Satellite Channels for Communication Connectivity

Satellite Channels for Communication Connectivity
Department of Electrical Engineering Indian Institute of Technology Kanpur Satellite Channels for Communication Connectivity Vishwanath Sinha Copyright © Telematics group Satellites for Communication Connectivity 1

COMMUNICATION CONNECTIVITY
Department of Electrical Engineering Indian Institute of Technology Kanpur SATELLITE CHANNEL for COMMUNICATION CONNECTIVITY COMMUNICATION from ANY PERSON to any PERSON at any PLACE The concept of a REPEATER (a BASE STATION) in the sky. Copyright © Telematics group Satellites for Communication Connectivity 2

Advantages of satellite linkages: VAST WIDE AREA COVERAGE
Department of Electrical Engineering Indian Institute of Technology Kanpur Advantages of satellite linkages: VAST WIDE AREA COVERAGE FLEXIBLE TRANSMITTER PARAMETERS DISTANCE INSENSITIVE COST STRUCTURE Disadvantages: RESTRICTED CHANNEL CAPACITY ORBITAL POSITIONS HIGH INITIAL INVESTMENTS LARGE SIGNAL PROPAGATION TIME Copyright © Telematics group Satellites for Communication Connectivity 3

Satellites have widely been used for -
Department of Electrical Engineering Indian Institute of Technology Kanpur Satellites have widely been used for - distribution functions; e.g. TV/radio broadcast/data navigation and aviation but now also for paging along with GPS (Global Positioning System) commercial mobile communication Long history of communication connectivity; but is still a very fertile area for research and development. Copyright © Telematics group Satellites for Communication Connectivity 4

and highly elliptical systems (HEO) like MOLNIYA
Department of Electrical Engineering Indian Institute of Technology Kanpur Satellite Orbits Not all regions are useful Outer Belt ~3.1 Earth Radii to 4.1 ER Inner Belt ~1.1 ER to 1.7 ER Not useful regions : ~ km above the surface of the earth ~ km above the surface of the earth LEO, MEO, GEO and highly elliptical systems (HEO) like MOLNIYA ORBITS OF SATELLITE SYSTEMS Copyright © Telematics group Satellites for Communication Connectivity 5

Department of Electrical Engineering
Indian Institute of Technology Kanpur Copyright © Telematics group Satellites for Communication Connectivity 6

GEOSTATIONARY SATELLITES 35,786 Km above the earth’s surface
Department of Electrical Engineering Indian Institute of Technology Kanpur GEOSTATIONARY SATELLITES 35,786 Km above the earth’s surface Advantages : Simple configuration Vast wide-area coverage capability (3 satellites at 1200 covers almost the entire globe) Minimum routing problems in the coverage area Insignificant doppler effect Copyright © Telematics group Satellites for Communication Connectivity 7

High transmitter power and large receiving antenna gains
Department of Electrical Engineering Indian Institute of Technology Kanpur Disadvantages : High transmitter power and large receiving antenna gains requirements (free space loss ~ 200 dB) Service to high latitudes not feasible Large signal propagation time (two-way propagation delay ~ 270 msec causing echo effect) Coverage to urban areas problematic (at high latitudes) due shadowing Copyright © Telematics group Satellites for Communication Connectivity 8

Even with the current high technologies of batteries and
Department of Electrical Engineering Indian Institute of Technology Kanpur Even with the current high technologies of batteries and hardware, the smallest terminal for a GEO is as large as A4 size paper and as heavy as 2.5 Kg (standard -M INMARSAT) NON-GEOSTATIONARY SATELLITES IN LOWER ORBITS REQUIRED An Access Technology is required that will meet the growing demand for high bandwidth wireless connectivity requirement. Copyright © Telematics group Satellites for Communication Connectivity 9

NON-GEOSTATIONARY SATELLITE SYSTEMS
Department of Electrical Engineering Indian Institute of Technology Kanpur NON-GEOSTATIONARY SATELLITE SYSTEMS Advantages of LEO/MEO systems over GEO Lower transmitter power requirement because of low orbit heights Higher average elevation angle (large number of satellites, hence satellite with short distance to be selected: better link quality) High operating reliability through increased redundancy Higher latitude region coverage Small signal propagation time Copyright © Telematics group Satellites for Communication Connectivity 10

Disadvantages of lower orbit satellites: Short link duration
Department of Electrical Engineering Indian Institute of Technology Kanpur Disadvantages of lower orbit satellites: Short link duration (more handover necessary) Smaller coverage area per satellite Complex system control Copyright © Telematics group Satellites for Communication Connectivity 11

