14 Mobile Satellite Communication ∗ 14.1 Fundamentals In principle communications satellites provide the same connectivity as ter- restrial (wireless and wireline) networks. The advantages of satellites, such as fast wide-area coverage, flexible transmission parameters and cost indepen- dence due to distance, are compared with the disadvantages, such as restricted channel capacity because of the frequencies available, orbital positions, need for line-of-sight connectivity and high initial investment besides relatively long signal propagation times. As a result, only certain application areas have been developed for satellites in the past. 14.1.1 Application Areas Satellites are being widely used for distribution functions, e.g., for transmit- ting television and radio programmes as well as for data. Existing communi- cations networks can be totally bridged through the use of satellite systems. Satellite communication, which until recently was almost only exclusively used for navigation and aviation as well as in land vehicles, is a branch that opens up a totally new world of applications. Satellite paging along with GPS (Global Positioning System) and GLONAS have recently been introduced for civil use. The interest in global personal communications is leading to big efforts in the development of new satellite systems that operate at the low orbital heights. Currently mobile satellite systems are being used mainly in areas where no other terrestrial communications systems are available (on the open seas, in the desert, in rural regions, etc.). These systems are also attractive to users who operate internationally and otherwise use different kinds of terres- trial mobile radio systems, requiring them to carry terminals with different standards. A differentiation is made between worldwide, regional and national systems, depending on the coverage area of a satellite system. In terms of institutional and organizational structure, a distinction is made between international, na- tional and private operators of satellite systems. Tables 14.1–14.5 present a compilation of the known parameters of all systems currently in development. ∗ With the collaboration of Branko Bjelajac and Alexander Guntsch Mobile Radio Networks: Networking and Protocols. Bernhard H. Walke Copyright©1999 John Wiley & Sons Ltd ISBNs: 0-471-97595-8 (Hardback); 0-470-84193-1 (Electronic) 716 14 Mobile Satellite Communication Table 14.1: Narrowband satellite systems concentrating on telephony applications—Part 1 System Globalstar ICO IRIDIUM Odyssey Ellipso ECCO (later: Aries) Company Loral, Qual- comm, Alcatel Espace ICO Global Communications Motorola TRW, Teleglobe Canada Mobile Communications Holdings Constellation Inc., Telebras Orbit LEO (circular) MEO (circular) LEO (circular) MEO (circular) MEO (circ. + ell.) LEO (circular) Path altitude [km] 1414 10 355 780 10 354 520–7846 (ell.) 8040 (circ.) 2000 No. of sats. + spare sats. 48 + 8 10 + 2 66 + 12 12 + 2 on the Ground 14 + 3 11 + 1 (later add’l 35 + 7) No. of orbits 8 2 11 3 3 (2 ellipt. + 1 circular) 1 equat. (later add’l 7) No. of ground stations 100 12 21 7 ≥ 20 11 (more later) Inclination [ ] 52 45 86 50 116.5 (ellipt.)/ 0 (circ.) 0 (later 62) Min. elevation [ ] 10 10 10 20 25–30 5 Cells/sat. 16 163 48 37 61 32 ISL — — 4/sat. — — — Access methods CDMA FDMA/TDMA FDMA/TDMA CDMA CDMA CDMA Duplex method FDD TDD Cluster size 6 180 (global) 5 (USA) 4 (Europa) 6.3 Error handling FEC r = 1 3 – 1 2 FEC MS: r = 4 3 Grnd.st.: r = 1 2 FEC r = 1 2 FEC Voice: r = 1 2 Data: r = 1 4 14.1 Fundamentals 717 Table 14.2: Narrowband satellite systems concentrating on telephony applications - Part 2 System Globalstar ICO IRIDIUM Odyssey Ellipso ECCO (later: Aries) Modulation QPSK QPSK QPSK BPSK No. of channels/sat. 2700/ 2.4 kbit/s 4500/ 4.8 kbit/s 4070/2.4 kbit/s 2800 1000 No. of channels in entire system 130 000 45 000 283 000 27 600 11 000 (later 46 000) Channel bandwidth [kHz] 25.2 Transmission rate [kbit/s] 2.4–9.6 4.8–38.4 2.4 2.4–9.6 0.3-9.6 bis 9.6 Voice transmission rate [kbit/s] 2.4/4.8/9.6 4.8 2.4 9.6 Bit-error ratio voice/data 10 −3 /10 −6 10 −2 /10 −3 