- Email: [email protected]
HICAT for International Medical Communications
TELEMEDICINE USING SMALL SATELLITE MEO/HICAT FOR INTERNATIONAL MEDICAL COMMUNICATIONS I. Nakajima ', Y. Sawada \ T. Maeda^ D. L. Martin ^ S. Nagano ^ and N. Hamano ^
; Tokai University School of Medicine, Emergency Medical Services, Boseidai, Isehara-city, Kanagawa, 259-11, Japan. Nakajima's e-mail: [email protected] 2 Hitachi, ltd. Space System Division, 6 Kanda-Surugadai 4-chome, Chiyoda-ku, Tokyo, 101, Japan. Maeda's e-mail: [email protected]. hitachi.co.jp
ABSTRACT Here is described the effectiveness of communication between medical facilities using satellite, in particular of international medical communications, targeted to communications between medical practitioners. Communications between these facilities are characterized by low call origination count, the range of the radio station is relatively large, and the communication time is relatively long. We belive an example of MEO is shown in consideration of this feature. We designed HiCAT (High-performance International Communications for Advanced Telemedicine) satellite; sun-synchronous quasi-recurrent Orbit (n=7), specifically, six satellites to be launched, three orbit planes, and two satellites for each plane, and the users targeted are those living in areas from the equator as the center to the latitude of 70 degree. The average angle of elevation of HiCAT is approximately twice that of Iridium. These advantages; higher visibility and higher elevation angles can be explained to make MEO suitable for communications between these facilities. Teleconsultations with clinical data as a store-and-forward packet communications linking with Internet, clinical image diagnosis with JPEG, and broadcasting medical news distribution services using MEO are believed to be one of the optimal applications of small satellite. OBJECT This document describes a Medium Earth Orbit (MEG) applications, especially suitable for satellites supporting telemedicine applications, in particular for international medical communications. TELEMEDICINE Definition Telemedicine is defined as medical assistance using communication methods (medical information distribution, consultation, patient information distribution, conference, home care assistance, and so on). Classification
258
Telemedicine is classified into three purposes: • Doctor to doctor: Medical consultation; • Nurse to doctor: Medical consultation; and • Patient to doctor: DPC (Direct Patient Care) by communication partners. While the world's legal systems sanction the first two purposes, DPC is not generally permitted though movements are underway to sanction it world wide. Here is described the effectiveness of communication between medical facilities using satellite, in particular of international medical communications, targeted to communications between medical practitioners. Image Quality and Speed Hospitals in developed countries are general hospitals including relatively independent departments for internal medicine, surgery, pediatrics, and so on. This structure provides advantage in connection to other medical institutes and implementing medical construction. To smoothly perform telemedicine, a corresponding structure should provide specialized diagnosis or advice. Therefore, telemedicine in developed countries inevitably requires high-quality images and high-speed communications to meet the demands from the users i.e., doctores. On the other hand, hospitals in developing countries function at widely disparate standards and do not provide internal structure to support specialized residence. To integrate distributed medical professionals, there is a great expectation for telemedicine in these countries. Cooperation between hospitals could be facilitated to advantage in developing countries. I believe, for this reason, there is high feasibility of telemedicine even in the case of low image quality and low-speed communications. Communications Between Medical Facilities Communications between medical facilities have the following features: The call origination count is significantly lower than for switched lines. A relatively large capacity of power could be supplied, so the radio station could communicate over large distances, much further than current mobile stations. The communication time is relatively long because there is a large amount of information including static images, literature, and so on during connection. In addition, in order for international organizations such as WHO to operate networks, the following is mandatory: Broadcasting all over the world Communications for islands or out-of-the-way places where there is no switched line. Universal Services It was already pointed out that telemedicine is useful for remote locations. There has been a disadvantage in that medical line charges for telemedicine are not discounted, but are the same as for entertainment. In May, 1997 the U.S. Conference decided on universal communication rules that were submitted by the FCC. In these rules, communications companies and associated organizations are obliged to provide schools, medical facilities, and physically handicapped peoples in remote areas with various public — 259 —
