A review of wideband spectrum sensing methods for Cognitive Radios

The paper presents a review of the scientific literature dealing with the wideband detection of signals. Such problem is critical in Cognitive Radios (CRs), as it allows identifying the portions of the radio spectrum, where the CR can transmit. The relevant literature has been classified into three main approaches to the wideband spectrum sensing problem. A first approach considers the observed wideband as a partition in which the width of each sub-band is fixed and known. This approach pays attention to the joint detection of the occupied and free sub-bands. A second approach jointly estimates the boundaries of the sub-bands and the power density level inside each sub-band. Finally, a third approach concentrates the attention to the estimation of the sub-band boundaries. The concepts of compressed sensing and cooperative sensing have been presented, and, several papers basing on these concepts have been analyzed, too.