The rapidly growing number of wireless devices running applications that require high bandwidths, hasresulted in increasing demands for the unlicensed frequency spectrum. Given the scarcity of allocatedunlicensed frequencies, meeting such demands can become a serious concern. Cognitive Radio (CR)technology opens the door for the opportunistic use of the licensed spectrum to partially address the issuesrelevant to the limited availability of unlicensed frequencies. Combining CR and Wi-Fi to form the socalledWhite-Fi networks, has been proposed for achieving higher spectrum utilization. This articlediscusses the spectrum sensing in White-Fi networks and the impacts that it has on the QoS of typicalapplications. It also reports the analysis of such impacts through various simulation studies. Our resultsdemonstrate the advantages of an adaptive sensing strategy that is capable of changing the relatedparameters based on QoS requirements. We also propose such a sensing strategy that can adapt to theIEEE 802.11e requirements. The goal of the proposed strategy is the enhancement of the overall QoS of theapplications while maintaining efficient sensing of the spectrum. Simulation results of the scenarios thatimplement the proposed mechanisms demonstrate noticeable QoS improvements compared to cases wherecommon sensing methods are utilized in IEEE802.11 networks.
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