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The Evolution of UWB and IEEE 802.15.3a for Very High Data

Rate WPANby Ketan Mandke, Haewoon Nam,

Lasya Yerramneni, and Christian ZunigaEE 381K-11 Wireless Communications

UWB Group, The University of Texas at Austin

presented May 3, 2003

Scope of Presentation

• Introduction– FCC Regulations, IEEE 802.15

• UWB Channel Model– Proposed Models, Current Measurements

• Impulse Radio v. Multibanded Approach• IEEE 802.15.3a

– Technical Specifications, Proposals Overview

UWB: Impulse Radio

* from “License Free Wireless Systems: Where are we headed?”, a tutorial by Dr. Kevin Kahn, Intel.

Historical Perspective of UWB

• 1900s: Marconi Spark Gap• 1900 – 1940s: Wireless goes tuned• 1960s: UWB radios/radar systems emerge

– subnanosecond pulse generation• 1990s: “Moore’s Law Radio”

– UWB in CMOS circuitry• 2002: FCC 02/48 First Report and Order

– approves use of unlicensed UWB devices– UWB defined as bandwidth > 500 MHz

FCC UWB Spectral Allocation

*graph from “Ultra Wideband Systems”, by Molisch and Zhang. http://www.wmrc.com/businessbriefing/pdf/wireless_2003/Publication/molisch.pdf

FCC Requirements for Indoor and Hand Held UWB Devices

10 secondsMax unacknowledged transmission period

60 dB above average emission levelPeak emission level in band

-51.3 / -61.3Above 10600

-41.3 / -41.33100-10600

-51.3 / -61.31900-3100

-53.3 / -63.31610-1900

-75.3 / -75.3960-1610

EIRP in dBm (indoor/ hand held)Frequency range (MHz)

Average radiated emissions limit

3.1 GHz to 10.6 GHzOperating frequency range

IEEE 802.15WPAN

TG1WPAN/

Bluetooth

TG2Coexistence

TG3High Rate

(20 Mbps+)WPAN

TG4Low Rate

WPAN

TG3aWPAN Higher Rate(110 – 480 Mbps) PHY Alternatives

Timeline of IEEE 802.15.3a

2003

J J A S O N D J F M A M J J DJ F M A M A S O N

Downselect

2002

CFA

D

DraftProject Definition

FCC approves UWB3 rounds ofproposals

*from IEEE 802.15-03/056r0

Selection Criteriaestablished

Technical Requirementsapproved

CFI/CFP

Complete drafting,Begin voting

UWB Channel Modeling

• Motivations for the UWB channel modeling– Only a limited number of measurements could be considered “Ultra-

WideBand” (500MHz +)– Current measurements are inconsistent with regard to bandwidth,

environment, separation distances, etc.

• The model should be “relatively simple” to be usable for testing and validation of various proposed UWB PHY

• Model evaluation– How to evaluate ‘goodness’ of model?

• Mean Excess Delay• Mean RMS Delay• Mean number of paths

– > 10 dB from peak– 85% energy capture

Multipath models

• Summary of models considered– Rayleigh Tap Delay Line Model (802.11)

• Arrival at every resolvable sample time

– Saleh-Valenzuela (S-V) Model• Random path arrivals following the Poisson process with double

exponential Multipath Intensity Profile (MIP)

– ∆-K Model• Random path arrivals using modified Poisson arrival process

with single exponential MIP

Multipath measurements

• Measurement environments– AT&T: home environment in 4.25-5.75 band (1.5 GHZ

BW) at separation distances 1-15 m– Intel: condo environment in 2-8 GHz band (6 GHz BW) at

separation distances 1-20 m– Mitsubishi/Win/Cramer: office environment in ~1-1.5 GHz

band (0.5 GHz BW) at separation distances of 8-13.5 m– Time Domain: office environment in 3-5 GHz band (2

GHz BW) at separation distances 1-10 m

The Intel channel model

• The model based on S-V model with following modifications from original model

– Cluster arrivals experience independent log-normal shadowing

• Observation from measurements that cluster arrivals later in time had larger amplitudes

– Characteristic not captured by S-V model with single cluster-ray amplitude distribution

– Ray arrivals within cluster experience independent log-normal fading (also considering Nakagami distribution)

– Similar approach of combining independent cluster shadowing and Ray fading considered in COST259 Indoor Channel models

