1. Cognitive Radio Networks
Lecture-5
Mazhar Hussain

2. Contents Introduction
Literature Review CRN Architecture/Routing Challenges
Issues
Applications
Conclusion & Issues for future work References

3. Introduction (Increased user demand)
The ISM ( industrial, scientific and medical) band is a host of many different wireless technologies.
WiFi
Bluetooth
Wimax
The number of devices that function at the ISM band is constantly growing.
Interference between these devices is growing as well.
This means degradation of performance.

4. “Regional Area Network”
IEEE Standards
IEEE
RAN
“Regional Area Network” km
18 Mbps
BW= 6,7,8 MHz
MHz
Fig. 1: IEEE Standards

5. Spectrum and Management
Set of Electromagnetic radiation and frequency bands
Ranges up to 300 GHz
Government entities own frequency channels, which are divided according to common frequency band characteristics
The International Telecommunications Union (ITU) divides the world into three different regions that influence wireless signal propagation:
Region 1 : Europe, Africa, parts of the Middle East and Northern Asia
Region 2 : The Americas, Caribbean and Hawaii
Region 3 : Asia, Southeast Asia, the Pacific Islands, Australia and New Zealand

6. Wireless Networking Terminologies
Wireless Radio Spectrum
• Fixed Spectrum Assignment
• Shared Spectrum Concept
Dynamic Spectrum Access (DSA)
NeXt Generation (xG) Network
• DAPRA* Dynamic Spectrum Access
*Defence Advance Research Project Agency

7. Cognitive Radio Network
Wireless communication in which the transmission or reception parameters (Operating Spectrum, Modulation, Transmission power and communication Technology) are changed to communicate efficiently without interfering with licensed users.
Parameter changes are based on the active monitoring of several factors in the radio environment (e.g. Radio frequency spectrum).

8. Literature Review
CRN was first described by Mitola in his Ph.D Thesis, “Cognitive radio: integrated agent architecture for software defined radio” in 2000.
Federal Communications Commission (FCC )has given the report in 2003.
DSA concept was firstly implemented by DARPA in 2003.
Radio‐scene analysis, Channel‐state estimation, predictive modeling, Transmit‐power control, dynamic spectrum management are described extensively by Simon Haykin in Feb

9. Literature Review
Dynamic Shared Spectrum access concept is described by I.F. Akyildiz in 2006 and also introduced concept of Cognitive Radio Ad Hoc Network (CRAHN) which is infrastrureless cognitive radio network in July 2009.
Wireless Regional Area Network (WRAN), also known as IEEE Working Group on Wireless Regional Area Networks.
Brief detail of CRN platforms : Universal Software Radio Peripheral (USRP), Wireless open Access Research Platform (WARP) and Sundance .

10. Cognitive Radio Network
Intelligent devices that can coexist with licensed users without affecting their quality of service.
Licensed users have higher priority and are called primary users.
Cognitive radios access the spectrum in an opportunistic way and are called secondary users.
Networks of cognitive radios could function at licensed portions of the spectrum.
Demand to access the ISM bands could be reduced.

11. Cognitive Radio Network
Fig. 3: Primary and Secondary User Concept

12. Why Cogitative Network
Underutilization of licensed spectrum
Fig. 4: Licensed Spectrum utilization analysis
Licensed portions of the spectrum are underutilized.
According to FCC, only 5% of the spectrum from 30 MHz to 30 GHz is used in the US.

13. How Cogitative Network Works
Restrictions to secondary users
Licensed portions of the spectrum consists of frequency bands that belong to one of the following categories:
White spaces: Primary users are absent. These bands can be utilized without any restriction.
Gray spaces: Primary users are present. Interference power at primary receivers should not exceed a certain threshold called interference temperature limit.
Black spaces: Primary user’s power is very high. Secondary users should use an interference cancellation technique in order to communicate.

