\documentstyle[epsf]{ieice} % $B>7BTO@J8(B
\FIELD{BII}
\YEAR{2001}
\VOL{ZZZ--Z}
\NO{5}
\TYPE{paper}% \TYPE{letter}
\THEME{Special Issue on Internet}
\TITLE{AI$^{3}$ Satellite Internet Infrastructure and the Deployment in Asia}
\authorlist{%
\authorentry{Tomomitsu Baba}{n}{KUSA}
\authorentry{Hidetaka Izumiyama}{n}{JSAT}
\authorentry{Suguru Yamaguchi}{m}{NAIST}
}
\affiliate[KUSA]
{Kurashiki University of Science and the Arts,\hfill\break
2640 Nishinoura, Tsurajima Kurashiki, 712-8505 Japan
% Tel : +81-86-440-1048
% Fax : +81-86-440-1032
}
\affiliate[JSAT]
{JSAT Corporation,\hfill\break
Toranomon 17 Mori Bldg. 5F
1-26-5 Toranomon, Minato-ku
Tokyo 105-0001
Japan
% Tel : +81-3-5511-7568
% Fax : +81-3-5512-7181
}
\affiliate[NAIST]
{Nara Institute of Science and Technology,\hfill\break
8916-5 Takayama, Ikoma 630-0101 Japan
% Tel : +81-743-72-5210
% Fax : +81-743-72-5219
}

%\received{}{}{}
%\revised{}{}{}

\def\aiii{{\sf AI$^{3}$} }

\begin{document}
\maketitle
\setcounter{page}{1}

\begin{SUMMARY}
A lot of efforts have been made to develop the international Internet
environment. In order to achieve a better and efficient information
infrastructure around the globe, there are very strong urgent demands
in the area of Asia and Pacific for a practical working environment
where engineers and researchers in related fields work cooperatively.

Our \aiii Project was kicked off in 1995 by WIDE Project and JSAT. It
has been operating a satellite based testbed network in Southeast Asia
and producing a series of research activities using the testbed. In
this paper, we explain \aiii satellite Internet infrastructure and
describe our efforts of the deployment in Asia using our developed
technology. Furthermore, we evaluate our testbed network from the
aspect of sustainable international collaboration.
\end{SUMMARY}
\begin{keywords}
Satellite Internet, Asia, information infrastructure
\end{keywords}

\section{Introduction}

Large number of technologies utilized for Internet have been developed
and improved continuously since 1980's.  The process of technology
development and improvement always require the network environment
where engineers and researchers can make implementation, test, and
evaluate the technologies.  This network environment is so called ``a
testbed network.''  It is quite popular for the Internet community to
provide testbed networks for specific technology development and
deployment.  Mbone for example, was set up and has been operated since
early 1990's.  The Mbone is a testbed network for for IP multicast
technology.  The other example is 6bone which has been composed for
IPv6 and operated since mid 1990's.  The testbed network can
accelerate the process of technology development and its engineering,
therefore, it is fairly important for research groups of Internet
technologies to construct and operate its testbed network.


The project discussed here in this article is an international
research consortium among research institutes in Asian region 
and is aiming to form a group of researchers to develop leading edge
technologies for the Internet, such as IPv6, WWW caching and
replication mechanisms, multimedia communication mechanism and
applications for the advanced usage of the Internet.
The name of the project is Asian Internet Interconnection 
Initiatives\cite{ai3-inet96,ai3-inet97}
or "\aiii" (ei-tripl-ai) in short.

This project was formed in 1995 by WIDE Project
and started its activities in 1996 with its initial partners 
that are Institute of Technology in Bandung (ITB) in Indonesia, 
Asian Institute of Technology (AIT) in Thailand and 
Hong Kong University of Science and Technologies (HKUST) in Hong Kong.
As its testbed network, 
Ku-band satellite communication channels have been used,
therefore, each \aiii partner is operating its Ku-band VSAT earth
station and gateway systems to attach its local testbed environment to 
\aiii backbone.
For the first three years of the project, 
all the members of this project worked hard to develop several
technologies for the Internet, and series of experiments utilizing
this testbed backbone were conducted.
The operation of our testbed network is a large-scale satellite
Internet infrastructure.
When our project was established, there
was no other Internet infrastructure
with satellite in the world.  Hence, we
had a good opportunity to develop
several technologies that are vital for
smooth operation of the satellite
Internet infrastructure.

