1

Prepared for

Communication System Objectives Reliable and available connections where needed Good quality Minimum delay Sufficient capacity Affordable cost

Efficient use of resources (recurring) Equipment value priced (one time)

2

Prepared for

Digital Comm System Model

SourceEncoder

UpConverterModulatorChannel

EncoderPower

Amplifier

Low NoiseAmplifier

ChannelDecoder Demodulator Down

ConverterSource

Decoder

voicefax

videosensors

data

reconstructedinformation

TransmitAntenna

ReceiveAntenna

conditioned/encodeddata streamdigital version

of source content

analog signal

3

Prepared for

Transmission Tradeoffs Analog or Digital Transmission

Analog signals represent information by varying some aspect of the signal in accordance with the original voice or video

Noisy channels degrade analog signals Amplifiers can be added, but they amplify noise as well

as signal The longer the signal path, the more noisy the result Digital transmission mitigates

Problems with additive noise during transmission Signal degradation during regeneration (e.g., repeaters)

4

Prepared for

Signal with Added Noise

Signal

Signal plus Noise Amplified

5

Prepared for

Digital Coding of Signals Represent information as a sequence of

samples:

At each sample time, choose the closest sample from the available set of values

6

Prepared for

Sample Transmission Each sample is represented by a group of

bits (example: 8 bits) Sending the information consists of sending a

stream of bits Suppose a 1 is represented by a positive

voltage, and 0 by negative:

1

0 0

1 1 1

7

Prepared for

Effects of Noise As long as the noise doesn’t obscure the bit

value, it will not affect ability to decode!

1

0 0

1 1 1

8

Prepared for

Recovery of Analog Signal

Digital-to-Analog

Converter

SmoothingFilter

bits samples analogsignal

9

Prepared for

Frequency Band Trade-off Frequency band

Lower frequencies bend, bounce, and follow the curvature of the earth, but do so in ways difficult to predict

Higher frequencies result in more dependable transmission characteristics, but travel only in straight lines

Covering a broad geographic region using the dependable higher frequencies requires a satellite to direct signals where they’re needed

10

Prepared for

One Optimal Selection Microwave frequencies

Line-of-sight propagation Predictable characteristics Requires satellite for broad geographic coverage while

avoiding use of repeaters Digital transmission

Efficient source coding algorithms Performance independent of distance Speech, video compatibility with data

11

Prepared for

Why Satellite? Can be more cost effective

Cost of use is independent of distance Service where you need it Price stability

Easy and fast service deployment No infrastructure required Remote sites can be assembled and on-air in under 30 minutes

Quality of service and capabilities can exceed terrestrial Availability & reliability Uniform service over coverage area Capability (rates, throughput, multicasting, etc.) Flexibility (types of service) Control & network monitoring

12

Prepared for

Why Satellite? (cont.)

Commercial Applications Voice, fax and telco data Internet & intranet networking Data and Bandwidth-on-Demand Video conferencing

Consumer Applications TV & Radio broadcasting Internet services Future

Telephony Internet

Public

Networks

Private

Networks

13

Prepared for

SATCOM Historical Summary

Viterbi Coding

Turbo Coding

RS Coding

SCPC Modem: 6-8 RU

SCPC Modem: 2 RU

SCPC Modem: 1 RU

1st (TDMA) VSATDeveloped & deployed(M/A-COM Linkabit)

DAMA: TDMA & SCPC

Big TDMA Systems

DVB / MPEG

BroadbandVSATs

14

Prepared for

SATCOM Overview Satellite Orbits

Geosynchronous Low-earth orbit Medium earth orbit Specialized

Orbit has considerableeffect on system costand capability

15

Prepared for

SATCOM Systems (by Service Type) Fixed Satellite Services (FSS)

Refers to fixed pointing requirement of the receiving /transmitting antenna used by the ground station as a GEO satellite system is used. Services include voice, fax, low and high-speed data. Terminal antennas range from very small (1.2 – 2.4M) VSAT to larger earth stations (3.7M to 18M).

