The 802.22 working group, founded in 2004, has the title Wireless Regional Area Network(WRAN) and deals with the standardization of regional radio networks. This technology is intended to realize high-speed connections in a regional area of up to 100 km. And it will be used everywhere where wired DSL technologies are not yet available nationwide.
In wireless regional area networks, radio transmission takes place in unused television bands or in the security frequency bands that lie between the television channels in the VHF range and in the UHF range. These frequency bands belong to the White Spaces. With Cognitive Radio, there is a technique to use such unused TV bands or little used frequency bands, such as the White Spaces, for transmission purposes. The bandwidth of the television channels is 6 MHz, 7 MHz or 8 MHz, depending on the frequency range in which they are located; the bandwidth of the intermediate bands is 1 MHz. The Federal Communications Commission( FCC) has approved license-free use of these frequency bands.
Working Group 802.22 specifies the air interface with Wireless RANMedium Access( MAC) and the physical layer, as well as the policies and procedures for operation in the television bands. The terrestrial television frequency range between 54 MHz and 862 MHz is available for this radio technology. Particular attention is paid to avoiding unwanted interference, which can occur between analog and digitaltelevision and other radio-related equipment. This is prevented by the cognitive radio technique, which is of central importance in wireless regional area networks.
The structure of 802.22 consists of base stations to which subscriber terminals are connected in point-to-multipoint links. The base station transmits data to the subscriber terminals via the downlink at 1.5 Mbit/s, and in the uplink, data is transmitted from the terminals to the base station at 384 kbit/s. In addition, the base station manages the access of the terminals to the radio channels, which is done with Orthogonal Frequency Division Multiple Access( OFDMA), and the Cognitive Radio, which scans the frequency bands for unused radio channels.
In addition to the basic 802.22 standard, there is 802.22.1, a standard that deals with protection against interference that occurs at low transmission power. There is also the 802. 22.2 standard for the provision and installation of 802.22 systems.