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Ultra Wide BandUltra Wide BandCommunicationsCommunications
TitleLecture 1 - September 26, 2011
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Course PresentationCourse PresentationMaria-Gabriella Di BenedettoMaria-Gabriella Di BenedettoProfessorDepartment of Information Engineering, Electronics and Telecommunications (DIET)[email protected]://acts.ing.uniroma1.it
Luca De NardisLuca De NardisAssistant ProfessorDepartment of Information Engineering, Electronics and Telecommunications (DIET)[email protected]://newyork.ing.uniroma1.it/~lucadn
Jocelyn FiorinaJocelyn FiorinaAssociate ProfessorSUPÉLEC, Département de Télé[email protected]://www.supelec.fr/384_p_11635/jocelyn-fiorina.html
Guido Carlo Guido Carlo FerranteFerranteMaster Thesis studentDepartment of Information Engineering, Electronics and Telecommunications (DIET)[email protected]
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Course PresentationCourse Presentation
http://acts.ing.uniroma1.it/mailman/listinfo/uwbcomhttp://acts.ing.uniroma1.it/mailman/listinfo/uwbcom
UWBCOMMailing List
CourseWebsite
http://acts.ing.uniroma1.it/courses/uwb/uwbcom.html
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Course NotesCourse Notes
Understanding UltraUnderstanding UltraWide Band RadioWide Band RadioFundamentalsFundamentalsby Maria-Gabriella Di Benedetto& Guerino Giancola
Published by Prentice HallISBN: 0131480030Published: June 17, 2004Copyright 2004
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Course OrganizationCourse Organization
• PART 1 – UWB Basics– Introduction to UWB Communications– Generation of UWB radio signals– Spectral characteristics of UWB radio signals
• PART 2 – UWB single user communications– Link Budget for an UWB radio link– Receiver structures for AWGN channels– Receiver structures for multipath-channels
• PART 3 – UWB multi user communications– MUI models for Impulse Radio– Time Reversal
• PART 4 – UWB special features– Pulse Shaping in UWB– Locationing and Positioning with UWB
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Practice WorkPractice Work
• UWB vs. non UWB• Generation of 2PPM-TH-UWB and 2PAM-TH-UWB signals• Shaping the spectrum of a 2PPM-TH-UWB signal by changing the
properties of the TH code (periodicity and cardinality)• Link Budget for UWB links• Performance of an UWB receiver in the presence of AWGN channels• Performance of an UWB receiver in the presence of multipath-affected
channels• Theoretical performance of multi-user UWB networks• Verification of the validity of the SGA• Evaluation of the effect of differentiation on the spectrum of an UWB
signal• Meeting the emission masks• Accuracy of Least Square Error algorithms
List of practice work lessons that will be given duringthe course (Adopted simulation tool: MATLAB®)
Lesson 1Lesson 1
Introduction to UWBCommunications
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UWB in modern communication systems (1/3)UWB in modern communication systems (1/3)
• The last few years have witnessed an increasedinterest of both chip manufacturing companiesand standardization bodies in UWB
…and others
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• Interesting UWB features are:1. Flexibility
• Spectral flexibility (coexistence)• Flexibility in providing wireless access to
heterogeneous applications.• Flexibility in system design (cross-layer system
optimization).
2. Robustness• Robustness to interference (external and internal)
3. High-precision ranging capabilities4. High capacity5. Low cost
UWB in modern communication systems (2/3)UWB in modern communication systems (2/3)
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UWB in modern communication systems (3/3)UWB in modern communication systems (3/3)
• Main challenges for UWB are:1.Acquisition and synchronization of
UWB signals2.Power constraints3.Accurate propagation models4.Accurate interference models5.Efficiency of implementation
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UWB domain of application (1/2)UWB domain of application (1/2)
Increased interesttowards UWB
Coexistence: Strongpower emissionconstraints imposedby regulatory bodies
UWB is emerging as an appealingtransmission technique for
applications requiring either high bitrates over short ranges or low bitrates over medium-to-long ranges
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UWB domain of application (2/2)UWB domain of application (2/2)
High bit rates overshort ranges
WPANs formultimedia traffic
Cable replacementfor high bit rate data
transfers
Wearable devices
Long-rangesensor networks
Non-real-time dataapplications (E-mail,
instant messaging …)
Low bit rates overmedium to long ranges
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What is UWB? (1/5)What is UWB? (1/5)
• A signal is UWB if its bandwidth is large withrespect to the carrier or center frequency of thespectrum, that is, if its Fractional Bandwidth(FB) is high.
