Abstract: Since from 1980ís, the US military has been working on SDR to increase the ease and flexibility of communication within and between the services. Different forces present at that time used dozens of different radios. Most of the radios could only communicate with the other radios of same kind. Software Defined Radio (SDR) offered the promise of not only interoperating with all existing radios, but also allowing those radios to communicate with each other. Just as important, SDR has enabled future communication systems to be implemented on already deployed hardware. Software Defined Radio (SDR) is a radio communication system where components that have been typically implemented on hardware are instead implemented by means of software on a personal computer or embedded system. While the Software defined radio is not new concept, the rapidly evolving capabilities of digital electronics render practical many processes which used to be only theoretically possible. A software defined radio (SDR) allows for digital communication system to easily adopt more sophisticated coding and modulation techniques, which is extremely important in meeting the ever increasing demands of the wireless communication .
Keywords: QPSK, Power efficiency, Spectral efficiency, Synchronisation.