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 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 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.