3. INTRODUCTION
Evolution of numerous wireless applications.
Limited Public Bandwidth or Spectrum
Inefficient use of Licensed Spectrum
What if one could use the licensed spectrum when no
primary users are using it?
5. WHAT IS COGNITIVE RADIO?
Intelligent Radio.
Senses Environment and Spectrum(Cognitive
capability).
Analyzes it(Self-organized capability).
Adapts to it(Reconfigurable capability).
Learns from the results.
15. PRIMARY USER EMULATION
Idle spectrum can be used by secondary users
without causing disturbance to the primary user.
But these secondary users must co-operate and use
the spectrum fairly.
Some secondary users prevent others from using this
idle spectrum by transmitting unrecognizable signals.
i.e. they emulate (imitate) the primary users and
hence prevent secondary users from utilizing it.
They are of two types:
Selfish PUE attackers
Malicious PUE attackers
17. Received power due to
Primary Transmitter,
Pr_p
PDF of Pr_p
Received power due to
Malicious users, Pr_m
PDF of Pr_m
18. SIMULATION & RESULTS
The following slides contain the simulated
results of the PDFs of signals received by the
secondary receiver due to primary
transmitter and malicious users.
23. SYSTEM MODEL ALTERATION
As it can be seen, the results of the previous
system model are not desirable.
So, another system model is presented to
counteract the PUE.