BUILDING BROADBAND NETWORKS phần 8 doc

wireless network include costs, legal regulations, transmission capabilities, and configuration requirements. Factors affecting wireless network performance include mobility, immunity to interference, power consumption, performance consistency, security, and network capacity, scalability, and reliability. Despite significant tech- nical advances and recent innovations, it is important to note that wireless informa- tion appliances are still limited in effectively providing access to Web resources and e-mail as a consequence of such constraints as battery life and processing power. Effective wireless network implementations overcome technical, architectural, and operational challenges as well as accommodate institutional mission, goals, and constraints; user objectives; and budgetary requirements. Wireless networks that support multimedia services enable individuals to utilize mobile terminals for seam- lessly accessing multiple databases at diverse locations on-demand. This capability also supports navigation through resources in digital libraries and participation in joint projects on curricular design and development with administrators using sta- tionary terminals in fixed locations. Widespread user acceptance and effective deployment of wireless networks in the learning environment ultimately depends on the ability of the wireless configurations to provide the same level of performance and quality of service (QoS) guarantees as their wireline counterparts. Challenges associated with wireless network implementation include providing on-demand bandwidth allocation to support a broad spectrum of applications. Mobil- ity management issues associated with wireless ATM, mobile IP, and next-generation wireless networks must also be addressed. Wireless network technologies work in concert with diverse narrowband and broadband wireline solutions. Third-generation cellular communicators enable increasingly sophisticated music, voice, video, imaging, and data services with QoS guarantees and provision access to networking applications in densely populated urban communities as well as in rural and isolated locations. Third-generation network solutions such as Bluetooth and UMTS are expected to deliver mobile IP services at rates ranging from 144 and 384 Kbps for users on the move to 2 Mbps for users at fixed locations. Research in wireless communications is progressing in many directions. Next- generation wireless networks are designed to provide seamless access to local and wider area applications via compact wireless appliances and enable dependable and reliable voice, video, and data transmissions at rates reaching 155.52 Mbps (OC-3). Accelerating demand for ubiquitous access to communications resources and wire- line and/or wireless networks, regardless of user location or mobility, drives the development and implementation of scalable and extendible next-generation wireless network solutions. 9.36 SELECTED WEB SITES Alcatel. Broadband Wireless Access Solutions Available: http://www.cid.alcatel.com/solutions/ Bluetooth. The Official Bluetooth Website. Available: http://www.bluetooth.com/ 0889Ch09Frame Page 436 Wednesday, April 17, 2002 2:59 PM © 2002 by CRC Press LLC Carnegie Mellon University School of Computer Science. Monarch Project. Research Papers. Last modified on April 25, 2000. Available: http://www.monarch.cs.cmu.edu/ Carnegie Mellon University Wearable Group. Spot. Last modified on September 5, 2001. Available: http://www.wearablegroup.org/hardware/spot/ Federal Communications Commission (FCC). FCC National Regulatory Research Institute. Community Broadband Deployment Database. Available: http://www.nrri.ohio- state.edu/programs/telcom/broadbandquery.php European Telecommunications Standards Institute (ETSI). HiperLAN2 Technical Overview. Available: http://www.etsi.org/technicalactiv/hiperlan/hiperlan2tech.htm Infrared Data Association (IrDA). The Association for Defining Infrared Standards. Welcome to IrDA. The IrDA Home Page. Available: http://www.irda.org/ Personal Communications and Industry Association (PCIA). About PCIA. Available: http://www.pcia.com/industryconnect/index.htm Rutgers University. WinLAB. Research Areas. Available: http://www.winlab.rutgers.edu/pub/Index.html Wireless Ethernet Compatibility Alliance (WECA). Articles and News. Available: http://www.wi-fi.com/articles.asp Wireless LAN Association (WLANA). The Wireless Networking Industry’s Information Source. Home Page. Available: http://www.wlana.org/index.html U.S. Department of Defense Advanced Research Projects Agency (DARPA) Information Technology Office (ITO). Global Mobile Information Systems (GloMo). Robert Ruth, Program