communication services. The rules are expected to accelerate the spread of telemedicine. Non-INTELSAT Satellite Communications There is no natural boundary in the need for medical services. In a similar sense, there is no boundary to radio waves from space. Radio waves that can cross over boundaries are a useful method for saving patients as far as they are properly used. Under such a background, there has been attempted telemedicine by means of non-commercial, non-inlets satellite communications. PEACESAT One of the attempts of several non-INTELSAT related international satellite communications is PEACESAT(Pan-Pacific Education and Communication Experiments by Satellite). This is a style in which volunteers operate non-conmiercially. At the initial stage, in 1971 Prof J. Bistro, Hawaii University performed small-scaled communication experiments in Hawaii using ATS-1 satellite (VHF/130 MHz band). Then, through Japanese Hawaiian Prof Nose's donation activities, 144 MHz amateur radio equipment was modified for ATS-I global station, and over 100 terminals were installed in the Pacific area. In 1985, ATS-1 operation was canceled because of the expiration of the service life ofATS-l satellite, however, around 1990 PEACESAT operation was restarted by new members using L band transponder of meteorological satellite GOES-3. The communication lines are intended for voice communication only, and image communication facilities are not installed. This network is extremely important in social community investigation, has high experience in educational activities, and is tested for medical applications with slow scan TV. SPACEBRIDGE TO MOSCOW NASA and Russia realized that telemedicine was effective for medical services in Armenia Earthquake in 1988. For one year from 1993, teleconference in medical fields was carried out using real-time two-way analog video and audio via geostationary satellite GTE Spacenet Gstar 2 (the U.S.), and WADRN Satellite (Russia). Spacebridge to Moscow was a multidisciplinary demonstration linking two diverse medical cultures during 22 clinical sessions. Case histories and patient information were provided prior to session so that clinical experts can became familiarized with the patient's case. VITASAT VITA (Volunteers in Technical Assistance) is a volunteer organization that provides technical training and education training overseas. At the initial stage VITA took active parts in the spread of training and education in communication technology, but is focusing attention to medical services. VITA uses UoSAT of the same type as amateur satellite in July 1991 and supports packet communications for activities against AIDS in Africa (Satellite is called Healthsat, SateLife mission:50% and VITASAT mission: 50% shared at the transponder level). VITA designs and develops satellites by their own based on technical experience of UoSAT. Unfortunately, their low-cost satellite VITASAT (43 kg producted by CTA/ex-DSI) failed and was lost in August 1995 because of rocket (LLV)failures on launch. The successive satellite launching is expected inside and outside the U.S. This plan took the Pioneer's Preference prize from the U.S. Goverment FCC in January 1993. This prize was the first given for Low Earth Orbiter (LEO) and it was significant in that this prize was given for "medical" service other than business and education. AMINE/PARTNERS In the PARTNERS project using Japanese Engineering Test Satellite No.5 (ETS-V) which the Ministry of — 260 —
Posts and Telecommunications (MPT) and National Space Development Agency ( NASDA ) carried out, a group ( Telemedicine Society of Japan ) in Tokai University School of Medicine mainly expanded medical network in Asia and Pacific areas between October 1992 and March 1995. This network was constructed at Earth Station that was installed in six medical organizations in Japan and 20 medical organizations outside Japan. Referred to as Network 2, this network is also called AMINE (Asia-Pacific Medical Information Network using with ETS-5). Five stations in Papua New Guinea, five stations in Thailand, five stations in Cambodia, four stations in Fuji, and one station in China were installed, opened, and operated for almost 24 hours a day, 7 days a week (see the Figure 1 ). In AMINE/PARTNERS, since the transmission bandwidth uses 16 kHz band-width FM modulation, it is limited in operation to color static images (18 pages; NTSC full color ), voice, and slow packet radio (MX.25 HDLC ) protocols. One advantage is that international communications and intra-national communications between developing countries is supported without the need for a dedicated and expensive hub station. The communication lines were used to carry out borderless teleconference, teleconsultation, personal computer communications, and so on. VSflT si^tem €Qrth Stations
The AMINE/PARTNERS network was linked with 26 VSATs via the south beam of ETS-S (L Band). Many clinical cases were consulted to Japanese specialist by doctors in developing country during 1992 to 1995.
26 Total Tholbnd Cambodia P.N.G. Fiji China Japan ''•^^^^^^?
Figure 1. AMINE/PARTNERS project. I
Satellie Number
1. Orbit type Sun Synchronous quasi-recurring Easy TT&C operation Simple onboard EPS 2. Parameters Recurring Days 13 days Recurring Revolution 93 rev. Orbital motion 7 rev./day 3. Epoch Feb. 1,1998
1 2 1 3 1 .'. 1 5 1 6
Height(km)
5,004
a (km)
11,382.14
i (deg)
138.67
e
0.000 90.0
oj (deg)
True Anomaly(deg)
0.0
1 180.0
0.0
1 180.0
Bird-View
Figure 2. Satellite constellation 261 —
240.0
120.0
0.0
n (deg)
0.0
1 180.0
EMPLOYING MEDIUM EARTH ORBIT (MEO) Communications between medical facilities are characterized by low call origination coimt, the range of the radio station is relatively large, and the communication time is relatively long. An example of MEO is shown in consideration of this feature. Satellite Orhit
Six orbit elements and parameters over Sun-Synchronous Quasi-Recurrent Orbit (n=7) were shown in the Figure 2 and in the Figure 3. Specifically, six satellites to be launched, three orbit planes, and two satellites for each plane are planned, and the users targeted are those living in areas from the equator as 4 t"' <» the center to the latitude of 70 degree.
Figure 3. Orbit on the world map Bus Specifiratinns
The items of buses are shown in the Figure 4.
