We present atelemedicineapplication thatprovides remotemedical care serviceswhile takingadvantage of thebroadcast andmulticast capabilitiesand the wide-bandcapacity of satellitesystems. Wedeveloped theapplication in anopen environment(Java) using a client-server architecturebased on TCP/IP. Weevaluated theperformance of theapplication onsatellite connections.

Satellite communication systems havegreat advantages, such as wide-area cov-erage and the flexibility of providingbroadcast and multicast connections.

Even if the current capacity of satellite commu-nications systems doesn’t suffice for future mul-timedia applications, the satellite will be afundamental element in the global informationinfrastructure (GII), which aims to carry infor-mation to anyone, anywhere, at any time, in anyform, at an affordable price. The role of satellitesmust be integrated with the ground networks,rather than competing with them, because theycan connect quickly to locations otherwise geo-graphically or economically unreachable. Satel-lites provide a new opportunity by adapting thecovered area to changes in demand for services.In particular, satellites offer a good facility formultimedia services where, up to now, it was dif-ficult to forecast the different types of servicesand bit rates.

Commissioned by the European CommissionEC-DGXIII within the frame of the AdvancedCommunications Technologies and Services(ACTS) 4th Framework Program, the InteractiveSatellite Multimedia Information System (Isis) pro-ject developed a satellite communications systembased on a dual-band concept and suitable for pro-

viding interactive multimedia services. The Isis sys-tem simultaneously uses a dual-band terminal, theKu frequency band for a high-rate forward link,and the Ka frequency band for the return link toprovide a small, low-cost transmitter/receiverthat’s easily transportable and installed.

The Isis project plans to offer interactive ser-vices for residential users in addition to the tradi-tional TV distribution, porting applicationstypically developed for terrestrial networks(Internet) to the satellite Digital VideoBroadcasting (DVB) environment. Using a PC andthe same commands as most Internet applica-tions, the connection by satellite will be transpar-ent to users. Moreover, users’ terminals can easilyconnect to terrestrial networks such as IntegratedServices Digital Network (ISDN) and the Internetto obtain integrated multimedia services. The pro-posed approach aims to keep the basic Web solu-tions, allowing access to special data, large images,video sequences, and animations through specialsatellite links. This also provides access to servicesfrom sites not connected to the Internet or con-nected only with low-speed links, or from sitesthat must be connected in emergency cases.

The Isis project demonstrated the feasibility ofsatellite-based interactive multimedia services.The project selected and analyzed a number ofapplications for residential users and communi-ties such as Internet services (file-transfer protocolor FTP, e-mail, and browsing services), distributionof electronic newspapers, teamworking, tele-education, and telemedicine.

These applications not only address commer-cial and business distribution, but applicationssuch as tele-education and telemedicine have afundamental impact on improving the quality oflife. This article describes the telemedicine appli-cation Medical Environment for DiagnosticImages (MEDI).

MEDI has an open architecture with the fol-lowing characteristics:

❚ developed in Java, it’s machine independent;

❚ it uses the transmission-control protocol/Internet protocol (TCP/IP), so can run on dif-ferent types of networks;

❚ it can be used on any commercial Web brows-er; and

❚ it supports broadcast connections for its client-server architecture.

76 1070-986X/00/$10.00 © 2000 IEEE

An InteractiveMultimediaSatelliteTelemedicineService

Laura Pierucci and Enrico Del ReUniversity of Florence, Italy

Feature Article

Service and terminalrequirements

Dual-band (Ku/Ka) terminals per-mit tailoring the satellite system’scharacteristics to the actual users’needs.1 In particular, the Ku band usestechnology readily available for devel-oping satellite terminals installed atthe user premises (direct-to-home, orDTH). This reduces the requireddevelopment costs and increases thegrowth of multimedia servicesbecause of the possibility of using theservice during the start-up phases ofcommercial satellite segments.

