ADVANCED TECHNOLOGY

SATELLITES IN THE

COMMERCIAL ENVIRONMENT

Volume 1: Executive Summary

Future Systems Incorporated

4 Professional Drive, Suite 141

Gaithersburg, Maryland 20879 U.S.A.
ADVANCED TECHNOLOGY

SATELLITES IN THE

COMMERCIAL ENVIRONMENT

Volume 1: Executive Summary

March 1984

Prepared for

NASA-LEWIS Research Center

21000 Brookpark Road

Cleveland, Ohio 44135

Prepared by

Future Systems Incorporated

7640 Standish Place

Rockville, Maryland 20855

Telephone: (301) 294-9117
1.

4

7

9.

12

Report No. 2. Government Accession No.

CR 174635

Title and Subtitle

Assistance to NASA in the Study of

Advanced Communications Satellites

Author(s)

Performing Organization Name and Address

Future Systems, Incorporated

4 Professional Drive, Suite 141

Gai thersburg, MD 20879

Sponsoring Agency Name and Address

NASA Lewis Research Center

21000 Brookpark Road

Cleveland, OH 44135

3

5

6.

8.

10.

11

13

14.

Recipient's Catalog No.

Report Date

Performing Organization Code

Performing Organization Report No

Work Unit No

Contract or Grant No.

NAS3-23783

Type of Report and Period Covered

Volume I: Executive Summary

Sponsoring Agency Code

15 Supplementary Notes

Project Manager, David Namkoong

One other volume prepared - Volume II, Main Report

16 Abstract

It is now possible to place relatively large communications satellites in geostationary

orbit, using the Shuttle. Other advanced technoloy, such as the use of 30/20 GHz (Ka) band has

reached or is near the point of commercial use. The satellite industry, however, is in a state

of transition from the early state with few operators, to a later state with many diverse operators

and correspondingly many satellites. It is not clear if or how advanced technology will be

incorporated into this enviroment.

This report postulates one set of scenarios, based on a set of traffic demand forecasts

derived from previous contracts performed by Western Union and ITT. The scenarios use a demanddriven model to launch new satellites, with other limits on the available (and economical)

technology. The results using a Low Traffic Forecast show a continuing oversupply of transponders.

However, the scenarios using a High Traffic Forecast show that considerable advanced technology

including the use of 30/20GHz will be needed to satisfy demand.

17. Key Words (Suggested by Author(s) I

Communications Satellites, 30/20GHZ, ACTS,

Geostationary Platforms

19 Security Classif. (of this report)

Unclassified

18. Distribution Statement

Unclassified

20. Security Classif (of this page) 21 No. of Pages 22 Price"

Unclassified

* For sale by the National Technical Information Service, Springfield, Virginia 22161

NASA-C-168 (Rev 10-75)
EXECUTIVE SUMMARY

1.0 Task 1

The basic aim of Task 1 is to massage the forecasts provided by

Western Union and ITT in order to obtain a forecast of transponder requirements

including various factors. The WU and ITT forecasts are of satellite addressable

traffic. This merely postulates the fraction of total traffic that is susceptible to

satellite carriage. The end product of Task 1 purports to be a forecast of traffic

that actually will be carried by satellite. Certain assumptions about system

configurations are also implicit in this process.

The factors that we included in Task 1 are, in order: interpolation of

the WU and ITT baseline year values to produce yearly figures; estimation of

satellite capture; effects of peak-hours and the time-zone staggering of peak

hours; circuit requirements for acceptable grade of service; capacity of satellite

transponders, including various compression methods where applicable; and requirements for spare transponders in orbit. As part of Task 1, we also estimated the

geographical distribution of traffic requirements.

These manipulations were applied to the basic forecasts to yield the

gross, in-orbit transponder forecases shown in Figures 1 and 2.

Summary

Table 1 illustrates the effect that various processes in Task 1 have had

on the base forecasts. We have illustrated this with the low traffic forecast for

1990. The basic satellite-addressable forecast is considered to be the normalized

value of 1.0. The table shows the relative value after processing through the

indicated stage. Thus, the combined effects of previous stages are included in

these figures. In general, the capture fraction calculation had the most effect.

