1. Project: IEEE P802.15 Working Group for
doc.: IEEE ban
<month year>
October 19October 19
Project: IEEE P Working Group for
Wireless Personal Area Networks (WPANs) ban
Submission Title: FM-UWB: A Low Complexity Constant Envelope
LDR UWB Communication System
Date Submitted: 16 July, 2007
Source: John F.M. Gerrits
CSEM Systems Engineering
Jaquet Droz 1, CH2002 Neuchatel, Switzerland
Voice: , FAX: ,
Re: This document is CSEM’s response to the Call For Application from the IEEE P Interest Group on BAN.
Abstract: This document presents FM-UWB: a constant envelope LDR UWB air interface for short range BAN applications.
Notice: This document has been prepared to assist the IEEE P 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 P
John F.M. Gerrits / John R. Farserotu, CSEM
<author>, <company>

2. http://www.csem.ch http://www.fmuwb.ch
October 19October 19
FM-UWB: A Low Complexity Constant Envelope LDR UWB Communication System
John F.M. Gerrits & John R. Farserotu
Wireless Communication Department
CSEM Systems Engineering
Switzerland
John F.M. Gerrits / John R. Farserotu, CSEM

3. John F.M. Gerrits / John R. Farserotu, CSEM
October 19October 19
Presentation Outline
Definition of and Applications for UWB
Principles and Performance of FM-UWB
Conclusions
Aalborg University ACORDE
CEA-LETI Lund University
John F.M. Gerrits / John R. Farserotu, CSEM

4. John F.M. Gerrits / John R. Farserotu, CSEM
October 19October 19
Definition of UWB
Bandwidth > 500 MHz for operation above 3.1 GHz
No particular air interface or modulation scheme specified
Signal needs to comply with the local spectral mask
Over time, UWB has become less and less wideband..
John F.M. Gerrits / John R. Farserotu, CSEM

5. John F.M. Gerrits / John R. Farserotu, CSEM
October 19October 19
Potential for UWB
High Data Rate MBOFDM Mbps
Robust MDR,
Localization/tracking Impulse Radio Mbps
Very Robust LDR FM < 250 kbps
Very promising Business Potential. [
John F.M. Gerrits / John R. Farserotu, CSEM

6. Low power consumption potential of UWB
October 19October 19
Low power consumption potential of UWB
The low radiated power of a UWB transmitter in principle may also yield
low power consumption. May yield, since power may be required to meet,
e.g., phase noise specifications or to perform baseband processing.
Usually, the receiver requires more power than the transmitter
(LNA gain, filtering, dynamic range)
A MB OFDM transceiver will never be the champion of the low power contest.
John F.M. Gerrits / John R. Farserotu, CSEM

7. Low-complexity UWB applications
October 19October 19
Low-complexity UWB applications
Short range (1-10m) Wireless Sensor Networks for monitoring and control:
Applications:
Health monitoring BAN
Home automation
Security and alarms
Requirements:
Low cost, low power systems (mW - mWs)
Portable (go anywhere)
Robust and reliable
Good coexistence with other RF systems
Fast access (short synchronization time)
BAN
[IMEC]
John F.M. Gerrits / John R. Farserotu, CSEM

8. Robust constant–envelope UWB: analog spread-spectrum
October 19October 19
Robust constant–envelope UWB: analog spread-spectrum
FM-UWB is an analog implementation of a spread-spectrum system:
Spreading in transmitter by analog wideband FM (b = 500)
Despreading in receiver wideband FM demodulator,
yielding bandwidth reduction from 500 MHz to 200 kHz
John F.M. Gerrits / John R. Farserotu, CSEM

9. John F.M. Gerrits / John R. Farserotu, CSEM
October 19October 19
FM-UWB features
True Low-Compexity and Robustness to interference and multipath
- Relaxed hardware specs (phase noise) > very low power potential
- No carrier synchronization but instantaneous despreading
- CSMA techniques may enhance performance
- Antennas are not critical
- Steep spectral roll-off
John F.M. Gerrits / John R. Farserotu, CSEM

10. Analog spreading in transmitter
October 19October 19
Analog spreading in transmitter
BW: 50 kHz kHz >500 MHz
freq: baseband MHz & 6-9 GHz
FSK FM
Sub
carrier
Data RF
modulation
spreading
An analog FM signal can have any bandwidth independent of modulation frequency or bit rate.
This is analog spread spectrum, i.e., multiple (b) copies of the FSK subcarrier signal.
John F.M. Gerrits / John R. Farserotu, CSEM

11. Data, subcarrier and FM-UWB signal in time domain
October 19October 19
Data, subcarrier and FM-UWB signal in time domain RF
Subcarrier
Data
John F.M. Gerrits / John R. Farserotu, CSEM

12. Direct Digital Synthesis subcarrier generation
October 19October 19
Direct Digital Synthesis subcarrier generation
No look-up tabe is required for the generation of a triangular waveform
Data pre-filtering lowers subcarrier sidelobes to an acceptable level.
fSUB = 1 MHz
DfSUB = 50 kHz
John F.M. Gerrits / John R. Farserotu, CSEM