Comparison of Different Satellite Systems
Department of Electrical Engineering Indian Institute of Technology Kanpur Comparison of Different Satellite Systems Parameters LEO MEO GEO Satellite cost Maximum Minimum Medium Satellite life (years) Handheld Possible Possible Very difficult terminals Propagation Short Medium Large delay Propagation Low Medium High loss Copyright © Telematics group Satellites for Communication Connectivity 12

Network Complex Medium Simple complexity
Department of Electrical Engineering Indian Institute of Technology Kanpur Parameters LEO MEO GEO Network Complex Medium Simple complexity Handoff Very Medium Not needed Development Long Short Long Period Visibility of Short Medium Always satellite Copyright © Telematics group Satellites for Communication Connectivity 13

Orbit Height Orbital Period Orbital Speed Radius of Illuminated Zone
Department of Electrical Engineering Indian Institute of Technology Kanpur Circular Orbits Orbit Height Orbital Period Orbital Speed Radius of Illuminated Zone (km) (min) (km/sec) (km) Copyright © Telematics group Satellites for Communication Connectivity 14

Nomenclature Frequency range Useful Satellite Services
Department of Electrical Engineering Indian Institute of Technology Kanpur Frequency Bands Nomenclature Frequency range Useful Satellite Services VHF MHz Messaging UHF MHz Military, Navigation, Mobile L GHz Mobile, Audio b’cast, radioloc. S GHz Mobile, Navigation C GHz Fixed Sat. Com. X GHz Military Ku GHz Fixed, Video b’cast K GHz Fixed Ka GHz Fixed, Video b’cast, ISL Copyright © Telematics group Satellites for Communication Connectivity 15

FREQUENCIES FOR SATELLITE SYSTEMS
Department of Electrical Engineering Indian Institute of Technology Kanpur FREQUENCIES FOR SATELLITE SYSTEMS Copyright © Telematics group Satellites for Communication Connectivity 16

In a constellation of satellites, the most efficient plan is to have
Department of Electrical Engineering Indian Institute of Technology Kanpur In a constellation of satellites, the most efficient plan is to have the satellites equally phased within a given orbital plane and the planes equally spaced around the equator. Total no. of satellites, N = ps ; s = no. of satellites per plane, p = no. of planes Optimal value for a given central angle  Copyright © Telematics group Satellites for Communication Connectivity 17

 related to minimum angle of elevation, earth’s radius (RE) and
Department of Electrical Engineering Indian Institute of Technology Kanpur  related to minimum angle of elevation, earth’s radius (RE) and the satellite orbit altitude (h); r = RE + h For example, Height Min. Elev.  s p km IRIDIUM GLOBALSTAR Copyright © Telematics group Satellites for Communication Connectivity 18

Study of Satellites for Access Several issues, including :
Department of Electrical Engineering Indian Institute of Technology Kanpur Study of Satellites for Access Several issues, including : Orbital considerations Channel modeling and capacity issues Propagation environment and interference Modulation techniques and performance issues Accessing issues Networking issues Handover issues Copyright © Telematics group Satellites for Communication Connectivity 19

Speech coding and quality
Department of Electrical Engineering Indian Institute of Technology Kanpur Antenna beamforming Speech coding and quality Integration of mobile satellite system with existing cellular systems Regulatory issues, etc. Some issues analogous to “SAT COM” environment, some to “Cellular” Only a few to be addressed Copyright © Telematics group Satellites for Communication Connectivity 20

KEY COMMUNICATION PARAMETERS
Department of Electrical Engineering Indian Institute of Technology Kanpur KEY COMMUNICATION PARAMETERS Elementary electromagnetic principles provide some key equations that are useful in any link design. Received Power is given by PR = T (PTGT/4R2).AR PT = Transmit Power GR = R (4  AR / 2) GT = Antenna Gain T, R = Antenna efficiencies R = distance in km between a transmitter and a satellite AR = Aperture Area of the satellite Antenna  = Wavelength Copyright © Telematics group Satellites for Communication Connectivity 21

PR = EIRP. GR . (1/Ls) ; where T/R  1;
Department of Electrical Engineering Indian Institute of Technology Kanpur PR = EIRP. GR . (1/Ls) ; where T/R  1; and Free Space Path Loss Ls = (4  R / )2 Overall Noise Power PN = kTsB Thus, PR/ PN = (EIRP. GR)/(Ls. k.TsB) Free space path loss LS in dB : LS = logR + 20logƒ R = distance in km between a transmitter and a satellite and ƒ = frequency of transmission in GHz. If N0 = kTs we can write the above expression in dB as Copyright © Telematics group Satellites for Communication Connectivity 22

