HomePlug Powerline Alliance
From Wikipedia, the free encyclopedia
HomePlug is an industry trade group for power line communication. This organization of about 50 companies define power line communication specifications. Currently at v 1.0. HomePlug 1.0 is the specification for a home networking technology that connects devices to each other through the power lines in a home. HomePlug certified products connect PCs and other devices that use Ethernet, USB, and 802.11. Many devices made by alliance members have HomePlug built in and to connect them to a network all one has to do is plug the device into the wall in a home with other HomePlug devices. Since surge protectors and similar devices may interfere with the high-frequency signals used by HomePlug, the directions included with HomePlug devices recommend plugging them directly into the wall outlets without using extension cords or outlet strips.
Contents |
[edit] Operation
Since the signals may travel a short distance outside the user's residence or business, like many other network standards, HomePlug includes the ability to set an encryption password. As with many other networking products, most HomePlug devices are Secure by default. The HomePlug standards require that all devices are set to a default out-of-box password - although a common one. Users should change this password.
To simplify the process of configuring passwords on a HomePlug network, each device has a built-in master password, chosen at random by the manufacturer and hard-wired into the device, which is used only for setting the encryption passwords. A printed label on the device lists its master password.
Since HomePlug devices typically function as transparent Ethernet bridges, computers running any operating system can use them for network access. However, some manufacturers only supply the password-setup software in a Microsoft Windows version; in other words, enabling encryption requires a computer running Windows [1]. Once the encryption password has been configured, Windows will no longer be needed, so in the case of a network where all computers run other systems a borrowed laptop could be used for initial setup purposes.
In residences and small businesses with Split phase wiring (common in North America), roughly half the 120-volt outlets in the building will be on each hot phase, and HomePlug signals may or may not be able to get from one side to the other. If one is unlucky, this may prevent some rooms from being connected via HomePlug.
[edit] Current and proposed functionality
The Ethernet data at either end of the HomePlug link is not encrypted (unless, of course, an encrypted higher-layer protocol such as https or a VPN is being used), only the link between HomePlug devices is encrypted, so the computers do not need to know anything about the encryption.
The original HomePlug 1.0 standard allows for speeds up to 14 Mbit/s. The current HomePlug AV standard allows for speeds greater than 100 Mbit/s (suitable for HDTV and VOIP) but still compatible with Homeplug 1.0. The alliance is developing a standard called HomePlug BPL for last-mile access networks.
The alliance certifies products for HomePlug compliance. Devices marked with the certification mark will interoperate with each other. However, they will not work with the newly-formed Consumer Electronics Powerline Communications Alliance (CEPCA) (Sony, Mitsubishi and Panasonic) which has developed powerline technologies which can offer speeds up to 170 Mbit/s.
On August 18, 2005 the HomePlug Powerline Alliance announced that its specification for HomePlug AV has been finalized and approved unanimously by the Board of Directors of the Alliance. HomePlug AV has been suggested to have a raw data rate of up to 200 Mbit/s with actual throughput rates around 100 Mbit/s.
Among other things, HomePlug brings back the ability to use Ethernet in bus topology, implied by its standard description (carrier sense multiple access and collision detection) and very desirable in some circumstances. This is achieved by use of advanced OFDM modulation that allows co-existence of several distinct data carriers in the same wire pair.
The HomePlug powerline alliance has defined a number of standards:
- HomePlug 1.0 — specification for connecting devices via power lines in the home
- HomePlug AV — designed for transmitting HDTV and VoIP around the home
- HomePlug BPL — a working group to develop a specification for to-the-home connection
- Homeplug CC — Command and Control is a low-speed, very low-cost technology intended to complement the alliance's higher-speed powerline communications technologies. The specification will enable advanced, whole-house control of lighting, appliances, climate control, security and other devices.
HomePlug is participating in the developing IEEE P1901 standard.
