S. M. Razavizadeh

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The spectrum sensing is a quite important part in cognitive radio. This paper discusses energy sensing, the common spectrum sensing algorithm in cognitive radio, as well as some cooperative algorithms such as AND, OR rule. Also some modified periodogram methods have been investigated and simulated, moreover these various methods of detection of signal(More)
This paper aims to improve the handover performance in the heterogeneous networks (HetNet). Since achieving high data rates, low signaling load, and better coverage area are highly dependent on the number of handovers, reducing the number of unnecessary handovers is crucial for both mobile users and the whole network. In this paper, a new decision-making(More)
In this paper, we consider a cognitive radio network in which the primary system base station acts as relay for the cognitive or secondary system as well as transmitting the primary users' data streams on the downlink channel. We propose a precoding technique which is used at the base station of the primary system. Using this technique, it is possible to(More)
—Cooperative communication is an efficient technique for improving the performance and coverage of cellular mobile networks. In this paper, we consider signal transmission in downlink of cooperative cellular direct sequence code division multiple access (DS-CDMA) systems. In this case, signal is transmitted to the destination mobile terminals via direct(More)
— In this paper, we propose two receiving schemes for multiple antenna multi-carrier code division multiple access (MC-CDMA) systems. Our proposed schemes are based on vertical Bell labs layered space-time (V-BLAST) architecture. The interference cancellation is performed serially on different sub-carriers. The channel matrices related to different(More)
In this paper, a new sphere decoding algorithm is introduced which is a modification of the Viterbo-Boutros (VB) algorithm. In the proposed algorithm, the problem of the initial selection of the search sphere radius in the VB algorithm has been removed, and furthermore, the speed of the algorithm is increased. To examine the performance of the proposed(More)
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