A performance trade-off in wideband cognitive radio for flexible wireless systems

As network geometry becomes complicated, it is difficult to allocate the frequency to user predeterminately. For this reason, open spectrum access paradigm gets an attention again. In a Flexible Wireless AP (FWAP), proposed by NTT [1], a unified wireless platform provides wideband frequency, e.g., from 0 Hz to 50 GHz, and it can receive various types of wireless signals. In this system, each mobile device should find a vacant frequency band, which requires to sample a wideband signal. In a mobile device, however, it is a huge burden to sample the wideband signal even though the sub-Nyquist sampler [2] is implemented. In this paper, we develop a new wideband cognitive radio technique that can provide available frequency candidates for a prospective user. This technique is based on a trade off between a minor performance and a major performance. By trading off a False Alarm (FA) performance, we can reduce a sampling rate for obtaining an appropriate False Negative (FN) performance.