A Cognitive Radio Receiver Supporting Wide-Band Sensing

IEEE 802.22 defines the world-wide first cognitive radio (CR) standard. In the range between 41 MHz and 910 MHz CR overlay-systems can be installed besides licensed radio services such as radio and TV broadcasting. In order to fulfill the regulative guidelines for interference limitations, adequate spectral sensing and user detection has to be supported by the CR terminals. The wide frequency range specified in IEEE 802.22 and the high dynamic range of signals in this band lead to high demands on the CR receiver´s front-end. Especially the performance requirements on analog-to-digital converters (ADCs) increase significantly compared to current wireless systems. Based on measurements taken in the frequency range between 41 MHz and 910 MHz requirements to CR´s ADCs are figured out. Furthermore, the measurement results are analyzed regarding expectable allocation scenarios and their impacts on spectral sensing. Derived from these results and a comparison of general spectral sensing mechanisms, an approach for a CR receiver enabling wide-band sensing is presented. By combining a-priori information resulting from scenario analysis with adapted information processing in the CR terminal, the ADC´s performance requirements can be reduced.