Though the word spectrum has been used frequently in the world of mobile phones,

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it is not easily understood by the consumers. Spectrum is the full range of electromagnetic radiation. Such radiation varies from very long radio waves of thousands of kilometres wavelength to microwaves, infrared, visible, ultraviolet, x-rays and gamma rays, the latter having a wavelength less than the size of an atom.

Each of these radiations has a wavelength and frequency at which it oscillates. Radio waves are a medium for carrying voice and data signals. Globally, radio frequencies are identified for different type of services – mobile services, fixed telecommunications, satellite and broadcasting, radar and radio services. Frequency bands are groupings of radio frequencies that are used by mobile networks to communicate with mobile phones.

Once a frequency band is identified for allocation, different slots are allotted to mobile operators (400 MHz or mega hertz is the start-up spectrum in India) in the same frequency band. The slots are offered so that it dose not create interference in service among different operators. It is similar to FM radio or TV channel bands allotted to different radio and TV stations.

Identification of frequency bands or radio waves for different types of services is known as the ‘harmonisation of spectrum’. Based on frequency identified for telecom, mobile operators are allocated frequency bands. Once the bands are allotted, operators set up base stations (which includes switches) to convert radio signals to voice and data signals.

Across the globe, different frequencies are used for mobile networks. The first commercial standard in the history of telecom was in the US in the 800 MHz frequency band. In some countries in Europe, the mobile network was based on the 450 MHz band. In India, for the existing mobile network, 2G (second generation) frequency bands are 900 MHz, 1.8 GHz, 1800 MHz and 1900 MHz.

According to the Department of Telecommunication, 3G systems represent the next step in the evolution. While 2G systems focus on voice communication, 3G systems allow high speed data transfer of a minimum of 144 kbps, mobile internet access, entertainment and other complex uses. They have greater capacity and reach than 2G systems.

Broadband wireless access (BWA) technologies enable high-speed data communication over wireless links. It can creat crucial advantages over fixed line broadband systems based on cable networks or digital subscriber line (DSL), in terms of better coverage, speedy deployment, high scalability, lower maintenance and upgradation costs. Also, it allows phased investment to match market growth.

The ‘right’ to use spectrum at specified frequencies are being offered by the government in the 3G auction. This includes 20 MHz of paired spectrum in the 2.1 GHz band in the telecom service areas. The next step, 4G, refers to the fourth generation of cellular wireless and is a successor to 3G and 2G standards.

According to the International Mobile Telecommunications, a 4G system may upgrade existing communication networks to offer facilities such as voice, data and streamed multimedia to users on an ‘anytime, anywhere’ basis and at much higher data rates compared to previous generations.

The 4G spectrum is being developed to accommodate forthcoming applications like wireless broadband access, Multimedia Messaging Service, video chat, mobile TV, HDTV content, Digital Video Broadcasting, voice and data, and other services that utilise wider bandwidth.

The 4G working group’s objectives are clear: it wants an efficient spectrum use, higher network capacity, more simultaneous users per cell, enhanced connectivity when a client moves at high speeds relative to the station, and a data rate of at least 100 Mbit/s between any two stationary points, smooth movement across heterogeneous networks, seamless connectivity and global roaming across multiple networks.

What still left to be finalized in 4G? Well, pending are a number of spectrum allocation decisions; standardization; technology innovations; component development: signal processing and switching enhancements; as well as inter-vendor cooperation. The 3G experience – good or bad – will be useful in guiding the industry into what’s next.