Bus Specifications Size: 59 in.hex by 80 in. Weight: 385,6kg (8501bs) Electrical Power : 370 W Attitude Control: 3-axis stabilized; zero momentum bias Propulsion: Eight 1-lbf hydrazine thrusters Telemetry: S Band (GSIDN cimpatible) Design Life: 5 years (goal) Reliability: 0.83 at 5 years Figure 4. Bus Specification — 262
Mission Communications concept are listed in the Table 1, in the Figure 5 and in the Figure 6. Since each satellite has a different callsign/ID (software division), communications interference is prevented by spatial separation due to antenna ( space division ), packet timing separation( time division), and relay frequency separation( frequency divison ). The link design in the Table 2. Assuming that the average visibility time per path is 40 minutes, 16 MB file data (approximately 30 JPEG images conforming with NTSC) can be transmitted at a 128 kbps line rate, in approximately 4 minutes 10 seconds. A total of 12 ( twelve ) channel 128 Kbps lines is available, therefore, up to 108 ground stations are available for use in a single path. In broadcasting mode, up to 640 MB can be distributed to all stations. Table 1. Telemedicine System Specifications
Telemedicine System Specifications Frequency: L Band, S Band Modulation: BPSK/QPSL, SS Digital Transponder (40 Wattes, Bandwidth:2 MHz) HDLC Packet Communication Broadcasting FEC 1/2 Viterbi Coding Bit Rate Maximum 1500 kbps 1 ch. (Broadcasting) Normal 128kbps I2ch.(HDLC) Calling. 9.6 kbps 2 ch.( HDLC) Call Channels Pure-ALOHA Other Ch. Reserved Analog Transponder (2 Wattes, Bandwidth: 200 KHz) Two-way Voice available Experimental Digital Communication Operational Concept (Forward E-mail Transmission from Developing Country)
Figure. 5 Operational concept 263
HiCAT/MEO Concept:Tele-consultation using e-mail via communications satellite Medical Center in Developing Countryj Care policy, Problems in giving medicine, etc.
Medical Center in Advanced Country e-mail via sateUite
Settlement of Problems
Solutions or Directions of Data Base Reference
Common Data Base (CD-ROM) (Information on Cases)
Common Data Base (CD-RONO (Information on Cases)
Figure 6. Concept of Tele-consultation
Table 2. Link design of digital transponder of HiCAT HDLC packet communication at 128 kbps
HiCAT UPLINK 128 kbps Freq. (GHz) 2.64 Ant. Dia. (n) 1.00 Ant. Gain. (dB! 24.61 Tx PWR CdBW, 10.00 EIRP CdBW, 34.61 Path. Loss (dB. 179.96 Abs. Loss (dB) 0.10 Ant. Dia (oO 0.40 Ant. Gain (dB) 16.66 Rev. PWR dBN) -128.79 Tsys K) 1160.00 No dBN/Hz) -197.96 G/T (dB Hz) -13.99 (dB Hz) C/No UP 69.17 (dB) 9.57 Margin
HiCAT DOWNLINK 128 kbps 1.54 Freq. (GHz) Ant. Dia. (m) 0.40 Ant. Gain (dB) 11.97 Tx PWR (dBW) 6.00 EIRP (dBW) 17.97 Path. Loss (dB) 175.28 Abs. Loss (dB) 0.10 Ant. Dia 1.00 Ant. Gain (dB) 19.93 Rev. PWR dBW) -137.47 Tsys 550.00 No (dBW/Hz) -201.20 G/T -7.47 (dB Hz) C/NodQwn (dBHz) 63-73 Margin (dB) 4.13
Data Rate (Mbps) BER Eb/No (dB) Coding Gain(dB)
Path(km) 9000 kn Antenna Eff. 60% Cable loss 2.00 (dB)
0.128 1.0E-06 10.53 2.00
264
—
DISCUSSION Comparison with T.FO The number of visibility intervals and the average in-view time is shown in the Table 3 and in the Figure 7 when compared with Iridium, a LEO system, with satellites in much lower orbit. The average angle of elevation is approximately twice that of Iridium. These advantages; higher visibility and higher elevation angles can be explained to make MEO suitable for communications between medical facilities. Call origination count is less, the coverage of the radio station is relatively large, and the communication time is relatively long during line connection. The detailed advantages of MEO satellite of the sunsynchronous quasi-recurrent orbit are sunmiarized in the Table 4. Table 3. Visibility comparison between Iridium and HiCAT
Ulan Bator ] Contact per Dajf 1 Lat.: 4 2 . 8 N ( d e g ) t o t a l Contact t i m e (sec/day) Long.: 107.0 E (deg) Average Contact t i m e (sec) Maximum Elevation (deg) Minimum Elevation (deg) Average Elevation (deg) 1 Maximum Range (km) 1 Minimum Range (km) 1 Average Range (km) 1 Lanzhou Contact per Da;^ Lat.: 36.0 N (deg) Total Contact Time (sec/day) Long.: 104.0 E (deg) ' Average Contact Time (sec) Maximum Elevation (deg) Minimum Elevation (deg) Average Elevation (deg) Maximum Range (km) Minimum Range (km) Average Range (km) Kunming Contact per Da^' Lat.: 25.0 N (deg) Total Contact Time (sec/day) Long.: 102.7 E (deg) Average Contact Time (sec) Maximum Elevation (deg) Minimum Elevation (deg)^ Average Elevation (deg) Maximum Range (km) Minimum Range (km) Average Range (km) Bangkok Contact per Day U t . : 13.8 N (deg) t o t a l Contact t i m e (sec/day) Long.: 100.B E (deg) Average Contact Time (sec) iNlaximum Elevation ( d e ^ Minimum Elevation (deg) Average Elevation ( d e ^ [ Maximum Ran^e (km) Minimum Range (km) Average Range (km) Singapore 1 Contact jger Day Ut; 1.2 N (deg) t o t a l Contact t i m e (sec/day) Long.: 103.9 E (deg) Average (Contact t i m e (sec) Maximum Elevation (deg) 1 [Minimum Elevation (deg) 1 lAverajge Elevation "(deg) 1 [Maximum Range (km) 1 [Minimum Range (km) 1 [Average Range (km)
— 265
Iridium
T
4
1
6
1 1 1 1 1 1
