IBAS : Internet-Based
Augmentation Systemfor GNSS

Overviewz The importance of “GNSS augmentation”
z The introduction of “IBAS”
z Results

Osamu TOBE
osamu-to@is.naist.jp
Internet Architecture andSystems Lab.

Experimental Environment
Positioning errorz Sample application
zz

z Future workz Summary

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Backgroundzzz

In mobile and ubiquitous computing, the position of a node
is not fixed.

zzGPS, RF-ID, Wireless LAN etc…
In the near future, we will use several devices at once.

z3

Existing Augmentation
Systemszz

D-GPS by FM radio, medium wave beaconz RTK-GPS by D-MCA radioz Global Differential by fixed satellitezzz

It comes to possible to send dedicated correction data toeach user.

Device dependencyz5

If only connected to the Internet, users can access to thesystem in anywhere.

Interactivity

Cellar phone network (au by KDDI “Ez NaviWalk”)

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Service Areaz

A-GPS

2005.1.27“GNSS augmentation”

Advantages in the Internet-Based
SystemError correction

zTo enhance the availability, it is necessary for a node toreceive the assist data (A-GPS).

2005.1.27zz

To enhance the accuracy, it is necessary for a node toreceive the error correction data (D-GPS, RTK-GPS).

GNSS can’t be used in low electric intensity area.
z

The 9th COE Presentation

GNSS can be used in the outdoors of all over the Earth.
The infrastructure has been established (No more infra.).

GNSS has limits on accuracy.
zz

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Global Navigation Satellite Systems (GNSS) is theone of the effective positioning device.
z

There are many positioning devices.
z

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GNSS’s effectivity and limits

The importance of discovering geographical location
information of a node increases.
z

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Users are able to select various connection devices
according to their circumstances.

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Existing Internet-based systemzcollects and provides satellite wave observation dataz

DGPS-IPz

Internet-Based Global Differential GPS (IGDG)zzprovides D-GPS correction data
provides error correction data for satellite information

Signal-In-Space through the InterNET (SiSNeT)zz

Scalability

Reusability ofreference stations

Extensibility

GEONET×△○DGPS-IP×××

IGDG×△△

SiSNeT××△

Propagate
server model○△△

GPS Earth Observation NETwork (GEONET)zz

System comparison

provides error correction data for satellite information“Propagate server model”
zprovides D-GPS and RTK-GPS correction data

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System architecture of IBAS

2005.1.27

We have proposed the Internet-Based
Augmentation System for GNSS (IBAS)

8

Experimental environmentz

We have experimental environment on “iCar”.
InternetCar

MobileRouter (FreeBSD)

WLAN ExternalAntennaPHS(128kbps)

Reference CollectStationServerCalculate
Server

Propagate
ServerWirelessLAN

ClientInternetCar (iCar)zzz

Hub (POE)

10H/W : H8 micro computer + GPS receiver
OS : μITRONz Supports IPv6z Supports SNMPv1
zAccelIPv6 Sensor
Direction
IPv6 Sensor

We can obtain location
information with “SNMPget request”.
z We can input D-GPS correction
data with “SNMP set request”.
z

DC12V

Cigarette
SocketPOE Ready NWGPSIPv6 Sensor

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Hub (POE Ready)IPv6 SensorszGPS,Temp,Humidity
Direction,Accell
MobileRouterz
PHS,WirelessLAN

Temp/Humi
IPv6 Sensor

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D-GPS IPv6 Sensor

iCar Packagez

9Serial Port

Ethernet * 2Internet
MobileRouter

PHS,WLAN

iCar Package

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Protocol procedure

Horizontal positioning error
54

GPS : 2drms = 3.75m
3correction data query

2

ExternalAgent

南北方向 (m)location information request

location information

D-GPS correction data
ServiceInformation

1-4-3

D-GPS
IPv6 Sensor-2-1-1

0

1

2

3

45-2

DGPS : 2drms = 2.36m-3Propagate
Server
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GPSDGPS

0-5-4
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Application example-5
東西方向 (m)2005.1.27

14Future workz

Study on location-based information distribution
modelzzz

Augmentation data has effective range and period.
Now, users (or “external agents”) select services andpropagate servers explicitly according to their location.
We need to examine the model for distributing theinformation depending on location and time to many clients
efficiently.
propagate server

client15

data effective range

16

Summary
In order to enhance the usability of GNSS, We
proposed “IBAS : the Internet-Based Augmentation
System for GNSS”.
z IBAS is comparable in positioning error to theexisting system, and its architecture has advancesin scalability, reusability of data, and extensibility.
z As future work, we will examine the model for the
distributing location-based information.
z2005.1.27

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