ULTRA WIDE BAND TECHNOLOGY

Low Power UWB

Technologyfor WBAN

2

What is Ultra Wide Band ? • UWB transmitter signal BW:

‘OR’

• BW 500 MHz regardless of fractional BW

fu-flfu+fl

2 0.20

Where: fu= upper 10 dB down point fl = lower 10 dB down point

Source: US 47 CFR Part15 Ultra-Wideband Operations FCC Report and Order, 22 April 2002:http://www.fcc.gov/Bureaus/Engineering_Technology/Orders/2002/fcc02048.pdf

UWB: Large Fractional Bandwidth

Po

wer

Sp

ect

ral

Den

sit

y (

dB

)

one “chip”one “chip”CDMA: 1.288Mcps/1.8 GHz 0.07% bandwidth

6% bandwidth

-80

-40

0

Frequency (GHz)

3 6 9 12 15

Random noise signal

100% bandwidth

UWBUWB

NBNB

20% bandwidth

Relative Bandwidth

• UWB is a form of extremely wide spread spectrum where RF energy is spread over gigahertz of spectrum– Wider than any narrowband system by orders of magnitude– Power seen by a narrowband system is a fraction of the total

UWB power– UWB signals can be designed to look like imperceptible

random noise to conventional radios

Narrowband (30kHz)

Wideband CDMA (5 MHz)

UWB (Several GHz)

Frequency

Part 15 Limit( -41.3dBm/Hz )

UWB Signal Characteristics7,500 MHz available spectrum for unlicensed use

US operating frequency: 3,100 – 10,600 MHz Emission limit: -41.3dBm/MHz EIRPIndoor and handheld systems

UWB signal transmitter defined as having the lesser ofFractional bandwidth greater than 20%Occupies more than 500 MHz

UWB is NOT defined in terms ofModulationor Carrierlessor Impulse radio

FCC First Report and Order Authorizes Five Types of Devices

Class / Application Frequency Band for Operation at Part 15 Limits

User Limitations

Communications and Measurement Systems

3.1 to 10.6 GHz(different “out-of-band” emission

limits for indoor and hand-held devices)

No

Imaging: Ground Penetrating Radar, Wall, Medical Imaging

<960 MHz or 3.1 to 10.6 GHz Yes

Imaging: Through-wall <960 MHz or 1.99 to 10.6 GHz Yes

Imaging: Surveillance 1.99 to 10.6 GHz Yes

Vehicular 22 to 29 GHz No

Effectiveness of Ultra Wide Band• Shannon showed that the system capacity, C, of a channel perturbed

by AWGN ---

)1(log 2 N

SBC

Where: C = Max Channel Capacity (bits/sec) B = Channel Bandwidth (Hz) S = Signal Power (watts) N = Noise Power (watts)

Capacity per channel (bps) BCapacity per channel (bps) log(1+S/N)

1. Increase B2. Increase S/N, use higher order modulation3. Increase number of channels using spatial separation (e.g., MIMO)

What if I do not require a high capacity ?

UWB

-5db 5 db 10 db 15 db

1

2

3

4

1/2

1/4

1/8

1/16

Bits/sec/Hz

Eb/N0

Bandwidth LimitedEnergy Limited

UWB Usual goal

Low signal to noise ratioBandwidth inefficient

4G

POTENTIAL FOR UWB

3G and beyond

UWB Properties• Extremely difficult to detect by unintended users

– Highly Secured• Non-interfering to other communication systems

– It appears like noise for other systems• Both Line of Sight and non-Line of Sight operation

– Can pass through walls and doors• High multipath immunity• Common architecture for communications, radar &

positioning (software re-definable)• Low cost, low power, nearly all-digital and single chip

architecture

UWB Emission Limits for GPRs, Wall Imaging, & Medical Imaging Systems

Operation is limited to law enforcement, fire and rescue organizations, scientific research institutions, commercial mining companies, and construction companies.

