Stephen Withers
Wednesday, 05 November 2008 07:14
IT Policy -
Government Tech Policy
Page 1 of 3
The US Federal Communications Commission (FCC) has decided to open the so called 'white spaces' in the TV spectrum for use by unlicensed devices for the delivery of wireless broadband services. Despite WiMAX and 3.5G services taking off in the US, will a new wave of wireless broadband soon be unleashed?
White space is radio-frequency spectrum that was reserved around TV channels when the system was first set up to prevent interference with broadcast signals.
More recently, wireless microphones used in theatres and other venues have been allowed to use some of these frequencies as the chances they would interfere with TV services was very small, but if wireless devices en masse start transmitting in these spaces, it's no surprise that. Much of the opposition to liberalising white space was due to TV stations' and wireless microphone users' fears of interference from unlicensed devices.
The approach adopted by the FCC is to require devices to use spectrum sensing to avoid interfering with nearby wireless microphones, although as a precautionary measure some channels have been reserved for wireless microphones in major markets.
Initially, manufacturers will be required to incorporate a geolocation facility that is used in conjunction with Internet access to a database of incumbent services. This will allow such devices to avoid interfering with nearby wireless microphones, TV stations, cable TV head-ends and other spectrum users.
In the future, the FCC may approve devices that solely rely on spectrum sensing following an especially rigourous testing process.
"Our testing has shown that this approach [spectrum sensing alone], right now, is not ready for prime time," said commissioner Michael Copps.
What will be involved in getting a device approved? See
page 2.
