Geesh! What the heck is going on down in Washington over at the Federal Communications Commission? Ever since broadband-over-powerline (BPL) debuted commercially in field tests a few years ago, radio interference has been plaguing the FCC’s Amateur Radio Service, and a report from NATO says BPL now threatens military radio users, too.
BPL technology, referred to in Europe as powerline carrier (PLC) or powerline telecommunications (PLT), uses the ac power infrastructure to transmit data. Running at speeds in excess of 1 Mbit/s, the physics of RFI is unavoidable; radios are picking up objectionable BPL noise. In some case, receivers in BPL test areas are unable to detect signals from distant stations. They’re simply covered by high levels of broadband noise.
With the emerging popularity of triple play service (voice, video, and Internet), BPL has bandwidth limitations. Nonetheless, the FCC continues to promote it as a viable alternative to cable and ADSL (asymmetric digital subscriber line). Electrical power lines are everywhere, they say, so BPL coverage could approach 100%. Perhaps blinded by dollar signs in the industries the agency is supposed to watchdog, the FCC contends BPL will reach every outlet in a home or office.
Fortunately, not everyone is as sanguine as the FCC. Some organizations are downright opposed to BPL. In the report just released by NATO, BPL is cited as a cause of interference to radio users of many stripes, not just attic and basement communicators.
NATO understands why power lines aren't much good for RF transmission. "BPL's unintentional RF emissions adversely affect the established radio noise-floor directly, or by cumulative propagation," reports NATO. It concludes that existing high-frequency (HF) background noise will probably increase through groundwave and/or skywave propagation from BPL emitters.
No COMINT
"Increase of the noise-floor by widespread use of BPL will bring up problems for HF military radio users as well as HF COMINT (communications intelligence) users," says NATO. "The SNR (signal-to-noise ratio) may be reduced for tactical and strategic HF radios as well as for fixed sensitive COMINT sites."
That's exactly what Amateur Radio operators are experiencing in BPL tests. "NATO's findings are based on good science," concurs American Radio Relay League lab manager, Ed Hare.
In his capacity as a ham radio advocate at the ARRL, Hare points to NATO's conclusion that protection levels well below 0 dBµV/m are needed to prevent interference to sensitive HF reception, and those levels haven't been reached. "NATO has advanced radio's state of the art," he adds, "determining that aggregate noise from large scale deployment of BPL will increase worldwide noise levels by skywave propagation."
Shut It Down
The ARRL is now suing the FCC, trying to force it to shut down at least one BPL pilot project, that of Ambient Corporation. ARRL attorneys object to the FCC's "inexplicable inaction" in the face of evidence gathered at Ambient’s Briarcliff Manor, New York BPL site.
ARRL argues that Ambient’s system is out of compliance with FCC-mandated RF interference rules. In a letter to the FCC's Spectrum Enforcement Division Chief, ARRL lawyers argue it's "long past time that the Commission enforce its own rules."
Bad Economics
But wait. There's more. Public debate about BPL is scanty, yet there are economic issues. "There are few details made public regarding the economics of BPL," argues Dr. Rahul Tongia, a research professor at Carnegie Mellon University's Department of Engineering.
"Because of its very nature, BPL is a shared medium, somewhat like cable," explains Tongia. "In contrast, DSL is a point-to-point connection. This has implications for the economics of BPL, as well as end-user throughput and security.”
"The FCC," says Tongia, is encouraging BPL, calling it a "monumental breakthrough in technology." Tongia contends the FCC "finesses a number of issues regarding ownership, open access and cost, to name a few."
Carnegie Mellon stochastic and parametric models, run using Analytica software, point to BPL costing about $35 a month. However, that figure doesn't include a provider's profitability. Tongia estimates actual uplinking bandwidth will cost between $80 and $100 per month. "Given the increased trend in peer-to-peer traffic, it isn't unreasonable to expect uplinking costs to remain high," he adds.
With improvements in DSL and cable, as well as eventual competition from fiber-to-the-home and wireless, Tongia envisions increasing competitiveness, and in that competitive environment equipment might need to be amortized sooner. "The implications are nonlinear," he reports. "In actuality, it's unclear whether there's a compelling business case for BPL, based on price for the end-user."
Cable’s Head Start
Tongia predicts BPL won't gain market share greater than a few percent, due to cable and DSL head starts. What's more, the technology isn't standardized, he says, with implementations varying from power utility to power utility. That makes BPL difficult to deploy.
"Even if BPL reaches one million users in three years," he states, "during that period cable and DSL will have improved significantly, perhaps by as much as 50%. The prices for cable and DSL are falling dramatically."
Ruining A Good Thing
Since 9/11, the Indian Ocean tsunami and Katrina, we’ve all benefited from decentralized ham radio communications. One reason it works so well in emergencies is that interference to the Amateur Radio Service is illegal. Hams operate in FCC-allocated bands of frequencies, where they’re protected from would-be radio intruders.
Now, what the heck is going on in Washington down at the FCC? Why is it attempting to get away with violating its own rules? The FCC should not permit and promote a communications technology that interferes with other FCC-licensed users of the spectrum, whether they're military, commercial, or even amateur.
The FCC's action is a deliberate breach of public faith and trust. It’s clear to me that jeopardizing licensed spectrum by BPL is unlawful. As far as I’m concerned, the FCC’s stance is downright un-American.