Manager. Available: http://www.darpa.mil/ito/research/pdf_files/glomo_approved.pdf U.S. Department of Defense Advanced Research Projects Agency (DARPA) Information Technology Office (ITO). NGI (Next-Generation Internet) Project List. Available: http://www.darpa.mil/ito/research/ngi/projlist.html U.S. Department of Defense Advanced Research Projects Agency(DARPA) Information Technology Office (ITO). Ubiquitous Computing. Goals. Dr. Jean Scholtz, Program Manager. Available: http://www.darpa.mil/ito/research/uc/goals.html 0889Ch09Frame Page 437 Wednesday, April 17, 2002 2:59 PM © 2002 by CRC Press LLC 10 Satellite Networks 10.1 INTRODUCTION This chapter presents an examination of satellite network capabilities, technical attributes, and implementations. Satellite systems employ radio waves in the super- high and extremely high RF (radio frequency) bands of the electromagnetic spectrum for enabling dependable transport of voice, video, data, and still images. Satellite configurations utilize state-of-the-art technologies for facilitating high-speed access to bandwidth-intensive resources and time-critical data. Rapidly evolving satellite networks are further distinguished by their provision of on-demand seamless mobile communication services at anytime and in every place and delivery of broadband multimedia applications to subscribers at rural locations. 10.2 PURPOSE The growing popularity of wireless communications and mobile computing inten- sifies interest in satellite technologies, services, and networks. Satellite communi- cation solutions support a broad array of tele-applications that include high-definition television (HDTV) broadcasts, video-on-demand (VOD), videoconferencing, tele- instruction, and Web browsing. In this chapter, satellite technical features, functions, regulations, standards, and operational considerations are examined. Challenges and prospects associated with utilization of satellite configurations for enabling routine access to present-day and next-generation networks and narrowband and broadband services are reviewed. Satellites are either natural or artificial. A natural satellite is a celestial body that revolves around a large-size planet such as the Earth. By contrast, an artificial satellite is an object placed into orbit around the Earth. Artificial satellites enable services that include weather forecasting, forest fire detection, scientific research, navigation, E-commerce (electronic commerce) transactions, photographic surveillance, and detection of nuclear explosions. In this chapter, the capabilities of artificial satellite constellations in enabling tele-education and telemedicine services are explored. 10.3 FOUNDATIONS First proposed in 1945 by the British science fiction writer Arthur C. Clarke, satellite communications became a reality with the launching of the Russian satellite Sputnik I in 1957 and the American satellite Explorer I by the National Aeronautics and Space Administration (NASA) in 1958. 0889Ch10Frame Page 439 Wednesday, April 17, 2002 2:58 PM © 2002 by CRC Press LLC The first National Oceanic and Atmospheric Administration (NOAA) series of Polar-Orbiting Environmental Satellites (POES) commenced in 1960 with the launch of the Television Infrared Operational Satellite (TIROS). The POES fleet provides global meteorological data for research and geographic and atmospheric applications. In the 1970s, NASA launched the first geostationary (GEO) Applications Tech- nology Satellite (ATS-1) with the capabilities to record weather systems in motion and SEASAT. SEASAT was the first earth orbiting satellite designed specifically to monitor oceanic activities remotely. ATS-1 and SEASAT also provided critical data on adverse weather conditions to NOAA scientists for enabling accurate weather forecasts. The first Synchronous Meteorological Satellite (SMS-1) was placed into orbit during the 1970s. This satellite served as the prototype for the Geostationary Oper- ational Environmental Satellite (GOES) system. The GOES system monitors the Earth’s atmosphere and surface in the Western Hemisphere. GOES imagery enables scientists to predict the amount of rainfall during hurricanes. 