13. Relaxed phase noise requirements
October 19October 19
Relaxed phase noise requirements
A Low-Power Ring Oscillator can do the job:
Unmodulated at 4.5 GHz FM-UWB with Df = 250 MHz
John F.M. Gerrits / John R. Farserotu, CSEM

14. FM-UWB spectrum and Regulations
October 19October 19
FM-UWB spectrum and Regulations
FM-UWB fits everywhere;
even in the European 4.2 – 4.8 and 6 – 9 GHz spectrum.
FM roll-off
TX phase noise
TX white noise
John F.M. Gerrits / John R. Farserotu, CSEM

15. Instantaneous despreading in the receiver
October 19October 19
Instantaneous despreading in the receiver
BW: >500 MHz kHz kHz
freq: 4.5 & 6-9 GHz MHz baseband
Subcarrier RF
Data
instantaneous
despreading
FSK
demodulation
250 MHz
GPdB = kbps
GPdB = kbps 1
John F.M. Gerrits / John R. Farserotu, CSEM

16. Receiver processing gain
October 19October 19
Receiver processing gain
Only noise/interference in the subcarrier banwidth is taken into account.
This bandwidth reduction after the wideband FM demodulator yields
real processing gain:
250 MHz 1
Processing gain increases for lower bit rates:
GPdB = 34 R = 100 kbps
GPdB = 44 R = 10 kbps
John F.M. Gerrits / John R. Farserotu, CSEM

17. Wideband FM demodulator
October 19October 19
Wideband FM demodulator
Phase det.
FM>PM
[ECWT 2006]
John F.M. Gerrits / John R. Farserotu, CSEM

18. Multiple RF and subcarrier signals in receiver
October 19October 19
Multiple RF and subcarrier signals in receiver
At receiver input:
GHz
(no multipath)
After FM demod:
FSK subcarriers: 1 – 2 MHz
John F.M. Gerrits / John R. Farserotu, CSEM

19. Receiver synchronization time
October 19October 19
Receiver synchronization time
Due to the instantaneous despreading, only bit synchronization
is required like in a narrowband FSK system!
John F.M. Gerrits / John R. Farserotu, CSEM

20. Multiple-access techniques
October 19October 19
Multiple-access techniques
Multiple users can be accommodated in a number of ways:
IEEE MAC (TDMA) for standard applications
RF FDMA, highest for QOS (no multiple-access interference)
Sub-carrier FDMA (“MAC-less”) for ultra low power applications
Proprietary MAC (TDMA) for sensor networks, e.g., WISENET
John F.M. Gerrits / John R. Farserotu, CSEM

21. John F.M. Gerrits / John R. Farserotu, CSEM
October 19October 19
RF FDMA techniques
Multiple users use different RF and sub-carrier frequencies
Highest QOS, since no multiple-access interference occurs
(no spectral overlap)
John F.M. Gerrits / John R. Farserotu, CSEM

22. Subcarrier FDMA techniques
October 19October 19
Subcarrier FDMA techniques
Multiple users can share the same RF center frequency
And distinguish themselves using different subcarrier frequencies
Subcarrier filtering, multiple-access interference and phase noise
determine the performance limits.
John F.M. Gerrits / John R. Farserotu, CSEM

23. Some figures on FM-UWB robustness1
October 19October 19
Some figures on FM-UWB robustness1
Impulse Radio interference with SIR = -14 dB yields BER = 10-3
MBOFDM interference with SIR = -15 dB yields BER = 10-3
FM-UWB performs very well in frequency-selective channels
as we will illustrate shortly.
1values mentioned are for a 100 kbps system
John F.M. Gerrits / John R. Farserotu, CSEM

24. Performance with frequency-selective fading
October 19October 19
Performance with frequency-selective fading
Channel impulse response (time domain)
CM1
CM4
Channel transfer function (frequency domain)
John F.M. Gerrits / John R. Farserotu, CSEM

25. FM-UWB performs better with strong multipath
October 19October 19
FM-UWB performs better with strong multipath
CM channel realizations CM4
John F.M. Gerrits / John R. Farserotu, CSEM

26. Good, flat and bad channels
October 19October 19
Good, flat and bad channels
good flat bad
John F.M. Gerrits / John R. Farserotu, CSEM

27. Statistics with various channels
October 19October 19
Statistics with various channels
Variations in RF sensitivity [dB] based upon 1000 channel realizations
CHANNEL
MIN
MAX
AVG
MEDIAN
CM1
-3.6
+2.1
-0.05
+0.10
CM2
-2.9
+2.0
-0.01
+0.01
CM3
-3.0
+1.9
-0.03
+0.04
CM4
-2.4
+1,6
-0.02
+0.02
[More at ICUWB2007]
John F.M. Gerrits / John R. Farserotu, CSEM

28. October 19October 19
Conclusions
FM-UWB is a Low-Complexity LDR UWB radio for BAN Applications:
Constant-envelope: low-voltage, low power
Analog spread-spectrum with instantaneous despreading
RX synchronization time only bit-sync. limited
Robustness to interference and multipath
Simple radio architecture
John F.M. Gerrits / John R. Farserotu, CSEM

29. John F.M. Gerrits / John R. Farserotu, CSEM
October 19October 19
Thank You!
John F.M. Gerrits / John R. Farserotu, CSEM