In 1999, \aiii project expanded its activities to more
countries and added several C-band satellite channels to span these new
partners as its new backbone network.
The project invited 5 research institutes as
its new partners: 
Temasek Polytechnic (TP) in Singapore, 
University Sains Malaysia (USM) in Malaysia, 
Advanced Science and Technology Institute (ASTI) in Philippines,
Institute of Information Technology (IOIT) in Vietnam and 
University of Colombo (CMB) in Sri Lanka.
Finally, \aiii testbed network has been expanded as shown in Figure
\ref{Fig.1}.
As of April 2001, IOIT finished to construct their earth station
and waits for the initial uplink test to establish the link. CMB
is in the process to procure the parts of their earth station
along with the minimum requirement as described in the section 3.

In this paper, we explain \aiii Project and detail of the \aiii
testbed network. Furthermore, we report our sustainable efforts on
research activities in Asia by using this testbed and evaluate
the results about deployment of our satellite Internet technology.


\section{Issues}

\subsection{Radio Frequency Band for Satellite Segment}

In deployment of information infrastructure in Asian region, it is
important for rapid development of infrastructure to adopt satellite
communication technology. Satellite communication can be rapidly and
directly established at any two points under its beam coverage and
this characteristic is proper for Asia, because Asian region includes
many highland and island nations where terrestrial communcation
infrastructure is currently not enough installed for the Internet.

\begin{figure}[t]
 \begin{center}
   \epsfile{file=topology2.eps,scale=0.35}
 \end{center}
 \caption{Topology of \aiii Testbed Network}
 \label{Fig.1}
\end{figure}

As radio frequency band providing information rate in megabit class,
Ku-band and C-band are available in Asia. Ku-band is permitted to use
for satellite service that means fixed satellite communication
service.  However, Ku-band has a weakness against rain attenuation. In
Asia, there are many areas which have heavy rainy season.  On the
other hand, C-band is much popular in Asia but some countries do not
permit to use C-band for satellite service. C-band is affected by sun
interference in equinox season.  We need to select radio frequency
band to be suitable for the purpose of deployment of information
infrastructure in Asia.


\subsection{Network Topology and Routing}

The major issue about infrastructure is to realize that Asian
countries can share scheme and expertise on the Internet development,
especially on the intra-Asia internetworking. In the early phase of
the Internet development, many countries and regions in Asia had
direct connections to the United States and European countries, but
there were less connections among Asian countries. However, as growing
demands of cooperative works among Asian countries, it became popular
to use the Internet as their ordinary communication channel.

As a result with this situation, many people complained about its
large RTT (Round-Trip Time) and lack of bandwidth of the intra-Asia
Internet connectivity, because few Internet links were installed
between Asian countries. We need a network topology to be suitable
for the intra-Asia communication.


\subsection{Towards Sustainable International Collaboration}

Our testbed network is expected to function as information
infrastructure for acceleration of more cooperative works among people
in and around the Internet in Asian countries.

% In deployment of an international cooperative environment from Japan
% to Asian countries, typical approach is on the donation basis. In
% this approach, at first, required equipments and workers are donated
% and arranged to set up a system by Japan. Then, operation staff are
% dispatched by Japan during the startup of this system. Finally they hand
% over the system to local operators and maintainers.
% 
% The donation approach involves problems. This approach is easy to
% fall into one-sided ``giver-receiver'' relationship. It tends to end
% in inefficient results of transfer of technical knowledge in developing
% countries. To begin with, the donated system may not be seriously
% required for donor applicants. The donation approach easily brings
% failure of the system and the project itself after the startup staff
% return to Japan.

In deployment of an international cooperative environment from Japan
to Asian countries, the typical approach is on the donation basis.
The donation approach involves the problems. This approach is easy to
fall into one-sided ``giver-receiver'' relationship.  The giver tends
to put more emphasis on the supply and the equipment side, while the
receiver needs to put more emphasis on knowledge transfer and
collaboration in building the knowledge for long lasting and
sustainable development. Therefore, this relationship causes the
problems concerning no transfer of technical knowledge and no
production of the environment fitted for the receiver's surroundings
in developing nations.

