Transcript Slide 1
Ultra WideBand
Paul Solecki
History of UWB
1962 – Study in time-domain
electromagnetics (Ross)
1968 - Short Pulse Radar and
Communications Systems conceived
1973 – First UWB patent issued
1978 – Developed SPR and CS
1984 – LPI/D developed
1989 – DoD refers to it as UWB
1994 to present – Most work done without
classified government restriction
Ultra WideBand
Also referred to as impulse, baseband or
zero-carrier technology
Pulses instead of continuous waves
Pulse length on order of sub-nanoseconds in time
domain
Result is that it uses a wide swath of bandwidth
in frequency domain
B 2 f h fl
Fractional Bandwidth: B f
> 20% , but not less than 500 MHz
Fc f h fl
Pulse vs. Continuous Wave
Benefits
100-500+ Mbps rate
Ideal for short range WPANs , < 10m
Virtually NO Multi-path interference
Very low power emission
• UWB radio – 75nW/GHz , .26mW aggregate
• 802.11b radio - 30 – 100mW
• Bluetooth radio – 1mW-1W
Shannons equation becomes linear with respect
to Bandwidth and Power
Simplified architecture, nearly all digital
Small silicon space usage
UWB – Disadvantages
Bad for > 10 Gbps
• Due to FCC limit of power emission
UWB - Applications
Wireless Networks – WPANs
Wireless home systems
• Computer
• Entertainment center
Covert communication
Radar
• fine resolution
• Automotive
• Ground penetrating
Streaming A/V for
• PDAs
• Digital camera
• MP3 players
Electronic measuring devices
Electronic positioning devices
• See through walls etc.
UWB Standard
IEEE 802.15.3a Task Force
FCC set aside 7500MHz of spectrum for
unlicensed use
3.1 GHz - 10.6 GHz
100/200/400 Mbps at 10/4/2m
OFDM vs. DS-CDMA
TI/Intel vs. Motorola/XtremeSpectrum
4.8 GHz is perceived to be the upper band due to
current CMOS technology
UWB
FCC spectral mask
• UWB signals must not exceed threshold of
spectral mask
UWB vs. WiFi
802.15.3a Debate
Sept. 2003 – IEEE conference results in
60% approval for OFDM
OFDM vs. DS-CDMA
TI/Intel vs. Motorola/XtremeSpectrum
75% needed for acceptance
Compatibility issues
UWB-OFDM
Multiple Bands in 3.1 GHz – 4.8 GHz
500 MHz slices
Interleave signals
UWB-OFDM
Advantages
Cost
Power consumption
Complexity of device
Proven in 802.11a
UWB – OFDM
Disadvantages
Interference
Time synchronization needed
UWB – DS-CDMA
Direct Sequence Spread Spectrum
In a direct sequence system, the
transmitted baseband signal is multiplied
by a pseudonoise code digital stream.
UWB - DS-CDMA
UWB – DS-CDMA
Advantages
Very low interference along ENTIRE
spectrum
Avoids potential cross-border
interference
UWB – DS-CDMA
Disadvantages
Complexity of device
Power use
Cost
UWB vs. Competing Technologies
UWB – Bi-phase Radio system
All Digital !!
No Power Amplifier
needed