i5,775.9 2.629.'3 •84.3
•2,'385.2' 596.3 83.'2 •5.0 16.3 •2,469.5 647.0 i,iB47.6
HICAT
5.6 •33.1 •8.96'3.4 •5.6^27.6 6,887.'5
4
6
2r278.'3 569.6 79.1
16.259.8 2,710.6 87.9
5.0
5.6
•35.2 s.'962.1
15.8 2.46'4.4
662.0
1
l.o'il'^ e.Wi.'s
1
18.146.1 •^•592.'3 •89."2
i,837.5
7
4 2.696.0 524.0 67.'7
1
5.6
5.6
32.& "8.899.2 •5.6O8.2 •6.iB85.*5
14.8 2.454.7 694.7 1.870.8
3
8
1.630.3 543.4 53.8
26,685.2 2,i5i6.7 •73."3
5.0
5.6
14.5 2.444."4 764.7 i.866.2
•28."3 •^•894.*9 5.i'25.2 •7.166.6
4
9
1,985.6 496.4 •77.2 5.6 15.2 2,434.5 657.9 i,84i.'5
22,6916 •2,454.7 •79.5
i
5.6
1
•24.'9 8,888."4 5,0^5i.6
[
iMo.o
'
Table 4. Advantages of Sun-Synchronous Quasi-Recurrent Orbit Advantages of Sun-Synchronous Quasi-Recurrent Orbit 1. Orbit groundtracks return back on the same tracks by 13 days period. This makes signal acquisition and communication operations easier. 2. Local time at equator ascenVdescent is constant. This makes broadcasting at constant local time easier. 3. Satellite design is easy because sun incident angle is stable. Constant sun incident angle for whole year makes designs of solar array, electric power system, and thermal control system easier. Elevatton of HICAT ( MEG ) at Singapore
Elevation of Iridium ( LEO ) at Singapore
80 70 60
¥ 40 IB
30 20 10 0
II 1 11
11 1
1 1 i l 1l 1 LLl .11
-3
6
9 12 Time (hr|
15
18
21
24
LL 9
12 15 Time |hrl
18
21
24
Figure 7. Comparison of elevations with Iridium at Singapore Importance of International Cooperation In developing countries, the fetus death rate is high, the average life is short, the interest for medical services for people is high. The governmental and administrative organizations are keen to obtain advanced medical news and therapy. In particular, since 1980, AIDS infection is a great medical problem in these countries. At that time, since there was insufficient information regarding AIDS diagnosis and therapy, the incidence of AIDS was drastically increased. Because of AIDS, development of economy of developing countries becomes slower and slower. For example, even in Thailand which made remarkable development of economy growth, 30% of total population around Chiang-Mai city of the northern part of Thai is HIV positive. In African and Asian developing countries, it is important to effectively and speedily introduce advanced medical technology( which the U.S. and Japan achieved in the past 30 years and to reduce medical expense in order to ensure further development of economy). Likewise communications, medical services are important in the future society and must be provided in developing countries, and remote areas, islands, and less populated places. There is a variety of available medical services, including primary care, high-level therapy for serious diseases. However, it is difFicuh to distribute high-level medical services to various areas from the viewpoint of economic efficiency. Teleconsultation with clinical data as a store-and-forward packet communications, clinical image diagnosis with JPEG, medical educations, and broadcasting medical news distribution services using 266
27
MEO are believed to be one of the optimal applications of small satellite. CONCLUSION MEO is more suitable to medical communications of a large amount of data than LEO. In addition, MEO is more inexpensive than geostationary satellite is worth discussing launching of MEO through international corporation. REFERENCE B.E.Dunn, et al.,;Use of telepathology for routine surgical pathology, Review in a test bed in the department of Veterans Affairs, Telemedicine Journal, 3, 1;1-10,1997. Mark Goldberg;Image data compression: Decreasing the time and cost of data transmission. The Annual Telemedicine 2000, Track B3: Chicago, IL 1996 John L. Boor, et al., "Technical Aspects of Health/Education Telecommunications Experiment", IEEE, Vol.AES-ll,No.6;1975 Isao Nakajima, et al.,; How to use an INS-64 interactive videoconferencing system for clinical applications. Program and Book of Abstracts, The 3rd International conference on the medical aspects oftelemedicine;207,1997 Emerio T. Alboliras, et al.,:"Transmission of Full-Length Echocardiographic Images over ISDN for Diagnosing Congenital Disease", Telemedicine Journal 2 ,4; 251-258,1996
267 —
; Tokai University School of Medicine, Emergency Medical Services, Boseidai, Isehara-city, Kanagawa, 259-11, Japan. Nakajima's e-mail: [email protected] 2 Hitachi, ltd. Space System Division, 6 Kanda-Surugadai 4-chome, Chiyoda-ku, Tokyo, 101, Japan. Maeda's e-mail: [email protected]. hitachi.co.jp
