Editing Internet access (section)

====Power-line Internet====
[[Power-line Internet]], also known as [[Broadband over power lines]] (BPL), carries Internet data on a conductor that is also used for [[electric power transmission]].<ref name="BERGU14">{{cite book|last1=Berger|first1=Lars T.|last2=Schwager|first2=Andreas|last3=Pagani|first3=Pascal|last4=Schneider|first4=Daniel M.|date=February 2014|title=MIMO Power Line Communications: Narrow and Broadband Standards, EMC, and Advanced Processing|publisher=CRC Press|series=Devices, Circuits, and Systems|isbn=9781466557529|doi=10.1201/b16540-1}}{{Dead link|date=January 2019 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Because of the extensive power line infrastructure already in place, this technology can provide people in rural and low population areas access to the Internet with little cost in terms of new transmission equipment, cables, or wires. Data rates are asymmetric and generally range from 256&nbsp;kbit/s to 2.7&nbsp;Mbit/s.<ref name="HSW-BPL">[http://computer.howstuffworks.com/bpl.htm "How Broadband Over Powerlines Works"] {{webarchive|url=https://web.archive.org/web/20120512090550/http://computer.howstuffworks.com/bpl.htm |date=2012-05-12 }}, Robert Valdes, ''How Stuff Works'', accessed 5 May 2012</ref>

Because these systems use parts of the radio spectrum allocated to other over-the-air communication services, interference between the services is a limiting factor in the introduction of power-line Internet systems. The [[IEEE P1901]] standard specifies that all power-line protocols must detect existing usage and avoid interfering with it.<ref name="HSW-BPL" />

Power-line Internet has developed faster in Europe than in the U.S. due to a historical difference in power system design philosophies. Data signals cannot pass through the step-down transformers used and so a repeater must be installed on each transformer.<ref name="HSW-BPL" /> In the U.S. a transformer serves a small cluster of from one to a few houses. In Europe, it is more common for a somewhat larger transformer to service larger clusters of from 10 to 100 houses. Thus a typical U.S. city requires an order of magnitude more repeaters than a comparable European city.<ref>[http://electrical-engineering-portal.com/north-american-versus-european-distribution-systems "North American versus European distribution systems"] {{webarchive|url=https://web.archive.org/web/20120507211603/http://electrical-engineering-portal.com/north-american-versus-european-distribution-systems |date=2012-05-07 }}, Edvard, Technical articles, Electrical Engineering Portal, 17 November 2011</ref>