Ý tưởng chính đằng sau PLC là giảm chi phí và chi phí trong việc thực hiện của các mạng viễn thông mới. Mạng lưới cấp điện áp cao hoặc trung bình có thể được sử dụng để cầu một khoảng cách xa hơn để tránh xây dựng một mạng lưới thông tin liên lạc thêm. | 14 Broadband Powerline Communications Networks Powerline Communications Systems Historical Overview PowerLine Communications is the usage of electrical power supply networks for communications purposes. In this case electrical distribution grids are additionally used as a transmission medium for the transfer of various telecommunications services. The main idea behind PLC is the reduction of cost and expenditure in the realization of new telecommunications networks. High- or middle-voltage power supply networks could be used to bridge a longer distance to avoid building an extra communications network. Low-voltage supply networks are available worldwide in a very large number of households and can be used for the realization of PLC access networks to overcome the so-called telecommunications last mile . Powerline communications can also be applied within buildings or houses where an internal electrical installation is used for the realization of in-home PLC networks. The application of electrical supply networks in telecommunications has been known since the beginning of the twentieth century. The first Carrier Frequency Systems CFS had been operated in high-voltage electrical networks that were able to span distances over 500km using 10-W signal transmission power Dost97 . Such systems have been used for internal communications of electrical utilities and realization of remote measuring and control tasks. Also the communications over medium- and low-voltage electrical networks has been realized. Ripple Carrier Signaling RCS systems have been applied to medium- and low-voltage networks for the realization of load management in electrical supply systems. Internal electrical networks have been mostly used for realization of various automation services. Application of in-home PLC systems makes possible the management of numerous electrical devices within a building or a private house from a central control position without the installation of an extra .