COMMERCIAL VOICE AND DATA MOBILE SATELLITE SYSTEMS: SUPPORT FUNCTIONS FOR MILITARY VOICE/DATA COMMUNICATIONS

Transcription

1 COMMERCIAL VOICE AND DATA MOBILE SATELLITE SYSTEMS: SUPPORT FUNCTIONS FOR MILITARY VOICE/DATA COMMUNICATIONS Michael S. K. Sushko Kensington & Icknield 5775 Wayzata Blvd, Suite 700 Minneapolis, MN Abstract - Low earth orbit (LEO) commercial communication satellite systems are currently being designed, constructed, and deployed. These systems are low Earth, nongeostationary satellite systems that will provide worldwide voice and/or data services. The first commercial voice and data LEO satellite communication systems went operational late last year. Additional systems are scheduled to become operational later this year. Broadband LEO satellite systems offering LAN networking and high-speed data links will also become operational in the next few years. This paper provides an overview of both operational and merging commercial lowearth orbit communication satellite systems. I. INTRODUCTION The deployment and success of military systems and services depends on both voice and data communication infrastructures. These infrastructures need to provide both flexibility and reliability along with extensive coverage for successful military operations. The introduction of new commercial Personal Communications Systems (PCS) will provide new wireless options for non-combat military voice and data support functions and services. These systems will be capable of providing true global wireless communication services using hand-held, battery operated phones for voice communications andlor fixed location satellite units for dataonly communications, Some of mobile satellite providers will offer voice-only systems that will operate similar to terrestrial-based cellular systems. They will provide the ability to dial other satellite phones over the satellite system or complete calls through the existing local PSTN (Public Switch Telephone Network) accessing the traditional wired phone system. Satellite phones that are dual mode will also be able to operate over cellular phone systems. Additional services of faxing, paging and low-speed data connections will also be available. Other satellite providers will be offering data only services. These satellite service providers will be offering narrow-band, low-speed data communications for near real-time data communications. Broadband-band satellite systems will be offering data communications at high optical-fiber data speeds. Satellite system providers of data-only systems will offer 2-way data communications between other satellite data units and/or terrestrial gateways providing PSTN interfaces. Mobile satellite PCS systems from different providers will consist of geostationary satellite (GEO) systems, medium earth orbit satellite (MEO) systems, low earth orbit satellite (LEO) systems and highly elliptical orbit satellite (HEO) systems. Non-geostationary satellite systems are classified according to the operational frequency bands, their orbits and the type of service they provide, These nongeostationary satellite systems are known as Big LEO s, Little LEO s and Broadband LEO s. The Big LEO and Little LEO systems are classified by the FCC as MSS (Mobile Satellite Service) and the broadband systems are classified as FSS (Fixed Satellite Services) services. The Big LEO systems are licensed by the FCC for usage of the L frequency band ( MHz) and the S band ( MHz). These bands are within the FCC s frequencies in the 2 GHz bands allocated for Mobile Satellite Service terminal and satellite service links. Big Leo systems are required to share portions of the L and S frequency bands with other Big Leo system providers. This is due to the limited amount of RF spectrum that is available for non-geostationary mobile satellite services worldwide. Under the FCC band-sharing plan, Big LEO providers using CDMA (Code Division Multiple Access) technology would share spectrum in the MHz band. A single license would be issued in the MHz band for TDMA/FDMA (Time Division Multiple Access/Frequency Division Multiple Access) technology [1], The Big LEO system providers will offer voice communications along with a wide variety of additional wireless services such as data, fax, position location and paging. The primary Big LEO (Low Earth Orbit) satellite systems are Iridium, Globalstar, ICO, Ellipse, and Aries/ECCO systems. II. BIG LEO SYSTEMS The Iridium system was proposed and developed by Motorola. It is now owned and operated by Iridium LLC, an international consortium of telecommunication companies. The Iridium satellite system began commercial services last fall with its constellation of 66 satellites in a LEO orbit 785 km in altitude. The system consists of 6 polar orbital inclined planes each containing 11 satellites with an orbital period of 100 minutes[l] [2]. The Iridium system uses the same identical uplink and downlink frequencies in 1,610 to 1,626.5 MHz band [1]. This follows the FCC Big LEO band-sharing plan for TDMA/FDMA architecture. It uses 50-Kbps TDMA bursts in both the uplink and downlink channels with data

