In Cognitive radio networks, the optimum utilisation of the spectrum can be ensured by detecting the unused spectrum by spectrum sensing techniques and sharing it without harmful interference to other users. One important requirement in a cognitive radio network is sensing spectrum holes reliably and efficiently. This paper outlines the different spectrum sensing techniques like matched filter ...

In this thesis, first, we address the problem of energy efficiency for spectrum sensing. We propose a combined censoring and ”on/off” scheme as an energy efficient technique for cognitive radio networks. We maximize the lifetime of the spectrum sensing system by minimizing the energy consumption of the system subject to a specific detection performance constraint. We show that our proposed tech...

Spectrum sensing has been put forward to make more efficient use of scarce radio frequency spectrum. The leading eigenvector of the sample covariance matrix has been applied to spectrum sensing under the frameworks of PCA and kernel PCA. In this paper, spectrum sensing with subspace matching is proposed. The subspace is comprised of the eigenvectors corresponding to dominant non-zero eigenvalue...

Cognitive Radio (CR) is a technique which is used to improve the utilization of the radio spectrum. It is a software controlled radio that senses the unused frequency spectrum at any time. The main problem in cognitive radio is spectrum sensing. In this paper, the comparison of different techniques for spectrum sensing and transceiver from different perspectives is presented and a new architect...

Spectrum sensing is the basic and essential mechanisms of Cognitive Radio (CR) to find the unused spectrum. This paper presents an overview of CR architecture, discusses the characteristics and benefits of a CR. Energy detectionbased spectrum sensing has beenproposed and used widely because it doesn’t require transmitted signal properties, channel information, or even the type of modulation. In...

Spectrum aggregation is an emerging technology to satisfy the data rate requirement of broadband services for next-generation wireless communication systems. In dynamic spectrum environment, in which the spectrum availability is time-varying, it is quite challenging to maintain the stability of spectrum aggregation. In this paper, we investigate the spectrum sensing and access schemes to minimi...

Spectrum sensing is the key component of cognitive radio technology. Spectrum sensing is a tough task because of shadowing, fading, and time-varying nature of wireless channels. However, detection is compromised when a user experiences shadowing or fading effects. In such cases, user cannot distinguish between an unused band and a deep fade. Thus, cooperative spectrum sensing is proposed to opt...

In this paper, we aim at deriving the outage rates achieved by the primary user due to spectrum sensing in a cognitive radio network, that we call sensing-induced primary outage rates. To reach this goal, in the first step, instead of classical spectrum sensing techniques that evaluate sensing performance only based on correct detection of the presence of the primary user’s signal, we propose a...

Due to the unavoidable use of mobile phone and another data communication as a result we face the problem of spectrum scarcity. Within the current spectrum regulatory framework, however, all of the frequency bands are exclusively allocated to specific services and no violation from unlicensed users is allowed.But as we know that most of the time band is either not utilized or underutilized. The...

It is well known that the successful operation of cognitive radio (CR) between CR transmitter and CR receiver (CR link) relies on reliable spectrum sensing. To network CRs requires more information from spectrum sensing beyond traditional techniques, executing at CR transmitter and further information regarding the spectrum availability at CR receiver. Redefining the spectrum sensing along with...