by: gamal el din fathy amin ahmed ossama el fiky supervised by: dr tarek el naffouri
TRANSCRIPT
By: Gamal El Din Fathy AminAhmed Ossama El Fiky
Supervised By: Dr Tarek El Naffouri
OutlineIntroduction.Why Cognitive Radio?
Issues.Benefits.
Applications.Challenges.Our Approach.
Proposed Protocol.
IntroductionCR Intelligent Wireless Technology.a radio that is aware of its surroundings and
adapts intelligentlyIntelligence Searching the spectrum.
Cognitive radio requirements co-exists with legacy wireless systems uses their spectrum resources does not interfere with them
Introduction
Embedded intelligence to determine optimal transmission and vary communication parameters (bandwidth, center frequency, QoS) based on primary users’ behavior
Defining new concepts:Spectrum sharing.Adaptive parameters.
Why CR?Recent measurements by the FCC in the US
show 70% of the allocated spectrum is not utilized. (Spectrum scarcity)
Why CR?Bandwidth is expensive and good
frequencies are taken
Unlicensed bands – biggest innovations in spectrum efficiency.
Spectrum utilization.
Applications
Band sharing, emergency services, broadband wireless services, multi-media networking
Non-time sensitive services, such as downloading could be most appropriate.
Cont. ApplicationCellular operator
Local KAUST free mobile network.
Sensing is limited of the operator’s band.
ChallengesHidden tunnel Cooperative Spectrum
Sensing Controlling CRs to ensure they have the same
spectrum picture.Spectrum sharing
Could add lots of interference.
Scarcer resources.A lot of control communications (increase
throughput)
Our Approach.
Mathematical tool that can help in reducing the number of measurements to solve a system given it is sparse.
What is Compressive Sensing?
Cont. What is Compressive Sensing?
•N equations is needed to solve this system.•M=N.
Cont. What is Compressive Sensing?
•S = number of nonzero elements in U.
•S<<N
•m = α S log (n/S) & S<<m<<N
Control Channels On Cognitive radio.
Handles the control communication between Cognitive base station (CBS) and Cognitive Radios (CR).
Ex. spectrum sensing information.Share scarce resources.
Collision Happens.Collision Resolving Algorithms Should Be Applied.
The channel is given to the strongest connection users:Support Higher rates.Increase throughput.
Control Channels On Cognitive radio.
DataReservati
on
•Increase Throughput:
•Increase the frame length.
•Decrease Reservation Time
DataReservati
on
Control Channels On Cognitive radio.
Apply Compressive Sensing to Optimize the number of slots.
DataReservati
on
Compressive Sensing Protocol
CBS has fixed reservation slots=m.CBS sends a beacon with a threshold level L.
• CRs compare their channel gain a with L.• If a>L Strong Connection CR
(SCR)• Otherwise, Weak connection
(WCR)
Cont. Compressive Sensing Protocol
WCR go to sleep mode.Saves Battery.Eliminate WCRs that can cause slow rates and
interference.SCR multiplies 1 by random sequence of
length m +1 &-1 and reply on all slots.
Cont. Compressive Sensing Protocol
CBS then knows SCRs.It reserves the channel randomly to any of SCRs.
• CBS receives the replies and form the system of independent equations.
Cont. Compressive Sensing Protocol
CBS senses the spectrum and send the spectrum information to SCRs.
SCRs sense spectrum and compare with CBS.If SCRs agree it remains silent and apply the
decision.If SCRs object they reply back.
CBS base a new decision on the amount of objection to its decision.
Cont. Compressive Sensing Protocol
Advantages:Shared control channels are used.Limit collision by limiting the number of users.decrease reservation time and increase data
time.Strong connection users only use channel.
Questions
Control Channels On Cognitive radioTraditional way N users send their ID and
Channel gain G to reserve the channel.
Apply Compressive Sensing to decrease reservation TimeIf N is limited to s users need to send s<<N,
compressive sensing can be used. m reservation slots is used each of one bit.
The goalIncrease throughput.Give channels to strong connection users.
They support high rates.
Limit the activity of weak connection users.