The carrier to noise density is given by
Department of Electrical Engineering Indian Institute of Technology Kanpur The carrier to noise density is given by where if the equation is used for uplink, say between a mobile and a satellite, the EIRP is the mobile’s effective isotropic radiated power, the G/T is the satellite’s figure of merit, and K is the Boltzmann’s constant having value (10logK = dBW/K). Similar expression for downlink. Copyright © Telematics group Satellites for Communication Connectivity 23

The combined C/N0) in absolute value is
Department of Electrical Engineering Indian Institute of Technology Kanpur The combined C/N0) in absolute value is For a parabolic reflector (efficiency  = 0.65) the gain of the antenna is given by GdB = logD + 10logƒ D = dia. of the antenna in meters; ƒ is the frequency in GHz For the same antenna gain a tradeoff between f and D Copyright © Telematics group Satellites for Communication Connectivity 24

In a direction  with respect to the boresight of the value of the
Department of Electrical Engineering Indian Institute of Technology Kanpur In a direction  with respect to the boresight of the value of the antenna gain is given by where Gmax = (Dƒ/c)2 where ƒ is in Hz and c is the velocity of light. The diagrams illustrating these are Copyright © Telematics group Satellites for Communication Connectivity 25

This expression is valid for very small angles, generally between
Department of Electrical Engineering Indian Institute of Technology Kanpur Antenna Radiation Pattern (a) Polar representation (b) Cartesian representation This expression is valid for very small angles, generally between 0 and 3dB/2. Antennas with spherical characteristics are normally used for mobile users. For a particular application, various values for IRIDIUM are shown. Copyright © Telematics group Satellites for Communication Connectivity 26

Distance from boresight
Department of Electrical Engineering Indian Institute of Technology Kanpur Distance from boresight Characteristics of Satellite Antennas (Values for IRIDIUM) Copyright © Telematics group Satellites for Communication Connectivity 27

ORBITAL CONSIDERATIONS
Department of Electrical Engineering Indian Institute of Technology Kanpur ORBITAL CONSIDERATIONS Copyright © Telematics group Satellites for Communication Connectivity 28

From the diagram, one gets
Department of Electrical Engineering Indian Institute of Technology Kanpur From the diagram, one gets where  is the satellite elevation angle and r is the distance of the satellite from the centre of the earth = RE + h, RE being the radius of the earth and h = height of the satellite above the earth’s surface. For better connectivity, so that this effect of terrestrial interference and shadowing are minimum, the desirable value of  > 100. Copyright © Telematics group Satellites for Communication Connectivity 29

Radius of an illuminated zone, rcov, is given by
Department of Electrical Engineering Indian Institute of Technology Kanpur Radius of an illuminated zone, rcov, is given by rcov = RE[arc cos(REcosmin/r) - min] and the corresponding area covered by the satellite is where Copyright © Telematics group Satellites for Communication Connectivity 30

and hybrid of these. Parameters of interest:
Department of Electrical Engineering Indian Institute of Technology Kanpur MULTIPLE ACCESS Sharing of the physical resources, in terms of frequency bandwidth, time and power for multiple accessing a satellite transponder FDMA TDMA CDMA and hybrid of these. Parameters of interest: * Maximum throughput (or, ), ** Complexity, *** Control FDD, TDD Copyright © Telematics group Satellites for Communication Connectivity 31

Structure and architecture Satellite coverage area and cell structure
Department of Electrical Engineering Indian Institute of Technology Kanpur Let us first study some of the known non-GEO satellite systems that are for mobile applications before we consider other issues. The issues that need be considered besides orbital considerations would include Structure and architecture Satellite coverage area and cell structure Modeling of propagation characteristic Degradation due to atmospheric conditions like rain etc., degradation due mismatch etc. Interference in satellite radio network Copyright © Telematics group Satellites for Communication Connectivity 32

Interconnection of the satellite network to other networks
Department of Electrical Engineering Indian Institute of Technology Kanpur Handover Interconnection of the satellite network to other networks (mobile/fixed). We will take up only a few issues in this talk. Copyright © Telematics group Satellites for Communication Connectivity 33

IRIDIUM Department of Electrical Engineering
Indian Institute of Technology Kanpur IRIDIUM Copyright © Telematics group Satellites for Communication Connectivity 34

