Spectrum Agile Radios

1. Spectrum Agile Radios Kiran Challapali, Stefan Mangold, and Bin Dong Philips kiran.challapali@philips.com Kiran Challapali, Philips

2. Motivation • Rapid growth of wireless communications over the past several years • Unlicensed (WLAN/WPAN) and licensed (Cellular) bands • Recently, wireless internet access using cellular networks • available in 14 US cities, $80/month, 60-80 kpbs* • Vast and growing demand for spectrum-based communication links • In some measurements, only about 10% of the allocated spectrum is in use at any given time • Spectrum access and efficiency becoming a critical public policy issue Kiran Challapali, Philips

3. Outline of talk • Introduction • Goal of the talk • What are Spectrum Agile/Cognitive Radios? • Applications of agile radios • Wireless internet and others • FCC policy modernization • Spectrum usage models • Actual spectrum usage (measurements) • Spectrum agile radios • Dynamic spectrum management concepts and key considerations • Standardization • Results • Discussions and Summary Kiran Challapali, Philips

4. 1. Introduction What are spectrum agile radios? • Cognitive radio • Cognition (Merriam-Webster) • To become acquainted with, to know, to come to know • The act or process of knowing including awareness and judgment • Cognitive radios term originally coined by Joseph Mitola III • Includes learning and reasoning • Spectrum agile radios • Radios that are: • Aware of their environment • Adapt transmission characteristics (based on environment) • Our definition close to FCC’s definition Kiran Challapali, Philips

5. 2. Applications Kiran Challapali, Philips

6. 2. Applications Source: BusinessWeek online Kiran Challapali, Philips

7. 2. Applications Remote patient monitoring • Motivation • Healthcare costs are staggering • Aging population, shortage of trained staff in hospitals • Advantages of remote monitoring • Patients spend less time in hospitals, reducing costs • Quality of care improved due to continuous monitoring • Staying at home improves quality of life Kiran Challapali, Philips

8. 2. Applications Public safety • Communications failure during 9-11 • All cellular communications were down for several hours • Cellular networks did not have enough capacity when needed • Public safety communications also failed • Fire and police could not communicate • Public safety under State control (no interoperability) Kiran Challapali, Philips

9. 3. FCC policy modernization Kiran Challapali, Philips

10. 3. FCC policy modernization • Spectrum reform becoming a global issue Source: FCC Website Kiran Challapali, Philips

11. FM TV TV Cell PCS Unlicensed 1 Duty Cycle 0 0 500 1000 1500 2000 2500 3000 Frequency in MHz 3. FCC policy modernization Observation • Spectrum usage in NYC during RNC ~ Sept 1st 2004. • Measurements by Share Spectrum Company • Result: 16 % duty cycle, 30 MHz - 3 GHz, over 24 hours • Actually, even lower (< 10%) occupancies Source: Shared Spectrum Company Kiran Challapali, Philips

12. 3. FCC policy modernization FCC’s Spectrum policy task force • Setup by Chairman Powell, headed by Paul Kolozdy • Submitted findings and recommendations Dec. 2002 • Findings • Spectrum access versus scarcity • New methods as a solution to access • Interference tolerance • Need to define rights and responsibilities • Recommendations • Modernizing the regulatory model • Increase access to spectrum • New interference management tech. • Legislative recommendations Kiran Challapali, Philips

13. Source: Paul Kolodzy @ ISART 2003 3. FCC policy modernization Spectrum usage models Kiran Challapali, Philips

14. 3. FCC policy modernization FCC NPRM on Cognitive Radio • Issued on December 30 2003 • Scope • Facilitating Opportunities for Flexible, Efficient, and Reliable Spectrum Use Employing Cognitive Radio Technologies • Authorization and Use of Software Defined Radios • A simpler definition of CR • CR use in four scenarios discussed • Licensee can make more efficient use of their own spectrum • Secondary markets: Based on agreements between licensees and third parties • Co-primaries: Automated frequency coordination • Unlicensed operation: Opportunistic usage (no explicit agreements) Kiran Challapali, Philips

15. 3. FCC policy modernization FCC NPRM on Unlicensed operation in TV Bands • Issued on May 13, 2004 • Scope • Unlicensed operations in the TV Broadcast Bands • New unlicensed devices will not cause interference to • Analog and Digital TV Broadcast stations • LPTV, TV Translator, TV Booster Stations, Auxiliary Operations, and Wireless Microphones • Land Mobile Radio Services (PLMRS and CMRS) • Operation in • Channels 5 to 13 and 21 to 51 (except ch. 37) (76 to 698 MHz) • In addition, Channels 14 to 20 permitted in rural areas Kiran Challapali, Philips