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Table 1

Normalized Effects on the

Low Forecast - 1990

Stage Voice

Video

Data Conferencing TV

Base Forecast

(satellite-addressable) 1.0

After Satellite Capture 0.21

Includes Time Zone

Effects 0.144

Includes Grade-ofService Factors 0.165

Includes Transponder

Spares 0.205

1.0

0.37

0.546

0.546

0.682

1.0

0.90

0.84

1.074

1.15

1.0

1.0

1.0

1.0

1.07
2.0 Task 2

Task 2 required the formation of a model for the satellite industry. Of

course, this model was primarily used to estimate the response of the industry to

the traffic forecasts of Task 1.

Various factors were unknown; we made assumptions that in some cases

were varied to form different scenarios. Since we implemented the model using a

computer program, other variations could be readily evaluated. We deliberatly

kept the number limited to avoid flooding the reader with data, much of which

would be useless.

Supply and Demand

An important consideration is the availability of orbital slots at the

desired frequency band or bands. We have recently seen what a great effect such a

limitation can have on the plans of would-be system operators. Depending on the

needs of the customer base to be addressed, there may be one band which is more

desirable than others; however, if slot is not available, then the operator will be

out of luck.

In Table 2 the longitude limits which we used in this study are shown

together with the number of slots available at two degree spacing at each

frequency band.

We have calculated the available supply (without launching any as-yet

unannounced satellites) in two ways: first, using only the satellites that have been

approved, and second, using all satellites for which we have information.* The

figures also include random failures of transponders, but don't include-relatively

recent events such as the failure of twelve transponders on SATCOM II (which is

almost dead anyway). These projections are plotted in Figures 3 and 4, along with

the Low and High traffic forecasts respectively.

*Note that several of the most recent group of satellites were not included. This

work was done before their applications were filed.
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Table 2

Orbital Arc

Number Orbital

Band of Slots Range

6/4 35* 59°-101°

119° - 143°

14/12 34 59°-105°

120°-139°

30/20 23 75°-119°

*Based on 1983 assignments, these are actually only 30

slots. The 35 figure assumes all 2° spacing.

Practical Satellite Efficiency

In constructing an actual multi-beam satellite, we would not necessarily

have to provide the maximum possible capacity per beam, but could use the

assumed traffic distribution to tailor the satellite to the beam loading. That is, if

at saturation a given beam will only carry 2 transponders, then we only install 2

transponders for that beam. Thus, although the efficiency with which the beam

pattern is used wiH be low, the efficiency with which the physical facilities of the

satellite are used will be much higher.

This can best be illustrated by some examples. These are shown in

Table 3.
Table 3

Satellite Capacity Examples

Band

C or Ku

30/20

C or Ku

30/20

C or Ku

30/20

C or Ku

30/20

CNet

24

24

36

36

48

48

96

96

N

1

10

18

10

27

10

96

10

Efficiency

T?

100%

49%

24%

49%

22%

49%

13%

49%

Gross

Capacity

24

29

45

41

61

53

144

101

Satellite Industry Scenarios

The model is traffic-driven, and includes a number of assumptions about

the distribution of traffic among the various frequency bands. Because of these

assumptions, we have run the model using several scenarios, varying the assumed

behavior to show the sensitivity of the results. Virtually all of the scenarios

converge to systems which make use of multiple-spot-beam antennas and/or the

30/20 GHz band. The specific traffic distributions and satellite constellations don't

all converge, however, and the difference can provide some illustration of the

effects of different constraints.

Scenario Results

Detailed results for all scenarios are too lengthy for inclusion in this

Summary. Tables 4 through 6 and Figures 5 through 7 were chosen as a covering

range of realistic conditions.
:=.i IMMARY FOR

CASE #1 — SOME DEMAND FOR EACH BAND — NO LIMIT ON C-BAND OR \ U-BAND

CAPACITY EXCEPT STRICTLY TECHNICAL. AS ESTIMATED.

LOW TRAFFIC FORECAST

FREQUENC V BAND

C-BAND I-U-BAND PA-BAND

MAX I MUM SATELL I TE ( TRANSPONDERS ; :

YEAR LAUNCHED:

FIRST MULT I BEAM SATELITE IN:

GROSS CAPACITY'

1 930

1990

2000

37 37 c.5

1 9 9 4 1 '•' '-' 9 2 0 0 0

1 9'-' 4 1 '~i~>'~> 1 c'92

1 28 0 0

672 744 O

'-n7 842 180

NET CAPACITY

1980

1990

2000

1 ~"'O

j_'_*

672

812

744

0

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164

AVERAGE CAPACITY

1980

r

r

'90

2000

19

24

u

Table 4

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SUMMARY FOR

CASE #1 — SOME DEMAND FOR EACH BAND — NO LIMIT ON C-BAND OR KU-BAND

CAPACITY EXCEPT STRICTLY TECHNICAL AS ESTIMATED.

