1. September 2009
doc.: IEEE
Nov 2010
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)‏
Submission Title: Real Time Locating System based on IEEE a and ISO/IEC
Date Submitted: 8 Nov, 2010
Company: Nanotron Technologies
Address: Alt-Moabit 60, Berlin, Germany
Voice:
Re:
Abstract: [Review of a Real Time Locating Sysem based on IEEE a and ISO/IEC ]
Purpose: [Illustrate the commonalities and differences between IEEE and ISO standards and give an overview over location performance achievable]
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
Rainer Hach (Nanotron Technologies)
Michael Bahr (Siemens AG) et al.

2. Real Time Locating System based on IEEE 802.15.4a and ISO/IEC 24730-5
Nov 2010
Real Time Locating System based on IEEE a and ISO/IEC
Outline
- General remarks on Real Time Locating Systems (RTLS)
- Relationship between IEEE a and ISO/IEC
- Overview over ISO/IEC
- Architectures and applications
- Summary
© Nanotron Technologies GmbH
A. Rommel, R. Hach: “Real-Time Locating System based on ISO/IEC ”
Rainer Hach (Nanotron Technologies) 2

3. General remarks on RTLS
Nov 2010
General remarks on RTLS
Typical applications are
tracking (location and time) of goods, assets, persons,…
All kind of media
RF,
inductive near field,
ultra sound,
(laser) optics, …
and techniques
Signal strength,
Time of arrival (TOA),
are known
Rainer Hach (Nanotron Technologies)

4. Focus of the presentation is RTLS based on TOA of RF signal
Nov 2010
Focus of the presentation is RTLS based on TOA of RF signal
The ability to detect the TOA of a signal enables the measurement of:
-(Round Trip) Time Of Flight (TOF)
and/or
-Time Difference of Arrival (TDOA)
Rainer Hach (Nanotron Technologies)

5. RTLS is strongly related with RFID
Nov 2010
RTLS is strongly related with RFID
Standardization of RFID is done in institutions like ISO
There is an ISO committee* dedicated to RTLS
*ISO/IEC JTC 1, Information technology,Subcommittee SC 31, Work Group 5
Tag
Reader
Rainer Hach (Nanotron Technologies)

6. Difference between an IEEE 802 and ISO standard
Nov 2010
Difference between an IEEE 802 and ISO standard
ISO: Air interface protocol
which can be interpreted to consist of three layers
IEEE 802
Tag application layer
MAC
MAC
PHY
PHY
Rainer Hach (Nanotron Technologies)

7. Relationship between IEEE 802.15.4a and ISO/IEC 24730-5
Nov 2010
Relationship between IEEE a and ISO/IEC
IEEE a
added 2 PHYs to 15.4
UWB
CSS (Chirp Spread Spectrum)
finalized and published in 2007
ISO/IEC
Air interface for RTLS
based on CSS
finalized and published in 2010
Rainer Hach (Nanotron Technologies)

8. Overview over ISO/IEC 24730-5
Nov 2010
Overview over ISO/IEC
Wordwide applicable in ISM band at 2.4 GHz
Based on CSS (Chirp Spread Spectrum)
2 modes of CSS
-2-ary orthogona
-DQPSK
250kbit/s, 1Mbit/s
Bandwidth: 80 MHz, 22 MHz
Accurate location
Reliable two way data communication
Low power consumption
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 8

9. Application packet types of ISO/IEC 24730-5
Nanotron Technologies GmbH
September 2009
doc.: IEEE
Nov 2010
Application packet types of ISO/IEC
4 types of packets:
Command packets are used by the infrastructure to transmit instructions to tags.
Report packets are used by tags to transmit any kind of information or notification to the infrastructure.
Ranging packets are used for ranging packet exchanges.
Blink packets are broadcast packets transmitted by tags.
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 9
- confidential - 9
Michael Bahr (Siemens AG) et al.

