Cognitive Radio Ad Hoc Networks (CRAHNs) constitute a viable solution to solve the current problems of inefficiency in the spectrum allocation, and to deploy highly reconfigurable and self-organizing wireless networks. Cognitive Radio (CR) devices are envisaged to utilize the spectrum in an opportunistic way by dynamically accessing different licensed portions of the spectrum. However the pheno...

Now a days, the available radio spectrum is divided between the licensed and unlicensed frequencies. But due to this, some frequency bands get occupied all the time and some are occupied for less time. This is leading to wastage of frequency spectrum. Again, in recent years, there has been huge growth in wireless communication devices and applications. To fulfill this demand of spectrum, we sho...

It is becoming increasingly evident that cognitive radio (CR) users in CR networks acting in uncertain dynamical environments often employ exact or approximate Bayesian statistical calculations in order to continuously estimate the channel states. In this work we propose a prediction/filtering channel state estimation model capable of exactly implementing Bayesian state estimation and predictio...

Cognitive radio has been demonstrated for improved spectrum utilization by secondary users in the presence of spectrum holes. In this paper, a Cognitive Radio (CR) network is implemented over the cooperative multihop wireless link. A multihop network is a collection of relay nodes within transmitter and receiver. A fixed infrastructure based multihop architecture is assumed for the performance ...

Cognitive Radio (CR) and Software Defined Radio (SDR), concepts which were mere proposals to solve the population of services over the past two decades, are now enabled by novel materials and components to offer fully reconfigurable devices. Thus, a convergence of services can be attained within a reduced, or even single RF (Radio Frequency) signal path in the device. A solid design of reconfig...

Cognitive radio (CR) is a key solution for the problem of inefficient usage of spectral resources. Spectrum sensing in each CR aims at detecting whether a preassigned spectrum band is occupied by a primary user or not. Conventional techniques do not allow the CR to communicate with its own base station during the spectrum sensing process. So, only a part of the frame can be used for cognitive d...

Cognitive radio (CR) technology has a great potential to maximize spectrum utilization. It exploits an underutilized licensed spectrum by enabling opportunistic communications for unlicensed users. In this work, we propose a distributed cognitive radio MAC protocol (COMAC) that enables unlicensed users to dynamically utilize the spectrum while limiting the interference imposed on primary (licen...

This paper presents a new spectrum-sharing strategy based on spatial information about mutual interference constraints, temporal spectrum usages and positions of devices. This strategy can solve the coexistence problem of Cognitive Radio (CR) networks and simplify the design of CR devices. In fact, it is a crosslayer design strategy that integrates useful information obtained from the physical,...

Designing a medium access control (MAC) protocol is a key for implementing any practical wireless network. In general, a MAC protocol is responsible for coordinating users in accessing spectrum resources. Given that a user in cognitive radio(CR) networks do not have priority in accessing spectrum resources, MAC protocols have to perform dynamic spectrum access (DSA) functions, including spectru...

Secured opportunistic Medium Access Control (MAC) and complexity reduction in channel estimation are proposed in the Cross layer design Cognitive Radio Networks deploying the secured dynamic channel allocation from the endorsed channel reservation. Channel Endorsement and Transmission policy is deployed to optimize the free channel selection as well as channel utilization to cognitive radio use...