[2011.3.8]Overcoming the Sensing-throughput Tradeoff in CRN
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Transcript of [2011.3.8]Overcoming the Sensing-throughput Tradeoff in CRN
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Overcoming the Sensing-Throughput
Tradeoff in Cognitive Radio Networks
S.Stotas, A.Nallanathan
ICC 2010
Mar.3 2011
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Outline
Introduction
Novel Cognitive Radio System
Throughput of the Proposed System Throughput of the Proposed System under the
Energy Detection Scheme
Simulation Results
Conclusions
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Introduction
The conventional frame structure exists a tradeoff
between sensing duration and data transmission
duration Its impossible to maximize throughput and sensing
capabilities at the same time
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Novel Cognitive Radio System
i)Novel Frame Structure
Advantages:
1.Increase sensing time better Pd and Pf
2.Decrease harmful interference and improve spectrumutilization
3.Continuity of data transmission
4.Improve throughput
5.Can use more complex sensing techniques(cyclostationary) 4
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Novel Cognitive Radio System
ii) Novel Cognitive Receiver Structure The received signal at the secondary user is
:the actual status of frequency band
sp:the received signal from primary users
hs:the channel between the secondary transmitter and the secondary receiver
xs:the signal from the secondary transmitter
n:the additive noise
The remaining signal
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Throughput of the Proposed System
Define two cases:
(i)A frequency band is correctly detected to be idle
(ii)A frequency band is falsely detected to be idle
The throughput of the cognitive radio network in
above two cases are denoted R0 and R1 respectively
Notations:
T:frame duration
:sensing time
P(H0):P{the frequency band is idle}
P(H1): P{the frequency band is active}
:target probability of detection
dP
dP
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The average achievable throughput with the
conventional frame structure is
where
The average achievable throughput of the novel
system is
and
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For a target detection probability
Namely
for0 < T
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Throughput of the Proposed System
under the Energy Detection Scheme
The test statistic for the energy detection is
yr:the received signal at the secondary user
M:the number of samples
For a complex-valued PSK signal and CSCG noise
and the false alarm for given target detection prob.
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Similar to the previous
Finally
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Fig 4. and fig 5. show that the novel system hasbetter false alarm and throughput performance than
the conventional frame structure
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Either the target detection prob. Increases or thetarget SNRp decreases, the achievable throughput of
novel system is better
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Conclusions
The proposed cognitive radio system exhibits
improved throughput and sensing capabilities
compared to the conventional system
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