05-10-2010, 05:38 PM
The use of cognitive radio techniques in wireless mobile networks can lead to significant capacity increase. Cognitive radios sense the radio spectrum environment and to switch dynamically to available frequency ranges. a framework for applying cognitive radio technology to mobile WiMAX is described in this article. In this framework , the base stations are
equipped with sensitive detectors which dynamically assign channels to
subscriber station depending upon the on spectrum availability. The frequency reuse is increased by Power control. The cognitive channel assignment is checked computer simulation and it is compared with the conventional dynamic channel assignment. The result shows that inherent spectrum hole opportunities can be exploited to increase the capacity of emerging WiMAX networks. characteristics of the radio propagation environment define the key performance parameters.
FREQUENCY-AGILE COGNITIVE RADIO TECHNOLOGY
A frequency-agile CognitiveRadio is capable of sensing the spectrum and dynamically tuning to frequency channels determined to be available. the listen-before-talk (LBT) DSA scheme is performance evaluated.
Listen-Before-Talk Spectrum Access
contains two states:
-listen or off state: In this mode, the CR node does not transmit a signal. The transmit power level is also estimated during this time.
- talk or on state:
COGNITIVE WiMAX
With the frequency-agile cognitive radio technology to WiMAX, we call it the COGNITIVE WiMAX. The fine-grained and flexible frequency allocation is the major reason why this techniques is more applicable to Wimax. In this system , every base station is equipped with a frequency agile CR and it takes up the role of a primary node or a victim node as depends on the dynamic spectrum access.
The report is available here:
http://filesonicfile/23103863/Cognitive wimax with frequency agility.PDF
