Spatial filtering approach for dynamic range reduction in cognitive radios

Cognitive radios (CRs) receive several users simultaneously. Therefore, the ADC of an CR requires a large dynamic range (DR) to guarantee adequate resolution per user. Thus far the ADC DR requirements have been prohibitive for the wide spread introduction of CR in the hand held market. The power consumption of an ADC reduces with an order of magnitude per decade. In the absence of disruptive new technologies, we expect this power trend to continue for the foreseeable future. Therefore, we propose an analog spatial filtering technique and present iterative methods to alleviate the ADC DR requirements and accelerate the overall power reduction of a CR. Simulation results indicate that for realistic scenarios the ADC resolution can be reduced by 4 bits per ADC, reducing the overall ADC power consumption with more than 90%.