802.11af is beside developed to use the unused television channels in urban ares. These range from 54 MHz to 790 MHz. The standard employs cognitive-radio technology and geolocation database access to ensure that there’s no interference to local TV signals or other services operating in this region. The base station queries a database to see what channels are available locally for data transmission.
The 802.11af standard works with TV channels that have bandwidths of 6, 7, or 8 MHz. Modulation is OFDM using BPSK, QPSK, 16QAM, 64QAM, or 256QAM. The maximum data rate per 6-MHz channel is about 24 Mb/s.
So far 802.11af has not been deployed anywhere yet.