Comparative study of Mamdani & Takagi-Sugeno models for spectrum access in cognitive radio networks

Rapid growth of wireless services demands more and more spectrum, but spectrum is limited resource. Recent studies show that the spectrum which is allocated to licensed users or primary users (PUs) is not fully utilized. To address this problem Cognitive Radio (CR) comes into the picture, which will detect the vacant spectrum and use it when the same is available. But in the scenario of multiple unlicensed users or secondary users (SUs), which SU will access the spectrum is an issue in the cognitive radio networks. In this paper, two Fuzzy Logic Models i.e. Mamdani and Takagi-Sugeno are used for the selection of SU to access the spectrum based upon the input parameters: spectrum efficiency, mobility of SU and distance between PU & SU. On the basis of these input parameters, 27 fuzzy rules are framed. Based upon these rules, output is obtained which shows the selection possibility of a SU to access the spectrum. A comparison is shown between two models by computing the correlation value for each of the inputs parameter.