The Y-source inverter uses different turns ratios of a coupled inductor and a controllable duty ratio to vary its gain. However, its input current is discontinuous, and any leakage inductances of its coupled inductor will lead to unintentional dc-link voltage spikes and gain reduction. To solve these problems, an extended quasi-Y-source inverter has been proposed in this study, which compared with the Y-source inverter, uses an extra inductor and an extra capacitor. Although the extras may not appear attractive, they have successfully helped with the suppression of leakage effects, which decrease the voltage spikes, and hence permit the main magnetic core size to be much smaller. Concurrently, the continuous input current can be also achieved. Besides, inrush current at startup has been reduced to a more acceptable value, which together with other features of the proposed inverter, have been proven through experiments.

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In this work, cooperative spectrum sensing technology is applied to optimize the outage probability of cognitive relay networks. The outage performance optimization problem of cognitive relay networks is resolved by designing the sensing time and fusion rule threshold appropriately. The outage probability by high signal to noise ratio (SNR) approximation under Rayleigh fading channels is derived theoretically, and the solution of optimal fusion rule threshold is given. Theoretical analysis and simulation results illustrate that the optimal sensing time and fusion rule threshold exist to minimize the outage probability. The outage performance of cognitive relay networks is significantly improved under the assistance of cooperative sensing compared with that of non-cooperative sensing scheme. ACM CCS (2012) Classification:Networks → Network components → Wireless access points, base stations and infrastructure → Cognitive radios; Networks → Network performance evaluation → Network performance analysis