Cognitive Radio Networks (CRNs) is mainly resulting to trim down the drawbacks of current unbalanced and inefficient spectrum utilization on licensed spectrum bands. Routing is one of the most important and fundamental mechanism in the cognitive radio networks. To overcome the limitations of existing routing mechanism, many researchers develop a routing framework which is based on Semi Structur...

Cognitive radio networks enable ubiquitous communications both in frequency and time domain, and hence enable opportunistic pervasive communications. Multi-hop cognitive radio networks are appealing to the researchers due to their wide range of application potential in commercial, emergency communication, and military tactical networks. However, the multi-hop nature of the network coupled with ...

Cognitive radio is one of the main technologies in the wireless communications. The cognitive radio networks are composed of cognitive, spectrum-agile devices which is able to modify their network configurations according to the spectral environment. This cognitive radio provides the chance reusing portions of the spectrum temporarily for the secondary users. But security is a main issue in the...

Cognitive radio networks are envisioned to drive the next generation wireless networks that can dynamically optimize spectrum use. However, the deployment of such networks is hindered by the vulnerabilities that these networks are exposed to. Securing communications while exploiting the flexibilities offered by cognitive radios still remains a daunting challenge. In this survey, we put forward ...

Cognitive Radios are promising solutions to the problem of overcrowed spectrum. Using channel selection techniques the access can be opportunistic by using frequency hopping, frequency tracking and frequency coding. Spectrum sharing cognitive radio networks allows cognitive radio users to share the spectrum bands of the licensed users. This paper explores various cognitive radio spectrum sharin...

In cognitive radio or dynamic spectrum access networks, a rendezvous represents meeting two or more users on a common channel, and negotiating to establish data communication. The rendezvous problem is one of the most challenging tasks in cognitive radio ad hoc networks. Generally, this problem is simplified by using two well-known mechanisms: the first uses a predefined common control channel,...

One critical issue for routing in cognitive radio ad hoc networks (CRAHNs) is how to select a reliable path for forwarding traffic. This is because mobility may cause radio links to break frequently. The reliability of a path depends on the availability of those links that constitutes the path. In this letter, we present a novel approach to predict the probability of the availability of the lin...