On the other hand, the Ka banddiffuses multimedia and interactiveTV services because of the availablewide-band capacity in the two direc-tions (forward and return). It reducesthe complexity of users’ small termi-nals and improves the cost effective-ness because of the increase ofsystem capacity throughput.

Depending on the type of information andconnection, the Isis project offers a highly flexibleplatform for to provide a wide range of services:

❚ Internet service (FTP, Telnet, e-mail, Webnavigation)

❚ bidirectional messaging (e-mail, paging)

❚ retrieval of documents, data, and high-resolutionimages

❚ interactive multimedia conversational applica-tions (broadband multipoint videoconferencing,teleworking, teleconsulting, tele-education, andso on)

❚ user-controlled distribution (restricted digital

information transmission, electronic newspa-pers, and so on)

Table 1 shows service requirements in terms ofstandards, required quality of service (QoS), bit-error rate (BER), acceptable time delay, and net-work connectivity for the major applicationsrelevant to the Isis system.1

System conceptFigure 1 shows the basic Isis architecture where

the main blocks include1

❚ a service center, sometimes called the broad-casting center or hub;

❚ a small earth station (SES), also called a DTHterminal, which is placed at residential users’homes; and

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Table 1. Applications requirements

Videoconference Multimedia Mail News on Demand Telework Telemedicine Tele-educationConnection Symmetrical Asymmetrical Asymmetrical Symmetrical Symmetrical Asymmetrical

Capacity BER 10−4 BER 10−6 BER 10−6 BER 10−6 BER 10−6 BER 10−6

Quality 128 Kbps 128 Kbps 128 Kbps 128 Kbps 384 Kbps 384 Kbps to

to 1.4 Mbps to 1.4 Mbps to 1.4 Mbps to 1.4 Mbps 3

Time Requirements 200 ms 1 s 500 ms 200 ms 200 ms 200 ms

Type of Connection Real time Scheduled Scheduled Real time Real time/ Real time/

scheduled scheduled

EutelsatHot-birdKu band

12-14 GHzItalsat

Ka band20-30 GHz

Smallearth station

Smallearth station

Mediumearth station

(hospital)

Mediumearth station(university)

Service center

Forward channel (Ku)Return channel (Ka)

Figure 1. Isis

architecture scheme.

❚ a medium earth station (MES), installed atcommunity buildings such as hospitals or uni-versities.

The service center has the followingfunctionality:

1. System management and administration ofthe network. It manages all the user activities(service access, service delivery, service release)as a network control center.

2. Information data and signaling informationuse the same channel (in-band signaling).

3. Transmitting and receiving communicationpaths belong to different frequency bands. TheKu band antenna and radio frequency equip-ment manage the forward channel transmis-sion toward the user DVB downstream (34Mbps) that contains the information relatedto the selected application. The Ka bandantenna and radio frequency equipment man-age the return channel at a low bit rate (64Kbps to 384 Kbps), carrying out signaling andinteractive information from the user to theservice center.

4. Storage of data, images, and videos of the Isisapplications in the video server, which pro-vides the digital MPEG-2 transport stream andcan support

❚ MPEG-2 video broadcasting. The user selects andwatches MPEG-2 videos (movies) among thosethe video server broadcasts. The movies arecyclically broadcast on the satellite high-speedlink, then the user selects the channel, andreal-time decoding starts at the client end.

❚ IP-based applications. The demonstration sys-tem gives the user full Internet access throughan Internet server and the possibility to runany standard Internet application like FTP, aWeb browser, and so on. Moreover, Isis part-ners developing their own IP-based client-serv-er applications can run them using the IP overa DVB transport mechanism that the videoserver supports.

5. The DVB modulator (DVB-S standard ETS 300421) receives the content information fromthe video server (that is, the MPEG-2 transportmultiplexer) in a format suitable for the Kuradio frequency equipment to transmit tousers through the satellite communicationlink.

6. The service center is connected to the Web bythe Internet server. The Internet server pro-vides connectivity for any server with IP-basedapplications, so it acts as a router for all the IPtraffic and accesses data from either remote orlocal servers.