2 rate of 4,800 bps for voice and 2,400 bps for data. Each Iridium satellite uses three L-band antennas with 48 spot beams. Each spot beam diameter covers 600 km on the surface of the Earth. The entire 66 satellite constellation provides 3,168 spot beam cells - only 2,150 spot beams are required to cover the entire Earth, The Iridium system is designed for each spot beam to support 80 RF channels. World wide channel capacity is 2,150 spot beams x 80 RF channels/spot beam for a total of 172,000 RF channels. Iridium uses intersatellite data communication links in the frequency band GHz for call connection between satellites [1]. Each Iridium satellite supports a total of four intersatellite communication links. It is able to communicate with the satellite in front and the satellite behind itself in the same orbital plane and one satellite in each of the adjacent orbits. The Iridium system provides both personal satellite handphone, paging and data services. The Iridium system operates ten communication gateways around the world. The U.S. DOD is currently leasing capacity on the Iridium system and operates it s own Iridium Gateway. The Globalstar system development is by Loral Qualcomm Partnership LP and will use 48 satellites in eight circular orbital planes with 6 satellites per plane. The Globalstar system will provide global coverage 74 degrees south to 74 degrees north [3]. The orbital altitude is 1,414 km with an orbital period of 114 minutes. It uses phased array antennas that divide user coverage into 16 beams. Beam coverage fills 5,760 km diameter circle of the Earth. Each satellite has a channel capacity of 2,148 channel links [3][4]. Globalstar use bent pipe transponders without intersatellite capability. User communications is in the 1,610 to 1,626.5 MHz band in accordance with the band-sharing plan as required by FCC licensing for CDMA architecture. User downlink communications is in the S band (2,483.5 to 2,500 MHz). Globalstar is licensed for feeder link communications in the MHz uplink band and the MHz downlink bands [3]. The Globalstar system uses CDMA (Code Division Multiple Access) voice communications that is modified by Qualcomm with efficient power control. It uses 4 different data rates of voice encoding (1,200, 2,400,4,800 and 9,600 bps). A data rate of 1,200 bps is used when no speech activity. Globalstar will provide personal satellite handphone and data services. Additional services of positioning (300 m), paging and messaging will be available. Commercial service will start in The emerging Medium Earth Orbit (MEO) satellite system is the ICO Global Communications (IGC) system. ICO is a MEO based system that was originally affiliated with Inmarsat as INMARSAT-P and now operates as a private British company to provide personal mobile satellite services. It will be a personal hand-held telephone service consisting of 10 satellites and 2 spares in two circular orbital planes at an altitude of 10,390 km with an orbital period of minutes [5]. Each satellite has 163 spot beams and handle 4,500 simultaneous calls using TDMA based on GSM technology. Total constellation will handle 45,000 calls [7]. It will use dual mode cellular and satellite TDMA phones, The system will provide duplex data at 2,400 bps and higher, fax, paging and positioning services. ICO is planning to use the service link fi-equencies 2,170 to 2,200 MHz for uplink transmission and 1,980 to 2,010 MHz for downlink transmission [7]. The ICO satellites will use a bent pipe architecture where calls are relayed between the ICO phone and the nearest Earth station. The Earth station provides a circuit connection to the existing terrestrial PSTN for call completion. Twelve Earth stations around the world are connected together as the ICONET network and provide the terrestrial communications link between satellites [7]. ICO is currently seeking FCC authority to provide MSS user services in the 2 GHz band for operation in the U.S. It plans to launch the first ICO satellites this summer. ICO is also seeking approval for building and operating ICO S Earth stations in the U.S. as part of it s ICONET. The FCC recently provided conditional approval for TT&C operation (without any feeder link operation) in the 5 and 7 GHz bands provided that ICO not cause any interference to existing licensed users [6]. Satellite TT&C operations normally occur within the feeder link ti-equency bands. The Ellipso system is being developed by Mobile Communications Holding. It will consist of two complementary/coordinated constellations: Ellipse-Borealis and Ellipso-Concordia. The Ellipse-Borealis constellation will consist of 10 satellites elliptical orbits in two planes - apogee orbit of 7,846 km and a perigee orbit of 520 km (a 3 hour orbit) [8][9]. The Borealis orbits will provide northern service for most of their orbits. The Ellipso-Concordia uses 6 satellites in circular equatorial orbits at 8,040 km. This constellation provides continuous coverage to tropical and temperate latitudes to 47 degrees south [9]. Ellipso satellite antennas will divide Earth into 61 adjoining areas. The 61 beams use the same 12 MHz frequency band - users will not change frequencies as satellite beams change during a call. The Ellipso system will operate in the L band (1,610 to 1,626.5 MHz) following the FCC Big LEO band-sharing plan for CDMA architecture [8]. It will use dual-mode Ellipse terminals that will operate in either satellite mode or terrestrial mode with digital voice coding at 4.15 Kbps. Data service support will be provided for modem, fax, messaging, positioning at various data rates to 9,600 bps. Commercial service will start in The Aries/ECCO Satellite system is under development by Constellation Communications along with other telecommunication companies. The Aries constellation will consist of a total of 46 satellites at an altitude of 2,000 km with 11 satellites in the equatorial plane and the remainder 35 satellites in seven circular inclined orbits with five satellites per orbital plane. Each satellite will have multibeam antennas supporting a minimum of 1,000 voice circuits

