History
The HomePlug Alliance was formed to develop standards and technology for enabling devices to communicate with each other, and the Internet, over existing home electrical wiring. One of the greatest technical challenges was finding a way to reduce sensitivity to the electrical noise that is inevitably present on power lines. Whenever an appliance is turned on or off, it creates electrical noise that can interfere with data transfer through the wiring. Noise sensitivity was problematic in early powerline technology, though later versions have solved this problem. Also, early powerline technology could not reliably communicate across different electrical phases. HomePlug solved this problem by increasing the communication carrier frequencies so that the signal is conveyed by the neutral conductor, which is common to all phases.
The first HomePlug specification, HomePlug 1.0, was released in June 2001. The HomePlug AV specification, which was released in 2005, increased physical layer (PHY) peak data rates from 14 to 200 Mbit/s. The HomePlug Green PHY specification was released in June 2010 and targets Smart Energy and Smart Grid applications as an interoperable "sibling" to HomePlug AV with lower cost, lower power consumption and decreased throughput. (HomePlug Command and Control low frequency specification was released in 2007, but later deprecated and replaced by HomePlug Green PHY.)
On September 30, 2010, the IEEE’s 1901 Broadband Powerline Standard was approved and HomePlug AV, as baseline technology for the FFT-OFDM PHY within the standard, is now ratified and validated as an international standard. The HomePlug Powerline Alliance is a certifying body for IEEE 1901 products. The three major specifications published by HomePlug (HomePlug AV, HomePlug Green PHY and HomePlug AV2) are interoperable and compliant. As of November 2011, there are 4 chip vendors that are shipping interoperable HomePlug AV chipsets with IEEE 1901 support (Broadcom, Qualcomm Atheros, Sigma Designs, and SPiDCOM) and millions of units are shipped each month throughout the world. Many HomePlug AV products are shipping from key vendors such as ATRIE Technology P Limited,Cisco, devolo, ZyXEL, D-Link, Logitech, NETGEAR and Western Digital. Major IPTV service providers such as France Telecom, British Telecom, and Deutsche Telekom are also shipping large volumes of HomePlug products. In November 2011, the HomePlug Green PHY specification was adopted by 7 key American and German automobile companies, Ford, General Motors, Audi, BMW, Daimler, Porsche, and Volkswagen, as a connectivity standard for Plug-In Electrical Vehicle.
Newer versions of HomePlug support the use of Ethernet in bus topology. This is achieved by means of OFDM modulation that enables several distinct data carriers to coexist in the same wire. Also, HomePlug's OFDM technology can turn off (mask) any sub-carriers that overlap previously allocated radio spectrum in a given geographic region, thus preventing interference. In North America, for instance, HomePlug AV only uses 917 of 1155 sub-carriers.
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