After the TRAI's recommendation on pricing of several spectrums, people might be thinking why 700 MHz band is priced so steep to 1800 Mhz band. The basic answer to this question is that lower level spectra can travel more with the same number of towers. In other words, operators would need to install much lower number of towers in lower-range spectra. As such, such spectra is more valuable.
Spectrum can be broadly divided into six classes. As their frequency (MHz) increases, their penetration power falls and the operators need to put more and more towers to cover the same area. It is approximately 70% cheaper to provide mobile broadband coverage at frequencies around 700MHz than using the core 3G frequencies at 2100 MHz.
Following is a short description on each of the spectrum bands currently being used in India.
700 MHz -- Used for terrestrial TV transmission (Doordarshan) and possibly ready for broadband use by 2015.
800 MHz -- Used for CDMA services (voice and EVDO high-speed data)
900 MHz -- Allocated to early GSM players such as Bharti Airtel and Vodafone for 2G voice
1800 MHz -- Allocated to late GSM players such as Uninor for 2G services
2100 MHz -- 3G services allocated in 2010
2300 MHz -- 4G spectrum (LTE/Wimax) allocated in 2010
2500 MHz -- 4G spectrum allocated in 2009 to BSNL