0.96 1.61

1.993.1 10.6

GPS Band

Source: www.fcc.gov

UWB Emission Limits for Thru-wall Imaging & Surveillance Systems

Operation is limited to law enforcement, fire and rescue organizations. Surveillance systems may also be operated by public utilities and industrial entities.

0.96 1.61

1.99 10.6GPS Band

Source: www.fcc.gov

UWB Emission Limit for Indoor Systems

0.96 1.61

1.99

3.1 10.6

GPS Band

Source: www.fcc.gov

0.96 1.61

1.99

3.1 10.6

GPS Band

Source: www.fcc.gov

UWB Emission Limit for Outdoor Systems

Proposed in preliminary Report and Order, Feb. 14, 2002.

First Report and Order, April 22, 2002.

0.01 0.1 1 10 100-80

-70

-60

-50

Frequency, GHz

-40EIRP, dBm/MHz

UWB Band-width must be contained here

Actual UWB Emission Limit for Hand-held Systems

Range Vs Data Rate

Tuesday, April 11, 2023 Dr. M.MEENAKSHI, DECE, CEG, ANNA UNIVERSITY 16

Wireless Body Area Network

WBAN Scenario

WIRELESS ACCESS POINT

(PCF MODE)

UWB TRANSCEIVER

SERVER


(PCF MODE)

UWB TRANSCEIVER


(PCF MODE)

UWB TRANSCEIVER


(PCF MODE)

UWB TRANSCEIVER


(PCF MODE)

UWB TRANSCEIVER

DATA BASE

CLOUD

ALARM TO APPROPRIATE PERSONNEL

UWB TR.

PROPOSED NETWORK ARCHITECTURE FOR PUBLIC HOSPITALS

WBAN Challenges

Requirements for WBAN

• Non-invasive/ remote operation• Bio-compatibility and biological/environment friendliness• Human safety (Low RF emission power)

– Limited Specific Absorption Rate (SAR)

• Low power Consumption • Scalability for data rate

–10Kbps(low data) ~10Mbps(raw data)• Range (say upto 3 meters)• Satisfying spectrum regulatory issues

Technologies for WBAN


Comparison with other technologies for WSN

Why UWB for WBAN ?

• Bluetooth (802.15.1) cable replacement technology, no support for multi-hop communication, complex protocol stack, high energy consumption

• ZigBee (802.15.4) energy consumption is higher, interference mitigation is difficult, poor multipath performance, however less complex and cost effective

UWB Characteristics suited to WBAN

• Penetration through obstacles• High precision ranging at the cm level• Low electromagnetic radiation• Low processing energy consumption• Low Interference • Security requirements – data confidentiality,

authenticity, integrity, freshness

WBAN Channels


In-body WBAN Channel Model

• 30-35 dB additional loss over free space loss• Path loss exponent ~ between 3 and 4

(depending on the body part considered)• Antenna height / distance also impacts loss• Loss 20 dB more at 5mm compared to at 5 cm

Extra-body WBAN Channel Model

• LoS / NLoS• Path loss exponent ~ between 5 and 6

(depending on the body part considered)• NLoS loss more than LoS loss

– Diffraction around the human body– Absorption of large amount of radiation by the

body

• Movement of limbs could cause loss > 30 dB

UWB Transmitter

Pulse Generation

ModulateData in

PulseGenerator

LNA Detector Data out

Simplified System; looking at pulse only

MF

)(tu ts

Pulse shapingfilter

Matched Filter

•A UWB system uses a long sequence of pulses for communication.•A regular pulse train produces energy spikes (comb-lines) at regular intervals.•Pulse train carries no information and “comb-lines” interfere with conventional radios.