10. TOF with fixed infrastructure
Nanotron Technologies GmbH
September 2009
doc.: IEEE
Nov 2010
TOF with fixed infrastructure
Distance measurement between Readers and Tag
Tag position calculated by trilateration
PRO: no synchronization of infrastructure required
CON: limited number of measurements per time interval due to high load of air interface. R1 R2 T R3 R4
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 10
- confidential - 10
Michael Bahr (Siemens AG) et al.

11. Measurement Results: TOF, Outdoor – Raw Data
Nov 2010
Measurement Results: TOF, Outdoor – Raw Data
Area 20 x 20 m
walking from anchor to anchor
Multipath-free environment
Accuracy better than 0.5m
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 11

12. Measurement Results: TOF, Outdoor – Filtered Data
Nov 2010
Measurement Results: TOF, Outdoor – Filtered Data
Moving Average #11
Accuracy in cm-range
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 12

13. Measurement Results, TOF, Indoor, Raw data
Nov 2010
Measurement Results, TOF, Indoor, Raw data
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 13

14. Applications specific for TOF
Nov 2010
Applications specific for TOF
No fixed location infrastructure
Loss protection:monitor distance between parent unit and child unit
Parent Unit
Child Unit
Cooperative RTLS: find locations relative to each other
Unit B
Unit A
Unit C
Rainer Hach (Nanotron Technologies)

15. TDOA Architecture 15 R R RTLS Server Tags send broadcast blinks
Nanotron Technologies GmbH
September 2009
doc.: IEEE
Nov 2010
TDOA Architecture R R
RTLS
Server
Tags send broadcast blinks
Readers measure TOA of tag blinks
RTLS server collects TOA measurements to calculate TDOA between reader pairs
PRO: Simultaneous reception of tag blinks by all readser, high number of measurements per time interval
CON: Readers require precise synchronization or very stable clocks T T T T T T T R R
Infrastructure (wired / wireless)
Reader R
Tag T
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 15
- confidential - 15
Michael Bahr (Siemens AG) et al.

16. Location is calculated by finding intersections between hyperbolas
Nanotron Technologies GmbH
September 2009
doc.: IEEE
Nov 2010
Location is calculated by finding intersections between hyperbolas R2 R1 T
TOA1
TOA2
TDOA = 0 R2 R1
TOA1
TOA2
TDOA = D = TOA1-TOA2 T
TDOA=0: Tag is on vertical line between R1 and R2
TDOA = D: Tag is on Hyperbola between R1 and R2
2D-Location requires 3 hyperbolas
3D-Location requires 4 hyperbolas
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 16
- confidential - 16
Michael Bahr (Siemens AG) et al.

17. TDOA Hyperbolas 17 Nov 2010 Rainer Hach (Nanotron Technologies)
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 17

18. Applying TOF or TDOA 18 Any blinking tags can be utilized for TDOA R
Nov 2010
Applying TOF or TDOA
Any blinking tags can be utilized for TDOA R
Tag enters area equipped with TDOA capable infrastructure R
Blink
State R T
Default State
(Broadcasting) R T R
Tag enters area equipped with
capable infrastructure T
Ranging R
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 18

19. Applying TOF and TDOA 19 TOF for tags outside of
Nov 2010
Applying TOF and TDOA
TOF for tags outside of
area surrounded by readers
TDOA for tags inside of
area surrounded by readers T R R
Blink
State R T R R
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 19

20. New Results Challenge for TDOA system:
Nanotron Technologies GmbH
September 2009
doc.: IEEE
Nov 2010
New Results
Challenge for TDOA system:
Precise synchronization of readers
in multipath environment
Albrecht Rommel, Rainer Hach: Real-Time Locating System
based on ISO/IEC
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies)
- confidential - 20
Michael Bahr (Siemens AG) et al.

