Spectrum Sensing of OFDMA Systems for Cognitive Radio Networks

Abstract

To fully exploit wireless radio resource and, thus, increase spectrum efficiency, cognitive radios shall sense wireless environments and identify interference to allow opportunistic transmissions for secondary systems. Based on Chen in their work about a terminal architecture for cognitive radio networks, by further obtaining transmission information with a rate-distance nature that is extended from an overlay concept, secondary systems can even leverage busy duration of primary systems to enhance the opportunity to use spectrum under derived tolerable interference to the primary orthogonal frequency-division multiple access (OFDMA) system. Our proposed novel multistate (i.e., existence, activity, and data transmission rate) spectrum sensing can thus effectively acquire a set of cognitive information for OFDMA mobile communication systems under a general system model. Through the received signal strength indicator (RSSI), fundamental symbol rate, cyclic property of the OFDMA signal, and the control and management signal, we can precisely determine the existence and activity of the primary (OFDMA) system within a subband via Neyman-Pearson (NP) criterion. With <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</i> <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">priori</i> knowledge of the frame structure of potential primary systems, communication parameters, including data transmission rate and resource allocation state, can be extracted by analyzing the frame header. Through appropriate parametric adjustments, our sensing procedure can be extended to state-of-the-art OFDMA systems.