In \aiii project, it is important to establish partnership where
technology transfer can be smoothly processed and partners can learn
knowledge or experience from each other.


\section{AI$^{3}$ Solutions}

\subsection{Radio Frequency Band for Satellite Segment}

We divided our deployment process into two phases to establish
satellite links amoung Asian countries as widely as possible. The
first step was to use Ku-band. The next step was to use C-band,
while holding the installed Ku-band links.

In the first phase, we challenged to use Ku-band in rainy Asian
countries where heavy rainy season is existing. At the early period in
this phase, many users in Asian countries such as Indonesia doubted
availability of Ku-band links as Internet backbone.  As a result of
evalution in the three years, we confirmed that Ku-band links using
Asian zone beam are enough feasible as Internet links to satisfy the
users in rainy Asian countries. In fact, more than 15 academic and
research institutes have been using the Ku-band link for their
backbone connection in Indonesia since the beginning.  Furthermore, we
developed satellite Internet monitoring products, so that we could
clarify the fault point in this complex system. These products
contributed to exclude many trouble cases not associated with rain
degradation while our link evaluation in Indonesia, Hong Kong and
Thailand.

In the second phase, we expanded the use of radio frequency band to
C-band. Our objective was to verify our developed technology in
C-band. As a result, we succeeded to establish IP connection using
C-band with the sites located in Singapore, Malaysia and Philippines.
To cope with sun interference, we started to share information about
predictions of the interference among the partners.


\subsection{Network Topology and Routing}

% directness

We installed direct links among Asian countries in order to carry
traffic for intra-Asian communication. First, we connected Indonesia,
Hong Kong and Thailand with Japan by using Ku-band. Secondly, we also
connected Singapore, Malaysia, Philippines with Japan by using C-band. 
Finally, we installed 10Mbps ATM terrestrial link between Ku-band and
C-band networks, as illustrated in Figure \ref{Fig.2}.  This ATM link
was installed between the two hub stations in Japan to achieve IP
routing among those countries via Japan. We have been field-testing
OSPFv2 and BGP4 over satellite to exchange route information with each
other and we confirmed that we can apply them in our intra-Asian
satellite links.

% RTT

RTT of our satellite link between Japan and the other country takes
around 500ms. RTT of the ATM link needs about 30ms. Thus, we can
estimate 500ms at minimum and 1030ms at maximum as RTT for our
intra-Asian communication. Compared with IP routing via Unitited
States, RTT values are not much improved but are constant in any
combination among us.

% bandwidth

All intra-Asia links are of asymmetric nature based on the volume of
information flow. Thus, each link was configured to 1.5Mbps from Japan
and 512kbps to Japan, while this configuration is flexible to be
allocated on the request basis under the permission of JSAT. The
bandwidth of the ATM link is enough to carry traffic between Ku-band
and C-band networks.


\subsection{Towards Sustainable International Collaboration}

As stated earlier, technology transfer and equal partnership are
important topics for international collaboration using our testbed.
Before starting this project, we made a project framework about \aiii
partnership. The framework defined that purchasing VSAT earth station,
obtaining appropriate licenses from the local authorities and anything
coordinated locally must be completed by each parter in each
country. This allowed no exception including the sites in Japan. On
the other hand, \aiii project provided satellite circuits (bandwidth
on transponders) and related technical information to all the
partners.

 \begin{table}[t]
  \caption{Minimum Requirement for \aiii C-band Earth Station
  in case of Colombo in Sri Lanka}
  \begin{center}
    \epsfile{file=min-requirement.eps,scale=0.50}
  \end{center}
  \label{Tab.1}
 \end{table}

 \begin{figure}[t]
  \begin{center}
    \epsfile{file=sat_topology.eps,scale=0.37}
  \end{center}
  \caption{\aiii Satellite Circuit}
  \label{Fig.2}
 \end{figure}

 \begin{figure}[t]
  \begin{center}
    \epsfile{file=stations2.eps,scale=0.28}
  \end{center}
  \caption{\aiii Earth Stations using the Different RF Units}
  \label{Fig.3}
 \end{figure}

Within this framework, \aiii partners were invited from 8 Asian
countries and we selected the groups who indeed need \aiii project. The
project members were on the equal partnership basis. Project related
information was shared through the mailing list and the web among the
members, though important issues such as bandwidth allocation of our
satellite circuit were fixed after discussion at our regular meeting
twice a year.

