Abstract
Software-Defined Radio (SDR) is a rapidly evolving technology that is receiving enormous recognition and generating widespread interest in the telecommunication industry. Over the last few years, analog radio systems are being replaced by digital radio systems for various radio applications in military, civilian and commercial spaces. In addition to this, programmable hardware modules are increasingly being used in digital radio systems at different functional levels. SDR technology aims to take advantage of these programmable hardware modules to build an open-architecture based radio system software.

SDR technology facilitates implementation of some of the functional modules in a radio system such as modulation/demodulation, signal generation, coding and link-layer protocols in software. This helps in building reconfigurable software radio systems where dynamic selection of parameters for each of the above-mentioned functional modules is possible. A complete hardware based radio system has limited utility since parameters for each of the functional modules are fixed. A radio system built using SDR technology extends the utility of the system for a wide range of applications that use different link-layer protocols and modulation/demodulation techniques.

Commercial wireless communication industry is currently facing problems due to constant evolution of link-layer protocol standards (2.5G, 3G, and 4G), existence of incompatible wireless network technologies in different countries inhibiting deployment of global roaming facilities and problems in rolling-out new services/features due to wide-spread presence of legacy subscriber handsets.

SDR technology promises to solve these problems by implementing the radio functionality as software modules running on a generic hardware platform. Further, multiple software modules implementing different standards can be present in the radio system. The system can take up different personalities depending on the software module being used. Also, the software modules that implement new services/features can be downloaded over-the-air onto the handsets. This kind of flexibility offered by SDR systems helps in dealing with problems due to differing standards and issues related to deployment of new services/features.

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