By Bob Brewin
February 21, 2013
The Federal Communications Commission kicked off the formal process to allocate more federal spectrum for unlicensed Wi-Fi use in the 5 GHz band to support speeds in the gigabit range, a plan first announced by FCC chairman Julius Genachowski on Jan. 11.
The 35 percent increase in spectrum will not only boost Wi-Fi speeds, which today max out at 600 megabits per second, it also will give cellular carriers more bandwidth to handle customers’ increased data use, Genachowski said. Though carriers such as Verizon Wireless use their licensed spectrum to transmit data at six megabits per second, Genachowski said the carriers currently offload 33 percent of their traffic to Wi-Fi networks, and he predicted that would jump to 46 percent by 2017.
Commissioner Robert McDowell said that in 2012, mobile data traffic hit 207 petabytes per month -- the equivalent of streaming 52 million DVDs -- and predicted mobile data traffic will increase nine-fold over the next five years. He said 96 percent of mobile data traffic was carried on Wi-Fi devices at some point, which means the unlicensed spectrum is experiencing congestion, which can be relieved by new bandwidth.
The FCC plans to allocate 75 MHz of spectrum in a new unlicensed band that runs from 5850 GHz to 5925 GHz and tap another 120 MHz in the 5150 GHz-5470 GHz band used by existing Wi-Fi systems, the Defense Department, FAA and commercial systems.
Commissioner Ajit Pai said the FCC is precluded by statue from allocating new unlicensed spectrum unless federal users are protected from interference.
The FCC, in its Notice of Proposed Rule Making on the new Wi-Fi spectrum, said FAA terminal Doppler weather radar systems operating in the 5600-5650 GHz band used to detect cloud microbursts over airports have already experienced interference from existing Wi-Fi systems modified to operate outside their authorized frequencies.
The Defense Department operates multiple radar systems in the new planned Wi-Fi bands; NASA operates a space radar system used to determine ocean height; and licensed domestic and international communications carriers and the Defense Department operate fixed Earth stations in the bandwidth eyed for Wi-Fi.
FCC has proposed a number of technical solutions to prevent interference with these federal systems by Wi-Fi gear operating in the 5 GHz bands and it seeks input from Chip manufacturers on those proposals. These include software security features that prevent end users from modifying equipment for out of band operation; geo-location technology built into a Wi-Fi device that uses an automated database to detect location of radars; caps on transmitter power; and a dynamic frequency system, in use today with current 5 GHz Wi-Fi gear, which detects radars and then selects non-interfering channels for unlicensed use.
Defense and Homeland Security Department drones use the 5625-5850 GHz and 5250-5475 GHz bands for command and control operations, but FCC said existing Wi-Fi signal detection technologies may not be able to detect signals that could lead to “performance degradation” of drones.
Considering the benefits that an expanded Wi-Fi spectrum can deliver, the onus should be on federal users to support unlicensed use, Pai said. “I hope that we will consider whether Federal users should (emphasis included) alter their systems or operations to accommodate unlicensed devices in this spectrum and what solutions will work, keeping in mind the costs and benefits of all potential options.”
By Bob Brewin
February 21, 2013