Ultra wideband technologies – research perspectives · Ultra wideband technologies – research...

Ultra wideband technologies – research perspectives

Prof. Matti Latva-ahoDirector for CWC

8th SAME forum, Sophia-Antipolis, Oct 5-6, 2005

2/488th SAME forum, Sophia-Antipolis, Oct 5-6, 2005

Contents

• Introduction to UWB

• UWB regulation and co-existence

• UWB applications potential

• UWB research challenges and research at CWC


• UWB was first used for military applications in 1960’s in the USA and Soviet union

– impulse radar has good spatial and distance good spatial and distance resolutionresolution due to large bandwidth

• Technology was later applied to civil applications

– at first, impulse principle was used in ground penetrating radars in the middle of 1970

• Commercial UWB represents an overlay spread spectrum technology.

Brief History


UWB Technology – Spectrum Underlay

Bandwidth [Hz]

Power Spectral Density [W/Hz]

Conventional Carrier Modulation

Direct Sequence Spread Spectrum

Ultra-Wideband (UWB)FCC / Part 15 Limit(–41.25 dBm/MHz)

Note – Drawing not to scale

Source: IBM Zurich Research Lab

Typical Pulsed UWB Signal

SOURCE: MultispectralSolutions

0.2 … 2 ns

3.1

(10.6)

Source: IBM Research

3.1

Frequency in GHz

1.5 2.51.70.7 0.9 1.1 1.3 1.9 2.1 2.3

GSM-900IS-54IS-95 AMPS

802.11bBluetoothHomeRF802.15.4 (ZigBee)

GSM-1.8DECTGSM-1.9IMT-2000

2.7 2.9 3.5 4.53.73.3 3.9 4.1 4.3 5.1 5.34.7 4.9 5.5 5.7 5.9

IEEE 802.11aETSI HiperlanARIB MMAC

UWB

– Total Bandwidth: 7.5 GHz

– Max. EIRP: 563 µW (ave)


Why UWB?

• Variety of Application Scenarios• Lower Power; compared to current systems• Lower Cost; compared to current systems• Large Spatial Capacity• Inherent Robustness and Scalability• New Features (Localization and Tracking)• Worldwide License Free Spectrum Allocations

with possibility to obtain a standard solution (Goal)• Complementary approach to existing wireless

technologies


Why Not UWB?

• Does cause extra interference to existing system.

• Current proposals in regulation do not necessarily

result in single chip CMOS devices.

• Positioning accuracies may not necessarily be as

good as promised.

• Challenges in building very small antennas for

sensor type applications.

=> Lot’s of challenges for research


FIRST DEFINITION FOR UWB

• UWB signal

– first UWB definition by DARPA at 1990:

– utilizes transmission of very narrow pulses• suitable pulse waveforms

– Gaussian, pulses, wavelets, doublets, Hermitean polynoms, etc.

• fast frequency chirps

• damped sine waves

• direct sequence spread spectrum approach

• time hopping spread spectrum approach

• multicarrier modulation

25.02 ≥+−=

LH

LHf ff

ffB Relative bandwidth


COMMERCIAL INTERESTS are rising

• FCC : Notice of Inquiry, NOI (Sept. 1, 1998): Rules Regarding Ultra-Wideband Transmission Systems– to evaluate UWB technology, to define standards and to define

operating requirements

• Notice for Proposed Rule Making, NPRM (May 11, 2000):– based on the replies to NOI– released for public comments (Oct. 30, 2000)– no permission for UWB devices

• includes, e.g., GPS interference test results

• Feb 14, 2002 FCC adopted the First Report and Order (RO) that permits the marketing and operation of certain types of UWB products– full report released Apr 22, 2002– New definition for UWB: Relative bandwidth ≥ 0.20 or the

signal bandwidth ≥ 500 MHz– Spectrum mask defined:

• 2nd RO released Dec 16, 2004– it allows any kind of system, regardless of the bandwidth, to

operate under the UWB standards


• different radiation masks were given for several UWB applications in the 1st Report and Order– communications and measurement systems

3.1 GHz - 10.6 GHz

– FCC Emission Limits (dBm/MHz) for UWB Systems


0 2 4 6 8 10 12-80

-70

-60

-50

-40

UW

B E

IRP

Em

issi

on le

vel[

dBm

/MH

z]

Frequency [GHz]

UWB Emission Limit

0.96 1.61

1.99

3.1 10.6Indoor hand-heldOutdoor hand-heldPart 15 LimitCEPT indoor mask (early proposal)CEPT outdoor mask (early proposal)

0 2 4 6 8 10 12-75

-70

-65

-60

-55

-50

-45

-40

UW

B E

IRP

Em

issi

on le

vel[

dBm

/MH

z]

