The idea of
cognitive radio was first given by the Joseph Mitola and Gerald Q. Maguire in
1999. Cognitive radio is Software Defined Radio (SDR) or Dynamic Spectrum
Access (DSA) a technology where radios detect white space in spectrum and
access based on the priority of users. Cognitive radio is one of the new long
term as well as good performance development take place in radio communication
technology. Cognitive radio minimizes the spectral congestion. Cognitive radio
works most effectively works in communication system. Cognitive radio able to
perform task of the spectrum, detect frequencies and adjust the parameters
according to modern signal processing techniques, according to the definition
of cognitive radio. Cognitive radio allows the sharing of spectrum much more
efficiently and used spectrum dynamically and intelligently. Cognitive radio
can manage spectrum themselves without human intervention.
I.
COGNITIVE RADIO
CRs are highly agile wireless platforms
capable of autonomously choosing operating parameters based on both prevailing
radio and network conditions. Consequently, CRs have the potential to revolutionize
how devices perform wireless networking. For instance, CRs allow radios
operating on different protocols and standards to communicate with each other.
This is known as interoperability.
Furthermore, CRs are capable of transmitting in unoccupied wireless spectrum
while minimizing interference with other signals in the spectral vicinity; that
is, DSA
The spectrum management process consists of
four major steps:
- Spectrum Sensing:
ð A Cognitive Radio user defined
unused portion in frequency spectrum. Therefore, the CR user should identify
the free space in spectrum bands, take their information and sense the spectrum
holes. Sensing is necessary if the device is to change its operation based on
its current knowledge of environment.
- Spectrum Decision:
ð CR users can allocate a channel
based on the spectrum available or not. This allocation not only depends on
spectrum availability, but it is also can be determined by internal (and
possibly external) policies.
- Spectrum Sharing:
ð Multiple CR users trying to access
on spectrum, CR network access should be coordinated in order to prevent
multiple users colliding in overlapping portions of the spectrum.
ð Which decide the secondary user
can use the spectrum for some particular time.
- Spectrum Mobility:
ð If the specific portion of the
spectrum in use is required by a primary user, the communication need to be
continued in other white space of the spectrum.
Which the process is
to exchanges its frequency operation for cognitive radio user.
Figure
1:
Cognitive Engine Components in Cognitive Loop
Professor,
Robin Hojiwala,
Mahavir Swami College of Polytechnic
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