When the mobile phone was first launched about two decades ago, not many envisioned that such a bulky and expensive device would go on to become one of the world’s most indispensable modes of communication. But despite its omnipresence many people are still ignorant how it functions.

Energy travels in the form of waves known as electromagnetic waves. These waves differ from each other in terms of frequencies. This whole range of frequencies is called the spectrum. In telecommunication like TV, radio and GPRS, radio waves of different wavelengths are used. They are divided into bands based on frequencies (see ‘Radio spectrum’). Mobile phones use two technologies based on different parts of the radio spectrum— GSM (global system for mobile communications) and CDMA (code division multiple access).

Most of the radio spectrum is reserved in countries for defence. The rest is available for public use. But following an increase in the number of phone users and new services, countries started auctioning the frequencies to telecom companies.

This sale has become a major revenue earner for governments around the world. But in India, the case is different (see ‘How India lost to scams’). It is currently auctioning the spectrum in the range of 1959-1979 MHz. This, however, is not sufficient to meet the growing appetite for mobile phones and its services.

Telecom industries are now looking towards new options. S band spectrum, for instance. The frequency of radio waves in this band ranges from two to four GHz.

S band was allocated by the World Radiocommunication Conference, organised by International Telecommunication Union (ITU), in 2000 for terrestrial mobile communications services.

ITU is a UN body that regulates information and communication technology issues. S band was initially used by meteorology departments and communications satellites. Mobile phones entered India based on 2G technology (see ‘Evolving mobile technology’).

Sixteen years later, demand for advanced technologies prompted the government to auction 2.1 GHz band for 3G services.