Ing. Petr Hampl, Ph.D.

The last twenty years of computer integration significantly changed the process of service in a call center service systems. Basic building modules of classical call centers – a switching system and a group of humans agents – was extended with other special modules such as skills-based routing module, automatic call distribution module, interactive voice response module and others to minimize the customer waiting time and wage costs. A calling customer of a modern call center is served in the first stage by the interactive voice response module without any human interaction. If the customer requirements are not satisfied in the first stage, the service continues to the second stage realized by the group of human agents. The service time of second stage – the average handle time – is divided into a conversation time and wrap-up time. During the conversation time, the agent answers customer questions and collects its requirements and during the wrap-up time (administrative time) the agent completes the task without any customer interaction. The analytical model presented in this contribution is solved under the condition of statistical equilibrium and takes into account the interactive voice response module service time, the conversation time and the wrap-up time.

Currently used telecommunication systems transport different types of interactive services. Available network devices are able to differentiate between these different services and process each service type data stream with different behaviour. Data flow processing without this treatment causes worse quality of service parameters of services with different bandwidth requirements. Technological progress of interactive multimedia services causes more significant differences between bandwidth requirements of these services. A very important part of network dimensioning process is to ensure optimal access to network resources for customers of different service types. Presented mathematical model could be very helpful for initial estimate of device configuration parameters.

The paper shows the significant influence of probability distribution functions of interarrival times, such as the exponential, the hyper-exponential and the Erlang's of the order k, on the loss probability of the multi-service system. These types of system models are often used for the capacity planning and network dimensioning. The presented analytical and simulation model supposes very specific character of input flow, which is formed from packet streams of interactive services with different bandwidth requirements. Simulation results for various interarrival time distributions are compared with the analytical solution of multidimensional Erlang's model.

This article use analytic model based on generalized multidimensional Erlang model which is often used in circuit switched network dimensioning. The presented model supposes very specific character of input flow, which is formed from packet streams of interactive services with different bandwidth requirements. These interactive services are aggregated in one common prioritised service class. The analytical solution is applicable only when interarrival time distribution of all service types can be approximated by exponential distribution. For other types of interarrival distributions a simulation program was designed. In case of Markov input stream the simulation results are in good agreement with analytical model.

For students graduating in telecommunications it is an important to know principals and standards used in IP mobility management protocols. This work describes the fundamentals of IP mobility management protocols for both IPv4 and IPv6. The main goal of this work is to explore current support of the IP mobility management protocols on network devices of leading manufacturers and operating systems. One of the main factors of IP mobility management protocols is handover latency while the mobile user is roaming to another network. The second goal of this work is to measure the Hannover latency in real experimental network.

This paper shows the influence of probability distribution function of interarrival times, such as the deterministic, exponential and lognormal with different coefficient of variation on the packet delay.

Subject Communication in Data Networks at Czech Technical University in Prague acquaints undergraduate students with an overview of basic principles and current state of Data Networks. The subject is mainly focused on LAN and WAN technologies such as Ethernet, token Ring, Frame Relay and Asynchronous Transfer Mode (ATM). A significant part of theoretical lectures is focused on explaining of basic principles of TCP/IP protocol family and incoming Internet Protocol Version 6 (IPv6) which is now gradually replacing Internet Protocol Version 4 (IPv4). The main goal of the project: Innovation of laboratory tasks of the course Communication in Data Network was to create new and upgrade present practical exercises.

This article describes creation an usage of virtualized monitoring solution for practical laboratory exercises. Network Management System (NMS) is one of the most important components of each production network. It detects problems and failures in a network or failure of servers and notifies system administrators so they can mitigate such failures as soon as possible. NMS is key component helping to comply with Service Level Agreement (SLA) - important part of business contracts in Information Technology (IT) industry. Standardized protocol used for monitoring network devices is Simple Network Management Protocol (SNMP). For students graduating in telecommunications it is important to know principals and standards used in network management. This article describes creation an usage of virtualized monitoring solution for practical laboratory exercises.

Příspěvek popisuje cíle a výstupy projektu "Inovace laboratorních úloh předmětu Komunikace v datových sítích", jež je zaměřen na modernizaci bloku praktických laboratorních cvičení tak, aby sledoval moderní vývojové trendy v oblasti datových sítí. V rámci řešení projektu vznikly podklady pro dvě nové laboratorní úlohy, které studentům pomohou na názorných příkladech z praxe upevnit teoretické znalosti získané studiem předmětu. Projekt si klade za cíl maximálně využít prostředků virtuální datové laboratoře (Netlab), dostupné na katedře telekomunikační techniky Fakulty elektrotechnické ČVUT v Praze. Využití e-learningu a moderního technického vybavení významnou měrou přispívá k zefektivnění a zatraktivnění výuky předmětu.

Subject Data Networks at Czech Technical University in Prague acquaints undergraduate students with an overview of principles and current state of Data Networks. The subject is mainly focused on WAN technologies such as Point-to-Point Protocol (PPP), High-Level Data Link Control (HDLC), Frame Relay, X.25, Ethernet and Asynchronous Transfer Mode (ATM). An important part of theoretical lectures is focused on Multiprotocol Label Switching (MPLS) technology which is now replacing technologies such as Frame Relay or ATM, mostly because it is better aligned with current and future technology needs. The practical exercises of subject are focused on practice with specialized networking equipment, such as routers, switches and protocol analyzers.

This paper deals with innovation of the subject Data Networks at Czech Technical University in Prague. There will be implemented a new practice exercise focused on Simulation-based learning environment for students to design, configure, and troubleshoot computer networks.

This paper provides theoretical description of a service system with variable intensity of input flow.

This contribution deals with the analysis of aggregation in ADSL access networks. Special interest will be devoted to the impact of aggregation ratio on the loss of packets. As a mathematical approaching reality the service system M/M/1/R will be used.

New practical exercise focused on the core issues in data networks, especially configuration and troubleshooting of ADSL technology

The purpose of the paper is to introduce the usage of FR and ISDN technologies with respect to economical costs that are accompanied by their operation. The contribution contains a case study that shows the usage of FR and ISDN on laboratory practice.

Příspěvek se zabývá modelováním agregačního bodu v ADSL přístupových sítích. Konkrétně se zaměřuje na vliv agregačního poměru na ztrátu paketů v agregačním bodě. Jako model agregačního bodu byl zvolen obsluhový systém M/M/1/R.

Influence of probability distribution functions of interarrival times, such as the exponential, the hyperexponential, the Erlang's of the order k and the deterministic, on the loss probability of the X+Y/M+M/N/0 service system Kendall's notation

Cílem tohoto článku je seznámit čtenáře se základním členěním obsluhových systémů a použitím Kendallova značení.

This paper describes the case when the N slots of a trunk group share two various multi-slot traffic flows (M+M / M+M / N / 0 system).