21. Synchronization of TDOA readers
Nov 2010
Synchronization of TDOA readers
Rx/Tx readers (ISO/IEC )
Since readers are at known locations
anyway they can serve as
‘reference tags’
Rx only readers
Reference Tag at known location
R2/Tref3 R2
R1/Tref1 R1 T T T T T T T T T T T
Tref T T T R4 R3
R4/Tref2
R3/Tref4
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 21

22. System Architecture - Anchor Synchronization
Nanotron Technologies GmbH
September 2009
doc.: IEEE
Nov 2010
System Architecture - Anchor Synchronization
Infrastructure (wired / wireless)
RTLS Apps,
GUI, ...
TOA1
Reader Synchronization
TOA2
Pacer blink received by readers
TDOA with expected TDOA (geometry!)
Difference of measured vs. expected TDOA = Reader Phase Error
Low cost reader synchronization
TCP R1 R2
Location
Server T T T T T T T
TOA3 P R3
Ethernet / UDP
Pro
TOA4 R
Reader (known location) T
Tags (up to 1Hz) P
Pacer (known location)
Tag Blinks Pacer Sync Blinks Tag RTC Synchronization (only for TDMA)
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 22
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Michael Bahr (Siemens AG) et al.

23. System Architecture – Dynamic Pacer
Nanotron Technologies GmbH
September 2009
doc.: IEEE
Nov 2010
System Architecture – Dynamic Pacer
Dynamic Pacer: better reach of tags and readers R1 R2 P R2 T T T T T T T T T T T T T T P R3 R4 R3 R1 R2 R1 P T T T T T T T T T T T T T T R4 P R4 R3
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 23
- confidential - 23
Michael Bahr (Siemens AG) et al.

24. Verification of time synchronization
Nov 2010
Verification of time synchronization
1. Measure true timebase difference
Common clock source
Use cable of identical length
Reader 1
Reader 2
Tag
2. Estimate timebase difference from pacer blink
Common clock source
Pacer blinks over air
Reader 1
Reader 2
Rainer Hach (Nanotron Technologies)

25. Nov 2010
1. Measure true timebase difference, 2. Estimate timebase difference from pacer blinks
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 25

26. TDOA Indoor – 80 MHz CSS 26 26 Setup September 2009
Nanotron Technologies GmbH
Nanotron Technologies GmbH
September 2009
doc.: IEEE
Nov 2010
Setup
TDOA Indoor – 80 MHz CSS
2.4 GHz ISM band
8 Dual-Channel Readers, sync over air
one known fixed tag position
Ethernet connection to Location Server
All 16 sources used for location estimation
1000 blinks, 90% with less than 1m error
© Nanotron Technologies GmbH
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 26 26
- confidential -
- confidential - 26 26
Michael Bahr (Siemens AG) et al.

27. TDOA Indoor – 22 MHz CSS 27 27 Setup September 2009
Nanotron Technologies GmbH
Nanotron Technologies GmbH
September 2009
doc.: IEEE
Nov 2010
Setup
TDOA Indoor – 22 MHz CSS
2.4 GHz ISM band
8 Dual-Channel Readers, sync over air
one known fixed tag position
Ethernet connection to Location Server
All 16 sources used for location estimation
1000 blinks, 90% less than 1.7m error
© Nanotron Technologies GmbH
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 27 27
- confidential -
- confidential - 27 27
Michael Bahr (Siemens AG) et al.

28. 28 Tag Nov 2010 Rainer Hach (Nanotron Technologies)
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 28

29. - is uses CSS (Chirp Spread Spectrum)
Nov 2010
Summary
There is a significant difference between an ISO air interface protocol standard and an IEEE PHY/MAC standard
ISO/IEC
- is uses CSS (Chirp Spread Spectrum)
- defines two bandwidth values: 22MHz and 80 MHz
- defines a blink mode
- defines message exchange protocols for ranging
- allows precise time synchronization over the air even in multipath environments
- can be used to realize applications like “loss protection” or “cooperative RTLS”
© Nanotron Technologies GmbH
Rainer Hach (Nanotron Technologies) 29

30. Nov 2010
Thank you!
Rainer Hach (Nanotron Technologies)