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The concept of cognitive radio (CR) is proposed to deal with the problem that the spectrum resource is almost used up but some licensed bands are under very low utilization at the same time. In CR networks, secondary users (SUs) are allowed to utilize the licensed spectrum bands by paying to the primary users (PUs) with the spectrum licenses. Besides, with the rapid development of wireless communications...
Cognitive radio (CR) as one of the most promising technologies to solve the problem of exhausting of spectrum resource, draws a lot of attention recently. However, for the highly intelligent wireless devices in the future, the assumption "CR devices introduce no interference to the primary users (PUs)" in traditional CR systems may do not exist anymore, due to that the devices are always...
Spectrum pooling, which allows the secondary networks to utilize the available spectrum bands from different licensed networks, is one of the most promising technologies for dynamic spectrum sharing in cognitive radio systems. Most previous work on spectrum pooling concentrates on the system architecture and the design of flexible access algorithms and schemes. In this paper, a distributed scheme...
Development of fair and efficient algorithms for resource allocation to secondary users (SUs) is one of the key issues in the design of cognitive radio (CR) systems. In this paper, we present a two-step resource allocation solution for multiuser based CR systems employing orthogonal frequency division multiplexing (OFDM). The solution allocates the subcarriers to SUs in the first step, considering...
In dynamic spectrum access systems, such as cognitive radio networks, spectrum pooling is one of the approaches to manage the available spectrum bands from different licensed networks. Based on the concept of spectrum pooling, most previous work focuses on the system architecture and the design of flexible access algorithms and schemes. In this paper, a cooperative and distributed scheme for dynamic...
In this paper, we focus on the Markov model of IEEE 802.11 distributed coordination function with power saving mode. The throughput evaluation is based on the model, with the comparison with the simulation result for validation. Furthermore, we notice that after each beacon transmission, there're more stations in contention than usual. Excessive contention results in high collision probability and...
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