Spectrum Sensing and Allocation Techniques in Cognitive Radio Networks with Primary User Traffic

Cognitive radio is a novel technology for increasing spectral efficiency by enabling secondary users (SUs) to access bands of spectrum that are allocated but currently unused unsensed primary users (PUs). However, Spectrum sensing is one essential operation that helps to Sense all the available Primary Users (PUs) so that the Secondary Users (SUs) can detect them and avoid interference. For this purpose, several spectrum sensing techniques have been suggested. Matched filter detection or Coherent Detection [6], and Cyclostationary-based detection that exploit different features of the received signal to sense PUs. Spectrum allocation is as important as spectrum sensing in CR networks. SUs might need help finding a spectrum band that is free for their transmissions since the system still allows SUs to access (contaminated) PU traffic. To combat this, different spectrum assignment mechanisms have been proposed, including opportunistic spectrum access (OSA) and dynamic spectrum access (DSA), allowing for SUs to opportunistically use some potential vacant bands based on heterogeneity in the temporal availability of these bands and allowing them to dynamically acquire/release shared spectrum according to QoS requirements.