3 using CDMA technology [10]. Uplink communications from mobiles to satellites in the 1,610-1,626,5 MHz band follows the band sharing plan for CDMA. Downlink communications for the Aries system will occur in the MHz band. The downlink feeder link communications will use the MHz band and uplink feeder links in the MHz band [10]. Market focus will be on fixed and mobile personal hand telephone, data, fax, paging and position services. III. LITTLE LEO SYSTEMS The Little LEO communication satellite systems operate in the VHFAJHF bands and are licensed by the FCC to provide data-only messaging communications as nonvoice non-geostationary mobile satellite service (NVNG MSS). All FCC licensed Little LEO satellite companies must share the same operational frequency bands under specific FCC guidelines. Sharing of RF spectrum is required since there is only a limited amount of RF bands available for non-geostationary mobile satellite services worldwide. Certain parts of the frequency bands available for Little LEO operation is generally already being used by either terrestrial or other Government satellite users. License requirements for U.S. companies require that these bands are shared between existing users and the Little LEO companies. All FCC licensing authorizations for Little LEO satellite construction, launching and operation is subject to frequency band sharing coordination. The Orbcomm system is the first fully operational Little LEO satellite system. It began fill commercial operation last year and consists of 36 LEO satellites in 4 orbital planes of 8 satellites with 4 spares. Satellite inclination is 45 degrees at satellite altitude of 775 km [11]. The Orbcomm satellites are continuously in view over 98% of the time. There is a small wait for direct satellite access at other times. The user uplink data rate is 2,400 bps QPSK signal at 148 MHz. The user downlink data rate is 4,800 bps BPSK signal al 137 MHz. FDMA multiple access is used for the user links [12]. TDMA multiple access is used for the feeder link. ljser terminals are available as portable, handheld and mobile units by different manufacturers. The LEO 1 system being proposed by the Leo One USA Corporation was licensed by the FCC in February Its constellation will consist of 48 satellites with 8 orbital planes with 6 satellites per plane. The satellite orbit altitude will be 950 km (590 miles) with near-polar orbits of 50 degrees orbit inclination [13]. The subscriber downlink data rate is 24,000 bps in the MHz band with a 2,400 9,600 bps uplink data rate in the MHz band. The Gateway uplink data rate will be 50,000 bps in the MHz band with the same data rate in the downlink band of MHz [13] [14]. It will be offering nearreal time messaging services for tracking, monitoring, remote control, fleet management, emergency services and general transaction processing. Commercial service is scheduled to begin in Other packet data Little LEO satellite systems include the Final Analysis Communication Services, Volunteers In Technical Assistance ( VITA ), CTA Commercial Systems ( CTA ), E-Sat ( E-Sat ) and GE American Communications ( GE Americom ) systems. These additional companies have either current or pending licenses from the FCC to launch and operate as a Little LEO satellite systems. Final Analysis Communications has a FCC license to operate twenty-six active satellites (and four spares) as a Non-Voice Non-Geostationary system in low Earth orbits. It is licensed for service uplink in MHz band and downlink in the MHz bands. Satellite feeder links are licensed in MHz uplink band and feeder downlinks in the MHz bands [15]. E- Sat, Incorporation is another company that has a FCC license for a Little LEO system. The E-Sat system will consist of six satellites at an altitude of km s using an orbital inclination of degrees. E-Sat proposes to use spread spectrum for it s communication links. It is licensed for the MHz band for service uplinks, followed by the feeder uplink band at MHz with the band MHz for service downlinks [16]. E-Sat s intends to provide data message services to both the gas and electric industries along with environmental monitoring. Service must be operational by September The Volunteers in Technical Assistance ( VITA ) is a non-profit, humanitarian aid organization that provides services to developing countries. It intends to offer technical data communication services for humanitarian purposes with its proposed Little LEO system. The non-commercial VITA satellite system consists of two Little LEO satellites. It is licensed for service uplinks in the MHz band with the service and feeder downlinks in the MHz frequency band [17]. Under its FCC license terms, complete system launching must be done by March Due to its small satellite constellation, limited coverage and status as non-profit organization, the VITA system would be of limited usefulness for military applications. IV. BROADBAND SYSTEMS In the last few years, the FCC has issued authorizations for the construction, launching and operation of various geostationary (GSO) and non-geostationary (NGSO) fixed satellite services (FSS) systems to provide broadband satellite communications. The only current licensed broadband non-geostationary fixed satellite system under development is the Teledesic system by the Teledesic Corporation. It will provide Optical-fiber speed for global

