NTIA-REPORT-80-32

Sharing of the Band

12.2-12.7 GHz Between the

Broadcasting-Satellite

and Fixed Services

H. Akima

u.s. DEPARTMENT OF COMMERCE

Ph ilip M. Klutzn ick, Secretary

Henry Geller, Assistant Secretary

for Communications and Information

January 1980

TABLE OF CONTENTS

Page

LIST OF SYMBOLS AND ABBREVIATIONS iv

ABSTRACT 1

1. INTRODUCTION 1

2. INTERFERENCE FROM BSS TO FS 2

2.1. Introduction 2

2.2. Interfering BSS Power 2

2.3. Receiver Noise Power 3

2.4. Interference to an FDM-FM Telephony System 5

2.5. Interference to an FM TV System 6

2.6. Interference to a Wideband Digital System 8

2.7. Summary 8

3. INTERFERENCE FROM FS TO BSS 9

3.1. Introduction 9

3.2. Permissible Limit of Interfering FS Signal Power 9

3.3. FS Signal Power Received by a BSS Receiver 10

3.4. Areas Where Interference is Intolerable 11

3.5. Sharing With FS of U.S. Applications 14

3.6. Sharing With FS of Canadian Applications 17

3.7. Summary 20

4. CONCLUSIONS 21

5. ACKNOWLEDGMENTS 22

6. REFERENCES 23

APPENDIX A. THE U.S. PROPOSAL OF REVISION OF THE INTERNATIONAL FREQUENCY

ALLOCATION TABLE IN THE BAND BETWEEN 11.7 GHz and 12.75 GHz 24

APPENDIX B. EXISTING STUDIES ON SHARING BETWEEN BSS AND FS 27

APPENDIX C. SOME STATISTICS OF THE 1977 WARC-BS PLAN FOR REGIONS 1 AND 3 35

iii
BS

BSS

CCIR

Comsat

D

dB

dBi

dBm2

dBW

DRS

FCC

FDM

FM

FS

FSS

GHz

GWARC

Hz

IFRB

ITU

kHz

km

m

MHz

NF

PFD

RF

SBS

SNR

SPM

TV

W

WARC

W'ARC-BS

LIST OF SYMBOLS AND ABBREVIATIONS

broadcasting service (terrestrial)

broadcasting-satellite service

International Radio Consultative Committee

Communications Satellite Corporation

diameter of antenna

decibel(s)

decibel(s) relative to isotropic antenna gain

decibel(s) relative to 1 m2 (one meter squared)

decibel(s) relative to 1 W(one watt)

Digital Radio System

Federal Communications Commission

frequency-division multiplex

frequency modulation

fixed service (terrestrial)

fixed-satellite service

gigahertz

General World Administrative Radio Conference

hertz

International Frequency Registration Board

International Telecommunication Union

kilohertz

kilometer(s)

meter(s)

megahertz

noise figure

power flux density

radiofrequency

Satellite Business System

signal-to-noise ratio

Special Preparatory Meeting

television

watt(s)

World Administrative Radio Conference

World Administrative Radio Conference for the Planning of the BroadcastingSatellite Service

iv
TI

wavelength (of a radio wave)

ratio of circumference to diameter of a circle

off-axis angle (of an antenna)

v

SHARING OF THE BAND 12.2-12.7 GHz BETWEEN THE BROADCASTING-SATELLITE AND

FIXED SERVICES

Hiroshi Akima*

The United States Administration has proposed for the 1979 WARe

(World Administrative Radio Conference) to move the BSS (broadcastingsatellite service) in ITU (International Telecommunication Union) Region

2 from the band 11.7-12.2 GHz to the band 12.2-12.7 GHz, which is also

allocated to the terrestrial FS (fixed service). This report discusses

the potential of sharing between the BSS and the FS in the band 12.2-

12.7 GHz. It is concluded that sharing is feasible under certain

conditions.

Key words: 1979 WARC (World Administrative Radio Conference), band sharing,

BSS (broadcasting-satellite service), FS (fixed service),

interference

1. INTRODUCTION

The U.S. preparatory effort for the 1979 WARC (World Administrative Radio

Conference) of the ITU (International Telecommunication Union) has concluded that the

existing shared allocation of the band 11.7-12.2 GHz between the BSS (broadcastingsatellite service) and FSS (fixed-satellite service) (space-to-Earth) in ITU Region 2

is irisufficient to meet the demands of these services (FCC, 1978). The United States

Administration has, therefore, proposed that the allocations for the BSS and FSS

(space-to-Earth) in the band 11.7-12.2 GHz in Region 2 be separated in such a way

that the FSS (space-to-Earth) is retained in the band 11.7-12.2 GHz and the BSS is

moved to the band 12.2-12.7 GHz. This separation of the two space services should

provide a greatly increased capacity for each of the services. This and related

proposals are shown in Appendix A.

If the band 12.2-12.7 GHz is allocated to the BSS, however, it must be shared

between the BSS and the terrestrial FS (fixed service), to which it is also allocated

as a primary service. Although various aspects of such sharing have been discussed

in several studies (CCIR, 1978 a, b, c; Comsat, 1978; SBS, 1978; Western Union, 1978;

Lee et al., 1979), each study is not necessarily complete enough to give a clear

picture of sharing between the BSS and the FS. As shown in Appendix B, some

conclusions of these studies even contradict each other. In this present study, we

try to give a clear and comprehensive picture of the sharing by examining various

*The author is with the Institute for Telecommunication Sciences, National Telecommunications and Information Admini~tration, U.S. Dept. of Commerce, Boulder, CO

80303.
cases of the sharing and by demonstrating in which cases, and how, the sharing

between the BSS and FS is feasible.

