BackgroundThe deployment and the initial
result of the Internet-Based
Augmentation System for
Global Navigation Satellite
SystemsInformation Technology Center
Osamu Tobe(osamu-to@is.naist.jp)
2004.07.22

the 4th COE Technical Presentation

 The importance of discovering geographicallocation information of a node increases.
In mobile and ubiquitous computing, the position of anode is not necessarily fixed.
 Global Navigation Satellite Systems (GNSS) is avery effective device.
GNSS can be used in the outdoors of the Earth.
 However, GNSS has limits on accuracy.

To enhance the accuracy, it is necessary for a nodeto receive the error correction data.

2004.07.22

Problems in the existing GNSS
correction systems

the 4th COE Technical Presentation

System architecture of IBAS

 Service Area

It can only cover a limited area with medium wave
beacon or FM radio wave.
 Interactivity

It is difficult to send dedicated correction data to eachuser.
 Device dependency

Users have to use a different device for every system.

I have proposed the Internet-Based
Augmentation System for GNSS (IBAS)
the 4th COE Technical Presentation

2004.07.22

Flow of Server Select Mechanism
Reference Station(5)receive dataListPropagate from the PS whose
Server (A) RTT is smallest(3)send queries
to PS

Client(4)receive “OK”
message

Propagate
Server (B)(1)search thenearest RS

Reference CollectStationServerCalculate
ServerPropagate
ServerClient

Deployments of RSs in Tokyo
Tokyo Univ.
Hongo Campus

Keio Univ.
Yagami Campus

Hitachi ICS Co.,Ltd.
Narashino Office

Tokyo Univ. of Marine
Science and Tech.
Ecchujima Campus

Propagate
Station List
(2)search the PS
that can provide
the nearest RS’s
data

Keio Univ.
Shonan Fujisawa
CampusKisarazu National
College of Tech.

1Deployments of RSs in Kansai

Configuration diagram of RS
Antenna

Campus LAN

Nara Institute ofScience and Technology

InternetObserve Server

GPS / GLONASS Receiver

Testbed architecture

Positioning Experiment

Networked RTK-GPS dataSFC

 I observed D-GPS positioning results withYagami
isvwh.e.kaiyodai.ac.jp
D-GPS data

Hitachi
Kisarazu

gnss.naist.wide.ad.jp

IBAS during moving around NAIST by car.
A Client is connected with AirH” 32k.
RS and PS at NAIST are selected
automatically by the above-mentioned
mechanism.

U-tokyo
NAIST

gnss-develop.naist.wide.ad.jp

Reference CollectStationServerCalculate
ServerPropagate
ServerPositioning with D-GPS200Positioning with D-GPS(Scaling Up)
-150

NAIST
0NAIST-200

R163
LAWSON-400

South - North (meter)

South - North (meter)the 4th COE Technical Presentation

2004.07.22

-600
-800
-1000
-1200
-1400-200

LAWSON-250-1600

R163-1800
-2000
-200

SEVEN ELEVEN
0200

400

600

-300200

800 1000 1200 1400 1600 1800 2000

West - East (meter)2004.07.22

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250300350West - East (meter)2004.07.22

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Transition of RTT and data delay
12106000

Packet Loss : 5%

Z-count
RTT

5000

4000
63000

RTT (msec)

8Z-count (sec)The enhancement of IBAS

7000

RTT (msec)
average : 605.116
min : 310.047
max : 6610.144

42000
2

 To realize higher reliability and accuracy…

Removal of the error ingredients fromobservation data Various error elements are contained inobservation data.

Networked D-GPS
 Enabling mobile nodes to position in high accuracy

1000

0

even if they are moving in high speed.

01

101

201

301

401

501

601

701

801

901

time (sec)2004.07.22

the 4th COE Technical Presentation

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Summary
 To enable mobile nodes to locate their positionin high accuracy, I proposed the Internet-Based
Augmentation System for GNSS (IBAS).
 IBAS can provide dedicated GNSS error
correction data with each node.
A user finds out the nearest RS and PS that canprovide the data calculated at that RS automatically.
 I have established the testbed of IBAS.

A client could obtain high accuracy location
information, enough to decide the lane he ran on.

2004.07.22

the 4th COE Technical Presentation3