Generalised Elementary Teletraffic System – Conceptual Model Prof dr sc. Ivan Bosnjak Prof dr sc. Gordana Stefancic



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Generalised Elementary Teletraffic System – Conceptual Model
Prof. dr. sc. Ivan Bosnjak

Prof. dr. sc. Gordana Stefancic

University of Zagreb, Faculty of Transport and Traffic Sciences

Zagreb, Croatia

Phone: +385 1 2380226

Fax.: +385 1 2314415

E-mail: bosnjaki@fpz.hr





ABSTRACT
The application of systems paradigm enable usable identification of generalized elementary teletraffic system as a common structural and functional model of traffic phenomenon in different telecommunication network. Defined UC-structure recognise five generalised subsystem: network facilities (NTE), traffic entity (TFE), transported entity (TNE), adapting of TFE to NTE, adapting of TNE to TFE. The basic common input and output quantities are associated with the input and output age of teletraffic entity (packet, cell, etc.).
Generalised elementary traffic system on the highest level of abstraction gives "explanation in principle". Structures and processes of teletraffic systems can be associated with fundamental quantities which can describe teletraffic phenomena independent of physical realisation of teletraffic systems.
Keywords: Systems, Teletraffic, Methodology, Generalisation.

1. INTRODUCTION
Systems problem solving in the field of telecommunications can be studied and developed at various level of generality and detail [1], [3]. In our research we are focused on developing generalised elementary teletraffic system as a usable model with explanatory and predictive power.
The use of systems problem solving methodology is based on the assumption that context specific subproblems (related with particular networks PSTN/ISDN, ATM/BISDN, GSM, UMTS, Internet, etc.) can be extracted from the overal teletraffic problem.
This paper discuss approach to system problem solving and explain generalised subsystems of elementary teletraffic system. Basic variables for describing traffic phenomenon in telecommunications network are also introduced. Depicted UC structure is directly applicable for advance packet/cells traffic, but circuit-switch traffic require further explanations.

2. PROCESSES OF SYSTEMS PROBLEM SOLVING
Scientific inquiry and systems problem solving in teletraffic science and concrete telecommunication area require abstraction and interpretation with proper interfaces. Basic approach to systems problem solving is illustrated on figure 1. (adapted from [5])





Figure 1. Iterative process of teletraffic system problem solving



The utilisation of Klir's General System Problem Solving (GSPS) or similar methodological support is possible whenever systems problems arise in the overal problem. The investigators have to be familiar with the basic systems concepts and language of GSPS to be able to interpretate systems problem within his own discipline or specialisation. The interfaces between the disciplines involved in systems problem solving require processes of abstraction and interpretation.
To be more useful and applicable system problem solving support must cover as large a class of systems problems as possible. In our research teletraffic system and classical traffic/transport systems (road, rail, air, etc.) are considered according generic traffic models which cover physical and virtual mobility.

3. GENERALISED ELEMENTARY TELETRAFFIC SYSTEM
Generalised elementary teletraffic system is illustrated in Figure 2. Generalised traffic, transport and transmission systems are considered in [2], [6].
Five generalised subsystems of teletraffic system are recognised:

  • the subsystem of the network facilities (NTE),

  • the subsystem of the traffic entity (TFE) (→ packet, cell, etc.),

  • the subsystem of adapting of the teletraffic entity to the requirements of the network facilities (TFE  NTC),

  • the transported entity (voice, data, video),

  • the subsystem of adapting of the transported entity to the requirements of the teletraffic entity (TNE  TFE).

The basic common input and output quantities for the defined UC-structure are:



  • the input age of the teletraffic entity lrl = lrA (where A denotes attachment and I denotes input) measured in the teletraffic entity inherent reference time;

  • the output space position co-ordinates of the traffic entity r, which may take predetermined particular values (or, in the case of intervention or error, any value) along the traffic corridors in the network reference space, prO = prD = {xrD, yrD, zrD}, where D denotes detachment, and O denotes output;

  • the output age of the teletraffic entity lrO = lrD (where D denotes detachment and O denotes output) measured in the traffic entity inherent reference time.



Figure 2. Generalised elementary teletraffic system


The generalised network of teletraffic facilities with the adapting structure. System's input quantities are prA and lrA . The system's output quantities are prD and lrD .
The teletraffic entity has the meaning of the "vehicle" appropriate for the respective teletraffic corridor or network facilities. Basic transfer modes in existed telecommunication networks are:

  • circuit

  • packet

  • frame

  • cell.

The teletraffic entity adapting subsystem adapts teletraffic entities (packet, cell, etc.) to the network of traffic corridors, preserving as much transported entities (content) as the respective teletraffic entities, according to the requirements of each specific teletraffic entity life time, assigned to the entities by their producers or operators.


The transported entity is any form of information, attached to the teletraffic system, with specified:

  • lifetime,

  • input/output space position co-ordinates, and

  • adaptation to teletraffic/transport entities procedures.

The transport entity adapting subsystem adapts transported entities to the requirements of teletraffic entities, preserving all attributes of each particular transported entity, especially the transported entity life time.



4. CONCLUSION
The rapid development of integrated telecommunications network and services generate new demand on knowledge and competence for everyone who takes an active part in modern telecommunications. A clear descriptions of functions and structure of teletraffic system is particularly important. The application of systems paradigm supports identification of generalised elementary teletraffic system as for description of traffic phenomenon in different telecommunications networks.
Defined UC-structure and basic input/output quantities are generic in terms that can be used for description of (almost all) telecommunications and transport (road, rail, etc.) traffic systems.
Proper understanding and implementation of generalised system concepts and methodologies (such as GSPS) to the field of traffic science have descriptive and considerable predictive values. Such explanations must be consistent with technological considerations (on a lower level of abstraction) and concrete problem solving in the field of traffic technologies.
Different (existing) disciplinary and specialist knowledge oriented to teletraffic system components thinkhood properties can be integrated horizontally using appropriate system transformations and expert tools.

REFERENCES:


  1. I. Bosnjak, Teletraffic Technology II, Zagreb, Faculty of Transport and Traffic Science, 2001.

  2. I. Bosnjak, "Systems problem Solving in Traffic Science and Technology", Annual of the Croatian Academy of Engineering. Vol 5, 2002, pp. 9-14

  3. Ericsson & Telia: Understanding Telecommunications, 1998.

  4. M. Frank, "Characteristics of Engineering Systems Thinking – A 3D Approach for Curriculum Content", IEEE Transactions on Systems, Man and Cybernetics, Vol. 32, No. 3, 2002, pp. 203-214.

  5. G.J. Klir, Architecture of System Problem Solving, New York, Plenum Press, 1985.

  6. Z. Radic, I. Bosnjak and H. Gold, "Generalized ITS Modelling for Improved Intermodal Interface", Proceedings of 5th World Congress on Intelligent Transportation Systems, Seoul, 1998.

  7. J. Roberts, V. Mocci and J. Virtamo: Broadband Network Teletraffic. Berlin, Springer-Verlag, 1996.





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