Title: UltraWideband communication technology for sensor network applications
1Ultra-Wideband communication technology for
sensor network applications
Julien.Ryckaert_at_imec.be
2The vision of Ambient Intelligence
An environment where technology is embedded,
hidden in the background
Fred Boekhorst Philips Research, ISSCC 02
3Health Care of the Future
Fitness for you!
4Increase Productivity
Home of the Future
5This vision requires the massive deployment of
sensor nodes
Network
6A sensor node is a completely autonomous device
Energy
clock
Sensing
Processing
Communication
7Three major challenges in the communication module
- Ultra-low power gt2 years autonomy
- Ultra-small size non-invasive
- Ultra-low cost disposable
- Low communication performance lt100kbps
8POWER CONSUMPTION
?
PERFORMANCE
9In reality, the total Energy consumption must be
minimized
What does it cost to transfer a bit of
information?
Power consumption (Energy/time)
Energy/bit
Data rate (bits/time)
10How does it look like today?
Increasing data rate
11POWER CONSUMPTION
UWB
?
PERFORMANCE
12Traditional Communication systems use continuous
waves
NarrowBand Communication
time
frequency
Each user/application has its own spectrum band
13Impulse Radio UWB uses short pulses
Pulse-based Ultra WideBand communication
frequency
time
Emitted power must be low enough to avoid jamming
14Activate the radio only when needed
Power
Active
Active
Sleep
The active time of the radio is reduced Radio
duty-cycling
15FCC UWB communication must be done in the
3.1-10GHz band
-41dBm/MHz
FCC
3.1
10.6
1
F GHz
16IEEE standard for low data-rate sensor networks
Burst
3 Active! 97 Inactive
- Activate the transmitter only when needed to
achieve low-power
17The standard imposes some constraints on the
signals
- Pulses are BPSK modulated
1
0
18Overall transmitter architecture
CONTROL LOOP
(ISSCC 07)
19Time-domain measurement of the output signal
Same energy efficiency as first transmitter!
20Correlation can be done either in Analog or in
Digital domain
High Sampling rate ? Power Hungry
21Full system block diagram
Analog Output
CAL
ADC
I/O bus
Digital Controller (System Configuration and
Interfacing)
LO
Timing circuit
LNA
RFin
Serial/Par Out
ADC
CAL
DL
DL
DL
DL
Clk/Rst
(ISSCC 06)
Clk
22What about power consumption?
- State-of-art narrowband solutions (Zigbee)
- TX 10mW
- RX 2mW
- UWB solutions
- TX 0.5-1mW
- RX 0.3mW
/ 10
23UWB has other advantages
- Positioning by measuring the time of arrival
- Security UWB power spectrum below the background
noise
DL
TX
RX
TX
DT
Background noise (kT)
24Other impulse Radio implementations exist
- Example MIT (US) proposes a similar concept
- But uses a proprietary UWB communication interface
25Therefore the question should sensor networks be
standardized?
- Pros
- Interoperability (add nodes in the network)
- Market pressure decreases cost
- Cons
- Solution biased by the big ones
- Security
- Less interferences (?)
- Sandardization aspect is an old controversial
debate for healthcare wireless systems
26Conclusions
- UWB offers today a 10x improvement on power
consumption. - UWB has other interesting advantages in the
context of sensor networks security,
positionning, - An IEEE standard exists today (IEEE 802.15.4a),
but its use in wireless healthcare systems is
still a debate.