Frequency [GHz]

0.96 1.61

1.993.1 10.6

Through-wall radarGPR (fc > 3.1 GHz)GPR (fc < 960 MHz)

Part 15 Limit

-41.3 dBm/MHz

FCC Part15

FCC Spectrum Masks

UWB is an overlay technology => succesful deployment requirescoexistence with all other wireless technologies


Other Regulatory Issues

• ITU-R TG 1/8 preparing global recommendation

• CEPT ECC TG 3 preparing European recommendation

• ETSI ERM TG 31A Harmonised Standards for EU

regulatory purposes– ERM TG31A: UWB for Short Range Devices

– ERM-TG31B: UWB Automotive Radar

– ERM TG31C: UWB Sensors


• CEPT ECC TG3 continues to work on the definition of an UWB regulatory framework

– Initial report (ECC Report 64) delivered to the European Commission (EC) in April 2005

– EC considers ECC Report 64 not sufficient to define an UWB regulation for Europe

– CEPT is expected to recommend tentative UWB regulation by the end of 2005

European Regulation


European Regulation (2)

• OFCOM (UK) proposed mask:P

SD

(d

Bm

/MH

z)

Frequency (GHz)

PS

D (

dB

m/M

Hz)

Frequency (GHz)


Asian Regulation - Japan

Japan

Indoor only

Maximum 1400MHz Maximum 3000MHz

Japan

Indoor only

Japan

Indoor only

Maximum 1400MHz Maximum 3000MHz

WLAN & 4GSystems


Global Regulation – ITU-R TG 1/8

� Since early 2004, ITU-R TG 1/8 carries out S1-level studies (= urgent studies completed within 2 years) to provide answers to two adopted UWB-related questions:

• ITU-R 226/1 – Spectrum management framework related to the introduction of UWB devices

• ITU-R 227/1 – Compatibility between UWB devices and radiocommunication services

� The 6th meeting of ITU-R TG 1/8 will be arranged in Geneva 13 - 19 Oct 2005• TG 1/8 conducts UWB impact studies for a large number of radiocommunication services

– Results based on “worst-case scenarios” track those reported by CEPT (“ECC Report 64”)

� Global ITU recommendations for UWB radio applications not expected before 2006

Decision 1/95Measurement Techniques WG 4

Question 226/1Spectrum Management FrameworkWG 3

Question 227/1UWB CompatibilityWG 2

Question 226/1 and 227/1UWB CharacteristicsWG 1

ITU-R Question/DecisionTitle Working Group


UWB System Characteristics


Impulse radio

• Typically, conventional radio systems are (super)-heterodyne systems, in which baseband signal is sent using higher frequencies

• In impulse radio, no carrier frequency is needed (baseband transmission)

�Very simple transeivers

UWB Main Characteristics


• Low power spectral density– low average transmitted power – low peak-to-average power ratio (3 dB)– processing gain requirements due to the weak signal

– UWB bandwidth from 500 MHz up to 7.5 GHz• sub-nanosecond pulse widths• spectrum is independent of the frame structure

– flexible selection of data rates– data rate changes the average psd

• signal is noise-like• covert

– good LPD/LPI properties for military communications

– co-existence with other radio systems



• Good penetration properties (low frequencies)

– through-wall, ground surface, forest, water,... • decreasing because of the current FCC radiation mask

– the use of the lower frequencies is forbidden in communications applications

• Due to the large bandwidth, good spatial and temporal resolution is achieved

• Very accurate positioning with data transmission

• Ad hoc network structure– no spectral planning needed– no fixed infrastructure

• Favours short coverage systems



UWB Capabilities and Potential Application Spaces

1

8

6.85 GHz

20 Mp/s

75 nW/MHz

7500 MHz

1500 MHz

1

Rx-NF 3 dB

10

10

C

PRF

T T

R

M

M

f

F

D G

B

B

G

P

P

−

−

==

===

===

=

BP-2-PAM / 256-PPM

BP-2-PAM / 64-PPM

BP-32-PAM / 1-PPM

BP-2-PAM / 1-PPM: 1N =

10N =

100N =

BP-2-PAM / 1-PPM:

BP-2-PAM / 1-PPM:

~Channel Capacity or Cutoff Rate [Mb/s]

Link Distance [m]

Channel Capacity:

Cutoff Rate:

C

oR%

Free Space UWB Channel

IBM Zurich Research Laboratory

Low Data Rateand/or

Location TrackingApplications

Very High Data RateApplications


UWB Capabilities and Potential Application Spaces (2)

UWB

UWB

HDR & VHDR

LDR & LDR-LT

4Gcellular


• For high data rates: IEEE802.15.3a– high speed wireless personal area networks– two proposals: DS-UWB and MB-OFDM-UWB– no agreement which one will be selected=> market will decide

=>Only a global standard would result in great success

• For low data rates: IEEE802.15.4a– communications and high precision ranging/location– standardization process is ongoing

=> Also proprietary solutions are needed

The Main Stream Approaches


The Main Stream Approaches (2)

• Three different transmission technologies:

– “Impulsive technology” �Pulsed UWB

– “Radar Type technology” �Direct Sequence-UWB

– “WLAN technology” �Multi Carrier UWB

• Also fast frequency chirp based concepts have been

proposed.