IDEALIZED CELL STRUCTURE OF IRIDIUM
Department of Electrical Engineering Indian Institute of Technology Kanpur IDEALIZED CELL STRUCTURE OF IRIDIUM Copyright © Telematics group Satellites for Communication Connectivity 35

Some key parameters for IRIDIUM (Motorola) are : Orbit : LEO
Department of Electrical Engineering Indian Institute of Technology Kanpur Some key parameters for IRIDIUM (Motorola) are : Orbit : LEO No. of satellites : (spares) No. of orbits : 6 (Polar) Height : 780 km Inclination : 86.40 Ground Stations : 21 Cells/satellite : 48 (spot beams) Services : voice, data, fax Copyright © Telematics group Satellites for Communication Connectivity 36

Special features : on-board processing; intersat link
Department of Electrical Engineering Indian Institute of Technology Kanpur Special features : on-board processing; intersat link Launch - service : Boeing (11 launches/55 satellites), provider China Great Wall (7/14), Khrunichev Proton (3/21) Weight/life of each S : 689 Kg./between 5 to 8 years Uplink/Downlink : MHz ;FDMA/TDMA Gateways : 12 (in 11 countries), GHz DL; GHz UL Inter Satellite Link : GHz Copyright © Telematics group Satellites for Communication Connectivity 37

GLOBALSTAR Department of Electrical Engineering
Indian Institute of Technology Kanpur GLOBALSTAR Copyright © Telematics group Satellites for Communication Connectivity 38

Indian Institute of Technology Kanpur GLOBALSTAR L-and-S band user links : MHz (user to satellite); MHz (satellite to user) C-band feeder links : MHz (gateway to satellite); MHz (satellite to gateway) Copyright © Telematics group Satellites for Communication Connectivity 41

CELL LAYOUT OF GLOBALSTAR DOWNLINK
Department of Electrical Engineering Indian Institute of Technology Kanpur CELL LAYOUT OF GLOBALSTAR DOWNLINK Copyright © Telematics group Satellites for Communication Connectivity 42

(Loral, Qualcom, Alcatel)
Department of Electrical Engineering Indian Institute of Technology Kanpur GLOBALSTAR (Loral, Qualcom, Alcatel) Orbit : LEO No. of satellites : No. of orbits : 8 (6 satellites each) Height : 1414 km Inclination : 520 Coverage : 700S to 700N latitude Ground Stations : 100 Copyright © Telematics group Satellites for Communication Connectivity 43

services : voice, data, fax Special features : path diversity
Department of Electrical Engineering Indian Institute of Technology Kanpur Cells/satellite : 16 services : voice, data, fax Special features : path diversity Copyright © Telematics group Satellites for Communication Connectivity 44

ARCHITECTURE OF SOME SYSTEMS
Department of Electrical Engineering Indian Institute of Technology Kanpur ARCHITECTURE OF SOME SYSTEMS We compare the architecture of one of the most commonly used cellular systems, GSM, with some of the promising mobile satellite systems, IRIDIUM and TELEDESIC. Copyright © Telematics group Satellites for Communication Connectivity 45

SATELLITE COVERAGE AREA AND CELL STRUCTURE
Department of Electrical Engineering Indian Institute of Technology Kanpur SATELLITE COVERAGE AREA AND CELL STRUCTURE Size and shape of cells produced by satellite antennas is dependent on the characteristic of the antenna used. Satellite antenna with BEAM FORMING Angle  is defined as usual. The cells are of circular shape. Antenna gain on the edge is given by G = Gmax - 3 dB Satellite antenna where BEAM FORMING is not possible. Copyright © Telematics group Satellites for Communication Connectivity 49

 is specified as spatial angle  seen by the satellite
Department of Electrical Engineering Indian Institute of Technology Kanpur  is specified as spatial angle  seen by the satellite between the cell centre and a point farther away on the earth’s surface. Cell boundaries are not circles. POSITION OF CELLS IN SATELLITE COVERAGE AREA GIVEN  SPOTBEAMS IN IRIDIUM ARE SHOWN Copyright © Telematics group Satellites for Communication Connectivity 50

(a) BEAM FORMING BY THE SATELLITE ANTENNA (b) DEFINITION OF  AND 
Department of Electrical Engineering Indian Institute of Technology Kanpur (a) (b) (a) BEAM FORMING BY THE SATELLITE ANTENNA (b) DEFINITION OF  AND  Copyright © Telematics group Satellites for Communication Connectivity 51