10.3.1 T HE U.S. D EPARTMENT OF D EFENSE G LOBAL P OSITIONING S YSTEM (GPS) 10.3.1.1 GPS Features and Functions A U.S. Department of Defense (DoD) initiative, the Global Positioning System (GPS) uses a fleet of 24 satellites that were launched between 1978 and 1994 for transmitting extremely precise positioning information to GPS receivers. GPS appli- cations were developed initially by the U.S. Department of Defense to accommodate military needs and support military operations. A satellite-based radio positioning system, GPS enables applications that include maritime navigation and messaging services. Satellite configurations consist of space, ground, and control segments. In terms of GPS, the space segment consists of a fleet of 24 satellites placed into orbit between 1978 and 1994. These satellites orbit the Earth every 12 hours. The ground segment is comprised of receivers that are handheld or mounted on aircraft, ships, trucks, tanks, and cars. Generally, GPS handheld receivers are about the same size as cellular phones. The control segment includes ground stations that monitor satellite opera- tions and functions. GPS supports information transport between the 1.559 and 1.610 GHz (Giga- hertz) frequency bands. GPS also enables signal transmission in the 1.227 GHz spectral block for non-safety critical applications and in the 1.176 GHz spectral block for life-threatening emergencies. Additional systems that supplement GPS services are expected to operate in spectrum between the 1.559 and 1.610 GHz frequency bands. GPS receivers process satellite signals to compute velocity, position, and time and generate accurate location and navigational data. The Global Positioning System supports Standard Positioning Service (SPS) and Precise Positioning Service (PPS). GPS services are used by surveyors, mapmakers, and motorists to determine loca- tions, and by police officers and firefighters for vehicle dispatch. In addition, GPS 0889Ch10Frame Page 440 Wednesday, April 17, 2002 2:58 PM © 2002 by CRC Press LLC services enable railway engineers to monitor train movements and naval officers on ships at sea to utilize GPS data for navigation. GPS data resulted in predictions of Hurricane Andrew in 1992, the floods in the Midwest in 1993, and the North Ridge Earthquake in California in 1994. During Operation Desert Storm, GPS data contributed to the execution of quick and suc- cessful air and ground attacks by American troops. The Southern California Inte- grated GPS Network (SCIGN) uses GPS technology for forecasting earthquakes. In addition, GPS supports diverse initiatives that demonstrate the application of space technologies in public health, travel, engineering, and public transportation. During the construction of the tunnel under the English Channel for linking Dover, England and Calais, France, construction crews used GPS communicators to check positions. The Global Positioning System also tracks oil spills, volcanic eruptions, droughts, and nuclear accidents to mitigate the effect of environmental disaster. Data derived from GPS satellites are maintained in the Global Disaster Information Network (GDIN). 10.3.2 NASA A DVANCED C OMMUNICATIONS T ECHNOLOGY S ATELLITE (ACTS) E XPERIMENT P ROGRAM NASA launched the Advanced Communications Technology Satellite (ACTS) aboard the space shuttle Discovery on September 12, 1993. Simultaneously with the ACTS launch, NASA initiated the NASA ACTS Experiment Program. The NASA ACTS Experiment Program supported innovative satellite applications in the edu- cational domain and contributed to the development of the global information infra- structure. In addition, capabilities of the Ka-band in enabling satellite-based voice, video, and data transmission were verified. With the initiation of the ACTS Experiment Program, NASA also began devel- opment of the National Research and Education Network (NASA-NREN). During the course of the NASA ACTS Experiment Program, organizations representing industry, academia, and government conducted approximately 100 research projects and education initiatives. On May 31, 2000, the NASA ACTS Experiment Program came to a close. At that time, NASA predicted that the Advanced Communications Technology Satellite (ACTS) still had from two to four years of useful life. 10.3.3 O HIO C ONSORTIUM FOR A DVANCED C OMMUNICATIONS T ECHNOLOGY (OCACT) Following the close of the NASA ACTS Experiment Program, the Ohio Consortium for Advanced Communications Technology (OCACT) under the leadership of Ohio University announced plans to take over continued operation of the NASA Advanced Technology Satellite. Ohio University indicated that this satellite would serve as a laboratory for enabling next-generation research projects and academic initiatives in space science, satellite communications, satellite operations, and distance learn- ing. In addition to Ohio University, OCACT participants include the NASA Glenn Research Center, Texas A&M University, the Ohio Board of Regents, the Naval 0889Ch10Frame Page 441 Wednesday, April 17, 2002 2:58 PM © 2002 by CRC Press LLC Postgraduate School, the Air Force Research Laboratory (Lab), and the Space and Naval Warfare Systems Center. 