Engineers at the Australian Communications and Media Authority have raised the prospect of utilising a small band of spectrum between 933 - 935 MHz for use in smart grids or cognitive radio.
The band was set aside in the mid-1990s by the Australian Government for the expected take-up of Digital Shortwave Radio.
Shortwave technology allowed users near any given telegraph pole to make wireless phone calls. It was made obsolete immediately by massive take-up of cellular (mobile phone) networks.
Dr Andrew Kerans, executive manager of communications infrastructure at the ACMA raised the band as a topic for discussion at this year’s RadComms conference, which starts today at Sydney’s Doltone House.
Dr Kerans said ACMA had noted some “empty spectrum set aside for technology that never took off” that could support smart meters or cognitive radio.
Like any policy decision, Dr Kerans said he assumed the Government had set aside the band for Digital Shortwave Radio after being “lobbied by proponents of this system that had put forward an argument it would take off.
“It’s another case of an interesting idea that came along, but was swamped by a more popular option.”
Dr Kerans proposed two technologies that might be suitable candidates for reallocation of the spectrum – the first being smart meters that monitor, control and ultimately attempt to minimise power usage in the home or business.
“At the moment, smart meters using spectrum that is quite noisy,” he said.
The other is for trials of what is termed ‘Cognitive radio’ – technology that dynamically changes transmission settings to avoid interference.
Described by Dr Kerans as a “radio system with a brain”, the technology could allow ACMA in the future to allow spectrum to be traded “in micro-second blocks”, assuming a fast enough auction system could be developed.
Unfortunately for ACMA, the original decision to put the spectrum aside was made under a “legislative band plan” – a scheduling of spectrum for a particular use that was ratified into law. A legislative band plan is usually required for spectrum the government intends to be fixed, such as for Defence networks.
The ACMA proposed that this instrument be reviewed in a 900 MHz band discussion paper released this month (pdf).
“It is one thing we intend to undo as it doesn’t allow us much flexibility,” Dr Kerans explained.
It meant that spectrum plans couldn’t be changed in line with rapidly evolving trends in technology adoption, he said.
ACMA prefers to use an alternative instrument – an ‘administrative band plan’. This would allow for ACMA to be ”very flexible” to keep up to date with technology change.
“The only disadvantage is that “any decision can be challenged in the AAT (Administrative Appeals Tribunal) as it is not made in law," he said.