Model CharacteristicsTarget Channel Characteristics

CM 1 CM 2 CM 3 CM 4

Mean excess delay (nsec) ( mτ ) 5.05 10.38 14.18

RMS delay (nsec) ( rmsτ ) 5.28 8.03 14.28 25NP10dB 35NP (85%) 24 36.1 61.54Model ParametersΛ (1/nsec) 0.0233 0.4 0.0667 0.0667λ (1/nsec) 3.5 1 3 3Γ (nsec) 7.1 5.2 14.00 24.00γ (nsec) 5 6.5067 8.5 12

1σ (dB) 3.3941 3.3941 3.3941 3.3941

2σ (dB) 3.3941 3.3941 3.3941 3.3941Model CharacteristicsMean excess delay (nsec) ( mτ ) 5.5 9.2 ns 14.9 26.3

RMS delay (nsec) ( rmsτ ) 6 8 14 25NP10dB 14.9 22.0 31.7 43.8NP (85%) 23.4 35.7 60.8 115.5

* Based on 167 psec resolutionIEEE P802.15-02/490r1-SG3a , Channel Modeling Sub-committee Report Final

0 20 40 60 80 100 120-2

-1.5

-1

-0.5

0

0.5

1Impulse response realizations

Time (nS)0 10 20 30 40 50 60 70 80 90 100

2

4

6

8

10

12

14Excess delay (nS)

Channel number

0 10 20 30 40 50 60 70 80 90 1002

4

6

8

10

12

14

16RMS delay (nS)

Channel number0 10 20 30 40 50 60 70 80 90 100

0

5

10

15

20

25Number of significant paths within 10 dB of peak

Channel number

IEEE P802.15-02/490r1-SG3a , Channel Modeling Sub-committee Report FinalCM1 : Line-Of-Sight , 0~4m

0 20 40 60 80 100 120 140-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1Impulse response realizations

Time (nS)0 10 20 30 40 50 60 70 80 90 100

2

4

6

8

10

12

14

16

18

20Excess delay (nS)

Channel number

IEEE P802.15-02/490r1-SG3a , Channel Modeling Sub-committee Report Final

0 10 20 30 40 50 60 70 80 90 1005

6

7

8

9

10

11

12

13

14RMS delay (nS)

Channel number0 10 20 30 40 50 60 70 80 90 100

0

5

10

15

20

25

30

35


Channel number

CM2 : Non Line-Of-Sight , 0~4m

0 50 100 150 200 250-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

0.15

0.2

Time (nsec)

Am

plitu

de

Example Impulse Response

0 10 20 30 40 50 60 70 80 90 1008

10

12

14

16

18

20RMS delay (nS)

Channel number

IEEE P802.15-02/490r1-SG3a , Channel Modeling Sub-committee Report Final

0 10 20 30 40 50 60 70 80 90 1008

10

12

14

16

18

20

22

24

26RMS delay (nS)

Channel number0 10 20 30 40 50 60 70 80 90 100

0

10

20

30

40

50

60

70


Channel number

CM3 : Non Line-Of-Sight , 4~10m

Impulse Radio v. MultibandedApproach

• Impulse Radio (IR) was the original approach to UWB.– Used short-duration baseband pulses with a bandwidth of a

few GHZ.– Pulses modulated using PPM or PAM– Multiple Access supported using a time-hopping scheme

• Multibanded Approach is currently favored by many companies (e.g. Intel, General Atomics, and Time Domain)– Spectrum is divided into separate bands (>500 MHZ)– Similar to conventional OFDM

Challenges of Impulse Radio*

SolutionsChallenge

• Using more rake taps increases receiver complexity

Multipath mitigation(ex. B = 500 MHz => Ts = 2 ns

B = 5 GHz => Ts = 0.2 ns mean excess delay = 5 ns)

• Fitting FCC spectral mask• Use of notch filters against NBI

Coexistence with existing wireless systems.

• Increasing the pulse-repetition frequency (PRF) increases ISI• Using higher-order modulation leads to higher peak-to-average power

Scaling to higher data rates.

• Preamble overhead may slow down acquisition time

Timing Acquisition.

*Somayazulu, Foerster, and Roy “Design Challenges for Very High Date Rate UWB Systems” Intel Labs

Multibanded Approach

• Spectrum is divided into separate bands (>500 MHz).• Static or Dynamic assignment of these bands.• Data modulated using a concatenation of these bands.

