System design of a high-IF to UHF converter enabling cognitive radio

It is known that cognitive radio (CR) is an attractive concept to overcome the prevailing spectrum scarcity and inefficient spectrum usage. Also, with their intermittent spectral vacancies, TV white spaces offer a faster deployment potential considered with respect to cognitive radios. In this paper, system design of a high intermediate frequency (IF) to UHF frequency converter for cognitive radios have been discussed and the performance of such a converter analyzed as a proof of concept. For the design of RF front-ends, CR brings forth huge architectural challenges such as in-band local oscillator harmonics, ultra low sensitivity and high linearity. As shown in this paper, a high-IF radio front-end can successfully tackle some of these challenges. Additionally, such a high-IF converter enables white space operation for existing commercial devices by acting as frequency converters. From detailed measurements, the capabilities in both physical layer and application layer performance of a high-IF front-end developed out of off-the-shelf components is explained and is shown to provide negligible degradation to the commercial device being connected to.