presentation of research methods of crn
DESCRIPTION
cognitive radio, PUE attacksTRANSCRIPT
Detecting PUE attacks in Cognitive Radio Networks
Research Methods
Fan Jin4047 8963
Cognitive RadioExisting frequency resources are almost allocated by companies or organizations
Utilization of frequency resources are unbalanced
Cognitive Radio can improve the efficiency of utilizing existing frequency resources
Simple Example:
Mobile phone user can use TV signal to talk or SMS
Some ConceptsPrimary user: user who has paid for a specific band
Secondary user: user who has not paid for a frequency, but wants to use a frequency for communication
White space, hole or fallow band: in a specific time frame, a primary user is not using his paid frequency channel
Hand-off: when primary user comes to use his frequency, secondary users have to quit and look for another white space
Primary User Emulation AttackMalicious users mimic primary user’s signal
Other secondary users believe the primary user is still in, hence they are unable to use the fallow band
Selfish PUE attacker and Malicious PUE attacker
Impact of PUE attacks
PUE attack detection
Secondary user needs to correctly identify primary user’s signal
No modification should be applied to primary user
Three research methods: Energy detection, Cyclostationary feature detection and Localization
a radio signal should look like…
a real TV signal …
Energy DetectionEnergy detector measures the energy in the input wave over a specific time interval.
Measures the power level of the received signal at the secondary user receiver and compare it with the signal from real primary user
A threshold is required for identification
Advantage: Former knowledge of the primary user signal characteristic (much more than the energy level) is not required.
Disadvantage: path loss, path fading
Cyclostationary Feature Detection
Utilizes the cyclic feature of a signal to detect it
If the amplitude is periodic and there exists a peak value for each period, the value is compared to a predetermined threshold
Cyclic autocorrelation function (CAF) and Cyclic spectrum density (CSD)
Advantage: robust against noise with unknown variance
Disadvantage: computational complexity and long observation time
LocalizationNon-interactive localization scheme is required
Location Verification scheme: ratio of distance and energy level
Localization scheme: Received Signal Strength (RSS) based
localization Triangulation
RSS based localization scheme
ConclusionA proper architecture is required, contains primary users, secondary users and secondary user base stations:
Secondary users will need to communicate each other or with base stations for exchanging messages and updating final results
A combination of above methods need to be used to successfully detect PUE attacks
Other techniques such as machine learning or data smoothing may be used to increase the accuracy of final decision
Questions?