Sensing techniques for Cognitive Radio - State of the art and trends

Abstract

This document was initiated in the framework of the IEEE Standards Coordinating Committee 411(Dynamic Spectrum Access Networks) within the 1900.6 Working group (Spectrum SensingInterfaces and Data Structures for Dynamic Spectrum Access and other Advanced RadioCommunication Systems).This documents aims at identifying the spectrum sensing techniques being used of researched and thatmay be considered for the 1900.6 standardization activities. Although it gathers State of the Artmaterial, this document does not aim at being a scientific paper in that regard that the equations arenot always justified or demonstrated. However, it provides sufficient information to have a goodperspective on the problems to solve, the techniques that have been proposed and the one that mayemerge in the next few years. Links to a wide bibliography section is systematically provided toenable the reader to get more technical details.Since 1900.6 deals with Spectrum Sensing, the focus is put on this issue in this paper.Section 3 deals with single sensor spectrum sensing. In this section, the level of a priori knowledgeabout the signal to detect is discussed and different techniques are presented according to thisparameter.Section 4 is somehow an extension of section 3 in which the problem is extended to the identificationof systems in presence through the estimation of key specific parameters. The example of OFDMsignal is highlighted for which sub-carrier spacing one of the parameters considered to differentiatethe standards.Section 5 extends the scope of section 3 by considering several sensors. Cooperative sensing andcollaborative sensing are discussed in this section.Section 6 briefly discussed the estimation of the load of a system. This information may be adetermining parameter to decide on the network to get connected to.Section 7 provides application examples of the spectrum sensing techniques described previously inscenarios involving standardized wireless systems. Performance of the techniques is discussed.Section 8 reminds that a cognitive radio often has to sense information that is not captured byspectrum sensing. For instance, battery lifetime may be relevant for decision making in batteryoperated devices.