1. Speaker: You-Min Lin Advisor: Dr. Kai-Wei Ke Date: 2011/04/25 Cognitive Radio Networks (CRN) 1

2. Outline Introduction Basic cognitive cycle MAC Layer Design Applications Conclusions and Future Reference 2

3. What is Cognitive Radio(CR) Mitola’s definition (1999): Software radio that is aware of its environment and its capabilities Alters its physical layer behavior Capable of following complex adaptation strategies “A radio or system that senses, and is aware of, its operation environment and can dynamically and autonomously adjust its radio operating parameters accordingly” 3

4. What is Cognitive Radio(CR) A “Cognitive Radio” is a radio that can change its transmitter parameters based on interaction with the environment in which it operates (FCC’2005) Capability to use or share the spectrum in an opportunistic manner 4

5. What is Cognitive Radio Networks (CRN) Primary Network Primary User (or Licensed User) Secondary Networks (or Unlicensed Network) Secondary User (or Unlicensed User) 5

6. Cognitive Radio Networks (CRN) 6

7. TV White Space Digital TV Broadcasting systems have freed up channels used in the analog TV frequency bands. These vacated channels are called “TV white space”. The economic potential for the TV white spaces was estimated at $100 billion. 7

8. Spectrum utility (1/3) Spectrum Scarcity 8

9. Spectrum utility (2/3) 9

10. Spectrum utility (3/3) 10 3kHz~300GHz

11. Spectrum hole 11

12. Worldwide Regulatory Agencies FCC in the US, Office of Communications (Ofcom) in the UK and Electronic Communication Committee (ECC) of CEPT in Europe. On February 17, 2009, the FCC released the final rules for “Unlicensed Operation in the TV Broadcast Bands” http://edocket.access.gpo.gov/2009/pdf/E9-3279.pdf 12

13. FCC “Unlicensed Operation in the TV Broadcast Bands” (1/3) TV Band Devices (TVBDs) can only operate on channels that are not adjacent to an incumbent TV signal in any channel between 2 and 51 except 3,4 and 37 TVBDs are divided into two categories: Fixed Higher power (< 4W) Must have a geolocation capability, capability to retrieve list of available channel from an authorized database, and a spectrum sensing capability. Personal/portable (channels 21-51(except 37) a maximum of 100mW on non-adjacent channel and 40mW on adjacent channels and are further divided into 2 types: Mode I and Mode II. 13

14. FCC “Unlicensed Operation in the TV Broadcast Bands” (2/3) Sensing is a mandatory function for all TVBDs. A channel must be sensed for 30 seconds before determining if it is available for use by a TVBD. Once Operation has started on a channel, sensing must be done at least once every 60 seconds and if a wireless microphone is detected the channel must be vacated within 2 seconds. 14

15. FCC “Unlicensed Operation in the TV Broadcast Bands” (3/3) Geolocation means must be present in all fixed and Mode II device (+/- 50 meters) Safe harbor channels for wireless microphone usage are defined in the 13 major metropolitan market to be the first available channel on either side of Channel 37.TVBDs cannot operate on these channels. 15

16. Some Fun 16

17. Some Fun 17

18. Some Fun 18

19. Basic cognitive cycle 19

20. Main functions Spectrum sensing Detecting unused spectrum Spectrum management Capturing the best available spectrum Spectrum mobility Maintaining seamless communication during the spectrum transition Spectrum sharing Providing fair spectrum scheduling method 20

21. MAC Layer Design The basic building blocks for MAC Beaconing protocols and channel access protocols. Multi-device beaconing Single-device beaconing can lead to the potential interference between adjacent networks. Channel reservation access To achieve high protocol efficiency and strict QoS provisioning. 21

22. MAC Structure and Beaconing 22

23. Single-device beaconing Client A and C becomes hidden terminal to each other. As a result, the channel reservation and QP scheduled for client A and C will be disrupted. 23

24. Multi-device beaconing Beaconing Client A and C devices exchange channel reservation information and QP schedule across network A and B periodically. Therefore, collision on channel reservation and QP is minimized. 24

25. Channel selection 25

26. Applications (1/2) Robust delivery of High Definition Video inside home and across multiple walls. The benefit of TVWS: Better propagation characteristics and therefore increased range and robustness, in comparison to higher frequencies. The ability to operate at lower power-levels for a given range would result in better energy efficiencies. Additional spectrum in the TVWS helps deal with overcrowding of ISM bands. 26

27. Applications (2/2) Robust coverage inside buildings and across campuses for wireless data applications Enhanced range for municipality, community and rural Internet access. Enhanced coverage for smart service and remote machine-to-machine and RFID deployments. New interactive applications for TV broadcasters, such as weather and news updates, upcoming program previews, interactive advertisements and games and web access. Enhanced range, robustness and quality for emergency-response and public service communication networks. 27

28. Conclusions and Future Fundamental research Implementation Government 28

29. Reference 29 [1] S. Haykin, “Cognitive radio: Brain-empowered wireless communications”, IEEE Journal on Selected Areas in Communications, pp. 201-220, 2005. [2] Ecma 392, ”MAC and PHY for Operation in TV White Space ”, Dec.2009. [3] Carlos Cordeiro, Kiran Challapali, and Dagnachew Birru, “IEEE 802.22: An Introduction To The First Wireless Standard Based On Cognitive Radios,” JOURNAL OF COMMUNICATIONS, VOL. 1, NO. 1, APRIL 2006. [4] I. F. Akyildiz et al., “NeXt Generation/Dynamic Spectrum Access/Cognitive Radio Wireless Networks: A Survey,” Comp. Networks J., vol. 50, Sept. 2006, pp. 2127–59