16. 3. FCC policy modernization FCC NPRM on Unlicensed operation in TV Bands (Contd.) • Two types of devices permitted • Personal/portable devices • Peak power 100mW • Devices must receive a control signal indicating which channels are vacant • Fixed access devices • Peak power 1W • Devices must either • Include GPS and means to know which channels are vacant • Professionally installed to operate in vacant channels Kiran Challapali, Philips

17. 4. Spectrum agile radios Kiran Challapali, Philips

18. 4. Agile radios Key considerations • How to harness spectrum “white spaces”? • Are reliable wireless services without licensed frequency allocation possible? • Can devices automatically find “white spaces”? • How can they avoid harmful interference to licensees? • What if receivers are silent? • How can devices share spectrum efficiently? • How to avoid many competing (interfering) devices in the same band? • What are the hardware/software design challenges? • How to ensure compliance? • FCC currently does not monitor emissions • Solution: Cognitive/Agile Radio technologies • Several approaches to dynamic spectrum sharing Kiran Challapali, Philips

19. 4. Agile radios Research directions • Several technical communities answering key questions • Joseph Mitola III • DARPA XG program • For defense needs, architecture based on Policy language • NSF ProWIN NeTS program • Significant investment on test-beds • Wireless Industry, Standards • IEEE 802.22 WG • IEEE 802.16h SG Kiran Challapali, Philips

20. 4. Agile radios Dynamic spectrum sharing concepts • Primary (vertical) sharing • Finding and using spectrum white space • Secondary (horizontal) sharing • Dissimilar networks then sharing the spectrum efficiently Kiran Challapali, Philips

21. 4. Agile radios Primary sharing approaches • Self-sensing (or real-time measurements) • Are measurements reliable • Does diversity solve the problem • GPS based location + Retrieval from database • Rely on up-to-date databases (difficult) and Machine readability • Lacks adaptability • Over the air control channel • Cost (infrastructure and receiver) • Professional installation • Lacks adaptability Kiran Challapali, Philips

22. 4. Agile radios Secondary sharing approaches • Capacity suffers if no co-ordination at all • Some approaches • Rules based sharing, e.g. Etiquette (Stefan Mangold) • WiFi Co-existence Task Group • Voluntary set of rules, e.g. LBT, max air time, etc. • Explicit coordination • Over the air (separate co-ordination channel) • Rutgers proposal • Via internet (could be broker assisted) • Regional aggregation (statistical multiplexing) • Stevens proposal Kiran Challapali, Philips

23. Aware/ Adaptive Learning/ Reasoning 4. Agile radios Definition of spectrum agile radios • Definition • A new paradigm for wireless communications. • The physical and medium access layers of spectrum agile radios adapt their transmission characteristics to the external radio environment, while retaining the flexibility to react to evolving FCC policies. • Our version of Cognitive Radio, and, Kiran Challapali, Philips

24. 4. Agile radios Definition of spectrum agile radios spectrum agile radio = flexible re-configurable radio + smart protocols and algorithms (“quickly adapts transmission characteristics” ) (“aware of spectrum usage in vicinity, makes intelligent decisions on that basis, and reacts to evolving FCC policies”) Kiran Challapali, Philips

25. 4. Agile radios Spectrum agile radio: Key components Policy interaction Opportunity identifier Opportunity manager Flexible PHY layer Kiran Challapali, Philips

26. 4. Agile radios Spectrum agile radio: Key components Kiran Challapali, Philips

27. 5. IEEE Standards Kiran Challapali, Philips

28. IEEE Standardization • IEEE 802.22 • A new Working Group formed in IEEE • Regional Area Network TV Band Specification • includes mechanisms to protect incumbent licensees from harmful interference. • Specifically, • SCOPE: This standard specifies the air interface, including the medium access control layer (MAC) and physical layer (PHY), of fixed point-to-multipoint regional area networks operating in the VHF/UHF TV broadcast bands between 54 MHz and 862 MHz. • PURPOSE:This standard is intended to enable deployment of interoperable 802 multivendor regional area network products, to facilitate competition in broadband access by providing alternatives to wireline broadband access and extending the deployability of such systems into diverse geographic areas, including sparsely populated rural areas, while preventing harmful interference to incumbent licensed services in the TV broadcast bands. Kiran Challapali, Philips

