to meet the requirements of the customers are considered.