Hex Blue Template

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Simulating The Basics Of A
Cognitive Radio System
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Goal

• To Simulate Cognitive Radio System which is so
  effective that it can harvest more band-width
• in highly desired bands than is currently in
• use!
• More than in use by cellular systems
• More than in use by unlicensed bands
• More than in use by private mobile
• systems
• This represents a paradigm shift in technology!

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Why Cognitive Radio?

• Todays radio systems are not aware of their
  radio spectrum environment and operate in a
  specific frequency band.
• In some locations or some times of the day, 70
  percent of the allocated spectrum may be sitting
  idle.
• New bandwidth-intensive wireless services are
  being offered.
• Unlicensed users constrained to a few overloaded
  bands
• Increasing number of users.
• This growth requires more
• spectral bandwidth to satisfy
• the demand.

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What is a Cognitive Radio?

• Intelligent radio that uses spectrum licensed to
  other users when they aren't using it.
• Bandwidth Harvesting
• It is a software-designed radio with cognitive
  software.
• CR can sense the environment.
• CR adapts its way of communication to minimize
  the caused interference.
• CR coexists with the primary user (using the same
  frequency band) in two ways Concurrent and
  Opportunistic.

Figure A four-nodes wireless sensor
network scenario.
5
When Will CR Happen?

• Full Cognitive Radios do not exist at the moment
  and are not likely to emerge until 2030.
• Requires practical implementation of fully
  flexible SDR technologies and the intelligence
  required to exploit them cognitively.
• But, true cognition and fully flexible radios may
  not be needed.
• Simple intelligence and basic reconfigurability
  at the physical layer could provide significant
  benefits over traditional types of radio.
• CR prototypes to emerge within the next five
  years.
• Some devices are already in use like WLANs

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Idea

• Dynamic Spectrum Access ( DSA )
• To fill the spectral holes with secondary users
  data.

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Our Code
Primary Users
Fc1 1000 Fc2 2000 Fc3 3000 Fc4 4000
Fc5 5000 Fs 12000 x1 cos(2pi1000t)
in_p input('\nDo you want to enter first
primary user Y/N ','s') if(in_p 'Y'
in_p 'y') y1 ammod(x1,Fc1,Fs)
end in_p input('Do you want to
enter fifth primary user Y/N ','s')
if(in_p 'Y' in_p 'y') y5
ammod(x1,Fc5,Fs) end y y1 y2 y3
y4 y5 Pxx periodogram(y)
Hpsd dspdata.psd(Pxx,'Fs',Fs)
plot(Hpsd)
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Our Code
Secondary Users
in_p input('\nDo you want to enter a secondary
user Y/N ','s') if(in_p 'Y' in_p
'y') chek1 Pxx(25)10000 chek2
Pxx(46)10000 chek3
Pxx(62)10000 Code Portion Skipped
else disp('all user
slots in use. try again later,') end
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Our Code
Emptying Slots
inp_tinput('do u want to empty a slot
','s') if(inp_t'Y'inp_t'y')
inp_tinput('which slot do u want to empty
for ur entry ','s')
switch(inp_t) case ('1')
y10 disp('slot1 is
fired') y y1 y2 y3
y4 y5 case('2') y20
disp('slot2 is fired')
y y1 y2 y3 y4 y5

otherwise disp('invalid slot
entered') end
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Our Code
Adding Noise Attenuation
inp_tinput('do u want to add noise ','s')
if(inp_t'y'inp_t'Y') d input('Enter
the SNR in dB ') figure Y
awgn(y,d) Pxx1 periodogram(Y) Code
Portion Skipped tm 1-tem Z y.tm
disp('attenuating') grid on
plot(Z)
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Results


Data assigned

Allocated / Used Spectrum Band Un-allocated Bands
/ Spectrum Holes
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Results

Left
over Spectral Gaps Spectral Gap Filled by
modulating the new incoming users data over it
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Results
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Applications

• Mobile multimedia downloads which require
  moderate data rates
• Emergency communications services that require a
  moderate data rate and localized coverage (for
  example, video transmission from firemens
  helmets)
• Broadband wireless networking (for example, using
  nomadic laptops), which needs high data rates,
  but where users may be satisfied with localized
  hot spot services
• Multimedia wireless networking services (e.g.
  audio/video distribution within homes) requiring
  high data rates.

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Thank You
www.intcube.com/forum for requesting the complete
project