Efforts to use electricity cables to transmit data took a step forward in Europe with the publication of an open specification for power line communications.The Open PLC European Research Alliance (OPERA), which is partly funded by the European Commission, said its specification will accelerate the development of products that use power lines for broadband Internet access, voice and video services, as well as utility applications such as automatic meter reading.The approval of the specification, announced Tuesday, comes after more than two years of development by a consortium of experts from 35 organizations, including 10 universities.Products based on the specification will deliver speeds of more than 200Mbps, according to OPERA. It is based on Orthogonal Frequency Division Multiplexing (OFDM) modulation and offers Frequency Division and Time Division repeating capabilities.Whether PLC will ever take off remains to be seen, however. Ham radio operators, particularly in the U.S., contend that broadband over power lines interferes with their radio signals. OPERA claimed in a white paper that its technology is "Ham radio friendly."Moreover, PLC competes head on with DSL and WLAN technologies in the local loop. In particular, WiMAX could pose a huge threat to PLC in rural areas where the Commission is keen to extend broadband coverage and, largely for this reason, has supported power line technology.Equally worrisome, early PLC deployments in Europe have mostly failed.A few years ago, Germany emerged as a hotbed of PLC development. Several regional electricity companies entered the fray, including Eon in D\u00fcsseldorf, EnBW Energie Baden-W\u00fcrttemberg in Karlsruhe and MVV Energie in Mannheim.Eon has since abandoned the PLC market, claiming the technology is too complicated and costly to deploy, with little chance of seeing a return on investment.Munich electronics giant Siemens had also hoped to be at the forefront of PLC. However, Siemens exited the market in 2001, citing regulatory delays and a lack of European standards.In 1999, Nortel, in Brampton, Ontario, pulled the plug on its PLC activities in the U.K., claiming the technology would remain a niche product at best. Like Eon, it saw little chance of recouping the millions of dollars needed to develop reliable products and market the service.OPERA hopes the publication of an open specification will change all that. Contained in the OPERA Technology White Paper, it can be downloaded from the group's Web site. Visitors must go to "Project Outputs," click on item "D59" and register with their e-mail address, name and organizationThe PLC network defined by the OPERA specification includes three types of PLC units: the head-end equipment, which connects the PLC network to the backbone infrastructure; the repeater equipment, which is used to extend the coverage of the network; and the customer premises equipment, which connects the end-user to a PLC access network.