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Channel allocation in cognitive radio networks completely determines the realizability and efficiency of cognitive radio since it is the final step before the cognitive subscribers can use the spectrum holes. In this paper, we consider channel allocation in cognitive radio networks as a resource allocation problem under the circumstance that the allocation of transmission rate, link and transmission...
In cognitive radio networks, multiple spectrum opportunities can be used together to satisfy the service requirement by spectrum aggregation. In this paper, an admission control algorithm and a spectrum assignment strategy are proposed in order for both increasing the spectrum aggregation aware access capacity and decreasing the channel switch times when the channel states change. Considering different...
In this paper, we discuss the spectrum management technologies including spectrum sensing, spectrum decision, spectrum sharing, and spectrum handoff schemes in cognitive radio (CR) networks. In order to evaluate performance of different spectrum management schemes, the preemptive resume priority (PRP) M/G/1 queuing model is suggested to characterize the spectrum usage behavior between the primary...
In this letter, a power-control scheme for maximum sum-rate is proposed for the fading multiple access channels by considering the presence of primary users. Both the average transmit-power constraints and the peak interference-temperature constraints are considered. The interference caused by cognitive users must be under a pre-specified threshold for protecting primary users. The power-control optimization...
Cognitive radio makes it possible for an unlicensed user to access a licensed spectrum opportunistically on the basis of non-interfering. This paper addresses the problem of joint route selection and resource allocation in OFDMA-based multihop cognitive radio networks, in the objective of optimizing different types of end-to-end performance. Aiming to solve it optimally, we first show that this problem...
As the first step in the basic cognitive cycle, spectrum sensing is a vital part of cognitive radio to become reliant and swift. And due to excellent detection performance, cooperative spectrum sensing has been applied more and more frequently. However, in cooperative spectrum sensing, the detection results of the secondary users (SUs) have a great degree of uncertainty. In this paper, in order to...
In this paper, we study the spectrum selection problem in cognitive radio network with emphasis on resolving the channel contention and the spectrum sharing issues of multiple secondary users. For the traditional channel selection methods, the secondary users select their operating channels based on various criteria. However, these methods neglect the effect that multiple secondary users may content...
In the whole working cycle of cognitive radio (CR), the primary job is to sense wireless communication environment of secondary users (SUs), therefore, spectrum sensing is the foundation and prerequisite for the application of CR. In order to get excellent detection performance, cooperative spectrum sensing has been applied widely. However, in cooperative spectrum sensing process, the detection results...
In this paper, we investigated the end-to-end throughput of a chain in Cognitive Radio Networks (CRNs). We found that, the end-to-end throughput is dependant on both the primary usage patterns and the transmission scheduling scheme being used. In addition, to increase the end-to-end throughput of a Cognitive Radio (CR) chain, the scheduling scheme should be adjusted according to the primary usage...
Cognitive radio makes it possible for an unlicensed user to access a licensed spectrum opportunistically on the basis of non-interfering. This paper addresses the problem of resource allocation for multiaccess channel (MAC) of OFDMA-based cognitive radio networks, taking into account of the interference temperature constraints. The objective is to maximize the system utility, which is used to quantify...
In this paper, we will investigate the spectrum handoff schemes for the cognitive radio networks. Spectrum handoff occurs when the primary users appear and the secondary users are using this particular primary user's licensed channel. We compare two major types of spectrum handoff schemes. One is the reactive-sensing spectrum handoff, where the target channel for spectrum handoff is selected or sensed...
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