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.

This paper examines the possibility of the implementation and application of new test scenarios for the detection of problems on IPTV services that are delivered over DSL lines. Through a number of specific examples of behaviour that could be related to a significant number of DSL lines that transmit IPTV services in a real system of commercial exploitation, this paper shows the actual possibilities of using this new test scenarios on a significant number of lines. Furthermore, this paper points to some advantages of this test scenarios compared to a similar existing solutions. A pure author's look is presented.

This paper analyses an influence of some primary parameters on some physical layer parameters for DSL (Digital Subscriber Line) transceivers. Main intention of this paper is to show that some very frequent and very intensive serial and shunt resistive faults in in-house cabling system in some circumstances will not always significantly impact on IPTV (Internet Protocol Television) QoS (Quality of Service) parameters. Detailed description of experiments and results of significant number of testing on a real system in practice are given. The testing is implemented under very different condition in terms of resistive faults and in period of several days. Object of observation is a pair from 1000 pairs copper cable with air-paper insulation, lead sheath and star-quad as stranding elements. The length of observed pair is 1570 metres.

This paper analyses a capability of commonly used copper cable to provide multimedia services over ADSL2+ (Asymmetrical Digital Subscriber Line) technology, with satisfied level of QoS (Quality of Service) and QoE (Quality of Experience). The observed quantities are achieved bit rate and some ADSL line performance parameters, listed in appropriate ITU-T recommendations. They are observed in respect to increase the percentage of active broadband signals on treated cable. A brief theoretical overview, following by practical experiment description is shown. Detailed experimental results, obtained by observation of real system in exploitation conditions are presented. An appropriate discuss observed results is performed also. The twenty pair copper cable, approximately 1000 metres long, is used as real object of analysis.

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.

This paper investigates a usability of several common crosstalk models in respect to DSL loop qualification. Short overviews of both common crosstalk models and testing procedures are introduced. A comparison of crosstalk which is calculated from observing models and obtained by testing of real system is done. Based on that, the possibilities of loop qualification using crosstalk models are discussed.

This paper analyses the impact of access network of physical impairments in DSL environment caused by primary parameters imperfections. It also analyses the correlation of BER (Bit Error Rate) and error control of DSL system with values of MDI (Media Delivery Index) which gives an indication of expected IPTV (Internet Protocol Television) QoE (Quality of Experience). Also this paper gives a review of different network impairments, proper values of QoS (Quality of Service) parameters, like MLR (Media Loss Rate) factor, and at the same time, their impact on quality of IPTV. At the end, practical examples are given of how different types of network physical impairments cause problems in delivering IPTV service.

This paper analyses a dependence of standard definition IPTV service continuity error on code violation block codes. A very reliable method of evaluating of several IPTV QoS parameters by observing the parameters of physical layer of DSL transceivers was introduced. Also, an ability to use the procedures, which have already implemented at common ATU-R and ATU-C ADSL2+ modems for estimation of IPTV QoS parameters, without appropriate performance monitoring system implemented was discussed.

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.

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.

This paper gives a short overview of methods of testing performance of triple play services. Also, it explains a simplified scenario of testing DSL lines. By considering and comparing results of simplified testing, it can be noticed that their usage helps in estimation of problems on copper twisted pair. It will be shown that using these results accordingly discovers the location of a fault in delivering of triple play services. All of this can be helpful for operators in decreasing their human resources and material expenditures, respectively.

Problem of models of parallel and twisted-pair conductors, as well as models of crosstalk between one or two lines, is a subject of many researches particularly in the domain of low-frequency signal transmission. However, in the case of high-frequency signal transmission or signal spectrum division into sub carriers like in DMT, there are many possibilities of considering the mutual influence between conductors used for high-frequency modulating signals which are basically digital signals. Digital signal transmission over a pair in comparison to transmission of the same signal using other technologies has certain pros and cons. The best of many pros is the usage of already existing infrastructure mostly concerning the dominant operators that have been investing in the building of copper telecommunication infrastructure for years. Beside this, the given band in comparison to the shared one is an obvious advantage in relation to wireless technologies and PON networks. Certainly, the theoretical capacity of the fiber is much bigger than the capacity realized over copper, but lately there are efforts to overcome this problem by using DSM and MIMO systems.

This paper analyses qualitative and quantitative impact of large number twisted pairs transmitting ADSL signal, on one specific pair in the same cable. Change of pair capability to establish ADSL signal in respect to number of near active ADSL signals is observed. Information capacity is chosen as parameter of observed pair quality. At the beginning of this paper, simplified mathematical model of treated case is presented. After that, one pair during exploitation is analysed.

This paper gives brief overview of possible methods for approximate locating of galvanic faults in cables with symmetrical copper pair cables as well as possible methods of repairing the same ones. The main focus is based on two principal methods of locating faults like the use of measuring instruments that run on the basis of bridge measuring methods and measuring instruments which use time domain impulse reflectometry.

This paper analyses possibility of ADSL signal over long symmetrical copper-based twisted pair (about 7000 meters) establish. Got rate, its stability and possibility of its increase by effect on symmetrical copper-based pair primary parameters is analysed. Establishment of stable rate ADSL signal of enough value can be used for multimedia services providing through such ADSL system. Pair from 7100 meters long cable, with 0.4 millimetres conductor diameter polyethylene insulation and aluminium sheath is measured.