Cognitive radio has been proposed as an innovative and effective technology to exploit the efficient reuse of the precious radio spectrum. In spectrum sensing which is a crucial step in cognitive radio networks, an adequate sensing range needs to be defined to prevent the hidden transmitter/receiver problems. Moreover, a secondary user may have unreliable detection of the existent primary users...

With the development of more types of devices which have bluetooth as a primary option to communicate, the importance of secure communication is growing. Bluetooth provides a short range wireless communication between devices making convenient for users and thus eliminating the need for messy cables. The proliferation of the Bluetooth devices in the workplace exposes organizations to security r...

In multi-hop wireless ad hoc network, the packets are transmitted through intermediate nodes to reach the destination. In this topological structure, there is no centralized co-ordinating, monitoring or control point. Due to this type of network environment, an intermediate node can act as either selfish or malicious to drop packets. The primary objective of such an untrustworthy behavior of th...

Radio spectrum is a very scarce and important resource for wireless communication systems. However, a recent study conducted by Federal Communications Commission (FCC) found that most of the currently allocated radio spectrum is not efficiently utilized by the licensed primary users. Granting opportunistic access of the spectrum to unlicensed secondary users has been suggested as a possible way...

With increasing demand of new wireless applications and increasing number of wireless user’s problem of spectrum scarcity arises. Cognitive Radio technology supports dynamic spectrum access to address spectrum scarcity problem. Reliability of cognitive operation entirely depends upon how effectively task of spectrum sensing has been performed. Spectrum sensing is a process of discovering voids ...

Cognitive radio is a new concept of reusing spectrum in an opportunistic manner. Cognitive radio is motivated by recent measurements of spectrum utilization, showing unused resources in frequency, time and space. Introducing cognitive radios in a primary network inevitably creates increased interference to the primary users. Secondary users must sense the spectrum and detect primary users’ sign...

A critical objective of cognitive radio (CR) system is to enhance the spectrum efficiency, and one of the key factors that can determine the spectrum efficiency is the system spectrum sensing performance with respect to sensing window length. For non-coherent detection-based sensing technique, the length of the sensing window required to meet the detection criteria is inversely proportional to ...

The shortage of spectrum is increasing day by day. To minimize this problem, dynamic spectrum access (DSA) technique is adopted by Cognitive Radio Technology. Spectrum sensing is an important technique of secondary users or cognitive users to scan the spectrum holes or white spaces. In this paper, they have discussed the sensing method in a Centralized Cognitive Cellular Network. They have also...

Cognitive radios are indispensable to shift paradigm from conventional exclusive spectrum assignment to dynamic spectrum access. They can boost up spectrum utilization significantly, by dynamically accessing unused primary spectrum while bringing no harm to primary users. The envisioned radio calls for fast and accurate spectrum sensing. Researchers are focusing on cooperative spectrum sensing ...