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What is UWB? (2/5)What is UWB? (2/5)• The common adoption of the term UWB comes
to us from the radar community, and refers toelectromagnetic waveforms with aninstantaneous fractional bandwidth greater thanabout 0.20–0.25
• Traditionally, UWB signals have been obtainedby transmitting very short pulses withtypically no Radio Frequencies modulation– In communication systems, “very short” refers to a
duration of the pulse that is typically about a fewhundred picoseconds
• This technique goes under the name of ImpulseRadio (IR)
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What is UWB? (3/5)What is UWB? (3/5)• Impulse Radio was the primal technique for
transfering information over the wireless medium
In Guglielmo Marconi’s first experiments,back in 1894-18961894-1896, Morse Code messageswere transmitted over two miles usingpulsed transmission.
Marconi’s “7777” Patent Marconi's handwritten notesfor the specifications for the
'7777' Patent
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In December 19001900, Reginal Fessendenused impulse radio signals fortransmitting speech over one mile
In 19461946 a remarkable microwave radio relay system wasdeveloped by Black, Beyer, Grieser, and Polkinghorn.This system was based on the transmission of pulses thatwere position-modulated and ensured two-way voicetransmission over radio links totalling 1600 miles, andone-way over 3200 miles
During the 19701970s, the first patent for an impulseradio receiver to be used in communicationsystems is filed by Gerald F. Ross.
What is UWB? (4/5)What is UWB? (4/5)
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During the 19901990s, a few small and medium-sizedenterprises reintroduced the idea of wirelesscommunications based on the impulse radioparadigm
The term Ultra Wide BandUltra Wide Band was coinedby the U.S. Department of Defense in19891989
During the 19901990ss, relevant researchesabout Impulse Radio are carried out at theUniversity of Southern California byScholtz and Win.
What is UWB? (5/5)What is UWB? (5/5)
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FCC regulation about UWB emissions (1/6)FCC regulation about UWB emissions (1/6)• In order to verify the possibility for UWB systems
to coexist with other existing systems, severalmeasurement campaigns were performed in theUnited States by research institutes and agencies.– Measurement reports were commissioned to the
National Telecommunications and InformationAdministration (NTIA) by the FederalCommunication Commission (FCC)
– The final report was released by NTIA in March2001.
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• The most influential milestone in the history ofUWB was set in 2002, when the FCC approvedin the U.S. the first guidelines allowing theallowing theintentional emission of UWB signals andintentional emission of UWB signals andspecified emission masksspecified emission masks
FCC regulation about UWB emissions (2/6)FCC regulation about UWB emissions (2/6)
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FCC regulation about UWB emissions (3/6)FCC regulation about UWB emissions (3/6)
• In the FCC document, UWB is presented as atechnology with enormous potentials
• In the same report, however, we find explicitconcern about the need for emission masks,due to the unknown effects that UWBtransmissions may have on othercommunication systems.
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FCC regulation about UWB emissions (4/6)FCC regulation about UWB emissions (4/6)
FCC indooremission mask
FCC outdooremission mask
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FCC regulation about UWB emissions (5/6)FCC regulation about UWB emissions (5/6)
• According to the FCC rules, the UWB concept isnot limited to Impulse Radio
• Any signal is UWB provided that its fractionalits fractionalbandwidth is greater than 0.2bandwidth is greater than 0.2 or its occupiedits occupiedbandwidth is greater than 500 MHzbandwidth is greater than 500 MHz.
