What is Power Line Networking?

Power line networking connects computers by using power outlets in the home. Its purpose is to provide a network easily and inexpensively with no new wires. It is one of the cheapest technologies for networking and does not raise the electric bill.

Though an older technology exists for power line networking, the industry alliance group HomePlug Alliance has made Intellon's PowerPacket the standard. This newer technology has many advantages over the older Passport technology. PowerPacket is much faster, is not disrupted by power usage in the home, and features built-in encryption. It is also not affected by aged wiring.

PowerPacket kits provide a power line networking card that fits into an internal PCI slot inside the computer. The card features a power cord that plugs into a wall outlet, connecting the computer to other computers in the network through electrical lines that run throughout the house.

Power line networking is based on a technology called OFDM, or orthogonal frequency-division multiplexing. OFDM utilizes the electrical lines to transmit data on frequencies unused by normal appliances. It divides this unused "real estate" into 84 separate channels or carriers. Data is sent along in parallel, on many channels simultaneously to increase speed. When one channel becomes disrupted or signal decay is detected, the controlling chip transfers the data to another carrier line. This "rate-adaptive" error correction is responsible for the Ethernet-like quality of power line networking. As of mid-2005, the rate of speed is 14 megabits per second (mbps) with an anticipated increase to 100 mbps.

The older Passport technology originally used for power line networking has several disadvantages. Encryption has to be manually installed and implemented with this system. Passport technology is also slower, at about 50—350 kilobits per second, and electrical usage in the home can impact performance. Old wiring may also interfere with the older power line networking scheme, as it does not use OFDM, but frequency key-shifting, or FSK. This is a simple "two channel highway" at a frequency much closer to that of line noise, and easily disrupted.

The cost of connecting two computers and a printer using the OFDM PowerPacket technology is about US$59. Power line networking is an extremely easy, quick way to install a home network and may suit your needs. However, phone line networking, wireless, and Ethernet should also be considered before making a final choice.