The MESs aren’t service providing centers.These remote stations possess improved transmit-ting (up to 2 Mbps) and receiving capabilities onlyto satisfy specific service requirements such as bitrate and real-time interaction.

The SESs have asymmetric communicationlinks to receive a great amount of data and totransmit low bit rates (64 Kbps) mainly for controlmessage purposes.

The user terminals are mainly PCs with dedi-cated boards. Users run the required applicationfrom their PC, generating user traffic (such asrequests or data) provided to the return channel.On the traffic channel, IP packets must be seg-mented for transmittal on the return channelslots, based on asynchronous transfer mode(ATM, ATM adaptation layer AAL5). The end-userterminal demodulates and demultiplexes theMPEG-2 DVB signal received from the forwardchannel (Ku band) containing the required infor-mation embedded on the MPEG-2 transportationstream.

A telemedicine applicationTelemedicine aims to provide remote medical

services to distant communities using current andemerging communications networks. Thetelemedicine application MEDI provides the fol-lowing two environments:2

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Telemedicine aims to provide

remote medical services to

distant communities using

current and emerging

communications networks.

❚ Medical image database access. Permits access toa medical diagnostic images database throughthe selection of search fields to retrieve themedical image, the image visualization andprocessing, and other image supports.

❚ Remote expert consultation. Provides interactiveimage transmission showing various medicaldiagnostic modalities with cooperative toolsamong physicians and specialists whoexchange information and opinions aboutpatient cases to obtain diagnoses in real timeand to plan the treatment.

Based on Java,3 the MEDI application runs ondifferent platforms (such as Unix or WindowsNT/95/98). We selected Java to develop MEDIbecause it provides interfaces and classes suitablefor developing network applications. Java pro-grams (applets) are architecture-independent,since they’re written in a high-level languagecompiled in code (bytecodes), which any machinecan interpret. Also, Java uses a virtual machine torun the applets, which can be embedded in otherapplications. For example, they can be enclosedin a Hypertext Markup Language (HTML) docu-ment to provide interactive, executable contenton a Web page. Java also supports database devel-opment through Java Database Connectivity(JDBC), which offers a set of classes and interfacesto execute Structured Query Language (SQL) state-ments—using JDBC, the SQL statements can besent easily to any commercial database (such asOracle, Informix, Access, and so on).

MEDI is a Web application based on HTMLpages with a Java client front end (applets) andJava servers connected via TCP/IP. All the imagesinvolved in the applications are in the Papyrus 3.0format (see http://www.expasy.ch/UIN/html1/projects/papyrus/papyrus.html), which is inagreement with the Digital Imaging and Comm-unications in Medicine (Dicom) 3.0 part 10 stan-dard (see http://www.xray.hmc.psu.edu/dicom/).

Since MEDI is a Web-based application, it hasa client-server architecture. A remote machinewith server functionality controls concurrentprocesses from the clients. It hosts and runs themedical image database, the other MEDI databas-es, and the Java and HTTP servers. Many clientscan start and see the MEDI application using anycommercial browser such as Netscape, InternetExplorer, or HotJava. MEDI uses a broadcastmodel to send the same images and events to allthe users sharing a medical session. In this model,

each user has a separate copy of the applicationallowing cooperative diagnosis among multipleusers by broadcasting the events required by eachuser to all the other users in the session. A syn-chronization system controls the use of a sharedmouse and of cooperative tools among the differ-ent users to avoid collision problems in the mul-ticast transmission. In this case only one user hasthe controls and can modify the image; the otherusers can see the results of the work on the imagesimultaneously. MEDI also lets participantsexchange text messages with each other.

Here’s an example of a typical client-serverwork session with MEDI:

❚ The client requests a service (database orremote consultation) through a homepagereceived from the HTTP server.

❚ After an authentication phase (login and pass-word), the HTTP server sends the client anHTML page containing the Java front end(applet). Then, a socket between the Java serv-er and the client is opened and a client-serverapplication session can start.