10.4 SATELLITE TECHNICAL FUNDAMENTALS Satellites are Earth-orbiting spacecraft that employ microwave technology in the super high and extremely high frequencies for enabling wide area interactive com- munications and transmission of broadcast services to locations that cannot readily be served by terrestrial facilities. As noted in the GPS description, satellite config- urations include three segments: space, ground, and control. The number of satellites in the space segment depends on service requirements and budget allocations. Control segments include low-cost Very Small Aperture Terminals (VSATs) that are linked to end-user equipment, as well as technically complex facilities costing millions of dollars that track the accuracy of satellite operations. As with control segments, ground components support varying functions. For example, receive-only Earth stations serve as distribution sites for broadcast television (TV) programs. Earth stations that support dual-mode operations for enabling signal reception and signal transmission are typically situated at key research centers, university cam- puses, and corporate headquarters. Earth stations can also support command and control operations. The pathway for transporting radiowaves from the satellite to the designated Earth station or reception site is called the downlink. The pathway for transmitting radiowaves or signals from the Earth station to the satellite is called the uplink. Transponders are combinations of receivers and transmitters carried by satellites for enabling signal reception on the downlink path, signal amplification, and signal retransmission on the uplink path. The crispness and robustness of satellite signals or radiowaves depends on the condition of the uplink and downlink. To reduce the effects of signal attenuation, the downlink typically operates at lower frequency levels than the uplink. The satellite, the transmitting Earth station, and the receiving Earth station form a basic three-node network with the satellite situated at the apex of the configuration. Because satellite signals cannot pass through the Earth’s surface, satellite transmis- sions travel in straight line-of-sight (LOS) paths from one point to another. Satellite systems are used extensively for enabling long-haul and transoceanic information distribution. Landline links such as coaxial cable, optical fiber, and twisted copper pair are used in conjunction with satellite networks for connecting residential, educational, medical, and corporate networks with Earth or ground stations. 10.4.1 A NTENNAS An antenna is an aerial communications device that receives and radiates radiowaves through free space to remote locations. An antenna enables a satellite to communicate with a ground or Earth station that can also provide command and control services. Conventional antennas for enabling wide area television broadcasts are omni-direc- tional. By contrast, higher gain directional antennas employ spot beam technology 0889Ch10Frame Page 442 Wednesday, April 17, 2002 2:58 PM © 2002 by CRC Press LLC to support full-duplex point-to-point transmissions. With spot-beam technology, an antenna system divides a single footprint or coverage area into smaller coverage areas or sub-footprints for supporting lower power transmissions from and to mul- tiple subscriber sites. Antenna shape and size depend on the wavelength of radiowaves that are trans- mitted or received. As an example, dish antennas work in concert with satellite signals that are transported in extremely high frequencies and feature very short wavelengths. The Federal Communications Commission (FCC) adopted rules governing antenna placement for receiving Direct Broadcast Satellite (DBS), Multichannel Multipoint Distribution System (MMDS), Local Multipoint Distribution System (LMDS), and Television Broadcast Station (TVBS) transmissions. These rules are included in the Telecommunications Act of 1996. Fire codes prevent antenna instal- lations on fire escapes, and local codes require antenna placement at specified distances from powerlines. 10.4.2 S ATELLITE P ROTOCOLS As with cellular technologies and communications services, protocols enabling satellite transmissions include Time-Division Multiple Access (TDMA) and Code- Division Multiple Access (CDMA). TDMA divides each satellite channel into timeslots in order to increase the quantity of data that are transported. Using TDMA, satellite networks support access to Web applications, Public Switched Telephone Network (PSTN) services, wireline network links, and MPEG-2 (Moving Pictures Experts Group-2) videoconferences. For enabling mobile satellite communications services, CDMA assigns a unique sequence code to each call so that multiple calls can then be overlaid on each other to optimize utilization of the available bandwidth. 