Half the emergency spectrum meets double the demand: ACMA

The Australian Communications and Media Authority (ACMA) has responded to claims made by Victorian Premier Ted Bailieu that its decision to allocate only 10MHz of the 800MHz spectrum to emergency services has put lives at risk.

Earlier this week, Bailieu said that lives would be put at risk by not giving public safety authorities (PSAs) the spectrum they requested. Also against the decision was Motorola Solutions Australian MD Gary Starr, who said that the decision mortgaged Australia's future and that company was disappointed with the outcome.

ACMA's decision on the spectrum allocation meant that PSAs would receive two 5MHz segments of spectrum from the 800MHz band and an additional 50MHz from the 4.9GHz, rather than the two 10MHz segments of 800MHz spectrum originally requested by PSAs. At the time of its decision, ACMA provided the reasoning behind the decision for reduced spectrum, stating that its own projections for demand on the network indicated that 20MHz of 800MHz spectrum would be "largely under-used".

Starr has since remained adamant that 20MHz of spectrum is the "minimum required for public safety to go about their day-to-day work," prompting ACMA to release even more of the details behind its decision.

ACMA Chairman Chris Chapman said that its calculations were derived from data provided from the PSAs themselves and, "based on a standard LTE deployment", even 6 MHz of spectrum would more than meet operational needs.

"The modelling shows the only way the 5 + 5MHz allocation would be overloaded for PSAs' normal operational needs is if the demand per cell was to increase by 135 percent over and above what PSAs themselves estimated for these scenarios. This would be equal to 2.35 times the original design requirement set by PSAs."

If, in the event that demand more than doubles, Chapman also said that PSAs will be able to immediately, but temporarily, increase the scale of the network by roaming on to carrier networks or using additional mobile cells.

"Where a permanent increase is needed, PSAs will be able to enhance their capacities simply by increasing the number of base stations in any given area. This provides key, inbuilt future-proofing."

ACMA may have conceded the additional 50MHz of spectrum offered in the 4.9GHz band, however. Starr described the extra spectrum as simply masking the issue, and likening it to a "mobile broadband hotspot" due to the characteristic of radio coverage to decrease in the higher ends of spectrum frequency.

Chapman didn't dispute this argument, even calling them Wi-Fi-like hotspots himself, but pointed out that they are another tool for PSAs to use, and that the core 5 + 5MHz allocation already provided a strong, robust network.

Coupled with an additional 25MHz from the 400MHz band, Chapman said that ACMA has already given PSAs considerable spectrum — a total of 85Mhz — that would meet their needs and provide them with the ability to scale their communications, should they need to.