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Cognitive
Radio and Cooperative Communication principles hope to redistribute the
currently scarce resource of Radio Frequency (RF) Spectrum. With the regulation
of RF transmission beginning in the early 20th century, access to RF Spectrum
has been limited while demand has steadily increased. There are technologies
currently being studied to ease demand by directly increasing the supply
available for use at any given time. Through more efficient use and increased
cooperation, spectrum shortage may be a thing of the past. Using available
bandwidth during lulls in demand, individual terminals in a wireless network
collaborate to find alternate transmission space. Networked and/or wireless
nodes exchange transmission and receipt principles while insuring no
interference with licensed user activity. In monitoring internal and external
factors within the radio environment such as frequency spectrum, user behavior
and network state, the overall transmission capacity of a communication system
is enhanced.
With
the ability to sense and adapt to the environment, cognitive radio networks can
reconstruct in the name of performance. Operating through a wide variety of
radio interference conditions and multiple protocol standards, Cognitive Radios
offer collaboration with neighboring radios to form a network with no tangible
infrastructure. Each node in the network acts as a transponder, retransmitting
data from throughout the network. This give and take provides an array of
benefits beyond just freeing up disappearing spectrum. Key among those benefits
is power reduction, since the node no longer needs to send information to the
end of the network. This allows for an increase in nodes without the threat of
increased interference. Cognitive Radio also allows for communication networks
to sense the situation and adapt to the environment. Through the use of
cognitive and frequency agile devices, the network can now measure radio
spectrum availability, traffic load and link quality in an effort to select a
lower capacity channel for transmission.
Cooperative
communications allow distributed terminals in a wireless network to collaborate
through signal processing. This allows for recognition of new forms of space
diversity to combat degradation of fading channels. It is possible that the
most benefit will derive from systems working together. A key enabler to the
success of these advances is software radios. Far more adaptable than a
traditional radio, software radio, originally used for cellular telephony,
could download appropriate software to begin receiving broadcast television
signals. A more likely application is accessing a network that uses a new
cellular transmission protocol or even the avoidance of other transmissions.
For more information on how the FCC regulates RF spectrum click HERE. |
