The Wireless Institute of Australia (WIA) seriously doubts that broadband over power lines (BPL) technology can deliver on its promises while overcoming its radio frequency pollution issues. WIA Director Phil Wait said, "It sounds like a very good idea in principle, but we believe it will fall short on implementation."
Mr Wait, who coordinates the WIA's working group on BPL, was recently invited to appear on the weekly TekTime program on Melbourne's 3MDR FM community radio. The WIA is the national society representing the interest of radio amateurs.
He explained that BPL had its genesis or beginning in low frequency narrow band control signals sent down power lines to remotely control off-peak hot-water systems and telemetry for power distribution management.
"In the 1980s experiments were conducted in transmitting higher speed data over power lines and with the recent growth in the Internet people have been looking at developing another 'pipe' into the home.
"Someone found, only a few years ago, that if you pump enough broadband power down one end of the powerline out in the street something is going to come out at the powerpoint. And that's BPL as we know it," Mr Wait said.
The main attraction of the technology is its potential to overcome what is termed the 'last mile', the problem of getting cables into somebody's home.
Particularly in home units with the building jointly owned through a body corporate where cabling access permission is hard to get. Because of this cable-based telecommunications providers do not provide broadband to those buildings.
The WIA Director said the bandwidth that has been achieved through BPL tests in Australia so far is comparable with rates from ADSL cable.
He said "The very latest BPL chip claims to deliver much higher bandwidth. But with high bandwidth comes limited range and more susceptibility to interference. It's the same old story that you don't get something for nothing.
"There are two major problems with BPL technology. One is the interference it generates and is also susceptible to, and the other is the bandwidth."
Mr Wait said, "The power lines were never designed to transmit anything like broadband frequencies. They are full of discontinuities, they've got branches, leaky insulators and are not shielded an enormous distributive antenna that runs around a city."
He said that radiation from BPL has the potential to affect all HF radio users in Australia such as aviation, maritime, emergency services, long distance transport, broadcasting and amateur radio. The Australian Radiocommunications Act and the International Telecommunications Union radio regulations prohibit telecommunications services from causing harmful interference to radio services.
During a recent trial of BPL at Queenbeyan in New South Wales measurements were taken and confirmed similar results recorded overseas.
Mr Wait said there's a lot of research on trying to get the interference levels of BPL down, including the use of 'notching' to reduce certain frequencies.
However he said the notching is only achieving about a 20dB difference which is insufficient to protect HF radio users. Mr Wait said interference can also be a problem for the consumer using BPL technology. It is susceptible to disruption by radio signals interfering with it. The operation of BPL relies on it sharing frequencies already used by radio services.
He said, "A number of tests done internationally show that very, very low power levels in the order of a few watts can interfere with a BPL system.
"This has the potential to interrupt the BPL signal. It will either slow it down or make it go away."
He said there were limited BPL trials underway in various parts of the world and a driving element for them is often a political determination to spread the availability of broadband access.
"There is a lot of political pressure in the US to improve the access to broadband services in rural America. The US is lagging behind many other countries in broadband penetration.
"President (George W) Bush has come out and said that he supports virtually anything that is going to increase broadband," Mr Wait said.
The situation in America is also interesting because the Federal Communications Commission has established 'exclusion zones' prohibiting BPL near government radio installations, obviously in recognition of the potential for interference.
In Australia the WIA sees BPL as being attractive to utility companies who have been looking at ways to 'bundle' services, giving them the opportunity combine electric supply with a telecommunications service.
BPL also can enable power companies to remotely read electricity meters and achieve micro-level control over their networks in the future.
The WIA believes that there may be BPL in some areas of Australia. Mr Wait said, "We will certainty see things like 'homeplug' which is an in-house distribution system. We will certainty see home-networking within building using this sort of technology.
"But I think the reality of the situation when they start to deploy (BPL) networks they're going to have a lot of problems."
He said there are a number of trials, and a few commercial trials. Some have been shutdown for commercial or technical reasons, including interference. There is still a lot of interest in it.
"BPL will probably be trialed and may find application in some areas in a limited way," Mr Wait said. "One of the arguments being put for BPL is that is it useful in rural areas.
"Well it may be useful in rural towns but it is not much good out on remote properties because the cost I believe in getting BPL signal out there to start with is going to be too prohibitive."
He said the most encouraging (BPL enabling) technology that is coming out is wireless such as WiFi and WiMax, with its price dropping and capabilities rapidly improving.
Another option for power companies to enter the field of telecommunications is to string fibre-optic cable under the neutral power conductor, and then every now and then have a wireless node serving an area.
"BPL itself is quite a good idea. The WIA is not opposed to BPL per se, the Wireless Institute is opposed to the interference that BPL generates," Mr Wait concluded.
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