Hamid Shahrokh Shahraki

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In this work, biodiesel has successfully prepared via ultrasonic method in a short time and low temperature by nano-solid-base catalyst (KF/γ-Al₂O₃). The catalyst was obtained by calcination of a mixture of KF and γ-Al₂O₃ m(KF)/m(γ-Al₂O₃) at 500 °C for 3 h. Nano-solid-base catalyst was characterized with scanning electron microscopy (SEM), transmission(More)
Due to their spectrum shaping capability and high adaptability, the multi-carrier systems are considered as prime candidates for use in the Cognitive Radio (CR) networks. In these structures, the deactivation of the primary users' (PUs) bands makes the secondary users (SUs) use a limited number of sub-carriers, so the total capacity of CR networks is(More)
A simplified method for single user detection based on Maximum-likelihood detection (MLD) for MC-CDMA systems has been proposed. The analysis and the simulations results show that this new method drastically reduces computational complexity of common MLD detectors, meanwhile the performance remain acceptable. Furthermore, the method outperforms other(More)
Improved Phantom cell is a new scenario which has been introduced recently to enhance the capacity of Heterogeneous Networks (HetNets). The main trait of this scenario is that, besides maximizing the total network capacity in both indoor and outdoor environments, it claims to reduce the handover number compared to the conventional scenarios. In this paper,(More)
—Vastly increasing capacity and coverage demand in communication networks accompanied by energy efficiency challenge is getting attraction in research topics of this area. In this paper, an improved structure of Phantom cell heterogeneous networks (HetNets) is proposed to fulfil these requirements in the next generation cellular networks.It will be shown(More)
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