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Transcript of Doc.: IEEE 802.11-03/xxxr0 Submission November 2004 Kiran Challapali, Philips Spectrum Agile Radios...
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
Spectrum Agile Radios
Kiran Challapali
Philips
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
Outline of talk1. Introduction
– Goal of the talk
– What are Spectrum Agile/Cognitive Radios?2. Applications of agile radios
– Wireless internet and others
3. FCC policy modernization
– Spectrum usage models
– Actual spectrum usage (measurements)
4. Spectrum agile radios
– Dynamic spectrum management concepts and key considerations
5. Standardization
6. Results
7. Discussions and Summary
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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
1. Introduction
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
2. Applications
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
2. Applications
Source: BusinessWeek online
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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
2. Applications
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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)
2. Applications
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
3. FCC policy modernization
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
Source: FCC Website• Spectrum reform becoming a global issue
3. FCC policy modernization
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
FCC’s Spectrum policy task force
• 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
• Setup by Chairman Powell, headed by Paul Kolozdy
• Submitted findings and recommendations Dec. 2002
3. FCC policy modernization
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
• 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
Observation
Frequency in MHz
500
1
0 1000 1500 2000 2500 30000
Duty
Cyc
le
TV CellTVFM UnlicensedPCS
Source: Shared Spectrum Company
3. FCC policy modernization
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
Spectrum usage models
Source: Paul Kolodzy @ ISART 2003
3. FCC policy modernization
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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)
3. FCC policy modernization
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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
3. FCC policy modernization
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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
3. FCC policy modernization
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
4. Spectrum agile radios
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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
4. Agile radios
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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
4. Agile radios
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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,
Aware/Adaptive
Learning/Reasoning
4. Agile radios
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
spectrum agile radio
=
flexible re-configurable radio
+
smart protocols and algorithms
Definition of spectrum agile radios
(“quickly adapts transmission characteristics” )
(“aware of spectrum usage in vicinity,
makes intelligent decisions on that basis, and
reacts to evolving FCC policies”)
4. Agile radios
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
Flexible PHY layer
Opportunity manager
Opp
ort
un
ity
iden
tifier
Policy interaction
Spectrum agile radio: Key components
4. Agile radios
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
Spectrum agile radio: Key components
TXpower
frequency[MHz]
time
Multicarrier - Spectrum AgileRadio for Broadband Applications
6 MHz TV channel
spectrum opportunities(unused TV channels)
adaptive sub-carrier bandwidth
(usage afteridentification)
adaptiveTX power
multicarrier transmissionsin unused TV-channels
4. Agile radios
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
Dynamic spectrum sharing concepts• Primary (vertical) sharing
– Finding and using spectrum white space
• Secondary (horizontal) sharing – Dissimilar networks then sharing the spectrum efficiently
4. Agile radios
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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
4. Agile radios
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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
4. Agile radios
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
5. IEEE Standards
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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.
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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.
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
6. Results
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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
21 89 62 31 03 02
Reported densities are indicators[0..255] for probability p of occurrence:
Density:
1 65432Bin:
Density(bin)p(bin) , bin=1...6255 SIFS DIFS
PIFS aSlotTime
density
time
CCA idle time histogramBin Interval = aSlotTimeBin Offset = SIFSNumber of Bins = 6
1 654
3
2
bin
p(bin) 1
Density Vector(m=var.)
21 89 62 31 03 02
Reported densities are indicators[0..255] for probability p of occurrence:
Density:
1 65432Bin:
Density(bin)p(bin) , bin=1...6255 SIFS DIFS
PIFS aSlotTime
density
time
CCA idle time histogramBin Interval = aSlotTimeBin Offset = SIFSNumber of Bins = 6
1 654
3
2
bin
p(bin) 1
Density Vector(m=var.)
6. Results
Author: Stefan Mangold/Zhun Zhong
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
Examples …heavily used no opportunity
unlicensed (4
channels)
licensed spectrum, used with
deterministic pattern
opportunity
6. Results
Author: Stefan Mangold/Zhun Zhong
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
802.11k MSTH measurement results• Simulation of high channel load (many stations)
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50
0.1
0.2
0.3
prob
(id
le d
ur.)
idle duration [ms]
CCAidle
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.01
0.02
0.03
0.04
0.05
prob
(bu
sy d
ur.)
busy duration [ms]
CCAbusy
typical geom. distribution high channel load,CSMA medium access`
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.50
0.1
0.2
0.3
prob
(id
le d
ur.)
idle duration [ms]
CCAidle
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10
0.01
0.02
0.03
0.04
0.05
prob
(bu
sy d
ur.)
busy duration [ms]
CCAbusy
typical geom. distribution high channel load,CSMA medium access`
6. Results
Author: Stefan Mangold/Zhun Zhong
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
Spectrum agile radio: cyclic spectrum for analog TV
2/
2/
2)2
()2
(1
limˆ T
T
ti
Tx dtetxtx
TR
deRfS fixx
2)(ˆ)(ˆ
6. Results
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
Spectrum agile radio: Cyclic correlation for digital TV
6. Results
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
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.
6. Results
November 2004
Kiran Challapali, Philips
doc.: IEEE 802.11-03/xxxr0
Submission
7. Summary
• A new paradigm for wireless communications
– Harness unused spectrum, thereby,
– Enable many new applications
• Substantial interest in many technical
communities