POSITION OF CELLS IN SATELLITE COVERAGE AREA
Department of Electrical Engineering Indian Institute of Technology Kanpur POSITION OF CELLS IN SATELLITE COVERAGE AREA Copyright © Telematics group Satellites for Communication Connectivity 52

latitude Longitude Department of Electrical Engineering
Indian Institute of Technology Kanpur latitude Longitude Copyright © Telematics group Satellites for Communication Connectivity 54

Modeling of Transmission Environment
Department of Electrical Engineering Indian Institute of Technology Kanpur MODELING Modeling of Transmission Environment (Also used for performance evaluation) - Two state (Gilbert Elliot) Markov model For non-shadowed conditions : RICIAN BEHAVIOUR shadowed conditions : RAYLEIGH / LOG-NORMAL BEHAVIOUR combination called Suzuki Process (LUNTZ MODEL) Copyright © Telematics group Satellites for Communication Connectivity 55

PROBABILITY DENSITY FUNCTION
Department of Electrical Engineering Indian Institute of Technology Kanpur PROBABILITY DENSITY FUNCTION Copyright © Telematics group Satellites for Communication Connectivity 56

I0 = modified zeroth order Bessel function
Department of Electrical Engineering Indian Institute of Technology Kanpur where of the received signal I0 = modified zeroth order Bessel function  = mean of the received power level 2 = variance of the received power level s : signal strength s0 = mean signal strength Copyright © Telematics group Satellites for Communication Connectivity 57

The combined prob. Density function for the channel model
Department of Electrical Engineering Indian Institute of Technology Kanpur The combined prob. Density function for the channel model A: Shadowing factor representing the probability of either being in the good state or in the bad state. Assuming a MF reception, (e.g. Viterbi decoder), the Eb/N0 can be directly calculated. With these background, one can model the satellite channel affected by FADING DUE SHADOWING and MULTIPATH PROPAGATION. Copyright © Telematics group Satellites for Communication Connectivity 58

MOBILE SATELLITE CHANNEL
Department of Electrical Engineering Indian Institute of Technology Kanpur ANALOG MODEL OF LAND MOBILE SATELLITE CHANNEL Copyright © Telematics group Satellites for Communication Connectivity 59

INTERFERENCE IN THE SATELLITE NETWORK
Department of Electrical Engineering Indian Institute of Technology Kanpur INTERFERENCE IN THE SATELLITE NETWORK 1. Co-channel interference (caused by the use of same radio channel in a neighbouring cluster) 2. Adjacent channel interference (……. in adjacent channels in the same cluster) Co-channel interference Copyright © Telematics group Satellites for Communication Connectivity 60

ex. ex. Department of Electrical Engineering
Indian Institute of Technology Kanpur ex. ex. Copyright © Telematics group Satellites for Communication Connectivity 61

CO-CHANNEL INTERFERENCE CAUSED BY THE USE OF THE SAME CHANNEL
Department of Electrical Engineering Indian Institute of Technology Kanpur CO-CHANNEL INTERFERENCE CAUSED BY THE USE OF THE SAME CHANNEL Copyright © Telematics group Satellites for Communication Connectivity 62

DEVELOPMENT OF UPLINK INTERFERENCE MODEL
Department of Electrical Engineering Indian Institute of Technology Kanpur DEVELOPMENT OF UPLINK INTERFERENCE MODEL Copyright © Telematics group Satellites for Communication Connectivity 63

DEVELOPMENT OF DOWNLINK INTERFERENCE MODEL
Department of Electrical Engineering Indian Institute of Technology Kanpur DEVELOPMENT OF DOWNLINK INTERFERENCE MODEL Copyright © Telematics group Satellites for Communication Connectivity 64

HANDOVER : When a call, during its progress, is to be transferred
Department of Electrical Engineering Indian Institute of Technology Kanpur HANDOVER (A Protocol) HANDOVER : When a call, during its progress, is to be transferred from one physical control mechanism to another (one base station to another), without interruption in connection. Requirement? Maintenance of an acceptable link quality throughout the call A mobile moving away from the service area of the controlling base station and entering service area of another base station : Copyright © Telematics group Satellites for Communication Connectivity 65

INTER-BASE-STATION HANDOVER
Department of Electrical Engineering Indian Institute of Technology Kanpur INTER-BASE-STATION HANDOVER (Better link quality from another base station) No. of handover  1/(Radii of the service area) INTRA-BASE-STATION HANDOVER (excessive interference) Parameters : Link Quality, Interference, Mobility Process : Link quality evaluation, handover initiation, allocation of radio and network resources Copyright © Telematics group Satellites for Communication Connectivity 66

