31-01-2009, 12:34 AM
Fast Internet access is growing from a convenience into a necessity in all aspects of our daily lives. Unfortunately, this has been held back by the high expenses of wiring infrastructure essential to deliver such high-speed internet access especially to private homes, small offices and rural areas, where the installation of any kind of new wires tilts the scales of the economic feasibility to a non-profitable state. This problem is known as the ?last mile problem? which has been an active area of research throughout research community.
But if broadband could be served through power lines, there would be no need to build a new infrastructure. Anywhere there is electricity there could be broadband. Broadband over Power Line (BPL) is a technology which allows transmission of data over the same lines used to transmit electrical power. Through signal modulation of existing power, electrical utilities can transmit low frequency signals at 50 Hz to 60 Hz (normal alternating current [AC] power) and higher frequency signals (data) above 1 MHz without any mutual interference. Power line communications uses the radio frequency (RF) signal sent over medium and low voltage AC power lines to allow end users to connect to the Internet. The RF signal is modulated with digital information that is converted by a modem in the home or small business into Ethernet-compatible data.
Historically, power utilities have used alternating current (AC) power line distribution facilities to carry information by coupling radio frequency (RF) energy to AC electrical wiring in houses or buildings. In the past, these devices have operated on frequencies below 2 MHz with limited communications capabilities. Due to power line characteristics it has been difficult to achieve dependable high-speed communications. However, technological advancements have resulted in the development of new systems which have overcome these technical obstacles. Trials have demonstrated that high-speed communication voice and data services can be achieved using the existing medium-voltage (MV) and low-voltage (LV) power distribution grid.