ABSTRACT Here is described the effectiveness of communication between medical facilities using satellite, in particular of international medical communications, targeted to communications between medical practitioners. Communications between these facilities are characterized by low call origination count, the range of the radio station is relatively large, and the communication time is relatively long. We belive an example of MEO is shown in consideration of this feature. We designed HiCAT (High-performance International Communications for Advanced Telemedicine) satellite; sun-synchronous quasi-recurrent Orbit (n=7), specifically, six satellites to be launched, three orbit planes, and two satellites for each plane, and the users targeted are those living in areas from the equator as the center to the latitude of 70 degree. The average angle of elevation of HiCAT is approximately twice that of Iridium. These advantages; higher visibility and higher elevation angles can be explained to make MEO suitable for communications between these facilities. Teleconsultations with clinical data as a store-and-forward packet communications linking with Internet, clinical image diagnosis with JPEG, and broadcasting medical news distribution services using MEO are believed to be one of the optimal applications of small satellite. OBJECT This document describes a Medium Earth Orbit (MEG) applications, especially suitable for satellites supporting telemedicine applications, in particular for international medical communications. TELEMEDICINE Definition Telemedicine is defined as medical assistance using communication methods (medical information distribution, consultation, patient information distribution, conference, home care assistance, and so on). Classification
258
Telemedicine is classified into three purposes: • Doctor to doctor: Medical consultation; • Nurse to doctor: Medical consultation; and • Patient to doctor: DPC (Direct Patient Care) by communication partners. While the world's legal systems sanction the first two purposes, DPC is not generally permitted though movements are underway to sanction it world wide. Here is described the effectiveness of communication between medical facilities using satellite, in particular of international medical communications, targeted to communications between medical practitioners. Image Quality and Speed Hospitals in developed countries are general hospitals including relatively independent departments for internal medicine, surgery, pediatrics, and so on. This structure provides advantage in connection to other medical institutes and implementing medical construction. To smoothly perform telemedicine, a corresponding structure should provide specialized diagnosis or advice. Therefore, telemedicine in developed countries inevitably requires high-quality images and high-speed communications to meet the demands from the users i.e., doctores. On the other hand, hospitals in developing countries function at widely disparate standards and do not provide internal structure to support specialized residence. To integrate distributed medical professionals, there is a great expectation for telemedicine in these countries. Cooperation between hospitals could be facilitated to advantage in developing countries. I believe, for this reason, there is high feasibility of telemedicine even in the case of low image quality and low-speed communications. Communications Between Medical Facilities Communications between medical facilities have the following features: The call origination count is significantly lower than for switched lines. A relatively large capacity of power could be supplied, so the radio station could communicate over large distances, much further than current mobile stations. The communication time is relatively long because there is a large amount of information including static images, literature, and so on during connection. In addition, in order for international organizations such as WHO to operate networks, the following is mandatory: Broadcasting all over the world Communications for islands or out-of-the-way places where there is no switched line. Universal Services It was already pointed out that telemedicine is useful for remote locations. There has been a disadvantage in that medical line charges for telemedicine are not discounted, but are the same as for entertainment. In May, 1997 the U.S. Conference decided on universal communication rules that were submitted by the FCC. In these rules, communications companies and associated organizations are obliged to provide schools, medical facilities, and physically handicapped peoples in remote areas with various public — 259 —
communication services. The rules are expected to accelerate the spread of telemedicine. Non-INTELSAT Satellite Communications There is no natural boundary in the need for medical services. In a similar sense, there is no boundary to radio waves from space. Radio waves that can cross over boundaries are a useful method for saving patients as far as they are properly used. Under such a background, there has been attempted telemedicine by means of non-commercial, non-inlets satellite communications. PEACESAT One of the attempts of several non-INTELSAT related international satellite communications is PEACESAT(Pan-Pacific Education and Communication Experiments by Satellite). This is a style in which volunteers operate non-conmiercially. At the initial stage, in 1971 Prof J. Bistro, Hawaii University performed small-scaled communication experiments in Hawaii using ATS-1 satellite (VHF/130 MHz band). Then, through Japanese Hawaiian Prof Nose's donation activities, 144 MHz amateur radio equipment was modified for ATS-I global station, and over 100 terminals were installed in the Pacific