Powerline Communications Extend Converged Home Networks

Within the past few years, American homes have become saturated with new forms of communications. Digital phones, data, and entertainment services such as video over IP were novelties in the home a decade ago, and are now commonplace, with more on the way. As the need to share different types of information among these systems becomes increasingly evident, service providers are looking for networking technologies that are capable of converging data, voice, and audio/video for delivery throughout the home. The solutions they discover should employ existing physical media whenever possible, since the converged home networks will have to be easy for consumers to understand, use, and afford.

One type of network that comes close to fitting the bill is the household electrical grid. Residential powerlines are not usually thought of when considering communications networks, but in many cases, they can provide an excellent medium for home networks transmitting converged digital services. With an average of over 40 power outlets in a typical U.S. home, each one becomes an entry point into a potential home network. In comparison, there are fewer numbers of coaxial cable or telephone jacks. As different technologies become spotlighted by various suppliers and the pros and cons become more evident, consumers and service providers may soon begin to take advantage of this valuable but overlooked resource.

Advantages of Powerline Communications

Consider the physical media available in todays typical home.

Telephone Lines Over 95 percent of U.S. homes have phone lines based on copper-based twisted-pair, but the number of telephone jacks in a home typically dont number more than six or seven. Bandwidth on the phone network may vary, depending on the wiring, but is usually reasonably high.

Coaxial Cables Over 90 percent of homes have coaxial TV cable, and coax is high-capacity by design. But, like telephone jacks, the number of coaxial cable jacks seldom number more than five or six.

Category 5 Wiring Like coax, Cat 5 is satisfactory for the high throughput requirements of digital video, but these networks normally go to only certain rooms in the house, and they provide a single outlet in each room. In addition, Cat 5 is available in less than 10 percent of U.S. homes and, thus, requires a laborious installation for a majority of Americans.

Household powerlines, on the other hand, go to every room and provide multiple sockets in each. If the electrical network were used for communications, every power outlet in the house would be a potential connection.

Wireless local area networks based on the 802.11 standard, are intended to reach everywhere in the home or at least they should. To their credit though, WiFi systems are inexpensive and easy to install and, as a result, they are already widely deployed as laptops with WiFi have also proliferated both consumer and business PC arenas. Unfortunately, wireless LANs do not have enough capacity for multiple streams of high-quality video and, in many installations, they vary in their transmission data rate and range, due to local interference such as cordless phones and other devices that use the same frequency spectrum. For data networks, wireless drop-offs normally do not present a serious problem because PCs (notably laptops) can be moved around for better reception, and the traffic tends to be low bandwidth, low priority data. But, for high bandwidth content that has to be received in real time, such as HD or SD video, erratic transmissions are unacceptable. As for the future of wireless LANs, the Ethernet 802.11n standard is intended to address these issues in the near future.