❚ Messages (SQL commands, medical images,actions, and so on) are exchanged among theclients (remote consultation) or between the

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AcronymsBER bit-error rateDicom Digital Imaging and

Communications in Medicine DTH direct-to-home, or DVB Digital Video Broadcasting FTP file-transfer protocolHTML Hypertext Markup Language HTTP hypertext transfer protocolISDN Integrated Services Digital

Network Isis Interactive Satellite Multimedia

Information SystemJDBC Java Database Connectivity MEDI Medical Environment for

Diagnostic Images MES medium earth station QoS quality of serviceSES small earth station SQL Structured Query Language TCP/IP transmission-control

protocol/Internet protocol

client and the server (medical image database)directly over the socket connections the Javaserver(s) provide.

To coordinate the information exchange andcollaboration with users, MEDI has three Javaservers:4

1. Database server. This server controls the userquery for the access to the medical images data-base. The user fills out a consultation applet (inHTML) according to the following fields: sex,

age, diagnostic modality, clinical history,American College of Radiology (ACR) diagno-sis coding, hospital name, date and time of themedical report, number of images in thePapyrus 3 file, and so on. The server also inter-acts with the ACR standards database(http://www.acr.org/f-products.html), whichcontains all the necessary information for cod-ing a diagnosis from the anatomical and patho-logical point of view. When users have selecteda particular record, the database server createsa new HTML page embedding an applet for thevisualization of the medical image(s) associat-ed with the selected record. The visualizationapplet is based on the Java Abstract WindowToolkit and establishes a connection to the Javateleconsult server, which has direct access tothe Papyrus 3.0 images.

2. Queue server. This server supports user requestsfor an expert service. In the queue databaseeach record represents a request and containsall the necessary patient information—age andsex of the patient, hospital name, date and timeof the request, and so on. The queue servermanages the reception of the image(s) thatmust be analyzed, along with some informa-tion about the patient and the subscriber (thedoctor). It controls the requests queue, the gen-eration of the HTML page containing the infor-mation of the selected request, and the remoteconsultation applet configured for receiving themedical image(s) associated with the selectedrequests. It also manages the request deletion atthe end of a remote consultation session.

❚ Teleconsult server. This server permits remoteconsultation sessions. It manages the trans-mission of the Papyrus 3.0 image(s) both to theuser and to the expert consulted during the ses-sion. It provides a multicast transmission ofeach command (such as events, data messages,and images) received from a user to all theother participants in the remote consultation.It also manages the generation of the HTMLpage containing the medical report written bythe expert at the end of the consultation andthe HTML page containing the applet for theMedbase upgrade.

Figure 2 shows an example of the flow of dataand control and the MEDI servers’ functionalityduring access to the medical database. Figure 3shows the applet for the MEDI medical image

80

Client

Servers

Databaseserver

HTTPserver

HTML pageswith applets

Teleconsultserver

Medicalimages

database

ACRdatabase

Imagedatabase

Figure 2. Data and

control flow in the

MEDI client-server

image database.

Figure 3. Applet of the

medical database

consultation.

database consultation, where it’s possible to selectthe pathological case using the different searchfields. After the form compilation, the appletinforms the Java database server which records theuser wants. Then the Java database server createsan HTML page containing the selected recordinformation and the remote consultation appletconfigured for receiving the medical image(s) asso-ciated to the selected record. The user automati-cally receives the selected Papyrus image from theJava teleconsult server (see Figure 4).

As Figure 4 shows, various image tools arealways available in MEDI, such as

❚ Tools for flipping, rotating, zooming, insertingtext over the image, calculating distancesbetween two points of the image, and grayadjustment of the current image.

❚ A movie mode, for showing all the receivedimages in a loop. Some diagnostic modalities(such as magnetic resonance, or MR) caninclude more than one image related to differ-

ent acquisition moments or points, or to dif-ferent patient positions.