Broadcast Satellite Services (BSS) A special category of FSS that requires the use of high-power GEO satellites for

the express purposes of broadcasting entertainment content (e.g., TV). FSS services are not permitted on a BSS satellite. The terminal antenna is small (0.5 to 1.0M) and is receive only.

Mobile Satellite Services (MSS) Provide voice and lower speed data services to a portable or mobile device on a

regional or global basis. Typically these systems operate in the lower frequency bands (S, L, and VHF). These terminals range from handheld phones (e.g., Iridium, Globalstar) to laptop sized terminals (e.g., Inmarsat)

16

Prepared for

SATCOM Frequency Bands

17

Prepared for

Satellite System Summary

18

Prepared for

Satellite Payloads On-board electronics

Bent-pipe: Acts like a microwave repeater in the sky

(receive, frequency down convert, amplify, transmit) Onboard processing

Decodes data and makes intelligent decisions based on content (e.g., routing, multiplexing, beam reuse, etc.)

Antennas Fixed Adjustable: steerable, beam forming, phase array, etc.

19

Prepared for

How FSS works

Satellite acts like a repeater in the sky Ground equipment translates signal

Am plifier/FrequencyConverter

Cu stom erPrem ises

Equipm ent

Custom erPrem ises

Equip m ent

Uplink Downlink

Outdoor Unit(ODU)

Indoor Unit (IDU)

ProtocolController Modem/Codec

I.F. Interface(70 or 140 MHz)

20

Prepared for

Power & Bandwidth When either is used up, transponder is full

< 70 percent of transponder BW used (operational considerations) System designers try to match bandwidth and power allocation to maximize utilization

Calculate requirements (Link Budget) End-user pays for the maximum resource used

Bandwidth (or PEB) or Power Controllable design considerations

Antenna size Modulation & FEC Coding

Fixed design considerations Location Available satellites Satellite performance parameters

(somewhat adjustable if full transponder lease)

Space Segment Resources

dBWdBW

HzHz

Power Limited

BW Limited

21

Prepared for

Space Segment Resources (cont.)

Transponder bandwidths 27, 36, 48, 54 or 72 MHz

Costs can vary widely Market location

Typical 36 MHz from US$1M - $2 M per year

Partial transponder use is higher Service type: premptable or non-premptable Coverage beam

22

Prepared for

Satellite Resource Reuse Spatial Reuse

Antenna beam width is narrow enough to see only one satellite

Spot beams on satellite only illuminate a portion of the earth

23

Prepared for

Satellite Resource Reuse (cont.)

Polarization Reuse Orthogonal signal polarization allows two links at same

frequency on same satellite Circular: right & left hand (no feed adjustment) Linear: vertical & horizontal (requires feed adjustment)

24

Prepared for

Coverage Beams Global

Lowest power; large user antennas Greatest connectivity All sites receive all signals

Hemispherical Large geographical area

Spot/Regional Smallest coverage Highest power May not be able to receive own uplink signal

25

Prepared for

Satellite Operator (example)

PamAmSat Polar View

26

Prepared for

Satellite Example PanAmSat XI

27

Prepared for

Trends in Transponder Usage (FSS)

33%

20%22%

20%5%

TV RelayDTH TVVoice TrunkingVSAT/WANInternet

2001 (Actuals)

Source: ViaSatellite Magazine

33%

28%

12%

15%

12%TV RelayDTH TVVoice TrunkingVSAT/WANInternet

2004 (Forecast)

28

Prepared for

Trends in SATCOM Design More powerful transponders More sophisticated on-board processing

Focused primarily on mass-market services (consumer and business)

More sophisticated RF power management in VSAT terminals (e.g., mitigate need for “static” power margin)

Lower cost terminals by leveraging mass-market components (e.g., DBS (DVB/MPEG), Cable (DOCSIS))

More efficient transmission technology Higher order modulation (8-PSK, 16-QAM) More power forward error correcting codes (e.g., turbo) Bandwidth saving techniques (PCMA)

29

Prepared for

The Network Cost Budget Three main factors in determining

total cost of ownership Satellite Space Segment Cost

(Recurring)

Equipment Cost(Capital)

Operating Costs(Maintenance, Staff, etc.)

