Why We Need Software Defined Radios?

With the emergence of new standards and protocols, wireless communications is developing at a furious pace. The concept of integrated seamless global coverage requires that the radio support two distinct features: first, global roaming or seamless coverage across geographical regions; second, interfacing with different systems and standards to provide seamless services at a fixed location. Multimode phones that can switch between different cellular standards like IS-95 and Global System Mobile (GSM) fall in the first category, while the ability to interface with other services like Bluetooth or IEEE 802.11 network falls in the second category.

Existing technologies for voice, video and data use different packet structures, data types, and signal processing techniques. Integrated services can be obtained with either a single device capable of delivering various services or with a radio that can communicate with devices providing complementary services. The supporting technologies and networks that the radio might have to use can vary with the physical location of the user. To successfully communicate with different systems, the radio has to communicate and decode the signals of devices using different air-interfaces.

Furthermore, to manage changes in networking protocols, services, and environment, mobile devices supporting reconfigurable hardware also need to seamlessly support multiple protocols, such as IP (Internet Protocol) and MExM (Mobile Execution Environment). Such radios can be implemented efficiently using software radio architectures in which the radio reconfigures itself based on the system it will be interfacing with and the functionality it will be supporting. n What is Software Defined Radio?

The SDR Forum defines the ultimate software radio (USR) as a radio that accepts fully programmable traffic and control information and supports a broad range of frequencies, air-interfaces, and application software. The user can switch from one air-interface format to another in milliseconds, use the Global Positioning System (GPS) for location, store money using smart card technology, or watch a local broadcast station or receive a satellite transmission.

A good working definition of a software radio is a radio that is substantially defined in software and whose physical layer behavior can be significantly altered through changes to its software. The degree of reconfigurability is largely determined by a complex interaction between a number of common issues in radio design, including systems engineering, antenna form factors, RF electronics, baseband processing, speed and reconfigurability of the hardware, and power supply management.

A software radio is a radio that is substantially defined in software and whose physical layer behavior can be significantly altered through changes to its software.