• The 500 MHz minimum bandwidth limit sets athreshold at 2.5 GHz– Below the threshold signals are UWB if their
fractional bandwidth exceeds 0.20– Above the threshold signals are UWB if their
bandwidth exceeds 500 MHz
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FCC regulation about UWB emissions (6/6)FCC regulation about UWB emissions (6/6)
• The effect of the FCC release was twofold
1. The FCC regulation of UWB emissionsraised the interest of major chipmanufacturers
2. Discussions were triggered around theadvantage of the Impulse Radio scheme vs.the traditional carrier-based continuoustransmission alternative
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IEEE UWB standardization activities IEEE UWB standardization activities (1/4)(1/4)
• The dichotomy between impulsive and non-impulsive UWB was reflected in the diatribeon UWB standardization, in particular in theframework of the IEEE 802.15 High RateAlternative PHY Task Group (IEEE 802.15.3aTask Group )
The IEEE 802.15.3a TaskGroup is working to provide ahigher speed PHY enhancementamendment to 802.15.3 forapplications involving imagingand multimedia
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IEEE UWB standardization activities IEEE UWB standardization activities (2/4)(2/4)• Two different proposals for a physical layer based on UWB
have been under discussion during several years:– a Multi-BandMulti-Band (MB) approach combining frequency hopping with
Orthogonal Frequency Division Multiplexing (OFDM)– a second approach using Direct-Sequence UWBDirect-Sequence UWB, or DS-UWB, which
preserves the original pulsed nature of UWB
• In the minutes of a IEEE 802.15.3a Task Group meetingheld in November 2004, the DS-UWB had obtained amajority of votes. A final agreement was however neverreached….
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UWB standards for high-rate data networks (3/4)UWB standards for high-rate data networks (3/4)
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UWB standards for high-rate data networks (4/4)UWB standards for high-rate data networks (4/4)
• After three years of dispute without a decisionbeing reached, the IEEE near unanimously votedto kill the 802.15.3a task group.
• The reason for the disband was that consensuscould not be reached between the two groupsbehind MB-OFDM and DS-UWB as to whichtechnology would become the 802.15.3astandard.
• Each group formed its own consortium:– WiMedia Alliance (for MB-OFDM) (– UWB Forum (for DS-UWB) (not exists anymore)
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UWB standards for low-rate data networks (1/2)UWB standards for low-rate data networks (1/2)
• Regarding the introduction of UWB in low-rate,location-enabled applications, standardization took itsfirst steps within the IEEE 802.15.4aIEEE 802.15.4a Task Group, thatis an evolution of IEEE 802.15.4IEEE 802.15.4
.4.4Standard for low-rate WPANswith multi-month to multi-yearbattery life.
• IEEE 802.15.4 features include data rates of 20-250 kbps, power management to ensure lowpower consumption, and low complexity.
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UWB standards for low-rate data networks (2/2)UWB standards for low-rate data networks (2/2)
• Within the 802.15.4, the Low Rate AlternativePHY Task Group (TG4a) is working toprovide high precision ranging / locationcapability (1 meter accuracy and better) andultra low power.
• In March 2005, TG4a selected two optionalPHYs consisting of:– a UWB Impulse Radio (operating in unlicensed
UWB spectrum)– a Chirp Spread Spectrum (operating in unlicensed
2.4GHz spectrum).
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Band Plan for IEEE 802.15.4a (1/2)Band Plan for IEEE 802.15.4a (1/2)
• IEEE 802.15.4a proposes a uniform band plan forthe UWB devices
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000Frequency MHz
TG4a Proposed Band Plan
Narrower Band ~ 500 MHz
Wider Band ~ 1300 MHz
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Band Plan for IEEE 802.15.4a (2/2)Band Plan for IEEE 802.15.4a (2/2)
• 802.15.4a devices will operate in two frequencyranges:– Low Frequency Band (LBF): 3211–4693 MHz (mandatory)– High Frequency Band (HFB): 5931.9-10304.25 MHz (optional)
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000Frequency MHz
TG4a Proposed Band Plan
1 2 3
4
5 6 7
13
8 9 10 11 12
14 15
LBF HBF
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Worldwide Band PlanWorldwide Band Plan
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000Frequency MHz
TG4a Proposed Band Plan
1 2 3
4
5 6 7
13
8 9 10 11 12
14 15
802.15.4a LBF
USAUSAJapanJapan(DAA)(DAA)
JapanJapan
EuropeEurope(DAA)(DAA)
EuropeEurope
802.15.4a HBF
DAA: DetectAnd Avoid