Space segment costs typically dominate unless right technology is applied $6K/mo/MHz (a good rate) Can be much more expensive

Technology & design implementations can reduce bandwidth/power requirements substantially

30

Prepared for

Link analysis is key trade-off tool Essential in making wise decisions

Capital cost vs. Recurring cost Implementation trade-off

Used to determine Antenna sizing across network Size of RF amplifiers Modem capability requirements Power head-room for future data rate increase

Optimize across entire network Helps to evaluate/compare various vendors’ solutions

SATCOM channel efficiencies Advanced features (e.g., power control, adaptive coding, etc.)

Must have concurrence with satellite operator for space segment pricing

31

Prepared for

Signal Transmissions System components

Satellite Earth stations

Transmit Receive

Environment Space loss Weather

32

Prepared for

Transmission Impairments Free space path loss

Absorptions, reflections, refractions, & scintillation Increases with lower antenna elevations Increases with frequency

Weather Frequency dependent Antenna elevation

Additive noise All electronic equipment creates noise Earth radiation/noise Sun (solar flares, sun outages, etc.) Induces transmission errors (random, statistical)

Interference (add’l slide)

33

Prepared for

Degradations (cont.)

Free-space lossdominates

34

Prepared for

That dB term Logarithmic ratio

10 Log (V1 / V2) Logs permit simple

addition

35

Prepared for

Interference Sources Adjacent satellites Other earth stations

Impacts satellite receive front end Adjacent carriers Cross pole carrier “bleed thru” Solar radiation

Sun spots Sun Outages

2x / year around Spring & Fall Equinox

Local RF Radiation C-band terrestrial microwave

Pwr

BW

36

Prepared for

Sun Outage Calculators Tools available on-line or in SatMaster Pro

http://www.panamsat.com/global_network/calc_sun_outage.asp

37

Prepared for

Design Trade-offs Satellite trade-offs

Available footprints for geographical coverage Type of coverage (global, hemi, spot) Frequency (Ku or C) Performance parameters (fixed unless lease entire transponder)

Antenna Size Modulation Forward Error Correction (FEC) Coding Data rates & information compression Transmission channel access & transmission efficiency

38

Prepared for

Antenna Size vs. Gain vs. Frequency A matter of physics Assumes 65% feed efficiency

Ant Size (M) Ku - Tx Ku - Rx C - Tx C - Rx0.75 39.1 37.6 31.8 27.91.0 41.6 40.1 34.3 30.41.2 43.2 41.7 35.9 32.01.8 46.7 45.2 39.4 35.52.4 49.2 47.7 41.9 38.03.7 53.0 51.4 45.7 41.74.5 54.7 53.1 47.4 43.45.6 56.6 55.0 49.3 45.36.0 57.2 55.6 49.9 45.97.6 59.2 57.7 51.9 48.08.1 59.8 58.2 52.5 48.59.5 61.2 59.6 53.8 49.9

Antenna Gain (dB)

39

Prepared for

Modulation Method to convert digital input to analog signal Phase Shift Keying

BPSK – binary (2) QPSK – quadrature (4) 8-PSK

Quadrature Amplitude Modulation (QAM) 16 level

frequency

Magnitud

eModulation & BW

BPSKQPSK

16 QAM

8PSK

40

Prepared for

Modulation improvements 8PSK & 16QAM available from several vendors

SCPC DVB 8PSK & 16QAM standardization coming

Higher level modulation waveforms are more susceptible to channel anomalies

Require higher power satellites and/or larger dishes High bandwidth applications driving demand