HANDOVER IN MOBILE SATELLITE SYSTEMS
Department of Electrical Engineering Indian Institute of Technology Kanpur HANDOVER IN MOBILE SATELLITE SYSTEMS Base stations (Satellites) move, MS on earth almost fixed. With h = 1500 km (LEO), the satellite has a linear ground speed of about 7.1 km/s Cell radius of satellite systems very large compared to terrestrial cellular Intersatellite Hanover Required if The signal quality falls below a certain threshold, e.g., when the distance between the satellite and user has become too large; Copyright © Telematics group Satellites for Communication Connectivity 67

The signal carrier-to-interference ratio is too low, e.g., when
Department of Electrical Engineering Indian Institute of Technology Kanpur The signal carrier-to-interference ratio is too low, e.g., when other users are using the same channel causing co-channel interference. Copyright © Telematics group Satellites for Communication Connectivity 68

INTER-SATELLITE HANDOVER INTRA-SATELLITE HANDOVER
Department of Electrical Engineering Indian Institute of Technology Kanpur SATELLITE HANDOVER INTER-SATELLITE HANDOVER INTRA-SATELLITE HANDOVER INTER-SPOT HANDOVER INTRA-SPOT HANDOVE Copyright © Telematics group Satellites for Communication Connectivity 69

a : Movement of a coverage zone
Department of Electrical Engineering Indian Institute of Technology Kanpur (a) (b) a : Movement of a coverage zone b: Area of an IRIDIUM system cell overflown in one minute Copyright © Telematics group Satellites for Communication Connectivity 70

Intersegment Handover Protocol from GSM to Satellite Segment
Department of Electrical Engineering Indian Institute of Technology Kanpur Intersegment Handover Protocol from GSM to Satellite Segment Copyright © Telematics group Satellites for Communication Connectivity 71

CONNECTION OF BASE STATIONS OVER SATELLITES
Department of Electrical Engineering Indian Institute of Technology Kanpur CONNECTION OF BASE STATIONS OVER SATELLITES Copyright © Telematics group Satellites for Communication Connectivity 73

SYSTEM LEVEL INTEGRATION SCENARIO IN GSM SYSTEMS
Department of Electrical Engineering Indian Institute of Technology Kanpur SYSTEM LEVEL INTEGRATION SCENARIO IN GSM SYSTEMS Copyright © Telematics group Satellites for Communication Connectivity 74

a : IRIDIUM FOR CONNECTION OF A WLL SYSTEM
Department of Electrical Engineering Indian Institute of Technology Kanpur (a) (b) a : IRIDIUM FOR CONNECTION OF A WLL SYSTEM b : TELEDESIC FOR CONNECTION OF DECT-WLL AND GSM SYSTEMS Copyright © Telematics group Satellites for Communication Connectivity 77

Narrowband satellite systems concentrating on message transfer - (A)
Department of Electrical Engineering Indian Institute of Technology Kanpur Narrowband satellite systems concentrating on message transfer - (A) Copyright © Telematics group Satellites for Communication Connectivity 81

Narrowband satellite systems concentrating on message transfer - (B)
Department of Electrical Engineering Indian Institute of Technology Kanpur Narrowband satellite systems concentrating on message transfer - (B) Copyright © Telematics group Satellites for Communication Connectivity 82

a : Motorola has joined the Teledesic consortium in 1998
Department of Electrical Engineering Indian Institute of Technology Kanpur a : Motorola has joined the Teledesic consortium in 1998 Broadband satellite systems concentrating on data transfer - (A) Copyright © Telematics group Satellites for Communication Connectivity 83

Broadband satellite systems concentrating on data transfer - (B)
Department of Electrical Engineering Indian Institute of Technology Kanpur Broadband satellite systems concentrating on data transfer - (B) Copyright © Telematics group Satellites for Communication Connectivity 84

Broadband GEO satellite systems concentrating on data transfer - (A)
Department of Electrical Engineering Indian Institute of Technology Kanpur Broadband GEO satellite systems concentrating on data transfer - (A) Copyright © Telematics group Satellites for Communication Connectivity 85

Broadband GEO satellite systems concentrating on data transfer - (B)
Department of Electrical Engineering Indian Institute of Technology Kanpur Broadband GEO satellite systems concentrating on data transfer - (B) Copyright © Telematics group Satellites for Communication Connectivity 86

Satellite Channels for Communication Connectivity

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