10 −3 /10 −5 10 −3 /10 −6 Frequency UL [MHz] 1610–1621.35 1980–2010 1621.35–1626.5 1610–1621.35 1610–1621.35 1610–1621.35 Frequency DL [MHz] 2483.5–2500 2170–2200 1621.35–1626.5 2483.5–2500 2483.5–2500 2483.5–2500 Bandwidth UL+DL [MHz] 27.85 a 70 5.15 27.85 a 27.85 a 27.85 a Frequency GW–Sat [GHz] 5.091–5.25 5.15–5.25 29.1–29.3 29.1–29.4 15.45–15.65 5.05–5.25 Frequency Sat–GW [GHz] 6.875–7.055 6.975–7.075 19.4–19.6 19.3–19.6 6.875–7.075 6.825–7.025 Satellite weight [kg] 450 2300 689 2000 689 & 877 425 Antenna type Planar horn Planar Dual refl. Satellite intelligence Available Available Available No No No Satellite transmission mode Transparent Regenerative Regenerative, switching Transparent Transparent Transparent Transmitter power [W] 1100 5000 1430 4500 2300 815 Power reserve [dB] 3–10 dyn. 16 6 Max. delay [ms] 11.5 8.22 44.3 Eavesdropping security Possible High Possible 718 14 Mobile Satellite Communication Table 14.2: Narrowband satellite systems concentrating on telephony applications—Part 2 (continued) System Globalstar ICO IRIDIUM Odyssey Ellipso ECCO (later: Aries) Terminal (mobile) Dual-mode Dual-mode Dual-mode Dual-mode Dual-mode Dual-mode Terminal trans. power [W] 3.8 Services Voice, data, fax, RDSS, SMS Voice, data, fax, RDSS, SMS Voice, data, fax, RDSS, SMS Voice, data, fax, RDSS, SMS Voice, data, fax, RDSS, SMS Voice, data, fax, RDSS, SMS RDSS accuracy [km] 0.3–2 0.5 Coverage area 74 S–74 N Global Global Global 55 S–90 N 23 S–23 N (later global) Availability [%] 90–95 90–95 99.5 (User) 99.9 (Grnd.st.) No. of users [Mill] 2–5 1.4 2.3 1.0 > 1.0 System cost [Mill. US$] 2.6 2.6 4.4 3.2 0.9 0.55 (later 1.7) Price of terminal [US$] 750 1000 2000–3000 550 1000 1500 Cost/min [US$] 0.35–0.53 1–2 3 0.65 0.12–0.5 Start comm. operations 1998 2000 1998 1998 2000 2000 Useful life [years] 7.5 12 5–10 15 5 5 German partners DB Aerospace Vebacom Licence 01/95 granted by FCC 10/95 frequency alloc. by ITU 01/95 granted by FCC 01/95 granted by FCC 06/97 granted by FCC 06/97 granted by FCC a The UL and DL frequency bands are occupied by CDMA systems simultaneously 14.1 Fundamentals 719 Table 14.3: Narrowband satellite systems concentrating on message transfer System Orbcomm E-Sat Faisat GE Starsys GEMnet LEO One Company Magellan Sys- tems, Teleglobe, Orbital Science Echostar Communica- tions Final Analysis, Polyglott Enterp., VITA GE Ameri- can Comm., CLS North America CTA Orbital Sciences dBX Corp. Orbit LEO LEO LEO LEO LEO LEO Path altitude [km] 775 1260 1067 1000 950 No. of satellites 28 + 8 6 26 + 4 24 38 48 No. of orbits 8 6 4 8 No. of ground stations min. 1 per country USA 3, others in other countries Inclination 45 50 Intersatellite links — — — — — — Access method CDMA CDMA Transmission rate [kbit/s] 0.3–2.4 UL: 1.2–19.2 DL: 1.2–38.4 2.4–9.6 Frequency uplink [MHz] 148–149.9 Fin. An.: 455–456, 459–460 VITA: 148–149.9 148–149.9 148–150.05 Frequency downlink [MHz] 137–138 400–401 (Fin. An. and VITA) 137–138 137–138 Bandwidth UL+DL [MHz] 2.9 2.9 3.05 Frequency GW–Sat [MHz] 148–149.9 148–150.05 Frequency Sat–GW [MHz] 137–138 400.15–401 Satellite weight [kg] 46 80 125 720 14 Mobile Satellite Communication Table 14.3: Narrowband satellite systems concentrating on message transfer (continued) System Orbcomm E-Sat Faisat GE Starsys GEMnet LEO One Terminal (communicator) × × × × × × Services (Monitoring, control, message transfer) × × × × × × Coverage area Global N. America Global Global Global 65 S–65 N System costs [Mill. US$] 0.35 0.05 0.25 0.17 0.16 0.25 Price of terminal [US$] 100–500 Start comm. operations 1998 1998 2002 1999 1999 2000 Useful life 4 5–7 5 14.1 Fundamentals 721 Table 14.4: Broadband satellite systems concentrating on data transfer System Teledesic Celestri LEO a M-Star SkyBridge Company Teledesic Motorola Motorola Alcatel Espace, Loral Space & Comm. Orbit LEO LEO LEO LEO Path altitude [km] 1375 1400 1350 1457 No. of satellites 288 63 72 64 No. of orbits 12 7 12 16 No. of ground stations 2 control + 6 antenna centres, many GWs 6 Inclination 40 48 47 No. of cells per sat. 576 260 Intersatellite links 8 per sat. (visual) 6 per sat. (visual) 4 per sat. No Access method DL: Asynch. TDMA UL: MF-TDMA DL: FDM/TDM UL: FDM/TDMA No. of channels per satellite 125 000 at 16 kbit/s No. of channels in total system Simult. 