41

Prepared for

Bandwidth vs. Power FEC Code Rate

Higher coding gain less power, but more bandwidth

FEC R=7/8

frequency

Magnitud

e FEC R=3/4

FEC R=1/2

Channel Spacing Power vs adjacent channel interference Nominal (1.4x) “Packed” (1.1x to 1.2x) requires additional signal power (0.2 to 0.5 dB) to compensate

42

Prepared for

Turbo code performance Low throughput delay Occupies ~50% of BW

for equivalent RS coding performance

1E-1

1E-2

1E-3

1E-4

1E-5

1E-6

1E-7

1E-8

1E-92 3 4 5 6 7 8 9 10 11 12

E /Nb oQPSK .32 TurboQPSK .79 Turbo

Rate ¾ Viterbi + RSRate ½ ViterbiUncoded

R1/2 +RS QPSK

1 MHz

0.79 Turbo QPSK

.56 MHz

Rate ½ Viterbi + RS

43

Prepared for

The Impact of Modulation & Coding

44

Prepared for

Link Analysis At CapRock Analysis guidelines being implemented

Consistency Calculation ease Cleaner interface to satellite operators Paper trail

Standardization of: Analysis tools

Intelsat: LST program Eutelsat: under consideration All other operators: SatMaster Pro

Assumptions and parameters to be used Link Budget Methods & Practices Link Budget Parameter Tables

45

Prepared for

Key Guidelines Satellite parameters

Location specific (EIRP, SFD, G/T) parameters or an average approximation should be used for location specific parameters; worst case (contour edge) should be used only when directed

Power Equivalent BW (PEB) determination is dependent on satellite operator used

Earth station parameters Standard configurations FEC coding limits (min) RF power amplifier (PA) back-offs

Single carrier & multi-carrier configurations

46

Prepared for

Key Guidelines (cont.) Other considerations

Bandwidth rounding Depends on satellite operator Round after summing all circuits, not on individual

Link performance: 1 x 10-6 (min) for data/IP data/VoIP and 1 x 10-4 (min) for compressed voice (non-VOIP)

Link availability: total amount of time that a service is available over a period of time (usually expressed over 12 months) The greater the availability the higher the operating costs Good starting point is 98% (175 outage hrs)

Availability = (1 – (HUB + RF + UNK)) / (TT-CI-SO) x 100 HUB = hub failuresRF = link outagesUNK = Unknown outagesTT = Total time in hours in reporting periodCI = Customer induced outagesSO = Schedule outages (maint, etc.)Typically excludes Force Majeure events

47

Prepared for

Key Guidelines (cont.) Optimization guidelines

Circuit tariff (SCPC) approach: select coding to optimize the full duplex link for best balance between power (PEB) and BW; use asymmetric coding rates to further optimize (if available)

Bulk tariff/network/BOD approach: select coding to optimize for a TOTAL best balance between PEB and BW across network

One-time costs vs. recurring cost: trade-off remote antenna size for best power/bandwidth balance; customer tolerance to antenna size should be specified

Recurring optimization: : updates to teleport facilities or equipment configuration changes should be taken into account for existing customers; re-optimize for new services and participate in existing services review

48

Prepared for

Link Budget Request Form

49

Prepared for

Link Budget Generalizations All programs perform analysis using the same

rules but with varying degrees of incorporated details (e.g., adjacent satellite interference factor) If all assumptions are the same, then results between

programs should be within 5 to 15% Required BW and PEB scales linearly with data

rates (Intelsat – Subsea7 example) Data Rate

(Kbps)PEB

(MHz)BW

(MHz)512 0.4523 0.4779

1024 0.9046 0.95572048 1.8091 1.9115

50

Prepared for

VSAT Terminal Characteristics Very Small Aperture Terminal (VSAT) Antenna (aperture) sizes < 3.5 M Low cost Terminals are located on user premises Data rates typically < 2 Mbps

VSAT-101 Part 2 has all the details

51

Prepared for

Increasing FSS Resource Efficiency

(Supplement)

52

Prepared for

Increasing FSS Resource Utilization Bandwidth can be a bottleneck

Higher power satellites are available Looking for > 1.5 bit/Hz capacity

(QPSK, Rate ¾ FEC)

