BROADBAND POWER LINES
Within a short period of time the Internet has become a vital part of life for many people in the world. Many businesses have invested in various communication networks to facilitate access to the Internet. Although there are many technologies to access the Internet, have you ever thought that the same wire system that is used to supply electricity to your house can be used to access the Internet? Well, with Broadband over Power Lines, or BPL, you can plug your computer into any electrical outlet in your house or office and instantly have access to high-speed Internet. This means that the existing infrastructure can be used to provide Internet facilities.
Standard AC electricity is transmitted at a frequency of 50 Hz or 60 Hz via normal power lines. Researchers found that this left almost the entire frequency range of the line free, which suggested that perhaps, like the local loop in fixed telephone lines, the power line could be used for additional purposes. Consequently, it was proposed to transmit data over the unused frequencies of the power lines, using methods similar to those used in DSL. This is the fundamental idea upon which BPL technology was constructed. With BPL, power lines now have two purposes, both of which must coexist without interference.
But, transmitting data over power lines for long distances leads to degradation of the signals. This problem is particularly exacerbated by high-voltage power lines. Consequently, data is typically transmitted over fibre optic cables for the length of the high-voltage lines, before being converted into electrical signals and added to the medium-voltage or low-voltage lines. Since the majority of electricity transmission companies have wrapped fibre optic cables around their high-voltage lines, this is not a major problem. However, as with most other technologies, boosters are required at regular intervals, even on medium- and low-voltage lines, for re-amplification to prevent signal loss. Finally, the signal makes its way to neighborhoods and customers who can access it, either wirelessly, through strategically placed utility poles, or by having it zipped directly into their homes via the regular electric current. Adaptors at individual power outlets ferry the data into computers through their usual ports.
Since it uses an existing infrastructure, BPL could mean that low-cost broadband could be made a reality in areas that cannot get DSL, cable or wireless broadband. Even households in extremely remote areas can now potentially have broadband access.
In-house BPL is another advantage we can obtain from this technology. With the use of a simple converter and the wiring system of a building or a house, an Ethernet can be configured. Once a computer is connected to this electric network, it will be able to control any electric appliance in the same network. In that sense this technology may be useful in the development of ‘Smart’ houses or buildings controlled by a single computer.
Problems and Solutions
In spite of all the potential advantages, the BPL system has a number of issues. The primary one is that power lines are inherently a very noisy environment. Every time a device turns on or off, it introduces a pop or click into the line. The system must be designed to deal with these natural signaling disruptions and work around them.
Power distribution uses step-down transformers to reduce the voltage for use by customers. But BPL signals cannot readily pass through transformers, as their high inductance makes them act as low-pass filters, blocking high-frequency signals. So, these transformers should be bypassed. In the U.S., it is common for a small transformer hung from a utility pole to service a single house or a small number of houses. In Europe, it is more common for a somewhat larger transformer to service 10 or 100 houses. Due to this difference, BPL has developed faster in Europe than in the USA.
The next major issue is the operating frequency. The system is expected to use frequencies of 10 to 30 MHz, which have been used for many decades by amateur radio operators, as well as international shortwave broadcasters and a variety of communications systems (military, aeronautical, etc.). Power lines are unshielded and will act as antennas for the signals they carry, and have the potential to interfere with shortwave radio communications. Due to this problem, some countries such as Japan did not adopt this technology. Also amateur radio enthusiasts all over the world seem to be united in their distaste for what BPL does to the airwaves. Another concern with BPL is security. Since it transmits on a shared medium, like cable broadband, it is easier to hack the line.
How this technology copes with the above-mentioned problems within the next few years will decide the future use of this technology. A BPL connection is faster than a normal DSL connection, and the price is in the same range as DSL. Currently, power company Scottish Hydro Electric in Scotland is offering BPL in three towns for £35.99 and £29.99 per month for 1 Mbps and 512 kbps connections respectively. Germany, too, has many companies offering commercially available BPL.
Even if BPL fails as a direct data transferring method, it still may be used as a backhaul for WiMAX networks or as a method of connectivity between electrical appliances in a house. Will this technology become a great success or will it be another failure? We will have to wait and see.