14. How Cogitative Network Works
Fig. 5: Secondary User and Spaces
Secondary users can identify white, gray and black spaces and adapt according to the corresponding restrictions.

15. Cognition Cycle Orient Plan Learn Observe Decide Outside Act World
Level
0 SDR
1 Goal Driven
2 Context Aware
3 Radio Aware
4 Planning
5 Negotiating
6 Learns Environment
7 Adapts Plans
8 Adapts Protocols
Orient
Infer from Context
Infer from Radio Model
States
Establish Priority
Generate Alternate
Goals
Select Alternate
Goals
Parse Stimuli
Pre-process
Plan
Normal
Immediate
Normal
Urgent
Learn
New
States
Observe
Outside
World
Decide
Act
User Driven
(Buttons)
Autonomous
Level 0 – No Cognitive Operations
Level 1 – Minimal Cognition
Establishes Minimum Cognition Cycle
Requires ability to observe environment
Environment includes RF, Network, Location, and Time
Level 2 - Knowledgeable of Application
Provides context to interpret stimuli from environment
May provide additional information to better decide which waveform to implement
e.g. Higher throughput for Data, Lower latency for voice
Level 3 – Knowledgeable of Radio, Network, Channel
Utilizes specific models to improve value of observations
Level 4 – Has several alternate strategies
Now chooses best strategy and best waveform to implement strategy
Level 5 – Possible to coordinate actions with other radios
Negotiation can be “Do you know this waveform?” or “Are you willing to pay $ for this service?”
Level 6 – Learning Begins
Significant Increase in complexity, may require AI
Learning is based on observations and decisions
At this stage CR can autonomously learn new models of the environment
This is used to improve observations, orientation and decisions
Level 7 – New Plans are learned in addition to pre-programmed plans
Level 8 – CR can invent new waveforms.
Must now Generate Best Waveform in response to selected plan.
Implies need to negotiate protocols
Determine “Best”
Plan
Determine “Best”
Known Waveform
Generate “Best”
Waveform
Allocate Resources
Initiate Processes
Negotiate Protocols
Negotiate
Source: “Cognitive Radio for Flexible Mobile Multimedia Communications ”, IEEE Mobile Multimedia Conference, 1999, pp 3-10.

16. Hole or White Space Concept
Fig. 6: CRN Concepts

17. CRN Architecture
Fig. 7: CRN Architecture

18. CRN Core Functions Spectrum Spectrum Spectrum Spectrum
sensing management
mobility sharing
Detecting
Maintaining
unused
seamless Providing the
Capturing the spectrum and
communicati fair spectrum
best available sharing the
spectrum to spectrum
on scheduling
meet user without
requirements method
during the among
communicati harmful
transition to coexisting CR on
interference requirements
better users spectrum.
with other users.

19. Cognitive Cycle Cognitive capability Reconfigurability
Fig 8: Cognitive Cycle

20. Cognitive Routing Schemes
Fig. 9: Cognitive Routing Scheme

21. Cognitive Routing Challenges CRN Key Consideration
Spectrum Awareness
Setting Quality of Routes
Maintaining / Reproducing Routes

22. Cognitive Routing Challenges Cognitive Networks challenges
Spectrum Knowledge
Overhead
Link Failure
Mobility handling
Best Path Selection

23. Some Other Issues Routing challenges Transport layer challenges
• Common control channel
• Intermittent connectivity
• Re‐routing
• Queue management
Transport layer challenges
• Spectrum Handoff Latency

24. Cross‐layer challenges
Challenges in spectrum management
• Dynamic Nature and Re‐routing
Challenges in spectrum handoff
• Spectrum Handoff Latency, Route Failure and Recovery
Challenges in spectrum sharing
• Spectrum Sensing Capability and Sharing Delay
Challenges in upper layers
• Dynamic Frequency, Multiple Hops and Spectrum handoffs,

25. Cognitive Routing Challenges CR Support Tools
The following can be support tools for CR
PRISM
OPNet Modular 14.5 or above
Ns-2
Matlab

26. Challenges in spectrum sensing
Interference temperature measurement
Spectrum sensing in multi‐user networks
Detection capability

27. Spectrum management challenges
Decision model.
Multiple spectrum band decision. Cooperation with reconfiguration.
Spectrum decision over heterogeneous spectrum bands.