4 broadband service in Ka band of GHz and GHz as a non-geostationary fixed satellite service. The original Teledesic application authorization by the FCC in 19$37called for the launch of 840 satellites at an altitude between 695 and 700 km [18]. Teledesic received FCC authorization in January 1999 for a revision of its original FCC application for a system constellation of 288 satellites at altitude of 1,375 km in 12 circular orbital planes. The inclination of the orbital planes was changed to nearpolar orbits at 84 degrees. The revised FCC authorization included the addition of optical inter-satellite links with Teledesic already authorized for RF inter-satellite links. Other aspects of the original license were also kept [18] [19]. As part of the original license, Teledesic is using 500 MHz of pair spectrum for uplink transmission in the GHz band and ,3 GHz for downlink transmission for its customer service links. For its high data speed gigalink gateway terminal service, Teledesic is using 800 MHz of spectrum in the GHz band for uplink and GHz for downlink transmission. Teledesic s application also called for the use of RF-based inter-satellite links in the GHz and GHz bands [18] [19]. Inter-satellite communications enables each satellite to communicate directly with another satellite in the same plane and/or satellites in adjacent planes, The Teledesic system is designed to support RF data communication links between up to eight different satellites at high data rates. Inter-satellite communications will enable the Teledesic system to operate as an interconnecting network mesh. This will enable packet data traffic to move between source and destination based on changing network topology. The proposed coverage is for 95 XOof the Earth s surface with complete coverage between 72 degrees north and south latitudes and partial coverage at higher latitudes. This would provide almost 1OO -XOcoverage of the total Earth s population [18]. The Teledesic network is being designed to provide service terminal two-way data rates up to 2 Mbps on the uplink channel and up to 64 Mbps on the downlink channel [20]. Data transmission would occur in the pair spectrum of GHz for uplink and GHz bands for downlink. Broadband terminals using its Gigalink connections would operate in the GHz uplink and GHz downlink bands [18] [19]. The broadband Gigalink data rates will be 64 Mbps of service terminal rates (128 Mbps uplink to 4096 Mbps downlink) [20]. The system provides downlink channel sharing between terminals in each satellite s cell by using Asynchronous Time Division Multiplexing Access (ATDMA). This enables channel bandwidth resources to be assigned to terminals on a demand basis to meet different levels of service. Uplink channel sharing is done using Multi-Frequency Time Division Multiple Access (MF-TDMA) [20]. Teledesic is designing the satellite link to operate at a BER (Bit Error Rate) of 10-10by using FEC (Forward Error Correction). The use of FEC is necessary due to the movement of the satellites overhead, associated hand-off between satellites and the nature noise level in the Ka frequency band. Teledesic is requiring a minimum elevation angle ( mask angle ) of 40 degrees. This is to help insure connection availability at 99.9 A or greater [20]. Teledesic is under schedule to construct, launch and operate a Low Earth Orbit Satellite system by the year 2002 Another fixed satellite service (FSS) broadband system is the SkyBridge system being proposed by SkyBridge LLC [24] [25]. It is currently waiting authority from the FCC to launch and operate a FSS non-geostationary orbit satellite system. The system will offer high-speed broadband data, voice and video services. The total system constellation will consist of a total of 80 satellites divided into two complete sub-constellations each with 40 satellites at an altitude of 1,469 km, Each sub-constellation will consist often orbital planes with four satellites per plane [21 ] [22]. Teledesic s FCC authorization states that it intends to provide a wide range of data information services that included high-quality voice, broadband communication applications and real-time two-way data communications [18] [19]. As a broadband service provider, it is necessary to support Quality-of-Service (QoS) performance levels that the network is expected to deliver. The Quality-of-Service (QoS) performance will be dependent on traffic routing efficiency, network Iatenc y, bit error rates (BER), channel availability, connection availability and bandwidth on demand. The Teledesic system will offer multi-megabit data rates, bandwidth on demand, low latencies of less than 75 msec ~ one way connections less than 5,000 km), connection availability of 99.9% and bit error rates (BER) of [20]. The proposed SkyBridge will use a total of 1.05 GHz of spectrum in GHz, GHz and GHz frequency bands for uplink transmission. This also includes the use of 1.05 GHz bandwidth in the GHz band for downlink operation. User terminals in the SkyBridge system would operate in the GHz band for uplink transmission and downlink transmission in the GHz band [21], The FCC is reviewing interference issues of the SkyBridge system with existing terrestrial, Fixed Satellite Service (FSS), and geostationary system users. The FCC is also reviewing SkyBridge s request for an amendment of FCC Parts 2 and 25 for use of 2 GHz of downlink bandwidth and 1.75 GHz of uplink bandwidth [21].