In preparation process of the earth stations, \aiii project provided
the information about minimum requirement of the station. An example
of this minimum requirement in case of Sri Lanka is shown in Table
\ref{Tab.1}.  Along with such minimum requirement, \aiii partners set
up their earth stations which were fitted for this requirement
considering procurement, cost, maintenance and operation in their
local circumstances.

Consequently, each earth station was set up using the different RF unit
as shown in Figure \ref{Fig.3}. Through this process, we found that
there were various regulations to start satellite communication in
Asian countries. The required licenses from local authorities were for
wireless communication, location of earth station, import permissions
of wireless devices and etc. ``Obtaining the licenses'' was much hard
for \aiii partners in some cases, however, they finally accomplished
this task in every way.

From the aspect of human resource development, \aiii partners learned
a complete {\it know-how} from the initial stage. Furthermore, a technical
tutorial day was scheduled before the regular meeting twice a year and
the modern technologies were reviewed for \aiii partners.


\section{Implementation and Evaluation}

 \begin{table}[t]
  \caption{The Type of Emission in Ku-band Link}
  \begin{center}
    \epsfile{file=4-1-table-b.eps,scale=0.50}
  \end{center}
  \label{Tab.2}
 \end{table}

 \begin{table}[t]
  \caption{An Example of Ku-band Link Budget}
  \begin{center}
    \epsfile{file=4-1-table-a.eps,scale=0.50}
  \end{center}
  \label{Tab.3}
 \end{table}

 \begin{table}[t]
  \caption{The Type of Emission in C-band Link}
  \begin{center}
    \epsfile{file=4-1-table-d.eps,scale=0.50}
  \end{center}
  \label{Tab.4}
 \end{table}

 \begin{table}[t]
  \caption{An Example of C-band Link Budget}
  \begin{center}
    \epsfile{file=4-1-table-c.eps,scale=0.50}
  \end{center}
  \label{Tab.5}
 \end{table}

\subsection{Satellite Link}

Our satellite links use Ku-band and C-band provided by JCSAT satellite
1B and 3 respectively. Those types of emission are designed as listed
in Table \ref{Tab.2} and Table \ref{Tab.4}. The information rate of
every link is asymmetric as described in Section 3.2. An
example of each link budget is designed as shown in Table \ref{Tab.3}
and Table \ref{Tab.5}.

Ku-band has a characteristics of rain degradation, so we designed to
keep the large number of clear sky margin. For example, between Japan
to Indonesia in Table \ref{Tab.2} clear sky margins are 8.8dB and 10.0dB.
In order to apply the required C/N = 7.0dB, the modulation is QPSK with
Viterbi FEC of 3/4.

On the other hand, C-band has less rain degradation, so small number
of clear sky margin is enough, we designed C-band link's clear sky
margin is lower than the Ku-band link's one.  For example, between
Japan to Singapore in Table \ref{Tab.4} clear sky margins are 4.7dB and
5.4dB.
For effective use of frequency bandwidth, 8PSK modulation was adapted.
The FEC is the combination of sequential decoding and Reed-Solomon,
but the required C/N is higher (8.7dB) than the one of Ku-band (7.0dB),
because we give the priority to the effective use of frequency
bandwidth.

\subsection{Network Topology and IP Routing}

We describe the implementation and the evaluation of \aiii testbed network
from the viewpoint of the international collaborations
achieved in the past.

 \begin{figure}[t]
  \begin{center}
    \epsfile{file=ai3net.eps,scale=0.37}
  \end{center}
  \caption{\aiii TCP/IP Network Topology}
  \label{Fig.4}
 \end{figure}
 \begin{figure}[t]
  \begin{center}
    \epsfile{file=telemed_net.eps,scale=0.47}
  \end{center}
  \caption{A Real-time Telemedicine over Satellite}
  \label{Fig.5}
 \end{figure}

First, our satellite circuit is a star shaped topology as shown in
Figure \ref{Fig.2}, where all of the earh stations have capability of
both data transmission and receiving. In comparison with other
topologies, our topology is more cost-effective and more flexible
against increase or decrease of earth stations.

