IEEE 802.15 subject

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Project IEEE 802.15 WPAN Low Rate Alternative
PHY Task Group 4a (TG4a) Submission Title
FM-UWB A Low Complexity Low Data Rate Constant
Envelope UWB Communications System Date
Submitted 7 January, 2005 Source John F.M.
Gerrits Company CSEM Address Jaquet Droz 1,
CH2007 Neuchatel, Switzerland Voice41 32 720
56 52, FAX [phone],
E-Mailjohn.gerrits_at_csem.ch Re IEEE P802.15
LDR ALT PHY Call For Proposals Abstract This
document presents a novel constant envelope LDR
UWB air interface for the IEEE P802.15 ALT PHY
Purpose For information to IEEE 802.15.4a
Task Group by CSEM Switzerland Notice This
document has been prepared to assist the IEEE
P802.15. It is offered as a basis for discussion
and is not binding on the contributing
individual(s) or organization(s). The material in
this document is subject to change in form and
content after further study. The contributor(s)
reserve(s) the right to add, amend or withdraw
material contained herein. Release The
contributor acknowledges and accepts that this
contribution becomes the property of IEEE and may
be made publicly available by P802.15.
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FM-UWB A Low Complexity Low Data Rate Constant
Envelope UWB Communications System for PAN/BAN
applications.

• John F.M. Gerrits / John R. Farserotu
• Wireless Communications Department
• CSEM Systems Engineering
• Switzerland

http//www.csem.ch
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Motivation for FM-UWB

• Impulse radio has proven to be a good solution
  for HDR UWB systems.
• It requires pulse synchroniation and accurate
  timing.
• We believe that it is not necessarily the best
  approach for a simple, low-cost,
• low-power, short-range, LDR communiciations
  system for PAN/BAN applications.

Since the definition of a UWB signal does not
specify a particular air interface or modulation
scheme, many different techniques may be
applicable to a UWB signal.

• More established modulation schemes may be used
• to generate a UWB signal.

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FM-UWB, How does it work?
Analog frequency modulation has the unique
property that the RF bandwidth BRF is not only
related to the bandwidth fm of the modulating
signal, but also to the modulation index b? that
can be chosen freely. High modulation index
FM can be seen as an analog implementation of a
spread spectrum system with spreading gain equal
to the modulation index b.
The power spectral density of a wideband FM
signal has the shape of the probability density
function of the modulating signal (subcarrier). A
triangular subcarrier signal will yield a flat RF
UWB spectrum with steep spectral roll-off. By
modulating the subcarrier, data can be
transmitted.
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FM-UWB Transmitter

• FM

• FSK

FSK subcarrier

• 1, 2

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FM-UWB Spectrum and Coexistence
FM-UWB uses a high modulation index FM
signal Modulated by a low-frequency triangular
signal (fSUB) An analog spread spectrum
system Bandwidth BRF 2(Df fSUB)
PSD lowered by 10 log10(Df /fSUB) For Df 600
MHz, fSUB 1 MHz PSD reduced 28 dB
Flat power spectral density
Rapid spectral roll-off
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FM-UWB Receiver
FSK subcarriers

• A multi-user system can be realized by
• FDMA at sub-carrier level
• FDMA at RF carrier level
• TDMA tecniques

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FDMA subcarrier techniques
3 x 10 kbit/s
1 x100 kbit/s
subcarrier frequency MHz

• When the users share the same RF carrier
  frequency, simultaneous
• demodulation of multiple signals must be
  performed in the receiver.
• As in a DSSS system, the limit is multiple-access
  interference
• (e.g., NMAX 15 _at_ 100 kbit/s, NMAX 150 _at_ 1
  kbit/s).

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Wideband FM Delay Line Demodulator

• This demodulator has been fully integrated on
  silicon.

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FM-UWB Performance in AWGN
500 MHz
Processing gain
2 R
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Robustness to MB-OFDM UWB signals
SIR -10 dB
BER lt 1x10-6
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Power Consumption Projections
Power consumption estimates for FM-UWB
(continuous) - Transmitter 2 mW, Receiver 5
mW These values can definitely compete with ISM
solutions. - Lower values possible dependent
on duty cycle
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IC Technology Requirements
Rx
Tx
A good CMOS or BiCMOS techno (fT 100 GHz), low
VT and low VDD (1 V), on-chip passives with
moderate Q factor.
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Frequency Domain Localization
FMCW radar

• 1 GHz 1 m

• 6.67 MHz

• 1 ms 3x108 m/s

• 3, 4

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FM-UWB Features

• Simple hardware implementation compatible with
  IC technology
• Low power consumption
• Relaxed hardware specs (antenna, phase noise,
  component tolerances)
• Receiver requires no local oscillator
• No carrier synchronization (as in impulse radio)
• Scalable technology
• Steep spectral roll-off
• Robustness to MB-OFDM interference and multipath
• CSMA techniques can enhance performance
• Localization compatibility

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References
1 John F.M. Gerrits, John R. Farserotu, "Ultra
Wide Band FM A Constant Envelope Frequency
Domain Approach",International Zurich Seminar on
Communications (IZS), Feb. 1820, 2004, Zürich,
Switzerland, pp. 90 - 93. 2 John F.M.
Gerrits, Michiel H.L. Kouwenhoven, Paul R. van
der Meer, John R. Farserotu, John R. Long,
"Principles and Limitations of UWBFM
Communications Systems", accepted by the
EURASIP Journal of Applied Signal Processing
3 John F.M. Gerrits, John R. Farserotu, John
R. Long, "UWB Considerations for My Personal
Global Adaptive Network (MAGNET) Systems",
Proceedings of the 30th European Solid-State
Circuits Conference, ESSCIRC 2004, Leuven,
Belgium, 21-23 September 2004, pp.
45-56. 4 John F.M. Gerrits, John R. Farserotu,
John R. Long, "UWBFM A Low and Medium Data Rate
Constant Envelope UWB Communications System with
Localization Potential". MAGNET Workshop,
November 11-12, Shanghai