Demonstration of the Software-Radio Concept

Since the early 1980’s an explosion-like increase of cellular mobile systems can be observed. A side effect of this rapid growth is an excess of mobile system standards. In fact, every major country has its own standard(s). Therefore, the software-radio concept is emerging as a potential pragmatic solution: a software implementation of the user terminal able to dynamically adapt to the radio environment in which it is located. First, this report presents a global overview of the software-radio concept. Furthermore it explains a software-radio transmitter and receiver built for demonstration purposes. The source code has been written as much as possible in C and is running on an evaluation module of Spectrum Digital (with the TMS320LC549 DSP from Texas Instruments). The software-radio transmitter and receiver are based on a modified version of the China Wireless Telecommunication Standard (CWTS). Because the used evaluation module has been designed for audio applications the software radio uses frequencies that are about 5000 times lower than the CWTS standard uses. Both the receiver and transmitter require about 75 million instructions for decoding/encoding one frame. Because the source code is not optimized, the total number of instructions can be reduced significantly. Finally the system has been verified by measuring the BER versus the bit-energy-to-noise-energy ratio