Then, we implemented our TCP/IP network over the satellite
circuit as illustrated in Figure \ref{Fig.4}. Each point to point
IP connection is established using Cisco
HDLC protocol. Routing information of the earth station networks
is exchanged by using OSPFv2. BGP4 protocol is used for route
exchange among \aiii partners.
We have been using and evaluating these protocols over satellite
since the beginning.
As a result, our link utilization
shows that Internet backbone can be composed of Ku-band and C-band
satellite links using Asian zone beam with the existing Internet
routing technology in Southeast Asia.
In particular we have confirmed that BGP4 over satellite in Ku-band
links has been working enough to provide international backbone
connectivity without parameter tuning and protocol enhancement in the
five years.

In this way, \aiii project has been providing the testbed network to
the users in and around \aiii partners. In fact, \aiii testbed network 
is helpful and sustainable for \aiii Indonesia group. More than 24
institutes in Indonesia have suvived economic crisis in Asia by using
this testbed as Internet backbone. Our link between Japan and
Indonesia is still fully occupied by IP commodity traffic. Our network
implemention being deployed in Asia is available and valuable for the
use of backbone connection.

\aiii also has been improving its network connectivity and making
collaboration in practice. \aiii is connected to both WIDE and
APAN\cite{apan-wwca,apan-ptc00} with 10Mbps ATM links.
\aiii partners have chances of tight collaboration with leading-edge
research universities and institutions in United States and other
western countries using APAN TranPAC connected with STAR TAP.

For example, during the event of UNFCCC/COP3 in 1997 and UNFCCC/COP4
in 1998\cite{suguru-cop34}, \aiii testbed network performed a part to
relay audio and video broadcasting from the conference hall to a large
Internet audience in Asia. In addition, our testbed was used for
real-time telemedicine experiments. A new telemedicine system which
enables us to perform real-time remote diagnosis using a low bit rate
medical image sequence up to 128kbps has been developed and was
applied to our testbed in June 1999. This experiment verified that the
proposed system provides real-time telemedicine environment over our
testbed between Thailand and Japan\cite{umeda-telemed}.  The both test
sites were connected as shown in Figure \ref{Fig.5} through our
testbed. The results implied that our testbed can contribute good
accessibility to Asian researchers in the field of
telemedicine\cite{umeda-telemed-lowbitrate}.

In summary, even though our satellite links are long delay thin
bandwidth Internet connection, it has been confirmed that our current
topology and routing are enough valuable for international
collaboration.

\subsection{Network Management}

Network operation is quite important to keep its environment healthy.
For this purpose, we are using an SNMP based network
management system. With the system, we keep tracking all the status of
routers, switches and other network devices and share this information
among network operators and researchers in our project, in order to
know fault point in the case links or gateway systems are down.

 \begin{figure}[t]
  \begin{center}
    \epsfile{file=vsat.eps,scale=0.8}
  \end{center}
  \begin{center}
    \epsfile{file=netmon.eps,scale=0.37}
  \end{center}
  \caption{\aiii VSAT Monitoring System}
  \label{Fig.6}
 \end{figure}
 \begin{figure}[t]
  \begin{center}
    \epsfile{file=idu-ait.eps,scale=0.5}
  \end{center}
  \caption{A Daily Output of anaslmp}
  \label{Fig.7}
 \end{figure}

However, unlike the ordinary Internet system, we are using a satellite
system for our backbone connections so that we also have to monitor
satellite links. Stationary satellites are always monitored by link
carrier's control center but those data are not opened online. Thus,
earth stations remain as our target.

In generall electoric devices consist of ODU and IDU in a VSAT earth
station as illustrated in Figure \ref{Fig.6}. Data available around ODU are
air temperature, precipitation and so on at the outdoor. IDU supplies
Eb/N0 and AGC level fluctuation. Spectrum Analyzer for IF frequency at
the hub stations provides changes of receiving signal
power. Furthermore the serial interface attached to the gateway shows
the link status, IP traffic volume, protocol distribution and
etc. These four components are important to diagnose satellite link
troubles such as no signal transmission.

Weather condition around ODU sometimes affects satellite
communication.  For example, ODU tends to be exposed under high
temperature in South Asia and it must be cooled down to work. A
measuring device for temperature and a big external fan have been
installed in Thailand since we found ODU over heated there. Rainfall
and snowfall should be also measured.
For example, ITB in Indonesia is running a weather station in
order to detect heavy rains and record them with fluctuation of IDU
status, since a heavy rain causes rain degradation against Ku-band
links.