28. Challenges of spectrum mobility
Spectrum handoff.
Spectrum mobility in multiple users.

29. Spectrum sharing challenges
Common control channel (CCC).
Dynamic radio range .
Spectrum unit.

30. Implementation issues
Readiness of the CRN backbone
Defining point of Interconnect and Interface. Definition of Uniform service based priorities. Default service and routing requirement. Service authentication and Authorization.

31. Regulatory issues
Migration from service based licensing to service neutral licensing regime. Issues related with converged licensing.
Re‐classification of the licenses.
Pricing issues to end users.
Migration from service based pricing to service neutral pricing.
Revenue settlement of the operators in CRN environment.

32. QoS issues
Need to define Quality of services parameters in CRN environment.
Monitoring QoS in various networks and ensuring compliance to defined QoS parameters in CRN environment.
Ensuring End to End QoS across the networks.
Need to define unique service based priorities.
Reliability across diverse applications.

33. Security issues Protection from various protocol attacks.
Application attacks.
Unauthorized user introduction.
Unauthorized access to system data.
Denial of services (DOS) and Distributed Denial of services attacks (DDOS).

34. CRN Applications CRN Applications Military CR Mesh Network Network
Emergency
Network
Multimedia
Leased
CRN
Cellular
Network
Applications
Networks

35. Conclusion Spectrum Awareness Concept. Very Useful for B3G Networks.
Spectrum sharing techniques can help us fill the regulatory “gaps” in a particular interference environment.
A great deal of research still needs to be done on simulating and explore these intelligent network ideas.

36. Conclusion
Cognitive radio technology can solve the problem of spectrum underutilization.
Channel assignment in cognitive radio networks is especially challenging in CRN.
Main aim of this research is Characterize and analyze, and enhance the throughput and provide security solutions

37. References XG WG, The XG Architectural Framework V1.0, 2003.
1. I.F. Akyildiz, Y. Altunbasak, F. Fekri, R. Sivakumar, ” AdaptNet: adaptive protocol suite for next
generation wireless internet”, IEEE Communications Magazine 42 (3) (2004) 128‐138. 2.
FCC, ” ET Docket No 03‐222 Notice of proposed rule making and order ”, December DARPA
XG WG, The XG Architectural Framework V1.0, 2003. 3.
S.A. Zekavat, X. Li, User‐central wireless system: ultimate dynamic channel allocation, in: Proc. IEEE DySPAN
2005, November 2005, pp. 82‐87. 4.
DARPA XG WG, The XG Vision RFC V1.0, 2003. 5.
S. Haykin, Cognitive radio: brain‐empowered wireless communications, IEEE Journal on Selected
Areas in Communications 23 (2) (2005) 201‐ 220. 6.
R.W. Thomas, L.A. DaSilva, A.B. MacKenzie, Cognitive networks, in: Proc. IEEE DySPAN 2005,
November 2005, pp. 352‐360. 7.
F.K. Jondral, Software‐defined radio‐basic and evolution to cognitive radio, EURASIP Journal on
Wireless Communication and Networking 2005
8. M.M. Buddhikot, P. Kolody, S. Miller, K. Ryan, J. Evans, DIMSUMNet: new directions in wireless
networking using coordinated dynamic spectrum access, in: Proc. IEEE WoWMoM 2005, June 2005, pp. 78‐85.
9. O. Ileri, D. Samardzija, N.B. Mandayam, Demand responsive pricing and competitive spectrum
allocation via spectrum server, in: Proc. IEEE DySPAN 2005, November 2005, pp. 194‐202.

38. Questions