29. IEEE Standardization • IEEE 802.16 • A new Task Group h proposed • PAR and 5 Criteria drafted • Will likely be voted on in November (this) meeting • SCOPE (DRAFT): This amendment specifies improved mechanisms, as policies and medium access control enhancements, to enable coexistence among license-exempt systems based on IEEE Standard 802.16 and to facilitate the coexistence of such systems with primary users. Kiran Challapali, Philips

30. 6. Results Kiran Challapali, Philips

31. 6. Results 802.11k medium sensing time histogram • With 802.11k, stations can report new measurement results • After sensing, results are reported with standardized frames • Histogram helps identifying opportunities Author: Stefan Mangold/Zhun Zhong Kiran Challapali, Philips

32. 6. Results heavily used  no opportunity unlicensed (4 channels) licensed spectrum, used with deterministic pattern  opportunity Examples … Author: Stefan Mangold/Zhun Zhong Kiran Challapali, Philips

33. 6. Results 802.11k MSTH measurement results • Simulation of high channel load (many stations) Author: Stefan Mangold/Zhun Zhong Kiran Challapali, Philips

34. 6. Results Spectrum agile radio: cyclic spectrum for analog TV Kiran Challapali, Philips

35. 6. Results Spectrum agile radio: Cyclic correlation for digital TV Kiran Challapali, Philips

36. Kiran Challapali, Philips

37. 6. Results Further reading … [1] MANGOLD, S. AND CHALLAPALI, K. (2003) Coexistence of Wireless Networks in Unlicensed Frequency Bands. Wireless World Research Forum #9 Zurich Switzerland July 2003. [2] CHALLAPALI, K. AND MANGOLD, S. AND ZHONG, Z. (2004) Spectrum Agile Radio: Detecting Spectrum Opportunities. International Symposium on Advanced Radio Technologies 2004 Boulder Colorado USA, Mar 2004. [3] CHALLAPALI, K. AND BIRRU, D. AND MANGOLD, S. (2004) Spectrum Agile Radio for Broadband Applications. EETimes In Focus Article Aug 23. [4] MANGOLD, S. AND ZHONG, Z. AND CHALLAPALI, K. (2004) Spectrum Agile Radio: Radio Resource Measurements for Opportunistic Spectrum Usage. IEEE Globecom 2004 Dallas TX, USA, Nov 2004. [5] MANGOLD, S. AND ZHONG, Z. AND HIERTZ, G. AND WALKE, B. (2004) IEEE 802.11e/802.11k Wireless LAN - Spectrum Awareness for Distributed Resource Sharing. Special Issue on Emerging WLAN Technologies and Applications. Wireless Communications and Mobile Computing. New York USA: John Wiley & Sons. [6] CHOU C.T., SAI SHANKAR N, KIM, H., and SHIN, K.G., “What and How Much to Gain from Spectrum Agility?”, Submitted to IEEE/ACM Trans. On Networking. June 2004 [7] SAI SHANKAR N, CHOU, C.T., CHALLAPALI, K., and MANGOLD, S., “Spectrum Agile Radio: Capacity and QoS Implications of Dynamic Spectrum Management”, Submitted to IEEE ICC 2005, Seoul, South Korea [8] XING, Y., CHANDRAMOULI, R., SAI SHANKAR N., and MANGOLD, S., “Analysis and Performance of a Fair Channel Access Protocol for Open Spectrum Wireless Networks”, Submitted to IEEE ICC 2005, Seoul, South Korea [9] MANGOLD, S. AND SAI SHANKAR N., S. AND BERLEMANN, L. (2005) Spectrum Agile Radio: A Society of Machines with Value-Orientation. Submission to IEEE European Wireless 2005. [10] MANGOLD, S. AND ZHONG, Z. AND CHALLAPALI, K. (2004) Spectrum Agile Radio: Radio Resource Measurements for Opportunistic Spectrum Usage. IEEE Globecom 2004 Dallas TX, USA, Nov 2004. Kiran Challapali, Philips

38. 7. Summary • A new paradigm for wireless communications • Based on harnessing unused spectrum • Spectrum agile radios enable new applications • Modernization of FCC policy • Dynamic spectrum sharing technologies being developed in many technical communities • Standards Kiran Challapali, Philips