area. In 1985, ATS-1 operation was canceled because of the expiration of the service life ofATS-l satellite, however, around 1990 PEACESAT operation was restarted by new members using L band transponder of meteorological satellite GOES-3. The communication lines are intended for voice communication only, and image communication facilities are not installed. This network is extremely important in social community investigation, has high experience in educational activities, and is tested for medical applications with slow scan TV. SPACEBRIDGE TO MOSCOW NASA and Russia realized that telemedicine was effective for medical services in Armenia Earthquake in 1988. For one year from 1993, teleconference in medical fields was carried out using real-time two-way analog video and audio via geostationary satellite GTE Spacenet Gstar 2 (the U.S.), and WADRN Satellite (Russia). Spacebridge to Moscow was a multidisciplinary demonstration linking two diverse medical cultures during 22 clinical sessions. Case histories and patient information were provided prior to session so that clinical experts can became familiarized with the patient's case. VITASAT VITA (Volunteers in Technical Assistance) is a volunteer organization that provides technical training and education training overseas. At the initial stage VITA took active parts in the spread of training and education in communication technology, but is focusing attention to medical services. VITA uses UoSAT of the same type as amateur satellite in July 1991 and supports packet communications for activities against AIDS in Africa (Satellite is called Healthsat, SateLife mission:50% and VITASAT mission: 50% shared at the transponder level). VITA designs and develops satellites by their own based on technical experience of UoSAT. Unfortunately, their low-cost satellite VITASAT (43 kg producted by CTA/ex-DSI) failed and was lost in August 1995 because of rocket (LLV)failures on launch. The successive satellite launching is expected inside and outside the U.S. This plan took the Pioneer's Preference prize from the U.S. Goverment FCC in January 1993. This prize was the first given for Low Earth Orbiter (LEO) and it was significant in that this prize was given for "medical" service other than business and education. AMINE/PARTNERS In the PARTNERS project using Japanese Engineering Test Satellite No.5 (ETS-V) which the Ministry of — 260 —
Posts and Telecommunications (MPT) and National Space Development Agency ( NASDA ) carried out, a group ( Telemedicine Society of Japan ) in Tokai University School of Medicine mainly expanded medical network in Asia and Pacific areas between October 1992 and March 1995. This network was constructed at Earth Station that was installed in six medical organizations in Japan and 20 medical organizations outside Japan. Referred to as Network 2, this network is also called AMINE (Asia-Pacific Medical Information Network using with ETS-5). Five stations in Papua New Guinea, five stations in Thailand, five stations in Cambodia, four stations in Fuji, and one station in China were installed, opened, and operated for almost 24 hours a day, 7 days a week (see the Figure 1 ). In AMINE/PARTNERS, since the transmission bandwidth uses 16 kHz band-width FM modulation, it is limited in operation to color static images (18 pages; NTSC full color ), voice, and slow packet radio (MX.25 HDLC ) protocols. One advantage is that international communications and intra-national communications between developing countries is supported without the need for a dedicated and expensive hub station. The communication lines were used to carry out borderless teleconference, teleconsultation, personal computer communications, and so on. VSflT si^tem €Qrth Stations
The AMINE/PARTNERS network was linked with 26 VSATs via the south beam of ETS-S (L Band). Many clinical cases were consulted to Japanese specialist by doctors in developing country during 1992 to 1995.
26 Total Tholbnd Cambodia P.N.G. Fiji China Japan ''•^^^^^^?
Figure 1. AMINE/PARTNERS project. I
Satellie Number
1. Orbit type Sun Synchronous quasi-recurring Easy TT&C operation Simple onboard EPS 2. Parameters Recurring Days 13 days Recurring Revolution 93 rev. Orbital motion 7 rev./day 3. Epoch Feb. 1,1998
1 2 1 3 1 .'. 1 5 1 6
Height(km)
5,004
a (km)
11,382.14
i (deg)
138.67
e
0.000 90.0
oj (deg)
True Anomaly(deg)
0.0
1 180.0
0.0
1 180.0
Bird-View
Figure 2. Satellite constellation 261 —
240.0
120.0
0.0
n (deg)
0.0
1 180.0
EMPLOYING MEDIUM EARTH ORBIT (MEO) Communications between medical facilities are characterized by low call origination coimt, the range of the radio station is relatively large, and the communication time is relatively long. An example of MEO is shown in consideration of this feature. Satellite Orhit
Six orbit elements and parameters over Sun-Synchronous Quasi-Recurrent Orbit (n=7) were shown in the Figure 2 and in the Figure 3. Specifically, six satellites to be launched, three orbit planes, and two satellites for each plane are planned, and the users targeted are those living in areas from the equator as 4 t"' <» the center to the latitude of 70 degree.
