Statistical CAC Methods in ATM

Admission control is a very useful tool for a network operator. It enables effective link utilization with QoS guaranty. Without doubts, CAC function will be important part in evolution of next generation networks. The question, how to choose suitable CAC method as admission control, is crucial for effective exploitation of CAC function. In this paper, we compare three statistical CAC methods providing their suitability as control for specific traffic: Method of Effective Bandwidth, Diffusion Approximation Method and Gaussian Approximation Method

Prepaid Voice Services Based on OpenBTS Platform

This article describes the design and implementation of prepaid voice services based on OpenBTS platform. By using various programming languages and open-source software tools, we can integrate prepaid voice services with this system, so its functionality is resembled as much as possible the operation of traditional GSM network provider. This article also provides description of how customers will approach their billing services, how they will access their accounts and pay their invoices

Study of Admission Control Methods for IPTV Services

The paper deals with admission control methods used in Internet Protocol (IP) Multimedia Subsystem. The purpose of implementing AC methods in IP Multimedia Subsystem (IMS) is to control the access of incoming connections to network resources. At the Institute of Telecommunications, we have built an experimental laboratory, which is used to test these methods. In this paper, we focus on Internet Protocol Television (IPTV) services; therefore, we have created a variable bit-rate IPTV traffic generator that is used as the input to the network, so we can test the behavior of selected AC methods. They are implemented in a simulated IPTV service provider access network, so we can examine the effects of variable bit-rate IPTV streams on the decisions made by those methods. To calculate the required bandwidth of an input stream, two simulation scenarios with different number of input packets were performed. One of these AC methods was modified where the peak input rate parameter of an IPTV stream was replaced by the average bit-rate of this stream. At the end of this paper, we discuss the achieved results

Preventive Methods for ATM Mode Control

Broadband transfer mode ATM represent one of alternative solutions for growing requirements on transfer capabilities. Its advantage is an effort for provisions of guaranteed quality of transport services with preservations of high transfer rate. This property is covered by several mechanisms, which role is to control not only the traffic of existing connections, but also the admission of new ones and prevent the violation of requirements on transport quality of existing and new connections.<br /

Presence Service in IMS

This paper describes the presence service, which is located in the IP multimedia subsystem. This service allows making many applications for different groups of people. The paper describes differences between a network without the service and with the service. The biggest change is an increased number of transmitted messages. The presence uses some part of the IP multimedia subsystem control layer, which is shown in communication between the user and the server. The paper deals with the number of generated messages depending on the behaviour of the users. This is described by a mathematical model using discrete Markov chains

Analyse of Measurement Based Admission Control Methods in IMS Networks and Simulation Principle

This paper deals with the quality of service in IP Multimedia Subsystem networks. The evaluation of Quality o Service (QoS) is done through admission control methods. We analyse various methods, which are based on the traffic measurement. The approach that can be applied in finding the suitable admission control method while considering selected QoS parameters is described. Different important QoS parameters can be defined, however we decided to focus on the loss parameter. In our simulations we have used Simple Sum method. Based on the simulation results, we have used new algorithm. The main difference is that it uses the mechanism of time window for achieving more accurate traffic estimate. Algorithm Measured Sum with implementation of time window T has better ability to predict the traffic fluctuation. Compared to the Simple Sum algorithm it achieves lower link utilisation, but also lower level of loss ratio

Analyse of Measurement Based Admission Control Methods in IMS Networks and Simulation Principle

This paper deals with the quality of service in IP Multimedia Subsystem networks. The evaluation of Quality o Service (QoS) is done through admission control methods. We analyse various methods, which are based on the traffic measurement. The approach that can be applied in finding the suitable admission control method while considering selected QoS parameters is described. Different important QoS parameters can be defined, however we decided to focus on the loss parameter. In our simulations we have used Simple Sum method. Based on the simulation results, we have used new algorithm. The main difference is that it uses the mechanism of time window for achieving more accurate traffic estimate. Algorithm Measured Sum with implementation of time window T has better ability to predict the traffic fluctuation. Compared to the Simple Sum algorithm it achieves lower link utilisation, but also lower level of loss ratio