10.5 SATELLITE FREQUENCY BANDS Satellite communications generally take place in that part of the radio spectrum that ranges between 1 and 30 GHz. In the United States, frequency bands typically employed for satellite communications include the C-band, Ku-band, and Ka-band. The letters designating the names of the frequency bands are randomly selected. 10.5.1 C-B AND T RANSMISSIONS Operating at the lower end of the spectrum, the C-band supports uplink operations between the 5.9 and 6.4 GHz frequency bands. For the downlink, frequencies ranging from 3.7 to 4.2 GHz are employed. C-band transmissions are fairly immune to atmospheric disturbances. Fixed satellite services supporting VSAT operations typically operate in the C- band and the Ku-band. In the United States, the C-band operates within the same portion of the frequency spectrum as terrestrial microwave. As a consequence, C- band transmissions are susceptible to radio frequency interference (RFI) from micro- wave signals. 0889Ch10Frame Page 443 Wednesday, April 17, 2002 2:58 PM © 2002 by CRC Press LLC 10.5.2 K U -B AND T RANSMISSIONS The higher power Ku-band supports communications services in densely populated urban areas. Ku-band uplinks support operations between the 14 and 14.5 GHz. frequencies and between the 17.3 and 17.8 GHz frequencies. Ku-band downlinks operate between the 11.7 and 12.7 GHz frequencies. 10.5.3 K A -B AND T RANSMISSIONS With the launching of the NASA Advanced Communications Technology Satellite (ACTS) spacecraft in 1993, the Ka-band portion of the RF spectrum in the 20 to 30 GHz frequency block became available. A GEO (Geosynchronous Earth-Orbit or Geostationary Earth-Orbit) spacecraft, ACTS enabled uplink operations in the 30 GHz frequency block and downlink operations in the 20 GHz frequency block. Currently, GEO and LEO (Low-Earth Orbit) constellations utilize Ka-band and Ku- band frequencies for enabling high-speed, bandwidth-intensive Web services. 10.5.4 L-B AND AND S-B AND T RANSMISSIONS L-band operations employ the spectral block between the 1.5 and 2.7 GHz frequen- cies. S-band operations utilize spectrum between the 2.7 and 3.5 GHz frequencies. Satellite constellations such as INMARSAT (International Maritime Satellite) and Globalstar employ the L-band and the S-band for enabling paging services, cellular telephony, and data transmissions. 10.6 GSM, 3GSM, AND S-UMTS The satellite components of next-generation mobile communications networks inter- operate with terrestrial technologies such as IP (Internet Protocol), Frame Relay, ISDN (Integrated Services Digital Network), and ATM (Asynchronous Transfer Mode). In addition, satellite components also work in concert with second-generation GSM (Global System for Mobile Communications) networks, and third-generation 3GSM (Third-Generation GSM), S-UMTS (Satellite-Universal Mobile Telecommu- nications Service), and GMPCS (Global Mobile Personal Communications by Sat- ellite) configurations. 10.6.1 G LOBAL S YSTEM FOR M OBILE C OMMUNICATIONS (GSM) AND 3GSM (T HIRD -G ENERATION GSM) The success of GSM mobile radio systems has contributed to research initiatives that explore methods for augmenting the capacity of GSM and 3GSM networks. For example, Ericsson developed ACeS (Asia Cellular Satellite System), a combined satellite and cellular telephony system that provisions digital services to computer and mobile phone users throughout the Asia-Pacific service area bounded by Indo- nesia, Japan, Pakistan, and New Guinea. By merging satellite communications capa- bilities with GSM and 3GSM technologies, ACeS enables subscribers using Ericsson dual-mode portable communicators to switch between local cellular service and 0889Ch10Frame Page 444 Wednesday, April 17, 2002 2:58 PM © 2002 by CRC Press LLC satellite service as they roam throughout the service region. ACeS subscribers employ GSM SIMs (Subscriber Identity Modules) or 3GSM SIMs and network codes to access ACeS services when outside the ACeS coverage area. 10.6.2 S ATELLITE -U NIVERSAL M OBILE T ELECOMMUNICATIONS S ERVICE (S-UMTS) Distinguished by its provision of global coverage, satellite technology is viewed as a key enabler for global operations. S-UMTS supports seamless roaming and trans- parent handovers between terrestrial and satellite networks. S-UMTS operates in spectrum between the 1.980 and 2.010 GHz frequencies and between the 2.170 and 2.200 GHz frequencies. It is interesting to note that conventional mobile satellite services support operations in two 30 MHz (Megahertz) channels in the 2 GHz frequency bands. Low-Earth Orbit (LEO), Mid-Earth Orbit (MEO), and Geosynchronous or Geo- stationary-Earth Orbit (GEO) constellations support S-UMTS