Frequency (GHz)

-50-40-30-20-10

0

0 1 2 3 4 5

Time

Pulse train

Data Modulation

Pulse Position Modulation (PPM)

Pulse Amplitude Modulation (PAM)

On-Off Keying (OOK)

Bi-Phase Modulation (BPSK)

UWB Transmitter•UWB Impulse systems use pulse position modulation (PPM)

•The PPM modulates the position of a pulse about a nominal position. A “1” and a “0” is determined by a pico-second delay T1 or T2 of a mono-pulse.

•PPM “smooths-out” the spectrum making the transmitted look almost like noise.

•The Pseudo-Random noise coding makes the spectrum appear very-much like noise.

•Only a receiver with the same PN-code template can decode the pulse transmission.

32

Frequency (GHz)

-50-40-30-20-10

0

0 1 2 3 4 5

Time

Pulse train

Frequency (GHz)

-50-40-30-20-10

0

0 1 2 3 4 5

T1T2

Time

Frequency (GHz)

-50-40-30-20-10

0

0 1 2 3 4 5

Time

hopping

Nominalpulse train

New positionafter hopping

TH-PPM UWB

Tf

Ts : data symbol time

Tc t

pulse wtr(t)Str(t)

cfchf

s

fsfss

ph

TTeiTNT

N

TTeiTNT

NNC

3..

symbol dataper pulses ofnumber :

4..

4 periodcode,2 , ]2001[ codeword

=0id

Tf

Ts

Tc t

Str(t)

=1id

Monocycle Shapes for UWB

• Monocycle shapes will affect the performance

– Gaussian pulse– Gaussian Monocycle– Scholtz’s Monocycle– Manchester Monocycle– RZ- Manchester Monocycle– Sine Monocycle– Rectangle Monocycle

Monocycle Shapes for UWB (cont.)• Gaussian Pulse • Gaussian monocycle

– first derivative of Gaussian pulse

Monocycle Shapes for UWB (cont.)• Scholtz’s monocycle

- second derivative of Gaussian pulse• Manchester Monocycle

Monocycle Shapes for UWB (cont.)• RZ- Manchester Monocycle • Sine Monocycle

Monocycle Shapes for UWB (cont.)• Rectangle Monocycle

UWB Receiver

Pulse Generation

ModulateData in

PulseGenerator

LNA Detector Data out

Simplified System; looking at pulse only

MF

)(tu ts

Pulse shapingfilter

Matched Filter

Autocorrelation of binary transmission

40

UWB versus Traditional Narrow Band Transceiver

All Digital UWB Radio

Conventional Integrated Narrowband Transceiver:

UWB “Mostly Digital” Radio:

D/A

I

QMIXERLNA

PA

A/D

A/D

DIGITAL:

F SYNTH

ANALOG:

MIXERD/A

D/A

ILNA

PA

A/D

DIGITAL:

ANALOG:

• Simplicity• Low Cost• Integration• Low Power• Large BW• Ranging• Unlicensed

Operation• Coexistence

UWB Promises:

Pulse Reception


time

time

Sample Time

Pulse ReceptionWindow

Pulse Transmission Rate

Volta

geRe

ceiv

erO

pera

tion Analog On

Sampling On

Digital Off

Analog Off

Sampling Off

Digital On

Analog Off

Sampling Off

Digital Off

Analog On

Sampling On

Digital Off

Only process data from a window of time:

Power Conservation


Duty-CycledTo ~1mW

(1 Mpulse/s)

Always On~8 mW

(32 Mpulse/s)

TX DLL CONTROL

GAIN

A/D

DIGITAL

OSC

BIAS

Duty-CyclingStarts

44

UWB Advantages - Limitations

• UWB radio systems have large bandwidth (> 1 GHz).• UWB has potential to address today’s “spectrum

drought”.• Emissions below conventional level.• Single technology with 3 distinct capabilities.• Secure transmission, low probability of interception or

detection and anti-jam immunity.• Not appropriate for a WAN (Wide Area Network)

deployment such as wireless broadband access. • UWB devices are power limited.