Figure 3. Orbit on the world map Bus Specifiratinns
The items of buses are shown in the Figure 4.
Bus Specifications Size: 59 in.hex by 80 in. Weight: 385,6kg (8501bs) Electrical Power : 370 W Attitude Control: 3-axis stabilized; zero momentum bias Propulsion: Eight 1-lbf hydrazine thrusters Telemetry: S Band (GSIDN cimpatible) Design Life: 5 years (goal) Reliability: 0.83 at 5 years Figure 4. Bus Specification — 262
Mission Communications concept are listed in the Table 1, in the Figure 5 and in the Figure 6. Since each satellite has a different callsign/ID (software division), communications interference is prevented by spatial separation due to antenna ( space division ), packet timing separation( time division), and relay frequency separation( frequency divison ). The link design in the Table 2. Assuming that the average visibility time per path is 40 minutes, 16 MB file data (approximately 30 JPEG images conforming with NTSC) can be transmitted at a 128 kbps line rate, in approximately 4 minutes 10 seconds. A total of 12 ( twelve ) channel 128 Kbps lines is available, therefore, up to 108 ground stations are available for use in a single path. In broadcasting mode, up to 640 MB can be distributed to all stations. Table 1. Telemedicine System Specifications
Telemedicine System Specifications Frequency: L Band, S Band Modulation: BPSK/QPSL, SS Digital Transponder (40 Wattes, Bandwidth:2 MHz) HDLC Packet Communication Broadcasting FEC 1/2 Viterbi Coding Bit Rate Maximum 1500 kbps 1 ch. (Broadcasting) Normal 128kbps I2ch.(HDLC) Calling. 9.6 kbps 2 ch.( HDLC) Call Channels Pure-ALOHA Other Ch. Reserved Analog Transponder (2 Wattes, Bandwidth: 200 KHz) Two-way Voice available Experimental Digital Communication Operational Concept (Forward E-mail Transmission from Developing Country)
Figure. 5 Operational concept 263
HiCAT/MEO Concept:Tele-consultation using e-mail via communications satellite Medical Center in Developing Countryj Care policy, Problems in giving medicine, etc.
Medical Center in Advanced Country e-mail via sateUite
Settlement of Problems
Solutions or Directions of Data Base Reference
Common Data Base (CD-ROM) (Information on Cases)
Common Data Base (CD-RONO (Information on Cases)
Figure 6. Concept of Tele-consultation
Table 2. Link design of digital transponder of HiCAT HDLC packet communication at 128 kbps
HiCAT UPLINK 128 kbps Freq. (GHz) 2.64 Ant. Dia. (n) 1.00 Ant. Gain. (dB! 24.61 Tx PWR CdBW, 10.00 EIRP CdBW, 34.61 Path. Loss (dB. 179.96 Abs. Loss (dB) 0.10 Ant. Dia (oO 0.40 Ant. Gain (dB) 16.66 Rev. PWR dBN) -128.79 Tsys K) 1160.00 No dBN/Hz) -197.96 G/T (dB Hz) -13.99 (dB Hz) C/No UP 69.17 (dB) 9.57 Margin
HiCAT DOWNLINK 128 kbps 1.54 Freq. (GHz) Ant. Dia. (m) 0.40 Ant. Gain (dB) 11.97 Tx PWR (dBW) 6.00 EIRP (dBW) 17.97 Path. Loss (dB) 175.28 Abs. Loss (dB) 0.10 Ant. Dia 1.00 Ant. Gain (dB) 19.93 Rev. PWR dBW) -137.47 Tsys 550.00 No (dBW/Hz) -201.20 G/T -7.47 (dB Hz) C/NodQwn (dBHz) 63-73 Margin (dB) 4.13
Data Rate (Mbps) BER Eb/No (dB) Coding Gain(dB)
Path(km) 9000 kn Antenna Eff. 60% Cable loss 2.00 (dB)
0.128 1.0E-06 10.53 2.00
264
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DISCUSSION Comparison with T.FO The number of visibility intervals and the average in-view time is shown in the Table 3 and in the Figure 7 when compared with Iridium, a LEO system, with satellites in much lower orbit. The average angle of elevation is approximately twice that of Iridium. These advantages; higher visibility and higher elevation angles can be explained to make MEO suitable for communications between medical facilities. Call origination count is less, the coverage of the radio station is relatively large, and the communication time is relatively long during line connection. The detailed advantages of MEO satellite of the sunsynchronous quasi-recurrent orbit are sunmiarized in the Table 4. Table 3. Visibility comparison between Iridium and HiCAT
Ulan Bator ] Contact per Dajf 1 Lat.: 4 2 . 8 N ( d e g ) t o t a l Contact t i m e (sec/day) Long.: 107.0 E (deg) Average Contact t i m e (sec) Maximum Elevation (deg) Minimum Elevation (deg) Average Elevation (deg) 1 Maximum Range (km) 1 Minimum Range (km) 1 Average Range (km) 1 Lanzhou Contact per Da;^ Lat.: 36.0 N (deg) Total Contact Time (sec/day) Long.: 104.0 E (deg) ' Average Contact Time (sec) Maximum Elevation (deg) Minimum Elevation (deg) Average Elevation (deg) Maximum Range (km) Minimum Range (km) Average Range (km) Kunming Contact per Da^' Lat.: 25.0 N (deg) Total Contact Time (sec/day) Long.: 102.7 E (deg) Average Contact Time (sec) Maximum Elevation (deg) Minimum Elevation (deg)^ Average Elevation (deg) Maximum Range (km) Minimum Range (km) Average Range (km) Bangkok Contact per Day U t . : 13.8 N (deg) t o t a l Contact t i m e (sec/day) Long.: 100.B E (deg) Average Contact Time (sec) iNlaximum Elevation ( d e ^ Minimum Elevation (deg) Average Elevation ( d e ^ [ Maximum Ran^e (km) Minimum Range (km) Average Range (km) Singapore 1 Contact jger Day Ut; 1.2 N (deg) t o t a l Contact t i m e (sec/day) Long.: 103.9 E (deg) Average (Contact t i m e (sec) Maximum Elevation (deg) 1 [Minimum Elevation (deg) 1 lAverajge Elevation "(deg) 1 [Maximum Range (km) 1 [Minimum Range (km) 1 [Average Range (km)