IDU status includes highly suggestive data to know dynamics of link
condition from remote sites. In case of Ku-band, rain attenuation
often causes a link to be unsynchronized and to be down during a heavy
rain, when it drains a link margin. We can remotely know such link
condition from IDU status. Statistical data recorded through a year
brings us Ku-band link utilization in toropical regions. \aiii project
has been using the three different IDU. We developed the three
software products, IDUmon, anaslmp and NWD which can respectively
monitor NEC NEXTER, ComStream CM701 and EFData SDM-300A as shown in
Figure \ref{Fig.6}. An example of daily output by anaslmp is also
shown in Figure \ref{Fig.7}.

Spectrum analyzer is useful in several senses. First, we can measure
received signals at the hub station. It simplifies for operators to
take a prompt action to check signals online. Secondly, it reveals
performance debasement of communication devices integrated around ODU.
In particular it is helpful at a complex earth station which has more
devices such as TWT and downconverter in addition to ODU.

In order to keep links up for IP connection, the serial interfaces
attached with IDU on the gateways are also monitored.

\subsection{Multicast Testbed}

Our objectives to run Multicast testbed are to share Mbone
experiences, to develop multicast applications and to reseach
multicast technology using satellite.

 \begin{figure}[t]
  \begin{center}
    \epsfile{file=cachebone.eps,scale=0.33}
  \end{center}
  \caption{\aiii Cache Bone}
  \label{Fig.8}
 \end{figure}

We have been experimenting with Mbone over our testbed since the
beginning. It is meaningful for Mbone beginners in the partners to
acquire expertise about Mbone technology. For example, a historical
event, Hong Kong Hand Over has been broadcasted through our Mbone
testbed by HKUST \aiii group on July 1st in 1997. Through this event,
\aiii members have learned some techniques such as use of scoped
multicast address to transmit video streams with different rates for
respective bounded networks. At NAIST earth station, 512 kbps Mbone
session was received with video from 3 to 8 fps and lossless audio
in 24 hours.

We have been making efforts to develop multicast applications. A
hierarchical WWW cache using multicast over satellite has been
proposed and developed for cache delivery. This system is called as
\aiii Cache Bone with formation for providing both higher hit rates and
saving the overall bandwidth consumption through fetching WWW objects
and multicasting them over satellite\cite{ai3-www-cache-inet97,webhint}.
Figure \ref{Fig.8} shows a basic model of
\aiii Cache Bone. In Asian region, we confirmed that the
performance of our rim cache is much improved by approximately three
folds when compared with an ordinary hierarchical cache system such as
Squid. We have finished all the implementation of the adaptive cache
including the multicast push caching. The average of the hit rate
observed at AIT cache was above 50\%\cite{panjai-cache}.


\section{Discussion}

We in turn installed the Ku-band and C-band networks to deploy our
network testbed in Asia. Pioneer use of Ku-band links explored
possibility for the application to Internet links. Development of
C-band links contributed to increase our link coverage in Asian
region. 

Using these networks, further collaboration is expected with new
invited \aiii partners such as in Vietnam or Sri Lanka. For example, in
Vietnam AI3-Vietnam was implemented involving around 17 universities
and research institutes in Hanoi where \aiii earth station is
located. AI3-Vietnam is a framework for Vietnamese researchers to
collaborate together on \aiii project. The southern universities and
research institutes will join them likewise as soon as their backbone
link between Hanoi and Ho Chi Minh City is improved enough. The
situtation is similar in Indonesia, Philippine and Sri Lanka. In this
way \aiii project accelerates opportunity for intra-Asia collaboration.

Although all the satellite links in our testbed network are currently
configured as bi-directional, we are planning to add unidirectional
links in our testbed. With those links we start to work research on
integration between point-to-point and point-to-multi point satellite
links to function well as satellite based network infrastructure.

For instance, we are going to develop a new routing mechanism working
with unidirectional link routing\cite{rfc3077}.
This link integration technique is
useful to control satellite link bandwidth in response to temporal
increases of one way traffic. Also it can be shared among multiple
sites to receive Internet application traffic such as Web cache
injection and replications, content mirroring and etc.
Developments of core technologies to enable us to configure this kind
of unidirectional link is undertaken.
With bandwidth available in our C-band channels, we are going to
conduct experiments of this unidirectional link technologies with our
partners. 