MEDI users may require the help of a remotespecialist to have more information on the select-ed image. MEDI lets users exchange text messagesaccording to a traffic-light control system (onlyone user at a time can transmit events and mes-sages to avoid misunderstanding) that controlsthe shared mouse and processing tools on thesame image. When the teleconsult session ends,the expert is invited to write a medical report,contained in an HTML page and automaticallysent to users when they leave the session. Theexpert can also choose to save this new clinicalcase to the medical images database.

Trial resultsDuring the trials of the Isis project the MEDI

servers were connected to the client via the Eutelsatsatellite (forward channel) and the link from theclient to the MEDI server via the Italsat satellite(return channel) using the Isis platform. The client,

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0

255

Tools bar Flip, rotatezoom, text

Main

Coloradjustment

Max gray value

Min gray value

Min

Max

212 28

Moviemode

Tile mode

Image number

Image selection

Control stateGet/release control

Quit

Anotherhave controlCantake controlHave control

Image gray level

Figure 4. Papyrus image

(top right) and the

various image tools in

MEDI (lower left).

equipped with a dual-band terminal, received andtransmitted multimedia signals and could start andsee the MEDI application using a commercialbrowser. Table 2 shows a number of tests (ping,FTP, HTTP) that validate the Isis platform.

The ping time of 600 ms was the usual satellitedelay, and the packet loss was nearly acceptable.For the HTTP tests, we evaluated two scenarios:

❚ retrieving data from the Web server and

❚ retrieving data from the Internet through aWeb proxy.

The results showed that the MEDI applicationon the Isis platform performed well: all the con-nected clients received the images and usedshared tools satisfactorily. Table 3 shows the trans-fer timing of images of different sizes from theserver to the client.

Experts and doctors at the University of FlorenceHospital—during the trials—quickly familiarizedthemselves with the MEDI tool and evaluated MEDIas a user-friendly application. During the trials ofthe Isis project, we carried out a teleconsult sessionon a clinical case of prostate cancer using medicalimages acquired from different medical equipmentand used an audio tool available in MEDI. Visithttp://lenst.die.unifi.it/isis/index.html for moreinformation about MEDI.

ConclusionsA satellite network can provide many more

advantages than a terrestrial connection for MEDI,including

❚ a wide band in the forward and return links,compatible with a bit rate of 2 Mbps requiredby the application;

❚ a guaranteed bit rate, whereas Internet perfor-mance is highly dependent on traffic intensity;

❚ broadcast and multicast capabilities that suitthe MEDI application based on a client-serverarchitecture; and

❚ secure connections for routine and emergencycases.

In the future, we plan to conduct extensive tri-als to test the MEDI application among differentEuropean hospitals connected by satellite usingthe Isis infrastructure. MM

AcknowledgmentsWe wish to thank the ACTS-Isis Consortium

members for supporting the work and colleaguesfrom the University of Florence Hospital for theirparticipation in the trials.

References1. Technical Annex, Isis Projects AC103 (Isis Project

Deliverables), AC103/NTLZ/IIS/DS/019/a1;

AC103/NTLZ/IIS/DS/018/a1;

AC103/NTLZ/IIS/DS/005/a1;

AC103/NTLZ/IIS/DS/022/a1 1996-1998. See also

http://www.at.infowin.org/ACTS/RUS/PROJECTS/ac

103.htm.

2. E. Del Re and L. Pierucci, “Experience and New

Approach for Remote Education in Heterogeneous

Networks,” Proc. IEEE 2nd Workshop on Multimedia

Signal Processing (MMSP 98), IEEE Press, Piscataway,

N.J., Dec. 1998.

3. L. Vanhelsuw et al., Mastering Java, Sybex, Alameda,

Calif., 1996.

4. A. Abrardo and L. Casini, “Embedded Java in a Web-

based Teleradiology System,” IEEE Internet

Computing, Vol. 2, No. 3, May/June 1998, pp. 60-68.