*taken from IEEE 802.15-03/143r2

0 1 2 3 4 5 6 7

Reserved 9 10 11 12 13 14 15

Low Frequency Group High Frequency Group

Drop band in Japan Drop band in Europe

0 1 2 3 4 5 6 7

Reserved 9 10 11 12 13 14 15


~ ~

0 1 2 3 4 5 6 7

Reserved 9 10 11 12 13 14 15


Drop band in Japan Drop band in Europe

0 1 2 3 4 5 6 7

Reserved 9 10 11 12 13 14 15


~ ~~ ~

Sacrifice 1 band for coexistence (dependent upon geographical location)

3.1 10.6

Unexpected Interferer

Advantages of the MultibandedApproach

• Coexistence– Greater flexibility and scalability

• Scaling to higher data rates– PRF can be lower than IR at the same peak

power.

• Faster Timing acquisition• Fewer Rake fingers• Implementation feasibility

Criteria for the alt-PHY solutions

• Unit Manufacturing Cost (UMC)/Complexity • Signal robustness

– Co-existence– Interference susceptibility

• Technical feasibility – Regulatory impact– Time to market

Criteria (cont.)

• Scalability• Location awareness• Size and form factor• Simultaneously operating piconets• Signal acquisition • Power management modes• Antenna practicality

Technical Requirements

Capabilities such as power save, device sleep, wakeup, etc.

Power management modes

4Co-located piconets

100mW, 250mWPower consumption10m, 4m and belowRange

110, 200 and 480Mb/s(optional)

Data RatesVALUEPARAMETER

Technical Requirements (cont.)

Interfering average power at least 6dB below the minimum sensitivity level of non-802.15.3a device*

Co-existence capability

PER<8% for a 1024 byte packet length*

Interference susceptibility

Location information to be propagated

Location awareness

VALUEPARAMETER

* With a separation of 1m between the interfering device and the victim receiver


VALUEPARAMETER

Minimal ~ comparable to Bluetooth

Unit manufacturing cost(UMC)/complexity

Backwards compatibility with 802.15, adaptable to various regulatory regulations like US (FCC), European, Japanese, etc.

Scalability


VALUEPARAMETER

Size and form factor consistent with original device

Antenna practicality

<20 µs for acquisition from the beginning of the preamble to the beginning of the header

Signal Acquisition

Proposal Overview

1-tap (robust to 60.6 ns delay spread) Multipath mitigation method

312.5 ns Symbol period

5.5 db @ 10 m @ 110 Mbps,10.2 db @ 4 m @ 200 Mbps,12.2 db @ 2 m @ 480 Mbps

Link margin

11/32 @ 110 Mbps, 5/8 @ 200 Mbps, ¾ @ 480 MbpsCode rates

Convolutional codingError correction codes

Not available# of simultaneous piconets

Not availableMultiple access method

null band for WLAN (~5GHz)Coexistence method

TFI-OFDM, QPSKModulation scheme

3.168 GHz – 4.752 GHzFrequency ranges

503.25 MHzBandwidths

3 (additional bands can be added in the future)# of bands

Spectrum Allocation:

Texas InstrumentsCompany

Decision feedback equalizerMultipath mitigation method

731 ps (Low band), 365.5 (High band)Chip Duration

9.9 db @ 10 m @ 110 Mbps,13.2 db @ 4 m @ 200 Mbps,3.4 db @ 2 m @ 600 Mbps

Link margin

½ @ 110 Mbps, RS(255,223) @ 200 Mbps, RS(255,223) @ 480 Mbps

Code rates

Convolutional coding, Reed Soloman codeError correction codes

4 piconets/ band# of simultaneous piconets

Ternary CDMAMultiple access method

AvoidanceCoexistence method

BPSK, QPSKModulation scheme

3.1 GHz – 5.15 GHz, 5.825 GHz – 10.6 GHzFrequency ranges

1.368 GHz, 2.736 GHzBandwidths

2# of bands


XtremeSpectrumCompany

frequency interleaving of MBOK chips; time frequency codes; feed forward filter

Multipath mitigation method

3 ns Symbol period

6.3 dB @ 10 m @ 108 Mbps,8.0 dB @ 4 m @ 288 Mbps,4.0 dB @ 4 m @ 577 Mbps

Link margin

6/32 @ 110 Mbps, 5/16 @ 200 Mbps, ¾ @ 480 MbpsCode rates

Convolutional coding, Reed-Soloman codeError correction codes

Not available# of simultaneous piconets

DS/FH CDMA, optional FDMAMultiple access method

Null band for WLAN (~5GHz)Coexistence method

M-ary Bi-orthogonal Keying, QPSKModulation scheme

3.6 GHz – 6.9 GHz, (7.45 GHz – 10.2 GHz optional)Frequency ranges

550 MHzBandwidths

7 (+ optional 6 bands for future use)# of bands


IntelCompany

Conclusions

• UWB advantages– tremendous capacity potential– fine multipath resolution

• Accurate channel models needed• Advantages of multibanded approach• TG3a proposal trends• IEEE 802.15.3a due to be drafted Nov. 2003

References• [1] Ellis, Siwiak, Roberts, “TG3a Technical Requirements,” IEEE 802.15-

03/030r0. December 27, 2002.• [2] FCC, First Report and Order 02-48. February 2002.• [3] A. F. Molish, J. Zhang, “Ultra Wideband Systems,”

http://www.wmrc.com/businessbriefing/pdf/wireless_2003/Publication/molisch.pdf. Last accessed May 5, 2003.

