Introduction
In India, there is a lot of excitement around on TV white spaces. Naturally so, as the targeted TV UHF Band IV spectrum (470 – 585 MHz) is at a much lower frequency – enabling the radio signals to travel much further. The lower the transmission frequency, the larger is the reach of the radio signals (it is just physics and has very little to do with technology in use). Whereas the mobile telephony spectrum bands operate at a higher frequency, the lowest among them is the 800 MHz CDMA band (824-844/869-889 MHz). Hence, if we operate cellular technologies in the TV UHF Band IV spectrum, then the coverage will be much better compared to all other cellular bands currently in use.
Broadcasting Services in TV UHF band has the best coverage
So why aren’t we operating cellular technologies in TV UHF Band IV? The key reason is that this band is globally used for high power terrestrial TV broadcasting and not available for cellular usage. The lower frequency spectrum is excellent for broadcasting (lower the frequency better is the coverage), more so when the transmission being unidirectional (subscriber terminal does not transmit back to the tower) the reach of the tower can be in hundreds of kilometers (resulting in fewer number of broadcast towers). On the contrary, the coverage of the conventional bi-directional cellular telephony is constrained by the handset’s capability to transmit back to the tower, and not limited by the tower’s capability to reach the subscriber. The handsets unlike towers need to conserve battery and therefore, have to transmit at a much lower power level compared to what towers can, and therefore if TV UHF band was to be used for cellular telephony, the coverage will be much lower compared with TV broadcasting.