Pulse Waveforms vs. Spectrum


Spectra of pulse trains in TH-mode without and with pseudo random code (no data modulation)

Pseudo random TH-code is usedPseudo random pulse repetition interval

Pseudo random TH-code is NOT usedFixed pulse repetition interval

Note: data modulation also affects to the line spectral components.

spectrum of a single pulse


• the 4th derivative of the Gaussian pulse matches FCC requirements

Time Hopping Time Hopping –– Binary Pulse Amplitude Modulation Binary Pulse Amplitude Modulation (TH(TH--BPAM)BPAM)


Multiband OFDM

• Background:

– E.g., Wi-Fi 802.11a/g and WiMAX 802.16a are based on OFDM.

• Motivation:

– Multicarrier modulation results in straight forward schemes to manipulate signal spectra

• Can be seen as a WiFi extension to shorter distances and higher data rates

– Major benefits of impulse radio are lost (CMOS based single chip TRXs)

– Instantaneous bandwidth ~500MHz => extremely accurate positioning capabilities are lost


Multi-Band Frequency-Plan

• Sub-bands are spaced 470 MHz apart

• Each sub band is generated by a pulse with 10 dB bandwidth of ~528 MHz

•A Second group overlap the first group by 235 MHz

•enhance system flexibility with respect to co-existence, interference mitigation and multiple access


UWB Applications

• Communications• Short range communication links

• WLANs• Ad hoc networks• Data & voice & control links• Wireless-USB

• Radar• Ground penetrating radars• Through-wall radars• Imaging and ranging• Buried victim rescue• Landmine detection

• Intelligent Sensors• Collision avoidance, proximity and altitude sensors

• Telemetry

• Motion detection

• RF tags

• Fluid level monitoring • Reverse driving and parking aids

• Intelligent Airbags

• Intelligent Transport System

• Others• Geolocation• Wireless door openers• Medical applications: e.g. radio stethoscope


• Bluetooth: PC - PDA, PC - cell phone, PC - mouse, cell phone -headset, etc., – Ptx = 0 dBm, ~10 m, 2.4 GHz ISM band, 64 kbps (sync.) -723.2 kbps (async.)

• HIPERLAN2: OFDM, 5 GHz, 6-54 Mbps@30 m• IEEE802.11b: DSSS, 2.4 GHz ISM band, 1-11 Mbps•• IEEE802.15.3a:IEEE802.15.3a: dd < 10 m, < 10 m, RRdd > 100 Mbps, UWB is proposed for > 100 Mbps, UWB is proposed for

PHYPHY--layerlayer• UWB:

– short range wireless communication links(about 10’s to 100’s m)

– low/high data rates (up to Gbps)• easy to adjust• no effect to spectral properties

– aggregate noise is increased with the increasing Rd

– single chip realization is possible– prefer CMOS technology

Communication Applications


• Carrier-less transmission– inexpensive CMOS technology can be used

• UWB localizers are suitable for indoor environment where GPS cannot be used

• Large bandwidth of UWB signal -> high resolution

• Relative distances between localizers are defined by measuring propagation times of the pulse sequences

• Ad hoc network structure will improve the accuracy – more calculation points

Positioning Systems


Examples of CWC’s Experimental Research on UWB

Case 1: UWB TRX chip design for LDR-LT


Table 2 Bit durations for the radio.

Bit duration = 240nsData modulation: Bit Position Modulation (BPM), Max. rate 4.2 Mbps

Bit energy spread on a pulse train (60 pulses) of length 100ns

Bit level

Monocycle transmitted pulse, pulse repetition rate 500 Mhz

Pulse width=300ps (240ps-320ps) ±2ns (process dependent)

Pulse level

Table 2 Specification for the ASIC.

3.3 VSupply voltage

115 mWRX power consumption

22 mWTX power consumption

5 MbpsData rate

3.1 – 4.1 GHzBandwidth

Figure 1 LDR-LT development platform block diagram.

