28-11-2012, 04:08 PM
The Performance Merit of Dynamic Threshold Energy Detection Algorithm in Cognitive Radio Systems
The Performance Merit of Dynamic Threshold.pdf (Size: 141.15 KB / Downloads: 25)
Abstract—
In cognitive radio systems, secondary users should
determine correctly whether the primary user is absent or not in
a certain spectrum within a short detection period. Traditional
spectrum sensing schemes based on fixed threshold are sensitive
to noise uncertainty, a fractional fluctuate of average noise
power in a short time will lead to the accuracy of spectrum
detection decreasing seriously. In this paper we propose a novel
dynamic threshold energy detection algorithm in cognitive radio
systems. Theoretical analysis and simulation results show that the
proposed strategy can combat the noise uncertainty effectively,
and good detection accuracy can be attained, if a suitable
detection threshold is chosen. That is, the proposed scheme can
enhance the robustness of combatting the noise uncertainty and
veracities of the spectrum sensing.
Index Terms—cognitive radio; detection threshold; noise uncertainty;
dynamic threshold detection
Introduction
Nowadays wireless communication systems are based basically
on fixed spectrum allocations, which means that the
spectral is assigned fixedly to authorized users at any time.
This leads to that the spectral resource is utilized un-efficiently
through practical measurements [1]. Dynamic spectrum access
techniques increase the spectrum efficiency and enhance
the chance of secondary users to access the idle frequency
spectrum. Cognitive radio is a resource sharing strategy which
allows the licensed user to share parts of its licensed spectrum
with a rental system (RS)[2], and the rental users must vacate
the spectrum as long as licensed users need communicate. The
objective of the cognitive radio is to improve the spectral
efficiency by overlaying new wireless radio systems on a
licensed one without interfering to the licensed system (LS).
In order to keep co-existing and no harmful to LS, cognitive
nodes must have the capability to detect the idle spectrum
instantaneously and continually, which is a very important in
cognitive radio systems.
Dynamic Threshold Algorithm Description
Since performance declined sharply as noise uncertainty,
and cognitive users’ accessing will be serious interference to
licensed users, which should be avoided in dynamic spectrum
access technology. For this reason, a new algorithm combatting
the noise uncertainty is presented.
Conclusion
Energy detection schemes based on fixed threshold are
sensitive to noise uncertainty, a fractional fluctuate of average
noise power will lead to the detection performance dropping
quickly. According to its drawback, we present dynamic
threshold spectrum detection algorithm in this paper. This algorithm
has an accurate detection performance even if there is
an serious noise uncertainty in the case of low signal-to-noise
ratio. Theoretical analysis and numerical simulation results
show that the proposed scheme improves the antagonism of
noise uncertainty, and gains a good detection performance as
long as a suitable dynamic threshold is chosen. In other words,
the dynamic threshold energy detection algorithm can enhance
the robust of combatting noise uncertainty and improve the
veracity of spectrum sensing. How to acquire the practical
detection threshold is our future work.