High speed powerline comms come home20 February 2001
High speed powerline communications (PLC) technology was included in a recent demonstration of a new standard for home networking.
While the use of powerlines for providing telecommunications services into the home has certainly proved more of a challenge than some of the early proponents would have expected, it is an area still attracting interest around the world.
One place where powerline telecommunication technology would appear to have a clear potential niche is its application to providing a network within the home, ie home networking. Whether its use can be extended to the access side of the meter/consumer unit remains to be seen, but the potential rewards would obviously be considerable. The access providers are looking for a reliable, dependable, predictable method for connecting to all types of consumers’ homes, and powerline could fit the bill. It minimises the need for expensive installation or service visits to a consumers home. In essence, the consumer need only check that devices are plugged in and the utility service provider can simply manage services remotely via a power distribution system that is already in place.
Low speed systems for applications such as meter reading are already available, while high speed technology would open the door to additional services related to telephony, entertainment and other control/automation services.
On the home networking side, high speed powerline communications technology was given a boost in January when it was used as part of the US Consumer Electronics Association’s Versatile Home Networking (VHN) demonstration. This was claimed to be the first ever demo of a true, protocol independent, multiple application home network.
The exercise involved powerline telecommunications pioneer Adaptive Networks (along with Sony, Philips, Leviton, Lexmark, Thomson Consumer Electronics, Samsung, Telcordia, Zayante, Echelon, QP-C, and MetroLink). Adaptive Networks contributed the high-speed powerline communications component of the demonstration, which included multiple simultaneous streams of audio and video over standard electric powerlines.
Clearly multi-megabit speed is required to handle the distribution of broadband around the home to all devices plugged into the powerline and thus into the home network. Home-wide connectivity is essential. Any networked device, wherever in the home, that it is plugged into the network, must be able to hear and be heard. Applications such as streaming audio and video, and telephony must have priority over applications such as printer sharing and lighting controls, whose requirements for the network are far less demanding.
Versatile Home Networking is a standard for seamlessly connecting all network-capable devices in a home. It uses Internet protocol (IP) to communicate between products, clusters of products, and to services outside the home using an IEEE1394b backbone. The VHN aims to provide a standard home intranet, allowing any product in the home to communicate with any other product in the home, regardless of the communication protocol they use.
In the absence of the VHN, the “home network” is actually not a true network in which all resources are shared and share data, but is really a group of unrelated clusters of networked devices. One such cluster might be two PCs sharing a printer. Another cluster could be a DVD player connected to a TV and stereo system. VHN enables these clusters to communicate with each other and thus exist as a single, true home network. The demonstration, based on the VHN initiative, is the first of its kind to show a multitude of hitherto unrelated devices not only coexisting, but also co-operating with each other in a home network. Once a utility services company has access to a consumer’s home, they would have a high degree of flexibility in connecting to devices and appliances with the VHN approach.
Using adaptive wideband signal processing technology and networking protocols, Adaptive’s High-Speed Powerline (HSP™) networking chip reliably transforms any electrical outlet in the home into a network interface for consumer electronics, multimedia appliances, PCs etc. The HSP chip set combines powerline-optimised wideband spread spectrum modulation, adaptive synchronisation and equalisation, error-control coding and powerline-optimised token passing protocols.
The high-speed (ie multi megabit) technology used in the VHN demonstration is based on Adaptive’s low-speed (100 kbps) powerline communications technology, which is already being used in commercial/industrial applications. In 2000, for example, this technology was selected as IEC’s draft standard for automated meter reading. Also, some years ago it was selected by the International Standards Organization as the standard for powerline communications aboard refrigerated container ships for the monitoring of perishable cargo. It also meets the criteria for reliability and speed of response demanded by such applications as factory automation and credit card transactions.
Few applications represent as natural a fit for powerline communications as automated meter reading. IKUSI of Spain, for example, has employed Adaptive Networks’ powerline communications technology in a turnkey meter reading system. This was deployed first for the electric utility Iberdrola. Electricity consumption information is read at the electricity meter and is transmitted back to the utility over LV powerlines that are delivering the electricity.
In the refrigerated container market, powerline technology is used to communicate information about the condition of each container to the ship’s bridge.
The technology has also been used for controlling cranes by sending signals over the electrified rails on which the cranes move, for train passenger information displays, for vending machine monitoring and for the interfacing of portable cash registers to a price-look-up and credit-card transaction-processing network using a store’s existing mains wiring.
The basis of the Adaptive Networks technology is a hierarchical approach, with very short packets, rapid synchronisation, adaptive equalisation, rigorous error control coding and noise-immune token passing.