Traditional spectrum sensing techniques such as energy detection, for instance, can sense the spectrum only when the cognitive radio (CR) is not in operation. This constraint is relaxed recently by some blind source separation techniques in which the CR can operate during spectrum sensing. The proposed method in this paper uses the fact that the primary spectrum usage is correlated across time ...

Introduction: Involving approximately 4% of malignancies in women, ovarian cancer remains one of the most fatal cancers. However, it is important to consider conditions which are not primary ovarian diseases, but mimic their behaviors. In the present study, the epidemiological characteristics of extra-ovarian conditions mimicking ovarian masses are evaluated. Meth...

The innovation of wireless technologies requires dynamic allocation of spectrum band in an efficient manner. This has been achieved by Cognitive Radio (CR) networks which allow unlicensed users to make use of free licensed spectrum, when the licensed users are kept away from that spectrum. The cognitive radio makes decision, switching from primary user to secondary user and vice-versa, based on...

—In this paper, we consider multiple primary and multiple secondary users cooperative cognitive radio networks, in which the primary users (PUs) lease a portion of their spectrum to the secondary users (SUs) for some revenue, and in return the SUs play as relays and help forward the data of the Pus in exchange for being granted spectrum opportunities. Both the PUs and SUs aim to maximize their...

Cognitive radio technology has been developed in recent years to make efficient use of the wireless spectrum especially for opportunistic spectrum access. Cognitive radio technology enables the secondary (cognitive) users to use the unused licensed spectrum of the primary users. Medium Access Control (MAC) protocol plays a vital role in spectrum utilization, primary user’s (PU) interference man...

a secundum atrial septal defect is the most common congenital heart defect. transcatheter treatment of secundum atrial septal defects is a popular and less invasive alternative to surgery. procedural complications may occur in a wide spectrum, particularly device embolus as the most emergent one, but luckily they do not commonly occur in the clinical setting. mortality from adverse events relat...

we define a new type of spectrum, called δ-approximate spectrum, of an element a in a complex unital banach algebra a and show that the δ-approximate spectrum σ_δ (a) of a is compact. the relation between the δ-approximate spectrum and the usual spectrum is investigated. also an analogue of the classical gleason-kahane-zelazko theorem is established: for each ε>0, there is δ>0 such that if ϕ is...

This paper explores the idea of predictive dynamic spectrum access (PDSA). Modern spectrum resource allocation research typically divides users into two classes: primary users and secondary users. Primary users own licenses to particular frequency bands and are allowed to use it whenever they wish. Secondary users can reuse the frequencies when they are not being used by a primary user. The goa...

Too high sampling rate is the bottleneck to wideband spectrum sensing for cognitive radio (CR). As the survey shows that the sensed signal has a sparse representation in frequency domain in the mass, compressed sensing (CS) can be used to transfer the sampling burden to the digital signal processor. An analog to information converter (AIC) can randomly sample the received signal with sub-Nyquis...

Cognitive Radio (CR) is a novel technology that can improve the utilization efficiency of the radio spectrum and also address the spectrum scarcity problem by opportunistically using the unused channels (spectrum holes / white spaces) in the Licensed Spectrum of Primary Users. Spectrum sensing is the primary function of CR which determines the spectrum holes for opportunistic usage by Secondary...