1. Cognitive Radio: Next Generation Communication SystemBy
V.ALAGU ABINAYA
11MCO02

2. Evolution of Communication Systems

3. Software Defined Radio
Software Defined Radio as a basic platform on which to build a Cognitive Radio
Cognitive Radio can provide the spectral awareness technology to support FCC initiatives in Spectral Use

4. Definition of SDR
Software defined radios -evolutionary process from purely hardware-based equipment to fully software-based equipment.
1. Hardware driven radios- Transmit frequencies, modulation type and other radio frequency (RF) parameters are determined by hardware and cannot be changed without hardware changes.
2. Digital radios -A digital radio performs part of the signal processing or transmission digitally, but is not programmable in the field
3. Software Defined Radios- All functions, modes and applications can be configured and reconfigured by software
SDR Forum-
- waveform properties, cryptography and applications, is re-programmable, and may be upgraded in the field with new capabilities
- Importance of Standards (APIs)
*Notice of Proposed Rule Making (NPRM) 8/12/00

5. Cognitive Radio

6. Spectrum Allocation

7. COGNITIVE RADIO Two-way radio
Automatically changes its transmission or reception parameters
communicates efficiently, avoiding interference with licensed or licensed exempt users.
Monitoring of several factors in the external and internal radio environment
-radio frequency spectrum, user behaviour and network state
FCC –Federal Communication Commission
“A software defined radio with a cognitive engine brain".

8. Cognitive Radio Means “Smart” and “Alert
It knows where it is
It knows what services are
available, for example, it can identify then use empty spectrum to communicate more efficiently
It knows what services interest the user, and knows how to find them
It knows the current degree of needs and future likelihood of needs of its user
Learns and recognizes usage patterns from the user
Applies “Model Based Reasoning” about user needs, local content, environmental context

9. Need for Cognitive Radio
Radio spectrum is a scarce resource and is regulated
Spectrum usage is one of the key issues in communication system challenges
The spectrum efficiency can be improved with idea of dynamic spectrum allocation.
Cognitive radio network - on effective spectrum utilization
-allocates to primary user or licensed user
-user is not utilizing ,secondary user can claim without interfering to primary user

10. What is needed for a CR ?

11. Cognitive Radio Evolution

12. How Cognitive radio works?
-Spectrum sensing
-Spectrum management
-Spectrum mobility
-Spectrum sharing
awareness of changes in its environment
response to these changes adapts - operating characteristics
- improve its performance or to minimize a loss in performance

13. How Does a Cognitive Radio Get So Smart?
External
Intelligence
Sources
Orient
Establish Priority
Plan
Normal
Generate Alternatives
(Program Generation)
Evaluate Alternatives
Register to Current Time
Decide
Alternate Resources
Initiate Process(es)
(Isochronism Is Key)
Act
Learn
Save Global
States
Set Display
Send a Message
Observe
Receive a Message
Read Buttons
Outside
World
New
The Cognition Cycle
Prior
Pre-process
Parse
Immediate
Urgent
Infer on Context Hierarchy
Mitola, “Cognitive Radio for Flexible Mobile Multimedia Communications”, IEEE Mobile Multimedia Conference, 1999, pp3-10

14. Spectrum Sensing Dynamic spectrum allocation Cognitive radio networks
– scans the entire spectral band for the presence/absence of primary users
Performed either locally
- secondary user
- collectively by a group
Contd…

15. Spectrum Sensing
Contd…
Transmitter detection- capability to determine if a signal from a primary transmitter is locally present in a certain spectrum.
There are several approaches
-Matched filter detection
-Energy detection
-Cyclostationary feature detection
Cooperative detection- information from multiple Cognitive radio users are incorporated for primary user detection.
Interference based detection

16. Spectrum Management
Spectrum Management - capturing the best available spectrum to meet user communication requirements
Decide on the best spectrum band -Quality of service
These management functions can be classified
spectrum analysis
spectrum decision
Practical implementation of functions
- very complex and multifaceted issue in itself.

17. Spectrum Mobility
Spectrum Mobility- when a user exchanges its frequency of operation
- use the spectrum in a dynamic manner with the best available frequency band
- maintaining seamless communication requirements with better spectrum.

18. Spectrum Sharing
Spectrum Sharing – provides the fair spectrum scheduling method
One of the major challenges is spectrum sharing.
It can be regarded to be similar to generic media access control MAC problems in existing systems

19. The future of CR
The unlicensed band in range of wireless devices and services
FCC - consider opening further bands for unlicensed use.
Exploits the inefficiently utilized licensed bands without causing interference to incumbent users
Unlicensed radios to operate in the TV broadcast bands and also TV services.

21. Thank u