Alen Begovic

Real time assuring QoE in the lowest OSI/ISO layers during delivering of IPTV services

This paper compares the values of data link layer QoS (Quality of Service) indicators of several access lines, which can serve as a measure of the physical link quality or QoPh (Quality of Physical Layer), in real environment without reference video signal (No Reference), during the delivering of IPTV (Internet Protocol Television) multicast services to multiple users. It also focuses on the fact that an increase in channel capacity reduces the number of signal degradation indicators in the data link layer, because it increases the resistance of useful information on the interference. The paper proves the fact that at the same time, improving the physical layer conditions, the values of network QoS indicators, such as packet loss or delay, is reduced which affects the final grade at the end-user QoE (Quality of Experience) of IPTV (Internet Protocol Television) services.

An example of improvement of access network triple-play ability by local loop shortening

This paper presents an example of improvement of access network ability to provide triple-play service with satisfied QoE. The improvement is made by copper twisted pair local loop shortening. The local loop shortening is done on real buried copper access network in the rural area. A comparison of parameters before and after loop shortening is shown. Some parameters of the physical layer defined in Recommendation ITU-T G.997.1, such as code violation, forward error correction code and the number of seconds with corrected errors on the observed loops are used for comparison. Of course, the quantities like up/down bit rate, line attenuation, SNR margin, etc. are also analysed. All of experiments are done by observing triple-play services in real ADSL2+ environment.

Research of symmetrical copper based twisted pair near active ADSL service parameters properties

This paper researches changing of some basic parameters of symmetrical copper based twisted pair which is near the other twisted pair where active ADSL service exists. Analyzed parameters are: attenuation, signal to noise ratio, wideband noise and characteristic impedance. Analyzed subject is one pair in cable whose capacity is 100 x 2 x 0.4, with foamed polyethylene insulation and laminated polyethylene sheath. Existing ADSL service is sent through the different pairs in the observe cable and changes of the treated pair parameters are measured depending on the distance of the existing ADSL service from it. Obtained results are compared among themselves and with the parameters which are obtained in absence of ADSL service.

Analysis of impact of adjacent local loops on some significant DSL transceivers parameters

This paper analyses the behaviour of the adjacent ten DSL local loops in the copper based twisted pair cable with foamed polyethylene insulation. Some parameters of the physical layer defined in Recommendation ITU-T G.997.1, such as code violation, forward error correction code and the number of seconds with corrected errors on the observed DSL lines are analysed. Also, this paper analyses the values of some electrical parameters on those same DSL lines. Based on the values of observed parameters, possibility of simultaneous operation of adjacent DSL lines, even that they carry triple-play services is shown.

A possibility of using wideband noise for qualification and troubleshooting of digital subscriber lines

This paper analysis the actual usefulness and importance of wideband noise as one of electrical parameters of symmetrical copper pairs. By the results of measuring wideband noise on the real system in practice on copper pairs with different conditions on them, this paper attempts to show the actual usefulness and importance of this parameter. In this manner, this paper intends to make the process of measuring the electrical parameters of symmetrical copper pairs more reliable.

A simple analysis of copper local loop faults in FTTB environment

This paper introduces a very simple testing scenario for detecting of faults in copper local loop that remains in access network after replacing copper wires from CO (Central Office) to DP (Distribution Point) with optical fibres, i.e. after implementation of FTTB (Fibre to the Building/Basement) solution. The scenario can be useful at first for quick and quite reliable loop troubleshooting, and in particular cases for loop qualification. The first part of the paper gives a short overview of copper loop model in DSL (Digital Subscriber Line) environment, its lead testing scenarios and FTTB solution. A main steps in fault analysis and testing scenario description follow. Below that, a discussion proposed scenario usability and reliability is provided. At the end an experimental verification of the scenario, which is based on data collecting on physical system in commercial exploitation is done.

An analytical model of copper local loop in FTTB environment

This paper introduces a very simple model of copper local loop that remains in access network after replacing copper wires from CO (Central Office) to DP (Distribution Point) with optical fibres, i.e. after implementing a FTTB (Fibre to the Building/Basement) solution. The model can be used for quick and quite reliable loop qualification and/or troubleshooting. The first part of the paper gives a short overview of copper loop model in DSL (Digital Subscriber Line) environment, its lead testing scenarios and FTTB solution. An explanation of main steps in developing of new model follows. Below that, a discussion model usability and reliability is provided. At the end an experimental verification of the model, which is based on data collecting on physical system in commercial exploitation is done.

A simple model of copper local loop for use in current DSL applications

This paper introduces a quite simple and comprehensible model of copper local loop in current DSL applications. The model is useful for engineers and other technical staff, who operate on local loop qualification and troubleshooting in order to evaluate its ability to provide reliable triple play service over DSL quickly. An overview of existing local loop model is presented briefly at the beginning of this paper. Based on pointed shortcomings of those models, a new one, which removes shortcomings, is proposed. A usability of proposed model in present-day conditions, especially in respect to broadband market situation, is analysed briefly.

A testing of IQX hypothesis: An example at data link layer in DSL environment

This paper discovers what parameters of data link layer can be tracked to find relation between QoE (Quality of Experience) and QoS (Quality of Service). It also introduces a new paradigm that relates to consideration of parameters of QoS at all layers of OSI (Open System Interconnection) reference model, and their influence on QoE of end users. In order to analyse relation between data link layer parameters and QoE, the paper presents modification of IQX hypothesis (exponential interdependency of quality of experience and quality of service) in consideration with the mentioned parameters and time. As an example IPTV (Internet Protocol Television) scenario is shown.

An example of estimation of twisted pair channel capacity in DSL environment

This paper analyses an example of estimation and calculation of channel capacity of twisted pair channel in DSL environment, from point of view of provider, instead of commonly used point of view of manufacturers of terminal equipment. A brief overview of twisted pair as communication channel was given. The channel capacity end-to end with primary parameters as variables was introduced. The results of measurement on real cable in commercial exploitation and its comparison with introduced theoretical approach were shown. The 20-pair, 1000-meter-long cable, completely buried, which had been occupied by 100% by DSL signals and operating in rural conditions, was used.