HIGH TRAFFIC FORECAST

FREQUENCY BAND

C-BAND KU-BAND KA-BAND

MAXIMUM SATELLITE (TRANSPONDERS):

YEAR LAUNCHED:

FIRST MULT I BE AM SATELITE IN:

GROSS CAPACITY

1 980

1990

2000

58

1996

1 992

128

672

1329

61

1 999

1 996

0

744

1 1 48

84

2000

1 992

O

0

641

NET CAPACITY

1980

1990

20OO

1 ii'"t

i>72

1 133

0

744

1016

0

0

595

AVERAGE CAPACITY

1980

1990

2000

19

24

38

0

22

34

0

0

58

Table 5
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SUMMARY FOR

CASE #1C — SOME DEMAND FOR EACH BAND — 24 TRANSPONDER LIMIT AT C-BAND

36 TRANSPONDER LIMIT AT KU-BAND

HIGH TRAFFIC: FORECAST

FREQUENCY BAND

C-BAND KU-BAND KA-BAND

MAXIMUM SATELLITE (TRANSPONDERS):

YEAR LAUNCHED:

FIRST MULT I BE AM SATELITE IN:

GROSS CAPACITY

1 980

1990

2000

NET CAPACITY

1980

1990

2000

AVERAGE CAPACITY

1980

1990

2000

24

1986

0

128

672

840

128

672

840

19

24

24

45

1995

1995

0

744

1233

0

744

1075

0

22

36

86

1998

1 992

0

0

908

0

0

849

0

0

65

Table 6

14
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15
3.0 Earth Station Forecasts

The growth of the earth station population is roughly proportional to

the traffic, varying according to the kind of traffic (i.e. — CPS or trunking or TV,

etc.). The number' of earth stations per transponder of traffic has historically been

an increasing function with time, and we expect this to continue within reasonable

limits. For TVRO or very thin route stations, the practical limits are quite high or

non-existant. However, for stations which carry a significant amount of traffic

and require access to one or more transponders on a continuous basis, there are

fairly low limits.

The earth station size mix will also vary according to traffic category.

This is partly an economic decision, since a smaller earth station of less complexity

and lower price will be needed to make lighter traffic economical to carry.

However, the consideration of physical placement is very important for CPS

services. This is especially so at Ku-band and 30/20 GHz, since these stations will

be located in metropolitan areas (as well as elsewhere) and hence must be as

unobtrusive as possible.

Since the various scenarios produce somewhat different distributions of

traffic among the frequency bands, we estimated the earth station requirements

for each one. Summary results of earth station requirements are shown in Table

7.

16
Table 7

Scenarios

Low Traffic

1

2

3

High Traffic

1

2

3

IB

2B

3B

1C

2C

3C

Total Earth Station

the Year

C-band

3,384

5,887

4,830

10,180

13,167

11,492

7,477

7,949

7,870

7,477

7,949

7,870

Estimates for

2000

Ku-band

3,168

1,223

2,281

11,460

9,830

11,498

9,377

8,974

9,053

11,953

11,949

12,467

Ka-band

556

0

0

5,837

4,478

4,487

10,621

9,388

9,388

8,047

7,579

7,137

17
4.0 Economic Analysis - Task 2

Satellite communications has developed into a rather large business,

with total investment in current satellites of over $1 billion in the U.S. domestic

systems alone. According to a recent article, the worldwide communications

satellite market is approaching $3 billion per year, excluding ground segment. Thus

it is important that we examine the effect of our postulated future satellites on

the overall market, in economic terms.

The cost of satellites launched during each scenario run in Task 2 was

estimated using the SAMSO cost model. Launch costs were estimated based on the

weight of the satellite and the costs of known launch vehicles. All these figures

were expressed in 1983 dollars to provide a common standard.

We also estimated costs for the example earth station configurations

that we used, using data of our own, plus information developed by Western Union.

Table 8 shows the total cumulative costs of meeting the earth station

requirements postulated in Section 11. We have not included costs for networking

of trunk and shared CPS earth stations in these costs.

Space segment costs are also shown. Investments for known satellites

(i.e. - not generated by the program) are not included.

