The IEEE published the 802.22 standard for Wireless Regional Area Networks (WRANs) using the favorable transmission characteristics of the VHF and UHF TV bands. 802.22 enables broadband wireless access over a large area up to 100 km from the transmitter. The standard specifies up to 22 Mbps per channel without interfering with reception of existing TV broadcast stations, using the so-called white spaces between the occupied TV channels.
IEEE 802.22 incorporates advanced cognitive radio capabilities including dynamic spectrum access, incumbent database access, accurate geolocation techniques, spectrum sensing, regulatory domain dependent policies, spectrum etiquette, and coexistence for optimal use of the available spectrum. Some key characteristics:
- It operates generally in the 54-862 MHz range. For the United States, it specifies the following VHF / UHF Bands54 – 60, 76 – 88, 174 – 216, 470 - 608 and 614 –698 MHz => Total of 282 MHz or 47 Channels.
- Network Topology – Point-to-Multipoint (PMP)
- Max EIRP and Cell Radius – Fixed BS and Fixed Subscribers using 4W EIRP, Cell Radius 10 – 100 km. Portable Subscribers Station Supported. (Higher power BS allowed in other countries)
- Tx / Rx antenna – BS uses sectorized or omni-directional antenna. At the subscriber Tx /Rx antenna is directional with 14 dB of front-to-back lobe suppression
- Sensing antenna - Requires horizontal and vertical polarization sensitivities to sense TV and microphone signals respectively, with omni-directional pattern.
- Geo-location - GPS based geo-location is mandatory, but terrestrial geo-location (triangulation) is supported.
- PHY Transport - 802.22 uses Orthogonal Frequency Division Multiplexing (OFDM) as transport mechanism. Orthogonal Frequency Division Multiple Access (OFDMA) is used in the UL.
- Modulation - QPSK, 16-QAM and 64-QAM supported.
- QoS – Various types of QoS services are supported (See below). ARQ supported. Uni-cast, Multi-cast and broadcast services are supported.
The IEEE expects 802.22 to be most suitable for less densely populated areas, such as rural areas, and developing countries where most vacant TV channels can be found.
Additional information on the standard can be found at the IEEE 802.22 WG page. http://www.ieee802.org/22/