services. S-UMTS is designed to work in conjunction with the wireline Public Switched Telephone Network (PSTN) and technologies that include cable modem, DSL (Digital Subscriber Line), ISDN (Integrated Services Digital Network), ATM (Asynchronous Transfer Mode), and Gigabit Ethernet. A core IMT-2000 (International Mobile Telecommunications-2000) technology, S-UMTS supports interactive videoconferences that are compliant with the MPEG- 4 specification and the ITU-T H.323 Recommendation. Advanced S-UMTS services are expected to provision bandwidth on-demand for accommodating multimedia requirements. The S-UMTS (Satellite-UMTS) Forum supports the allocation of a 50 MHz spectral block in 2005 and a 90 MHz spectral block in 2010 for supporting universal broadband S-UMTS applications that are accessible at anytime and from every place. 10.6.3 G LOBAL M OBILE P ERSONAL C OMMUNICATIONS BY S ATELLITE (GMPCS) S PECIFICATIONS AND S ERVICES 10.6.3.1 World Telecommunications Policy Forum and ITU The World Telecommunication Policy Forum (WTPF) develops regulatory guide- lines for the deployment of third-generation GMPCS (Global Mobile Personal Com- munications by Satellite) systems. A core IMT-2000 (International Mobile Telecom- munications-2000) technology, GMPCS systems provision global, regional, and transborder personal telephony services, and enable access to narrowband and broad- band applications via GEO and LEO satellite constellations. Building upon the framework established by the WTPF, the ITU-T finalized GMPCS specifications by working with an informal group of GMPCS service providers, operators, and terminal manufacturers. This group approved procedures for GMPCS implementations and developed a Memorandum of Understanding (MoU) for provisioning GMPCS services. In conformance with this MoU, signatories such as Motorola agree to support the utilization of interoperable and compact GMPCS communicators so that GMPCS subscribers can use GMPCS-compliant devices, regardless of the manufacturer, in 0889Ch10Frame Page 445 Wednesday, April 17, 2002 2:58 PM © 2002 by CRC Press LLC each member state in the European Union in which GMPCS services are licensed. GMPCS MoU signatories also develop the framework for GMPCS maritime, aero- nautical, and terrestrial services and clarify system architecture for vehicular mobile Earth stations. 10.7 NATIONAL AND INTERNATIONAL STANDARDS ORGANIZATIONS AND ACTIVITIES Satellite service involves the use of radiowaves in the super high and extremely high frequency bands of the RF spectrum for enabling utilization of voice, video, images, and data services by educational military, government, and corporate entities. National administrations such as the Federal Communications Commission (FCC), the Canadian Department of Communications (DOC), and the European Technical Standards Institute (ETSI) establish procedures for frequency band allocations. The ITU (International Telecommunications Union) coordinates policies for spectral allocations internationally. 10.7.1 I NTERNATIONAL T ELECOMMUNICATIONS U NION -T ELECOMMUNICATIONS S ECTOR (ITU-T) The ITU-T (International Telecommunications Union-Telecommunications Stan- dards Sector) defines specifications for satellite transmission of digital television programs and supports utilization of MPEG-2-compliant applications for enabling uniform services in the ITU-T J.84 Recommendation. In addition, this Recommen- dation clarifies procedures for channel coding and modulation of voice, video, and audio signals received from satellite systems and distributed by Satellite Master Antenna Television (SMATV) networks. 10.7.2 I NTERNATIONAL T ELECOMMUNICATIONS U NION -T ELECOMMUNICATIONS D EVELOPMENT S ECTOR (ITU-D) The International Telecommunications Union-Telecommunications Development Sector (ITU-D) supports programs that provision affordable access to wireless appli- cations in rural and remote communities, and promotes implementation of satellite communications services in developing countries with a severe shortage of phone- lines. ITU-D initiatives are carried out in the African countries of Benin, Tanzania, Mali, and Uganda, as well as in India, Romania, and Vietnam. 10.7.3 D IGITAL A UDIO V ISUAL C OUNCIL (DAVIC) Based in Geneva, Switzerland, the ETSI-sponsored Digital AudioVisual Council (DAVIC) developed specifications for the design, implementation, and maintenance of satellite broadband video networks. To facilitate cost-effective transport and distribution of digital television services, DAVIC established agreed-upon methods for equipment interoperability. 0889Ch10Frame Page 446 Wednesday, April 17, 2002 2:58 PM © 2002 by CRC Press LLC [...]