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Table 2. Network tests.

Test ResultsPing Connectivity OK

Round-trip times: 600 ms

Packet loss: 0.014%

FTP Connectivity OK

10K-100K-1000K file transfer OK

Greater than 20 Kbps for one session

No packet loss

HTTP Acceptable performance

Table 3. Timing transfer on the forward link.

Images Transfer EvaluationX ray (135 Kbytes) 15 seconds Tools OK

Cinecard (2 Mbytes) 95 seconds Movie/tools OK

MR (1Mbyte) 60 seconds Tools OK

Laura Pierucci is Technical

Researcher in the Electronics and

Telecommunications Department

at the University of Florence, Italy.

Her main research interests are

digital signal processing, adaptive

systems, neural networks, and mobile and satellite com-

munication systems. She received her PhD in electron-

ics engineering from the University of Florence in 1987.

She won a fellowship from the Research National

Council, Italy, in 1989.

She participates in the Italian Space Agency

(ASI)/Ministry of Research (Murst) project and in the

European Isis project, where she is involved in the analy-

sis of telecommunications systems on terrestrial and

satellite networks and their applications (such as tele-

education and telemedicine). Presently, she is the

Scientific Secretariat of the European Cooperation in the

(EU Cost) field of Scientific and Technical Research

Action 252 “Evolution of satellite personal communica-

tions from second to future generation systems.”

Enrico Del Re is Professor and the

head of the Digital Signal Process-

ing and Telematics Laboratory in

the of Electronics and Telecom-

munications Department at the

University of Florence, Italy. His

main research interests are digital signal processing, dig-

ital transmission techniques, and communication net-

works. He received his PhD in electronics engineering

from the University of Pisa, Italy, in 1971. He is the co-

editor of the book Satellite Integrated Communications Net-

works (North-Holland, 1988), a co-author of the book

Data Compression and Error Control Techniques with Appli-

cations (Academic, 1985), and editor of the book Mobile

and Personal Communications (Elsevier, 1995). He

received the 1988-1989 premium from the IEE (UK) for

the paper “Multicarrier Demodulator for Digital Satellite

Communication Systems.” He is a senior member of the

IEEE, and a member of the Italian Electronics Associa-

tion (AEI) and the European Association for Signal Pro-

cessing (Eurasip).

Readers may contact Pierucci at the Electronics and Telecommunications Department, University of Florence,

V.S. Marta 3, 50139, Florence, Italy, e-mail pierucci@lenst.die.unifi.it.

JAN/FEB — Top 10 Algorithms of the CenturyJack Dongarra, dongarra@cs.utk.edu, University of Tennessee, and Francis Sullivan, fran@super.org, IDA Center for Computing Sciences The 10 algorithms that have had the largest influence on the development andpractice of science and engineering in the 20th century (also the challenges facing usin the 21st century).

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MAY/JUN — Earth Systems ScienceJohn Rundle, rundle@hopfield.colorado.edu, Colorado Center for Chaos and Complexity The articles featured in this special issue will document the progress being made inmodeling and simulating the earth as a planet.

JUL/AUG — New DirectionsThis issue explores the various new directions facing the computing in science andengineering field. Articles cover topics about Monte Carlo arithmetic, graphicmodeling, and satellite technology.

SEP/OCT — Computing in MedicineMartin S. Weinhous, weinhous@radonc.ccf.org, Cleveland Clinic, and Joseph M. Rosen, joseph.m.rosen@hitchcock.orgIn medicine, computational methods have let us predict the outcomes of ourprocedures through mathematical simulation methods. Modeling the human bodyremains a challenge for computational mathematics.

NOV/DEC — Computational ChemistryDonald G. Truhlar, truhlar@chem.umn.edu, University of Minnesota, and B. Vincent McKoy, mckoy@its.caltech.edu, California Institute of TechnologyOverviews of the state of the art in diverse areas of computational chemistry with anemphasis on the computational science aspects.

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