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CR technology enables CR users the capability to share the wireless channel with licensed users in an opportunistic manner. In cognitive network, once the primary user appears on the spectrum during the entire communication of the CR user, the CR user has to vacate the channel and switch to another one. In this paper, a Spectrum Decision based on Up-Time Ratio of spectrum (SDUTR) is presented, which...
A scheme based on optimal polarization receiving (OPR) is proposed for the cognitive radios to improve the signal to interference and noise ratio (SINR) of the cognitive user. This OPR-Based scheme will not produce extra interference to the licensed user. The simulation results show that without increasing the transmitting power of the cognitive user, the cognitive receiver with OPR-Based scheme can...
In cognitive radio networks, secondary users can share frequency spectrum with primary users, where the primary users charge secondary users for radio resource usage. Pricing schemes adopted by primary users is crucial to both primary users and secondary users. In this paper, we investigate three different pricing models in a cognitive network. Under the Bertrand competition, all sellers make decision...
This paper presents the concepts of centralizing spectrum sharing scheme for cellular networks. We consider the scenario where the cognitive radio network is formed by secondary users with low power personal/portable devices and when both systems are operating simultaneously based on co-channel spectrum sharing. The goal of this paper is to study how to maximize the utilities of the cognitive network...
IEEE 802.22 is the first worldwide wireless standard based on Cognitive Radio (CR) for Wireless Regional Area Networks (WRAN). Usually, Secondary Users (SUs) have to be interrupted periodically for spectrum sensing so as to avoid interference to Primary Users (PUs) operating in the licensed bands. Such interruptions of data transmission, however, impair the Quality of Service (QoS) of SUs. Dynamic...
This paper focuses on pre-coding schemes for the downlink of multiple user multi-input multi-output (MU-MIMO) system in cognitive radio (CR) network. The spectrum band can be utilized by allowing a number of cognitive users to coexist with primary users (PUs) through a pre-coding scheme. The capacity problems maximize the sum rate of CUs subject to the interference constraint for PUs and total transmitted...
The introduction of cognitive radio relieves the pressure brought by the lack of spectrum resources. However, it also brings new problems to the resources scheduling. The currently existed scheduling algorithms have not considered the different identities of primary users (PUs) and secondary users (SUs), delay urgency and implementation progress. Considering the different demands on the spectrum scheduling...
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