this paper surveys recent research on Low Noise Amplifier (LNA) design for Cognitive Radios (CR). Design challenges and requirements of CR are discussed and recent advances in topologies and design techniques are presented, compared and summarized. The classical trade-offs of linearity, gain, input impedance matching and noise are discussed herein with respect to the Wide Bandwidth requirement....

The spectrum allocation policies of the Federal Communications Commission (FCC) [1] only allow spectrum access to primary users, it has been proven by various spectrum measurement campaigns that, the current spectrum usage across time and frequency is inefficient. Therefore, in order for the secondary users to access the unused portions of the licensed spectrum, the concept of “spectrum pooling...

Cognitive radio (CR) is a promising wireless technology that provides efficient spectral usage. Medium Access Control (MAC) has an important role in several cognitive radio functions such as sensing, spectrum mobility, resource allocation and spectrum sharing. We focus on the opportunistic spectrum access (OSA) functionality of the CR network MAC layer by which the secondary users (SUs) access ...

In wireless communication spectrum is the most important commodity and utilizing the spectrum is also one of the important issue. For the best and proper utilization of the spectrum this cognitive radio technology is very useful. The main issues in cognitive radio now a days is the spectrum sensing problem and it gained a new aspects and opportunistic in the concept of spectrum access. Various ...

Dynamic Spectrum Allocation using Cognitive Radio (CR) is a promising solution to the spectrum availability problem in wireless networks. Cognitive Radio, however, opens up certain new issues, mainly at the physical, medium access control and routing layer levels. Several solutions have been proposed to tackle these issues and use dynamic spectrum allocation to improve the performance of wirele...

With the advancement in wireless technology, there is an increasing problem of spectrum scarcity. To resolve this issue, a technology called Cognitive Radio (CR), based on Joseph Mitola’s Software Defined Radio (SDR) was introduced, in which the secondary users can sense the spectrum and utilize the licensed bands when the spectrum is not being utilized by the primary user. Because of its wirel...

Cognitive radio (CR) is a technology that is of growing interest internationally. Currently, there is a highly active worldwide community of academic and industrial researchers working in this field. Significant efforts have been made and focused on the many technical questions as well as on the economic and political challenges in order to move this new technology from research concept to real...

In the last decade, the usage of portable communication devices has continuously increased, together with the number of wireless communication standards. As a consequence, optimal radio resources allocation has become a problem requiring more complex solutions, including the possibility of thinking of a re-configurable, adaptive use of spectrum. A cognitive approach to radio spectrum management...

Frequency spectrum is scared resource and efficient use of it can easily fulfil the need of future applications. But its efficient use is not possible within the existing system, where the allocation of spectrum is done based on fixed spectrum access policy that causes under use of spectrum. For efficient utilization of spectrum new inventive techniques are needed. Using Dynamic spectrum access...

Cognitive radio (CR) technology will have significant impacts on upper layer performance in mobile ad hoc networks (MANETs). In this paper, we study topology control and routing in CR-MANETs. We propose a distributed Prediction-based Cognitive Topology Control (PCTC) scheme to provision cognition capability to routing in CR-MANETs. PCTC is a midware-like cross-layer module residing between CR m...