The use of power lines for telecommunications is proving to be a more elusive commercial proposition than some of the more enthusiastic proponents would have led us to believe. This has been dramatically demonstrated by the recent unexpected demise of the Nor.Web Digital Power Line (DPL) venture, as reported in this month's news, and that of RMS Communications Systems earlier this year.
Nor.Web, a joint venture of Nortel Networks and United Utilities (which includes Norweb, the UK electricity and gas distribution company) was founded just two years ago. The aim was to commercialize Norweb's pioneering research (under Professor Paul Brown) which had demonstrated that high speed data connections were possible through the existing power cable infrastructure.
Low frequency power line communications for telemetry and monitoring have been in use for a number of years, but in 1992 Norweb made a major breakthrough when its research demonstrated that, with ingenuity, high frequency signals (over 1 MHz) could be successfully propagated over operational power distribution/transmission networks.
1995 saw the first customer trials of a power line based telephony system, using adapted mobile radios supplied by Nortel. In the trial 25 residential customers were provided with 32 kbit digital voice communication and several also used the system for Internet access. In 1996 and 1997 successful trials were completed in the USA, Australia and Germany.
Nor.Web, founded in 1997, achieved a great deal during its brief life. At the time it was closed down, its technology had been well proven in trials involving no less than 18 networks in ten countries. Around £15-20 million had been spent and the company employed about 50 people.
Nor.Web had built up a strong portfolio of intellectual property rights in the power line communications area, eg covering filtering and signal input and removal. Indeed it has a base patent covering propagation of signals over 1 MHz, which might require any operators of power line communications to become licensees.
So why was the plug pulled? According to Nor.Web's backers, "the projected volumes and profitability within the competitive broadband access market" were "insufficient to justify the investment required".
The Nor.Web idea was to use power line communications to provide high speed data services to homes, schools, smaller businesses and the SOHO (small office, home office) sector. The initial concept did not anticipate providing real time voice communication, nor did the technology lend itself to making use of in-building wiring to provide broadband "home networking". Home networking provides considerable added value for end-users and has been attracting interest from major players recently. For example Ericsson and a consortium including Microsoft, IBM, Motorola and Hewlett Packard are looking at radio-based systems, while a consortium of 3 Com, AT&T, Compaq and Hewlett Packard is developing technology which can use in-building copper telephone cable as a high bandwidth network.
The Nor.Web technology was facing some regulatory issues, eg concerning the irradiation of high frequency signals. There was also some stiff competition from other technologies.
One major attraction of powerline telecommunications is the large bandwidth delivery it can potentially provide, but when it comes to increased bandwidth the competitors are not sitting still and the target is constantly moving. For example ADSL (Asymmetric Digital Subscriber Line) promises to vastly increase the data handling capabilities of ordinary copper phone lines.
It is however far too soon to write the obituary for power line telecommunications. The process of transforming a good idea into commercial reality is rarely free of problems and surprises. The use of existing power cables for telecommunications remains an inherently attractive proposition.
But power line telecommunications has yet to find its particular market niche, its killer application. The RMS Communications strategy focused on automated meter reading, which apparently could not pay its way. The Nor.Web game plan targetted the very competitive area of data services but its technology was not geared to making use of in-building wiring. Other players in the power line communications field, while building on the Nor.Web experience, are looking at different approaches, including provision of 10 Mbit home networking on in-building power networks and real time voice communication. There are also companies developing powerline telecommunications technologies which potentially could deliver much greater bandwidth than the Nor.Web technology (for example, using OFDM (Orthogonal Frequency Division Multiplexing)). Nevertheless it seems likely that at least some of the technology pioneered by Nor.Web DPL will be taken up by other companies in the field. There might even be an attempt to relaunch Nor.Web under new ownership.
The demand for bandwidth is proving insatiable and it is likely that power line telecommunications systems will have a role to play. But it will take another few years to determine what precisely this role is to be.
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