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A Fuzzy Inference System for Automatic Setting of the Processing Threshold in an IEEE 802.11 Cognitive Radio

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Cognitive radios learn from the environment in order to modify their parameters, enhancing the efficiency in the communication. Fuzzy inference systems allow to reproduce nonlinear and uncertainty relationships among multiple variables, representing a major development opportunity in cognitive radios. This approach is explored in the present work to build the first IEEE802.11 cognitive radio where an automatic real-time setting of the receiver processing threshold is carried out. The paper presents the design and implementation of a fuzzy inference system that adapts a no-conventional parameter in the OFDM physical layer (processing threshold) of an IEEE 802.11 radio to the environmental conditions through four characteristic wireless network parameters. The fuzzy system is tuned up through a novel technique which includes experts’ knowledge and problem behaviour, allowing to keep semantic descriptions, while the membership functions are adjusted and the number of rules reduced. The proposed development is implemented in GNU Radio including the IEEE802.11/a/g/p flowgraph. In addition, a proof-of-concept over USRP N210 is carried out in order to evaluate and analyze the fuzzy system performance in the cognitive radio. Results show how a fuzzy system reproduces properly non-linear relations in the threshold assignment decision. The design is deeply described and shared under GNU V3 license in order to encourage the inclusion of fuzzy systems in cognitive radio.
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Cognitive Radio; IEEE 802.11; Fuzzy Systems; Physical Layer; OFDM; USRP N210; GNU Radio

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