Public-safety and vendor officials have continued their debate concerning the appropriate emissions mask for equipment operating in the newly allocated 4.9 GHz spectrum for first responders.
At issue is whether the emission mask for 4.9 GHz equipment for wireless broadband applications should be tight enough to avoid interference issues — the position of industry giant— or be loose enough to let public safety reap the economic and innovation benefits of using commercial off-the-shelf equipment used in the unlicensed band at 5 GHz.
Motorola believes the mission-critical nature of public-safety communications is worthy of a tighter mask to prevent interference issues from arising in the future, according to Chuck Jackson, vice president and director of systems operations at Motorola.
“We just spent three years arguing over interference at 800 MHz,” Jackson said. “Why would we want to risk repeating that with this spectrum?”
But National Public Safety Telecommunications Council representatives fear the tighter mask will prevent many commercial vendors developing similar equipment at 5 GHz from entering the public-safety market.
“[Vendors like Motorola] don't want to see nine vendors on a bid,” said Steve Devine, patrol frequency coordinator for the Missouri Highway Patrol and chairman of NPSTC's 4.9 GHz Task Force. “And we don't want to send out a request for proposal and get two bids.”
The concern is that a limited number of vendors cannot possibly maintain the pace of innovation that will be realized in the commercial market, he said.
“We need to keep abreast with the refresh period,” Devine said. “If we only have two manufacturers, we can't do it.”
Also, as 802.11 technology evolves, Devine said he expects the price gap between public-safety and commercial equipment would widen if a tighter mask is required at 4.9 GHz — a scenario that has occurred in the oft-proprietary arena of public-safety voice communications.
“It might not be much more today,” Devine said. “But we're talking about a refresh period of every two to three years, which is something [public safety has] never been able to do before.”
As for interference concerns, Devine noted that public safety's greatest protection is that it has exclusive use of the 4.9 GHz band. In addition, most broadband data applications are not mission-critical. “We get along without them now,” he said. Those that are may be worthy of a tighter mask, but public safety should make that decision, not industry vendors, according to Devine.
Devine also said he believes the vendors seeking the tighter mask and the Federal Communications Commission may be overlooking the fact that incident commanders provide on-scene interference avoidance strategies at incidents.
“They make it seem like we won't manage it, like we're a bunch of drunken hooligans at a soccer game,” Devine said.
Devine notes the impact of interference on data applications operating at 4.9 GHz is not as much of a problem as interference with voice applications. “Interference will be detrimental but not debilitating,” Devine said. “It will just go slower, not stop altogether.”
Jackson said Motorola's engineers believe the tighter mask standards can be met with external filters, which would limit the impact on the more cost-sensitive chipsets required in the radios. Regardless of the FCC's decision, Motorola plans to use the tighter mask for its products, which are being beta tested and are expected to be available by the end of the year or during the first quarter of 2005, he said.
Meanwhile, Jackson expressed optimism that the various parties are close to a compromise on the emissions-mask issue.
“The industry and public safety are pretty close on this,” Jackson said.
Devine also said he believes the FCC will try to proceed quickly on the matter after deciding the contentious issue of addressing interference for public-safety communications at 800 MHz.
“[The 4.9 GHz emissions mask proceeding is] supposedly on the calendar,” Devine said. “What's bogging it down is [the 800 MHz interference proceeding]. Once we get past that, I think things will move a lot faster.”
In addition to deciding on an emissions mask for 4.9 GHz equipment, Devine said the FCC also needs to clearly give regional planning committees authority to enforce their plans. Unless this is done, individual licensees can undermine the integrity of regional plans, he said.
“If the FCC doesn't give [regional planning committees] authority, it will be tough to manage,” Devine said. “If there is no authority, it's basically unlicensed commons spectrum.”