Specification for CWC UWB LDR-LT Platform


Transmitter Architecture

• Transmitter based on – an UWB pulse transmitter

with accurate timing based on a DLL

– a DLL-based frequency multiplier

Circuits developed in 0.35 µm CMOS :

• one delay locked-loop• edge combiner• UWB pulse generator• The output is a differential

monocycle pulse with a typical pulse width of less than 400 ps.

• Area: 0.5 mm2.• Power consumption: 20 mW.


Receiver Architecture

• Incoming signal is amplified, squared by multiplier and integrated.

• Disadvantage - noise as well as signal is amplified by the receiver.

Circuits designed in 0.35 µm SiGe BiCMOS include:

• variable gain amplifier (VGA)

• squaring circuit

• integration circuits

• A/D converter

• the digital control logic (DCL)

Decison( )2 IntegratorBPF


TRX Chip

• Total area: 9 mm2

Test structures (VGA, Gilbert, ADC) are included

(RF frontend, current sources and quartz oscillator not included)

CWC is looking for partners in completing the ASIC design process.


Examples of CWC’s Experimental Research on UWB

Case 2: Co-existence measurements against UMTS


Co-Existence

• Due to the wide UWB signal occupation the co-existence issues are very important

• Several potential victim systems:– Fixed Service (FS), Mobile Satellite Service (MSS, Earth Exploration

Satellite Service (EESS), Radio Astronomy Service (RAS),Digital video broadcasting: DVB–T, Digital audio broadcasting: T–DAB, Bluetooth PAN, Radio LAN, Public Land Mobile Service (MS): IMT-2000, Radio Navigation Satellite Service (RNSS), Fixed Satellite Service (FSS), Amateur/Amateur Satellite Services (Amateur), Maritime mobile service (Maritime), Global Maritime Distress & Safety Systems(GMDSS), Aeronautical Mobile Service and radio determination service(Aeronautical, AMS, ARNS), Meteorological Radars.

• Research have been carried out by simulations, analytical calculations and field trials.


CWC Co-Existence Measurements

• an anechoic chamber

– with Anritsu MT8820A (MS -> BS: 3 m)

• a shielded room

– operational UMTS network (MS -> BS: link ca. 300 m)

– a cell boundary condition (weak UMTS signal)

Anritsu

MT8820A

Nemo

OutdoorTM

BSMS

3 m

24 UWB transmitters

36 cm - 252 cm from MS

Anechoic chamber

ARA CMA-118


Measurements: UWB devices (1)

• 24 FCC compatible UWB transmitters are used

– based on DS-UWB concept (single-band UWB)• length of m-sequence: 220-1 = 1048575

– transmitted power at the output of the pulse generator PTX = 0.0661 mW (-11.8 dBm)

– two pulse repetition frequencies are used: PRF = 100 MHz and 200 MHz

– Activity factor is varied: AF values 1%, 5%, 10%, 20%, 50% and 100%

x

y

timeTransmission OFF

Transmission ON Transmission ON


Filtered out by the antenna

Conducted

Background noise

Radiated: Different antenna separation


Measurements: UMTS victim system

• Two cases studied for Network

1. Anritsu MT8820A Radio Communication Analyzer and ARA CMA-118/A wideband omni-antenna

2. Operational UMTS network

• Mobile terminal - commercial UMTS mobile phone

• Parameters are monitored using NemoNemo “Outdoor Field Measurement™” software

• UMTS link was fixed (MS or BS antenna were not moved) to maintain propagation conditions during the measurements


Measurements: parameters examined

• Ec/N0: chip energy divided by noise spectral density at common pilot channel (CPICH)

• RSSI: received signal strength indicator at carrier @ 5 MHz bandwidth

– all the received power at the corresponding band

• BER: bit error rate at downlink pilot channel (also BLER)

• RSCP: received signal code power at CPICH is calculated by

RSCP = RSSI + Ec/N0


Base station antennaARA CMA-118/A

Mobile

Fixed to 3 m

36 cm – 252 cm

Anechoic Chamber Scenario


Results – Anechoic Chamber (7)

• BER

– For AF ≤ 50%, no impact can be seen

– For AF = 100% UMTS performance degradation observable for distances of less than 70 cm. Beyond 1 m, the UWB impact is insignificant

• Next we introduce only one parameter from the set of Ec/N0, RSSI and RSCP for shielded room measurements (cell boundary)


Results – Shielded Room (1)

• Shielded room with an operational UMTS network

• Ec/N0 versus number of UWB devices

• Separation distance (UWB to victim) is 100 cm

Limit is found from the measurements

No measurable impact


Co-Existence - Conclusions

• Based on the measurements, it appears that UWB devices can co-exist with UMTS/WCDMA under the practical scenarios (based on the single active link measurements)

– with a realistic number of simultaneously active UWB devices in the vicinity of the victim system (1…4)

– realistic activity factor (< 5%).


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