August 22, 2012
AT&T Disables Cell Tower Frequencies Interfering With Police Radios
redOrbit Staff & Wire Reports - Your Universe Online
AT&T Wireless has temporarily deactivated a frequency used by 16 of its cell-phone towers after they were found to be interfering with radio communications among police officers and firefighters in Oakland, California, the San Francisco Chronicle reported on Tuesday.
Oakland officials said they notified AT&T about the problem last week, and that the wireless carrier is cooperating with their requests.
A spokesman for AT&T told The Chronicle that the impact on customers would be minimal, and would only affect subscribers using the company's oldest mobile phones.
David Cruise, Oakland's public safety systems adviser, said the 16 cell towers continuously interfered with public safety radios, particularly when a police car was within a quarter to half a mile of a tower.
"If the officer is in an area close to one of their cell sites, essentially the cell site overpowers their radios," he told The Chronicle.
However, the number of officers reporting no radio connection fell immediately after the frequency was curbed at the first cell site, he added.
The city's public safety radio communications system has experienced repeated failures, with officers routinely losing contact with dispatchers and each other. Furthermore, the radios do not work in hundreds of buildings, including the basement of Oakland´s police headquarters.
Last July, during a visit by President Obama, police radios went down entirely after the president had left town.
Cruise stressed that cell tower interference was only one part of the city's probe.
"Our investigation is continuing," he said.
"This is not the end of it, for sure. There are plenty more issues we're looking at. We're working on plans to remove all of them,” said Cruise, who was hired in early August, in part, to help resolve the problem.
The city will also be investigating cell phone towers of other carriers, particularly T-Mobile, which uses a frequency that might also interfere with public safety radios, Cruise said.
Oakland worked with the Federal Communications Commission (FCC) to investigate the police radio communications problems, and mapped the various locations of radio blackouts, Cruise said. After analyzing these maps, investigators concluded that cell phone interference was playing a role. The FCC confirmed these suspicions on Thursday, and AT&T disabled the problem frequency the following night.
FCC rules give public safety agencies priority in communications, Oakland city officials said.
AT&T spokesman John Britton told The Chronicle that the company´s cell towers emit three distinct frequencies: 850 MHz, 1900 MHz and 700 MHz. Additionally, the carrier operates three different cellular networks - 2G, 3G and 4G.
The company temporarily shut down the 850 MHz frequency for 2G customers only. AT&T´s 2G network is the company's oldest, meaning few customers would be affected. Those on 2G are using some of the company's oldest cell phones, and would still be supported in the affected areas on the 1900 MHz frequency, Britton said.
While AT&T does not divulge the specific number of cell towers it has in Oakland, Britton said the carrier has more than a thousand towers in the Bay Area.
Cell-tower interference is not unique to Oakland, or to AT&T. Sprint Nextel is investing over a billion dollars nationwide to relocate public safety radio frequencies, something known as ℠re-banding´. The carrier paid $10.5 million in direct costs to shift Oakland's $7.5 million radio system to a frequency further from the city´s network, Cruise said.
Oakland moved to its new frequency in July 2011. The company that installed the city´s radio system did check for interference, although it is not clear how close it got to each of the cell towers, Cruise said.
"Unless they drove close to a cell site, they wouldn't have seen this.”