— 265
Iridium
T
4
1
6
1 1 1 1 1 1
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•2,'385.2' 596.3 83.'2 •5.0 16.3 •2,469.5 647.0 i,iB47.6
HICAT
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4
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Table 4. Advantages of Sun-Synchronous Quasi-Recurrent Orbit Advantages of Sun-Synchronous Quasi-Recurrent Orbit 1. Orbit groundtracks return back on the same tracks by 13 days period. This makes signal acquisition and communication operations easier. 2. Local time at equator ascenVdescent is constant. This makes broadcasting at constant local time easier. 3. Satellite design is easy because sun incident angle is stable. Constant sun incident angle for whole year makes designs of solar array, electric power system, and thermal control system easier. Elevatton of HICAT ( MEG ) at Singapore
Elevation of Iridium ( LEO ) at Singapore
80 70 60
¥ 40 IB
30 20 10 0
II 1 11
11 1
1 1 i l 1l 1 LLl .11
-3
6
9 12 Time (hr|
15
18
21
24
LL 9
12 15 Time |hrl
18
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24
Figure 7. Comparison of elevations with Iridium at Singapore Importance of International Cooperation In developing countries, the fetus death rate is high, the average life is short, the interest for medical services for people is high. The governmental and administrative organizations are keen to obtain advanced medical news and therapy. In particular, since 1980, AIDS infection is a great medical problem in these countries. At that time, since there was insufficient information regarding AIDS diagnosis and therapy, the incidence of AIDS was drastically increased. Because of AIDS, development of economy of developing countries becomes slower and slower. For example, even in Thailand which made remarkable development of economy growth, 30% of total population around Chiang-Mai city of the northern part of Thai is HIV positive. In African and Asian developing countries, it is important to effectively and speedily introduce advanced medical technology( which the U.S. and Japan achieved in the past 30 years and to reduce medical expense in order to ensure further development of economy). Likewise communications, medical services are important in the future society and must be provided in developing countries, and remote areas, islands, and less populated places. There is a variety of available medical services, including primary care, high-level therapy for serious diseases. However, it is difFicuh to distribute high-level medical services to various areas from the viewpoint of economic efficiency. Teleconsultation with clinical data as a store-and-forward packet communications, clinical image diagnosis with JPEG, medical educations, and broadcasting medical news distribution services using 266
27
MEO are believed to be one of the optimal applications of small satellite. CONCLUSION MEO is more suitable to medical communications of a large amount of data than LEO. In addition, MEO is more inexpensive than geostationary satellite is worth discussing launching of MEO through international corporation. REFERENCE B.E.Dunn, et al.,;Use of telepathology for routine surgical pathology, Review in a test bed in the department of Veterans Affairs, Telemedicine Journal, 3, 1;1-10,1997. Mark Goldberg;Image data compression: Decreasing the time and cost of data transmission. The Annual Telemedicine 2000, Track B3: Chicago, IL 1996 John L. Boor, et al., "Technical Aspects of Health/Education Telecommunications Experiment", IEEE, Vol.AES-ll,No.6;1975 Isao Nakajima, et al.,; How to use an INS-64 interactive videoconferencing system for clinical applications. Program and Book of Abstracts, The 3rd International conference on the medical aspects oftelemedicine;207,1997 Emerio T. Alboliras, et al.,:"Transmission of Full-Length Echocardiographic Images over ISDN for Diagnosing Congenital Disease", Telemedicine Journal 2 ,4; 251-258,1996
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