Spectrum sensing is key to many applications like dynamic spectrum access (DSA) systems or telecom regulators who need to measure utilization of frequency bands. The International Telecommunication Union (ITU) recommends a 10 dB threshold above the noise to decide whether a channel is occupied or not. However, radio frequency (RF) receiver front-ends are non-ideal. This means that the obtained ...

Cognitive radio (CR) has become a tempting technology that achieves significant improvement in spectrum utilization. To resolve the hidden terminal problem, collaborative spectrum sensing (CSS), which profits from spatial diversity, has been studied intensively in recent years. As CSS is vulnerable to the attacks launched by malicious secondary users (SUs), certain CSS security schemes based on...

In cognitive radio networks, cognitive users can be coordinated to perform cooperative spectrum sensing so as to detect the primary user more accurately. In this paper, a hybrid cooperative spectrum sensing method is investigated to improve the sensing performance by exploiting double-fusion approach. In special, data fusion and decision fusion are both studied. For the first stage, cognitive u...

Popper’s well-known arguments describe the need for advancing social theory through a process of falsification. Despite Popper’s call, there has been little change in the academic process of theory development and testing. This paper builds on Popper’s lesser-known idea of “three worlds” (physical, emotional/conceptual, and theoretical) to investigate the relationship between knowledge, theory,...

In this chapter, we present the state of the art of the spectrum sensing techniques for cognitive radio networks as well and their comparisons. The rest of the chapter is organized as below: Section I.1, Section I.2, and Section I.3 present the spectrum management problem and the cognitive radio cycle as well as the compressive sensing solution; Section II.1 describes the spectrum sensing model...

In cognitive radio networks, spectrum sensing is a crucial component in the discovery of spectrum opportunities for secondary systems (or unlicensed systems). The performance of spectrum sensing is characterized by both accuracy and efficiency. Currently, significant research effort has been made on improving the sensing accuracy. Several exemplary techniques include energy detectors, feature d...

In the process of spectrum sensing applied to wireless communications, it is possible to build interference maps based on acquired power spectral values. This allows the characterization of spectral occupation, which is crucial to take management spectrum decisions. However, the amount of information both in the space and frequency domains that needs to be processed generates an enormous amount...

In the developing world, the usage of Mobile phones and other data communication devices are unavoidable which results in the congestion of Spectrum. Recent studies have showed that nearly 70% of spectrum was unused most of the time. The band width becomes expensive due to shortage of frequencies. Therefore to use the spectrum effectively, we need to identify whether the spectrum is occupied or...

Vehicular Ad hoc Networks (VANETs) is an essential part of Intelligent Transportation System (ITS), which aims to improve the road safety. However, the main challenge in VANET is the spectrum scarcity which is more severe especially in the urban environment. In this view using Cognitive Radio (CR) technology in VANET has emerged as a promising solution providing additional resources and allowin...

Neisseria gonorrhoeae has developed resistance to most of the available therapeutic antimicrobials. The susceptibility to extended-spectrum cephalosporins, the last remaining first-line treatment option, is decreasing globally. This report describes the first two cases outside Japan of verified gonorrhoea clinical failures using internationally recommended first-line cefixime treatment. Enhance...