Basic Satellite Communication Basic Satellite Communication (5)(5)

Ground Segment and Practical Ground Segment and Practical Aspects of SatComAspects of SatCom

Dr. Joseph N. Pelton

Typical VSAT SystemTypical VSAT System(Very Small Aperture Terminals)(Very Small Aperture Terminals)Applications

•Credit Card Validation•ATM/Pay at the Pump•Inventory Control•Store Monitoring•Electronic Pricing•Training Videos•In-Store Audio•Broadband Internet Access•Distance Learning

Apartment Buildings

Branch offices

Gas Stations

Corporate Offices

Residential

Corporate Data Center

Key Trends for Satellite and User TerminalsKey Trends for Satellite and User Terminals Satellite in general are becoming more capable, with higher power and

larger aperture antennas to promote frequency re-use and higher flux density. Thus satellites are increasingly massive (due to antenna and power systems) but are, in essence, highly capable “super-computers-in-the-sky” with specialized digital software.

This allows user terminals to become smaller, lighter in weight and still handle broader band services. This is sometimes called technology inversion. Overall systems costs have decreased because of the explosion of low cost user terminals that can now receive video via hand-held units.

User terminals with Geo-systems do not have to be re-pointed, but LEO or MEO-systems must be able to track or have omni (or quasi-omni) antennas so that signals can be received from all possible angles.

Key in User TerminalsKey in User TerminalsGrowth in VSATs towards 1 million with virtually all of

them optimized via new IP over Satellite (IPoS) standard.Size of VSATs has decreased from around 3 meters down

to about 1 to 1.2 meters and costs have continued to decline especially driven by Digital Video Broadcast and DOCSIS standards that allow very high speed low cost links (i.e. 45 to 60 Mbps) with return channel service (RCS) that allows up stream speeds in the 56 to 384 kbps range.

Ground Equipment TrendsGround Equipment TrendsTerminalsOmni directional or “patch” antennasSmaller, lighter, cheaperYet more capable (i.e. video signals & broadband)Pocket, notebook, ruggedSophisticated (ASIC driven) yet simpleApplication specific terminals, embedded modems

PhonesSatellite capability + 3 GSM frequencies + “video”Voice, Asynchronous Data and Packet DataSmaller (antenna and battery in particular)Long stand-by mode

Minimal Set-Up Time, Robust, Portable, Easy to Use

Rural – Hybrid NetworksRural – Hybrid NetworksInternet backbone distribution using satellite –

local distribution using 2.4 GHz wireless

Satellite-Fiber ComparisonSatellite-Fiber ComparisonComparing Satellite and Fiber CharacteristicsComparing Satellite and Fiber Characteristics

Capability Fiber Optic Cable Systems

Geo Satellite in a Global System

Meo Satellite in a Global System

Leo Satellite in a Global System

Transmission Speed

10 Gbps – 3.2 Terabits/second*

Single Sat 1Gbps-10Gbps

Single Sat 0.5Gbps-5Gbps

Single Sat .01Gbps-

2Gbps

Quality of Service

10-11 - 10-12 10-2 - 10-11 10-2 - 10-11 10-2 - 10-11

Transmission latency

25 to 50 ms 250ms 100-150 ms 25-75 ms

System Availability w/o

Backup

93 to 99.5% 99.98% (C-Ku band )

99% (Ka band)

99.9% (C-Ku band)

99%( Ka band)

99.5% (L-C-Ku band )

99% (Ka band)

Broadcasting Capabilities

Low to Nil High Low Low

Multicasting Capabilities

Low High High Medium

Trunking Capabilities

Very High High Medium Low

Mobile Services Nil Medium-to-High High High

Dramatic decrease in the cost of Dramatic decrease in the cost of Fiber Optic SystemsFiber Optic Systems

1995lifetime

Satellite Based IP Services GrowingSatellite Based IP Services Growing Demand for all types of IP based satellite services is

growing including VoIP and MMIP. Satellite service today requires special “spoofing”

systems to achieve reasonable transmission efficiency (85% + possible with the best system from Mentat, ViaSat, etc. and use of the new IPoS standards.

Improvements can be achieved by increasing window sizes to reduce misinterpretation of latency for system congestion, spoofing software, and other modifications to satellites to address IP Security issues.

Satellite Lifecycle and Failure ModesSatellite Lifecycle and Failure Modes Most failures occur at start or end of life Many satellite failures are due to software or operator

errors rather than hardware failures Infant Failures (deployment of antenna and solar arrays,

failure to reach proper orbit, etc.) End-of-Life Failures and Wear-out (MTTF) Bathtub Curve of Satellite Failures Catastrophic Failures can occur at any time. (Orbital

debris, Electro-Magnetic Storms, Cosmic Rays, Micro-meteorites, etc.)

Satellite Employment Patterns Satellite Employment Patterns 1998-2004 1998-2004 (97,000 to 162,000)(97,000 to 162,000)

Launch Vehicle Manufacturing of Experimental SatComSatellite Manufacturing

Ground Equipment Manufacturing

Satellite Services

1998 1999 2000 2001 2002 2003 2004

190,000

170,000

150,000

130,000

110,000

105,000

100,000

98,000

96,000

0

Satellite Technologies of the FutureSatellite Technologies of the FutureOn-Board ProcessingSignal RegenerationAdvanced Antenna Systems (hopping/scanning

beams, phased-array, inflatable structures, piezo-electric systems)

More Efficient Power SystemsTurbo-codingAdvanced Modems and Enhanced Vocoder

Algorithms and Error Correction Systems

Satellite Technologies of the FutureSatellite Technologies of the Future

More Efficient Use of SpectrumNew Materials for Light Weight Antennas

and Satellite ConstructionAdvanced Orientation and Propulsion

Systems (and Autonomous Operation)Advances in Launch SystemsUSATs, VSATs, Micro-terminals (MEMS &

ASIC break-throughs)

Course ReviewCourse Review

Satellite Services and Markets (Overview)Development of Satellite Technology from

the 1960s onwardBasic Elements of Satellite TransmissionSatellite Orbits (Pros and Cons)Satellite Frequencies and Spectrum AllocationKey Satellite Terms & Concepts

AssignmentAssignment

Assignment 6:– Write short notes on the terms highlighted in

yellow color