The other research goal related to this unidirectional link is to
develop applications for receive only site.
Research and development on distant learning have become active in
Asia\cite{internet-manufac}\cite{kawai-soi}. 
However, in some areas in Asia, there is still no communication infrastructure
including stable telephone lines, 
but there is heavy demand to feed up-to-date information for people
living in such area, especially for education purposes. 
Making ``receive-only'' satellite earth station is inexpensive and
normally not required to obtain appropriate license from authorities.
With this kind of ``receive-only'' terminals,
we are going to make on-demand data feed mechanism on the
unidirectional links. 

IPv6 is a key technologies for the Internet next generation. In the
\aiii testbed network, 6bone-{\aiii} is in operation and it is connected
with 6bone. We gradually expand IPv6 experimental networks to 
Asian countries through our testbed. In fact, our deployment efforts
accelerate each IPv6 promotion and regional deployment in Asian
countries such as Indonesia, Philippine and Malaysia. In Malaysia,
there is a multimedia conferencing system called MCS\cite{sures-mcs}
developed by \aiii Malaysia group and they started to work for enabling
MCS to run as one of IPv6 applications\cite{sures-mcsv6}.

Now that we confirmed worth of Ku-band and C-band links as described
earlier, let us consider Ka-band links. Ka-band is worse affected than
Ku-band against rain attenuation but Ka-band brings faster link
performance upto the Gigabit order. As a result of this link property,
we face a problem that is less utilization of Ka-band links in rainy
region. However, in redundant implementation, other bands and/or
terrestrial lines can automatically backup Ka-band links by means of
Internet routing technology as well as Ku-band.


\section{Conclusion}

We've been running \aiii project for these four years. During this
period, many international collaborations have been produced and our
testbed has been used for the purposes of experiments in the process
of technology development and deployment.

% Although our satellite links have much less bandwidth than modern
% terrestrial Internet links, we confirmed worth of our testbed network
% based on satellite links through our experiments.

For application technology development, our project enables
researchers to develop advanced Web caching mechanism and to achieve
the international telemedicine experiment.
For Internet development, \aiii project verified feasibility of the use
of Ku-band satellite links in tropical region in Asia. This result
accelerated satellite operators to provide Ku-band transponders which
covers Asian countries.

\aiii project also has helped sustainable development of human
resources.  We can find a notable case study from our experiences in
Indonesia.  Because \aiii testbed network has survived even in economics
crisis in Indonesia, ITB has been taking a leading part in this human
resource development in Indonesia with is many mailing lists.
Now the number of mail delivery on their
server has grown to send more than 70,000 mails every day to Internet
community in the country.  \aiii project is expected in the other Asian
countries such as Vietnam to accelerate their research and development
activities focused on Internet technologies.

\aiii project has provided our efforts to make international
collaboration since its beginning. As a part of APII testbed and also
as a part of APAN, our testbed is continuously expected to work as a
network infrastructure interconnecting among Asian countries for
academic and research purposes.


\section*{Acknowledgement}
We would like to thank JSAT Corporation for their technical support
in satellite communication and Communication Research Laboratory for
the joint researches as APII. We also would like to thank for all
members of \aiii project.

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\profile
{Tomomitsu Baba}
{He received the BE and ME degrees in communication engineering from Osaka University in 1989 and 1991.  Since 1999 he has been a lecturer in Kurashiki University of Science and the Arts.  His research interests are in technologies for satellite Internet infrastructure and Internet robust architecture tolerant to disaster.}
\profile
{Hidetaka Izumiyama}
{He received the B.E. of information science from Tsukuba University in 1988.  Since 1993 he has been a system engineer in JSAT Corp. and belongs to the advanced technology division.}

\profile
{Suguru Yamaguchi}
{He is a professor, the Graduate School of Information Science,
Nara Institute of Science and Technology.
He received the M.E. and D.E. degrees in computer science from Osaka
Unviersity in 1988 and 1991.
His research interests include technologies for information sharing,
multimedia communication over high speed communication channels,
network security and network management for the Internet.
}

\end{document}