... distance and international telephony, HDTV (High-Definition Television) programming, and broadband applications © 2002 by CRC Press LLC 088 9Ch10Frame Page 4 48 Wednesday, April 17, 2002 2: 58 PM In 2000, the ITU established power limits for GEO, MEO, and LEO configurations and procedures for sharing spectrum between the 10 and 18 GHz frequency bands in the Ku-band These controls enable the coexistence of GEO,... operations via a Little LEO constellation that is expected to consist of approximately 288 satellites The Teledesic configuration © 2002 by CRC Press LLC 088 9Ch10Frame Page 450 Wednesday, April 17, 2002 2: 58 PM will enable bi-directional high-speed, location-insensitive connections to the Web and Virtual Private Networks (VPNs) in real-time and will provide on-demand gigalink services for multimedia... (GPS) are examples of MEO satellite fleets © 2002 by CRC Press LLC 088 9Ch10Frame Page 449 Wednesday, April 17, 2002 2: 58 PM 10 .8. 2.1 Constellation Currently in development, the Constellation satellite initiative will support voice, data, and fax applications and CDMA (Code-Division Multiple Access) technology for enabling subscriber access to broadband applications The Constellation MEO configuration consists... multimedia services, tele-healthcare, and tele-education The ARTES Program also enables utilization of broadband mobile services that work in conjunction with VSAT networks To support the ARTES Program, the European Space © 2002 by CRC Press LLC 088 9Ch10Frame Page 455 Wednesday, April 17, 2002 2: 58 PM Agency (ECA) establishes partnerships with the European Commission, member states in the European... (EUTELSAT) EUTELSAT provides digital and analog television programs, radio broadcasts, and multimedia services to more than 70 million homes connected to cable networks or © 2002 by CRC Press LLC 088 9Ch10Frame Page 4 58 Wednesday, April 17, 2002 2: 58 PM equipped with VSATs for DBS reception in the European Union, the Middle East, Africa, and Asia EUTELSAT also fosters development of multimedia digital platforms... regional and national networks such as Internet2 © 2002 by CRC Press LLC 088 9Ch10Frame Page 472 Wednesday, April 17, 2002 2: 58 PM The Oklahoma State University K–12 Distance Learning Academy uses OneNet to broadcast satellite telecourses in mathematics, German, and Spanish to students in Grades 3 to 12 In addition, the Oklahoma Telemedicine Network uses OneNet satellite services for enabling doctors at rural... distributed reception sites In conventional satellite networks, numerous programs are transmitted to the satellite and then rebroadcast to specified earth or ground stations or operators that then in turn distribute the programs to individual viewers For example, PBS (Public Broadcasting © 2002 by CRC Press LLC 088 9Ch10Frame Page 456 Wednesday, April 17, 2002 2: 58 PM System) distributes television programming... CRC Press LLC 088 9Ch10Frame Page 453 Wednesday, April 17, 2002 2: 58 PM Channel via Satellite) installations in a series of pilot implementations This DTTH (Direct-to-the-Home) system transports voice, video, and data and radio and television broadcasts directly to the subscriber site at 40 Mbps on the downlink path On the uplink path, transmissions at rates of 2 Mbps are enabled The ASTRA Broadband Interactive... and © 2002 by CRC Press LLC 088 9Ch10Frame Page 461 Wednesday, April 17, 2002 2: 58 PM telemetry from robotic planetary excursions, virtual participation in remote geological experiments, and real-time transport of echocardiograms NASA-NREN initiatives such as the NASA ATM Research and Industrial Studies (ARIES) demonstrate capabilities of mixed-mode satellite and terrestrial networks in supporting emergency... on smoking and cancer management, and hospital in-service staff education teleprograms on fire safety, violence in the workplace, and radiation safety © 2002 by CRC Press LLC 088 9Ch10Frame Page 4 68 Wednesday, April 17, 2002 2: 58 PM KUTM-TV also features satellite broadcasts for underserved school children and patients under hospice care 10.15.10 10.15.10.1 MARYLAND Baltimore City Public School System . Posi- tioning System (GPS) are examples of MEO satellite fleets. 088 9Ch10Frame Page 4 48 Wednesday, April 17, 2002 2: 58 PM © 2002 by CRC Press LLC 10 .8. 2.1 Constellation Currently in development, the Constellation. constellation that is expected to consist of approximately 288 satellites. The Teledesic configuration 088 9Ch10Frame Page 449 Wednesday, April 17, 2002 2: 58 PM © 2002 by CRC Press LLC will enable bi-directional. utilization of broadband mobile services that work in conjunc- tion with VSAT networks. To support the ARTES Program, the European Space 088 9Ch10Frame Page 454 Wednesday, April 17, 2002 2: 58 PM © 2002