36 Mill. Simult. 395 000 at 64 kbit/s, in total 1.8 Mill. users at 64 kbit/s Transmission rate [Mbit/s] UL: up to 2, DL: up to 64 Up to 155.52 2.048–51.84 0.016–60 Frequency UL [GHz] 28.6–29.1 and 27.6–28.4 a 28.6–29.1 & 29.5–30 47.2–50.2 14–14.5 Frequency DL [GHz] 18.8–19.8 and 17.8–18.6 a 18.8–19.8 & 19.7–20.2 37.5–40.5 11.7–12.7 a Motorola in 1998 has joined the Teledesic consortium 722 14 Mobile Satellite Communication Table 14.4: Broadband satellite systems concentrating on data transfer (continued) System Teledesic Celestri LEO M-Star SkyBridge Bandwidth UL+DL [MHz] 2600 2000 6000 1500 Frequency GW–Sat [GHz] In above band In above band In user-sat. band 12.75–13.25 and 13.75–14 and 17.3–17.8 Frequency Sat–GW [GHz] In above band In above band In user-sat. band 10.7–11.7 Terminal Fixed terminal (Ant Ø 0.16–1.8 m) Fixed terminal Terminal (Ant Ø 0.66–1.5 m) Fixed terminal Trans. power terminal [W] 0.01–4.7 Services Multimedia, video, data Multimedia, video, data Data, high-rate network connection Multimedia, video, data Coverage area 95 % of area and 100 % of population 70 S–70 N (with Celestri b global) Global Global System costs [Mill. US$] 9 12.9 6.1 3.5 Start comm. operations 2002 2002 2002 2002 Useful life [years] 10 8 Licence from FCC Granted March 1997 Application accepted Application accepted Application accepted a Gigalinks b The Celestri system consists of the Celestri-LEO, M-Star and Millenium (GEO systems) 14.1 Fundamentals 723 Table 14.5: Broadband GEO satellite systems concentrating on data transfer System Spaceway Express- way Millenium (Celestri- GEO) Astrolink GE Star PAC 1–8 and Galaxy Sat. Inmarsat-3 Company Hughes Hughes Motorola, Vebacom Lockheed Martin Comm. GE Americom PanAmSat Inmarsat Contractors Orbit GEO GEO GEO GEO GEO GEO GEO Path altitude [km] 35 786 35 786 35 786 35 786 35 786 35 786 35 786 No. of satellites 9 (Type HS702) 14 4 9 9 16 5 No. of different satellite positions 5 5 No. of ground stations 7 No. of cells per sat. 48 44 Intersatellite links Yes Yes No Access method UL: TDMA/ FDMA DL: TDM UL: TDMA/ FDMA DL: TDM No. of channels per sat. 276 480 at 16 kbit/s 64 at 125 MHz, 4 at 250 MHz No. of channels in total system 248 832 588 000 576 at 125 MHz Transmission rate [kbit/s] 16–6000 16–9600 384–40 000 Frequency uplink [GHz] 28.35–28.6 and 29.25–30 V- and Ku-band 29.5–30 28.35–28.6 and 29.25–30 28.35–28.6 and 29.25–30 5.925–6.425 Frequency downlink [GHz] 19.7–20.2 + 5 GHz in-band 17.7–18.8 V- and Ku-band 18.55–18.8 and 19.7–20.2 19.7–20.2 + 5 GHz in-band 17.7–18.8 19.7–20.2 + 5 GHz in-band 17.7–18.8 3.7–4.2 724 14 Mobile Satellite Communication Table 14.5: Broadband GEO satellite systems concentrating on data transfer (continued) System Spaceway Express- way Millenium (Celestri- GEO) Astrolink GE Star PAC 1-8 u. Galaxy Sat. Inmarsat-3 Bandwidth UL+DL [GHz] 2 a 1.25 2 a 2 a 1 Frequency GW–Sat [GHz] In-band user-sat. In-band user-Sat. In-band user-sat. 14.0–14.5 Frequency Sat–GW [GHz] In-band user-sat. In-band user-sat. In-band user-sat. 11.7–12.2 Terminal Terminal (Ant Ø 0.7 m) Terminal Terminal Terminal Terminal Terminal Terminal Services Multimedia, video, data, voice Video, data broadcast Data, video, Internet Data, video, audio Voice, data, fax, multi- media, RDSS Voice, data, fax, Pos. det. Coverage area Continents ex. parts of Russia Global America Global America, Europe, Asia, West Pacific, Caribbean Global 70 §–70 N System costs [Mill. US$] 3.2 3.9 2.3 9 4 0.69 Price of terminal [US$] 1000 Several 100 Start comm. operations 2000 2001 2000 In operation since 1997 Useful life [years] 15 11 13 Licence from FCC 05/97 05/97 05/97 a Several systems share frequency band [...]