Download - 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
WIRELESS ACCESS POINT
(PCF MODE)
UWB TRANSCEIVER
WIRELESS ACCESS POINT
(PCF MODE)
UWB TRANSCEIVER
WIRELESS ACCESS POINT
(PCF MODE)
UWB TRANSCEIVER
WIRELESS ACCESS POINT
(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
Tuesday, April 11, 2023 Dr. M.MEENAKSHI, DECE, CEG, ANNA UNIVERSITY 22
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
Tuesday, April 11, 2023 Dr. M.MEENAKSHI, DECE, CEG, ANNA UNIVERSITY 26
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.
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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
Tuesday, April 11, 2023 Dr. M.MEENAKSHI, DECE, CEG, ANNA UNIVERSITY 42
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
Tuesday, April 11, 2023 Dr. M.MEENAKSHI, DECE, CEG, ANNA UNIVERSITY 43
Duty-CycledTo ~1mW
(1 Mpulse/s)
Always On~8 mW
(32 Mpulse/s)
TX DLL CONTROL
GAIN
A/D
DIGITAL
OSC
BIAS
Duty-CyclingStarts
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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.