• [4] W. M. Lovelace and J. K. Townsend, “The Effects of Timing Jitter and Tracking on the Performance of Impulse Radio,” in IEEE Journal on Selected Areas in Communications, vol. 20 no. 9, pages 251-254, December 2002.

• [5] 802.11Hotspots.com. http://www.multispectral.com/history.html. Last accessed April 24, 2003.

• [6] R. F. Heile, “TG3a Project Timeline,” IEEE 802.15-03/056r0. January, 2003.

• [7] D. Cassioli, M. Z. Win, and A. F. Molisch, “The Ultra-Wide Bandwidth Indoor Channel: from Statistical Model to Simulations,” IEEE P802.15-02/284-SG3a. September 4, 2002.

• [8] J. Foerster and Q. Li, “UWB Channel Modeling Contribution from Intel,” IEEE P802.15- 02/279-SG3a. September 4, 2002.

References (cont.)• [9] M. Pendergrass, “Empirically Based Statistical Ultra-Wideband

Channel Model,” IEEE P802.15-02/240-SG3a. September 4, 2002.• [10] J. Kunisch and J. Pamp, “Radio Channel Model for Indoor UWB

WPAN Environments,” IEEE P802.15-02/281-SG3a. September 4, 2002.• [11] J. Foerster, “Channel Modeling Sub-committee Report,” IEEE

P802.15-02/368r1-SG3a. November 5, 2002.• [12] A. Saleh and R. Valenzuela, “A Statistical Model for Indoor Multipath• Propagation,” IEEE JSAC, Vol. SAC-5, No. 2, Feb. 1987, pp. 128-137.• [13] Q. H. Spencer, B. D. Jeffs, M. A. Jense, A. L. Swindlehurst, "Modeling

the Statistical Time and Angle of Arrival Characteristics of an Indoor Multipath Channel," IEEE JSAC, Vol. 18, No. 3, March 2000.

• [14] T. S. Rappaport and S. Sandhu, “Radio-Wave Propagation for Emerging Wireless Personal Communication Systems,” IEEE Antennas and Propagation Magazine, Vol. 36, No. 5, pg. 14-24, Oct. 1994

• [15] H. Hashemi, “Impulse Response Modeling of Indoor Radio Propagation

• Channels,” IEEE JSAC, Vol. 11, No. 7, Sept. 1993, pp. 967-978.• [16] M. Z. Win and R. A. Scholtz, “Impulse Radio: How it Works” IEEE

Communications Letters, Vo. 2, No.2, p. 36, February 1998.

References (cont.)• [17] http://grouper.ieee.org/groups/802/15/pub/2003/Mar03/. Last

accessed May 5, 2002.• [18] M. Pendergrass, Time Domain Corporation, “Time Domain Supporting

Text for 802.15.3 Alternate Physical Layer Proposal,” IEEE 802.15-03/144r1. March 3, 2003.

• [19] Somayazulu, Foerster, and Roy, “Design Challenges for Very High Data Rate UWB Systems,” Intel Labs, http://www.intel.com/technology/ultrawideband/ downloads/Asilomar_2002_final.pdf. Last accessed May 5, 2003.

• [20] T. S. Rappaport, Wireless Communications. Prentice Hall. December 2001.

• [21] Ellis, Siwiak, Roberts, “P802.15.3a Alt PHY Selection Criteria,” IEEE 802.15-03/031r9. March 13, 2003.

• [22] A. Batra, et. al. “TI Physical Layer Proposal for IEEE 802.15 Task Group 3a,” IEEE P802.15-03/142r0. March 3, 2003.

• [23] R. Roberts, “XtremeSpectrum CFP Document,” IEEE P802.15-03/154r1. March 3, 2003.

• [24] J. Foerster, V. Somayazulu, S. Roy, et. al., “Intel CFP Presentation for a UWB PHY,” IEEE P802.15-03/109r1. March 3, 2003.

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