... orbits may use phased-array antennas Individual dipoles act as omnidirectional beams However, if groups of dipoles are used, a certain directional pattern is created through the phase di erence at the receiver, which in a distant field is only dependent on the direction The directional pattern of a dipole group is dependent on the layout, phases and amplitudes of the dipoles This is exploited when phased-array... carried out by state-run operating companies such as Intelsat, Eutelsat and Inmarsat (see Appendix B) The primary responsibility of Intelsat is to provide regular radio services worldwide, namely telephony and data links as well as the transmission and distribution of TV and radio programmes Satellites for regular radio services specifically for Europe are operated by Eutelsat (European Telecommunications... frequencies reused according to a 12-cell cluster configuration; see Figure 14.8 The satellite antennas are phased-array antennas which compensate for the di erence in path loss between inner and outer cells using the di erent antenna gain of the respective radiation diagram The first satellites were launched into orbit in July 1997 Commercial operation has been opened in November 1998 The IRIDIUM system uses... satellite radio is currently using frequencies mainly in the Cand Ku-bands In the C-band these are 5.925–6.425 GHz range for the uplink and 3.7–4.2 GHz for the downlink; and in the Ku-band they are 11.7–12.2 GHz for the downlink and 14–14.5 GHz for the uplink Because of the growing interest in satellite communications, additional frequencies in the S- and the K/Ka-bands were reserved for satellite radio. .. Zones With LEO satellite systems the radio coverage zone on the ground is divided, following the usual cellular principles, into individual cells by a satellite to allow the reuse of frequency bands within the entire coverage zone The size of the illuminated zone is established by the minimum elevation angle min , which can be determined from the maximum possible distance between a mobile terminal and... and paging (see Figure 14.10) The IRIDIUM system uses a QPSK modulation technique with 50 kbit/s Frequency planning for IRIDIUM before the allocation of an additional 5.15 MHz by the FCC is shown in Figure 14.11 The channel bandwidth is 31.5 kHz and the frequency spacing is 41.67 kHz [8] The 5.15 MHz frequency band allocated by the FCC to the IRIDIUM system is divided into 124 carriers, each containing... min , which for practical reasons is typically at 10 to avoid larger areas without radio coverage because of shadowing [12] The radius of a coverage zone depends on the earth’s radius re and the path height h of the satellite above the earth’s surface: ° rcov = re arccos re cos re + h min − min With a given maximum distance dmax and a minimum elevation orbit height works out as h= d2 + 2dre sin max... Systems As mentioned above, the free-space attenuation depends on the frequency and the distance of the mobile user or base stations from the ground to the satellite The existence of di erent constellations of the systems produces di erent freespace attenuations There is a big di erence between maximum and minimum distance owing to the low flight paths and relatively large illumination zones, especially... constellations, illustrated in Figure 14.29 for a LEO constellation According to Equation (2.5), the free-space attenuation is dependent on the frequency used and the distance between satellite and mobile station The di erent distances that can exist between users and their connecting satellites produce varying levels of free-space attenuation The distance d between a user and a satellite depends on the elevation... path diversity It is very probable that two satellites will be visible at the lower elevation, and the satellite with the best channel quality will be selected It is anticipated that the greatest proportion of users of the ICO system will be accessing through GSM dual-mode terminals, and will use the satellite system only if the GSM network cannot guarantee an adequate radio connection ICO will be dispersing . and otherwise use di erent kinds of terres- trial mobile radio systems, requiring them to carry terminals with di erent standards. A di erentiation is. data links as well as the transmission and distribution of TV and radio programmes. Satellites for regular radio services specifically for Europe are operated