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Spectrum detection technology in cognitive radio includes two processes: channel sensing and channel monitoring. For each process, longer detection time may result in fewer opportunities for cognitive radios to fill in spectrum holes, while shorter sensing time may make cognitive radios miss the chance to detect the presence of primary users which will bring harmful interference to primary users....
Multi-channel spectrum sensing is prevailing but also very challenging in wideband cognitive radio systems. Conventional multi-channel spectrum detection such as channel-by-channel scan costs much time and energy. This paper aims to show a novel multi-user cooperative spectrum sensing method which can reduce the sensing ability requirement for secondary users while still guaranteeing the sensing accuracy...
In cognitive radio systems, as the sensing ability of single cognitive user is limited, the opportunistic spectrum access has to allow different cognitive users to cooperatively search for and exploit instantaneous spectrum availability. In this paper, we address the design of opportunistic spectrum access for cognitive radio system employing cooperative spectrum sensing. The opportunistic spectrum...
In cognitive networks, since the secondary users are not licensed owners of the spectrum, they can only access the spectrum opportunistically and cooperatively to exploit the best effort throughput for themselves while guaranteeing that their transmissions would not break the QoS performance of the primary communications. In this paper, we consider the cognitive network in which the primary users...
In this paper, the problem of wireless resource management in broadband cognitive OFDMA networks is addressed. Our objective is to maximize multiple cognitive users' weighted rate sum by jointly adjusting their rate, frequency, and power resource, under the constraints of multiple primary users' interference temperatures. First, we formulate the studied problem as a nonlinear and non-convex optimization...
In this paper, we consider a simple cognitive MIMO system, in which the cognitive link communicates using two transmission antennas and one receiving antenna. In order to ensure the primary link's transmission unaffected, the cognitive user has to detect the activity of the primary link, and transmit when it senses an idle slot. The maximum stable throughput of the cognitive link in this scenario...
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