New approaches in production 8 PSK & 16 QAM (multiple vendors) Turbo codes (multiple vendors) Frequency reuse

(PCMA--ViaSat patent)

53

Prepared for

Frequency f1 & f2

W Hz

PCMA – Frequency Re-use Allows 2 different satellite signals on one carrier

2-way circuits only Can be used with asymmetric links (power or bandwidth)

Frequency

f1

f2

W HzW Hz

54

Prepared for

PCMA -- “Paired Carrier Multiple Access” Overlapping uplink signal is subtracted

(cancelled) to get desired downlink

Terminal 1 Uplink Terminal2 Uplink

Downlink = Terminal1 +

Terminal2

- -Rx Terminal2 Rx Terminal1

55

Prepared for

PCMA (Paired Carrier Multiple Access) Patented technology that permits two carriers to

operate on same frequency Bandwidth is reduced by up to 1/2 Power is slightly (0.3 dB) increased over standard

frequency pair approach Design network to take advantage of BW savings

Balance power & bandwidth with antenna size FEC (concatenated coding or turbo codes)

Operating BW reduction means Less space segment cost for given amount of services More services for given amount of space segment

56

Prepared for

Cost Savings Example Scenario

10 site network with 384 Kbps carriers Star topology--hub and 10 remotes Full-duplex

QPSK Rate 1/2 Coding 11 MHz bandwidth needed Monthly cost = $66,000; $792K/year Equipment cost $300K (assumes SCPC)

With PCMA Savings = $33,000/mo Savings = $396K/year

Savings pays forthe hardware inless than a year!!

57

Prepared for

System Availability(Supplement)

58

Prepared for

Definition of Availability

Availability is the probability that an item will be able to perform its designed functions at the stated performance level, within the stated conditions and in the stated environment when called upon to do so.

ReliabilityReliability + Recovery

Availability =

59

Prepared for

Quantification

Percent Availability

N-Nines Downtime Time Minutes/Year

99% 2-Nines 5,000 Min/Yr

99.9% 3-Nines 500 Min/Yr

99.99% 4-Nines 50 Min/Yr

99.999% 5-Nines 5 Min/Yr

99.9999% 6-Nines .5 Min/Yr

60

Prepared for

PSTN : The Yardstick? Individual elements have an availability of

99.99% One Cut off call in 8000 calls (3 min for

average call). Five ineffective calls in every 10,000 calls.

Facility Facility EntranceEntrance Facility Facility

EntranceEntrance

ANAN0.01 %0.01 %

0.005 %0.005 % 0.005 %0.005 %

0.02 %0.02 %

0.005 %0.005 % 0.005 %0.005 %

LELE

NINI

LELE

NINI

LDLD

ANAN0.01 %0.01 %

PSTN End-2-End Availability 99.94%

NI : Network InterfaceLE : Local Exchange LD : Long Distance AN : Access Network

Source : http://www.packetcable.com/downloads/specs/pkt-tr-voipar-v01-001128.pdf

61

Prepared for

Calculating Availability: Series

EE11 EE22 EE33

.999999 .999999

.999991xx = .9999890

Multiplicative method: E1 x E2 x E3= As

Additive method of UA (unavailability).00000

1.000009.00000

1++ = .000011

0Total Availability of a system (As) is always less than the least available element.

One Weak Link Significantly Weakens This One Weak Link Significantly Weakens This Chain!Chain!

62

Prepared for

Calculating Availability: Parallel

Additive Rule: As = E1+ E2 – E1 E2

Multiplicative Rule: As = 1–[(1-E1)(1-E2)]Not for Parallel Systems Where Both Elements Are Not for Parallel Systems Where Both Elements Are RequiredRequiredAssumption is that Switchover Time is zeroAssumption is that Switchover Time is zero

As = .999999+.999999-(.999999*.999999)As = .999999999999

For 1 out of 2 redundancy..EE11

EE22