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224B: Fundamentals of Wireless Communications
Professor David Tse
Experimental Study of Energy Detection
and Cooperation for Cognitive Radios
Artem TkachenkoStela Llusha
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Agenda
1. Introduction
2. Theoretical Background 3. Experimental Setup
4. Experimental Results5. Future Work
6. Questions
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INTRODUCTION
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FCC Spectrum Allocation
Spectrum is scarce
Frequencies below 3
GHz has been fullyallocated
Multiple allocations in
a same band
Low and inefficient spectrum utilization
Cognitive Radios have been proposed toimprove spectrum utilization
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Cognitive Radios
Two types of Cognitive Radio schemes:
1. Primary Receiver Detectors
Mainly in indoor environment2. Primary Transmitter Detectors
Indoor and outdoor environments
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Project Goals
Experimental analysis of the following issues ofdetecting Primary Rx using energy detection:SNR wallShow that under noise uncertainty, detection for a
single secondary user is impossible at sufficientlylow SNRCooperationShow that cooperation among cognitive radios canimprove the probability of detection, as a functionof the number of radios and their spatial separation.
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THEORETICAL BACKGROUND
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Energy DetectorsBinary Hypothesis Testing:
H 0 : Y[n] = W[n] n = 1,.,NH
1 : Y[n] = X[n] + W[n] n = 1,.,NEnergy Detector Test Statistics:
T (Y) =[ ]
0
11
0
2
H
H N
n
nY