18
Table 8

Cumulative Investment Costs

for Scenario Runs

(millions of 1984 dollars)

Scenario

Space

Segment

Ground

Segment

Low Traffic

1

2

3

7,545

8,072

7,469

4,797

4,576

4,682

High Traffic

1

2

3

10,528

11,239

10,340

14,270

14,150

14,340

IB

2B

3B

13,143

12,287

12,287

13,868

13,337

13,330

1C

2C

3C

11,506

11,500

10,330

14,203

14,264

14,315

19
5.0 Summary and Conslusions

This report has covered a rather wide range of topics relating to

satellite communications in the U.S. To one extent or another, of course, the

various results depend on one another and on assumptions that we made during the

course of the study. Some of these assumptions are more arguable than others, for

instance, our selection of data rate for a CPS transponder, and our speculations

about the courses of action of the several long-haul carriers using satellite

transmission. Given the traffic forecasts that we began with, however, we are of

the opinion that no reasonable variation of assumptions would change the magnitude of either the high or low traffic forecast by more than a factor of about two.

Conclusions from the Scenarios

With the currently-mandated 2 degree spacing at C-band and Ku-band,

the scenario runs clearly indicate that the average capacity needed at each band is

relatively modest for the Low traffic cases, and feasible, but rather advanced for

the High traffic. It's worth noting that the 2B and 3B scenarios used every slot,

even at 30/20 GHz. However, it would be instructive to investigate different ways

in which this capacity might be provided. The scenario runs present one way, but

not the only way, in which satellites might be launched to satisfy demand. The

various possibilities might be loosely classified as: Multiple Small Satellites (as in

the scenarios); Multiple Hybrids of modest specific capacity; Rapid Transition to

Large Satellites.

The Role of Satellites in the Overall Communications Structure

Satellites are, and will remain, ideally suited for broadcast applications.

It is hard to conceive of a development in terrestrial communications technology

that would undermine this advantage, at least in the United States. There are a

number of countries whose physical extent is limited enough that it is actually less

expensive for them to install a terrestrial broadcast system (for TV and radio) than

to launch a satellite or even share a satellite for DBS purposes. However, our large

land area and common interests, along with our seemingly inexhaustible appetite

for programming, will ensure a continuing role for satellites in broadcast. But

what of point-to-point communications?

20
In point-to-point communications, satellites have been used mainly to

enable the "great leap" whereby new communications modes are offered, or

conventional modes expanded or opened to competition. This leap is generally

necessary because terrestrial communications systems suffer from a "critical

mass" or "critical density" syndrome. Until and unless the density of users becomes

relatively high, the distance-sensitivity of terrestial links makes the cost of the

system exorbitant. An added user is likely to cause the system to incur a very high

added cost. Once the density of users is high enough, the incremental cost per user

drops and continues to drop as the user base expands. In a satellite system,

different rules prevail.

An additional satellite user always incurs (roughly) the same incremental cost no matter where he is located. The network can therefore add service

points and grow without penalizing any particular users with high costs. This

feature makes satellites ideal for new systems or modes of communications, where

users are initially few and far between. This is why satellites have been used for

trans-oceanic communications, greatly expanding the available facilities and

improving quality, and for new services such as wideband data communications and

videoconferencing.

As such services become better established, and the density of users

increases, terrestrial technologies begin to encroach. This process can readily be

seen at work today. It is our view that several factors will keep satellites viable

for many years. Among these are: the continuing existance of remote users, the

competitive environment in the U.S., and the economic advantage of existing

facilities.

Footnote; The Year 2000

The year 2000 has become something of a touchstone for long-range

planning. Indeed, one sometimes gets the impression that there is a veil drawn

across time which prevents us from seeing beyond that date. The usual short-term

focus of commercial firms, for whom five years is "long-range", probably causes

some of the reluctance to look beyond the end of the century.

21
However, it's our opinion that some interesting things will just be

beginning to happen by the year 2000, in communications and in space generally.

We are already in a position where the firm plans of communications carriers today

wiH affect the actual events of the early 1990s. This leaves relatively little scope

for action if we limit our future vision to the year 2000. To alter the course of

events requires either enormous power acting in a short time, or a long time for

moderate influence to be effective. We respectfully note that we (and NASA) are

more likely to be in the latter position than the former. Therefore, we need to

look further and identify decision points that are within the range of our influence.

22