5 V. CONCLUSION The completion of these new satellite systems will provide a broad array of new wireless communication service options for military support fimctions. These new mobile systems will provide worldwide hand-held voice andlor data services, including fixed location high-speed broadband services that can be used for non-combat military applications. These new robust commercial voice and/or data satellite systems will be able to provide immediate noncombat military communication solutions where traditional military communication services would be infeasible. Voice, Non-Geostationary Mobile Satellite System in the MHz, MHz, and MHz Frequency Bands, File Nos. 28-SAT-MP/ML-95, March 31, [12] Orbcomm Sales and Marketing Literature [13] Leo One USA Corporation For Authorization to Construct, Launch and Operate a Non-Voice, Non- Geostationary Mobile Satellite System in the , and MHz Frequency Bands, File Nos. 57-DDS-P/LA-94 (48), February 13, VI. REFERENCES [1] Motorola Satellite Communications, Inc. For Authority to Construct, Launch, and Operate a Low Earth Orbit Satellite System in the MHz Band, File Nos. 9- DSS-P-91 (87), January31, 1995 [2] Iridium Marketing Literature [3] L/Q LICENSEE, INC Application for modification of license to construct, launch, and operate low-earth-orbit satellites and request for waiver of Table of Allocations, File Nos. 88-SAT-WAIV-96 and 90-SAT-ML-96, November 19, 1996 [14] System Specifications, Leo One Announces Revolutionary Integrated Communications Facility, System Technology Profile, [15] Final Analysis Communication Services, Inc. For Authority to Construct, Launch and Operate a Non-Voice, Non-Geostationary Mobile Satellite System in the MHz, MHz and MHz Bands, File Nos. 25-SAT-P/LA-95, April 1, [16] E-Sat, Inc, For Authority to Construct, Launch and Operate a Non-Voice, Non-Geostationary Mobile Satellite System in the MHz and MHz Frequency Bands, File Nos. 26-SAT-P/LA-95, March 31, [4] Globalstar Sales and Marketing Literature [5] COMSAT Corporation For Authority to Participate in the Procurement of Facilities of the ICO Global Communications Limited System, File No. 106-SAT-MISC- 95, February 25, 1999 [6] U.S. Electrodynamics, Inc. For authority to construct and operate five transmitkeceive Earth stations at Brewster, Washington for operation with the ICO Medium Earth Orbit satellite system., File Nos.SES-LIC , June 24, 1999 [7] ICO Sales and Marketing Literature [8] Mobile Communications Holdings, Inc. For Authority to Construct, Launch, and Operate an elliptical low earth orbit Mobile Satellite System, File Nos. 11-DSS-P-91(6), July 1, [17] Volunteers In Technical Assistance For Authority to Construct, Launch and Operate a Non-Voice, Non- Geostationary Mobile Satellite System in the MHz and MHz Frequency Bands, File Nos. 29- SAT-AMEND-95, March 31, [18] Teledesic Corporation Application for Authority to Construct, Launch, and Operate a Low Earth Orbit Satellite System in the Domestic and International Fixed Satellite Service. FCC Order and Authorization, File Nos. 22-DSS- P/LA-94, March 14, [19] Teledesic LLC for Minor Modification of License to Construct, Lauch and Operate a Non-Geostationary Fixed Satellite Service System. FCC Order and Authorization, File No. 195-SAT-ML-97. January 29, 1999 [20] Teledesic Technical Details, Teledesic Latency White Paper, Teledesic Overview, [9] Mobile Communications Holding Marketing Literature [1 O] Constellation Communications, Inc. For Authority to Construct, Launch and Operate a low earth orbit Mobile Satellite System, File Nos. 17-DSS-P-91(48), July 1, [11] Orbital Communications Corporation For Modification of Its Authority to Construct, Launch and Operate a Non- [21] Amendment of Parts 2 and 25 of the Commission s Rules to Permit Operation of NGSO FSS Systems Co- Frequency with GSO and Terrestrial Systems in the Ku-Band Frequency Range, ET Docket No , Nov 24, 1998 [22] FCC Public Notice, International Bureau, Satellite Policy Information, Report No. SPB- 141, Nov 2, 1998