2. INTERFERENCE FROM BSS TQ FS

2.1. Introduction

Interference from BSS to FS (i.e., interference caused by a BSS transmitter on

an FS receiver) is considered tolerable, if the interfering BSS signal power is very

small compared with the wanted FS signal power. Judgment as to whether the interference is tolerable, therefore, can be made by comparing the interfering BSS signal

power with the wanted FS signal power. This way of judgment, however, requires

knowledge of both the FS signal power and the signal-to-interference protection

ratio. Unless the measured value for the operational FS system or the design value

for the planned system is available, the value of the signal power must be estimated

from the system noise power and the required SNR (signal-to-noise ratio), or from the

wanted-signal transmitter power, the antenna gains, and the propagation loss. The

signal-to-interference protection ratio depends on the type of information signal,

the type of modulation, the SNR·, and the required signal quality. When all of the

above items are not known, some of them must be postulated. This may leave unsettled

arguments.

The same judgment can be made in a simpler way by comparing the BSS signal power

with the noise power of the FS receiver. Regardless of the type of information

signal and type of modulation, a communication system is designed in such a way that

the wanted signal power is greater than the receiver noise power by a ratio, called

signal-to-noise protection ratio, with some system margin. If the interfering signal

power is small compared with the noise power, therefore, the interfering signal

reduces the system margin only by a small amount, and the performance of the wanted

system remains at an acceptable level. This way of judgment will obviate the need

for postulating some of the debatable assumptions.

2.2. Interfering BSS Power

To determine the BSS signal power received at an FS receiver, we first examine

the PFD (power-flux density) of the BSS signal on the surface of the Earth. The PFD

of the BSS signal to be exceeded for 99% of the worst month at the edge of the BSS

service area should be equal to -103 dBW/m2 for service areas in Regions 1 and 3,

and -105 dBW/m2 for service areas in Region 2 (ITU, 1977, p. 82). The PFD at the

center of the service area is 3 dB higher than that at the edge. In clear weather,

2
the PFD are higher than the above values by the amount ,of rain attenuation. Although

the rain attenuation largely depends on the rain-climatic zones and the elevation

angle of the satellite, the attenuation exceeded for not more than 1% of the worst

month is limited to a maximum of 2 dB (ITU, 1977, p. 91). Therefore, the PFD of the

BSS signal at the center of the service area should be bet~en -100 dBW/m2 and

-98 dBW/m2 in Regions 1 and 3, and between -102 dBW/m2 and -100 dBW/m2 in Region 2,

The analysis of the 1977 WARC-BS (World Administrative Radio Conference for the

Planning of the Broadcasting-Satellite Service) plan for Regions 1 and 3 (ITU, 1977,

Article 11) indicates that the clear-weather PFD at the center of the service area

falls in a range between -100 dBW/m2 and -97 dBW/m2 (with a center value of

-98,5 dBW/m2) in nearly 90% of the assignments and that it can be as high as

-94.7 dBW/m2 (see Appendix C). Since the PFD for Region 2 is 2 dB lower than that

for Regions 1 and 3, we will take -100.5 dBW/m2 and -96.7 dBW/m2

as the typical value

and the maximum value, respectively~ of the PFD of the BSS signal at the center of

the service area.

Next, we convert the PFD to the signal pow~r received with an isotropic antenna.

This is done by multiplying the PFD by the effective area of the isotropic antenna,

which is represented by A2/(4n), where A is the wavelength. At the frequency of

12.45 GHz, which is the center frequency of the band 12.2-12.7 GHz, the effective

area of an isotropic antenna is calculated to be 0.00004622 m

2, or -43.3 dBm2.

Therefore, the typical value and the maximum value of the BSS signal power received

with an isotropic antenna at the center of the service area are -T43.8 dBW and

-140.0 dBW, respectively.

Finally, we convert the signal power received with an isotropic antenna to the

signal power received with an FS receiving antenna by multiplying by the gain of the

latter antenna. The reference pattern of a circular-aperture parabolic antenna used

in a microwave radio-relay system is given in CCIR (International Radio Consultative

Committee) Report 614 (CCIR, 1974). Using the equation given there, we calculate the

off-axis gain of the antenna as a function of the antenna diameter and the off-axis

angle. The result is sho\vn in Table 1. The typical value and the maximum value of

the BSS signal power received by an FS receiver so obtained are given in Tables 2 and

3, respectively.

2.3. Receiver Noise Power

Since we have calculated the interfering BSS signal power at the output of the

receiving antenna, we will calculate the receiver noise power at the same reference

point. This reference point ;s before ,any intervening circuits such as the waveguide

and branching circuit if the antenna is used for both reception and transmission.

3
Table 1. Off-Axis Antenna Gain of a Circular-Aperture

Parabolic Antenna (The ¢ denotes the off-axis

angle, and 0 denotes the antenna diameter.)

Antenna Gain (dB)

ep

(degrees) 0=0.6 m 1.0 1.5 2.0 ~2.41

20 5.5 3.3 1.6 0.3 0.0

15 8.6 6.4 4.7 3.4 2.6

10 13.0 10.8 9.1 7.8 7.0

Table 2. Typical Value of the BSS Signal Power Received by an

FS Receiver (The ¢ denotes the off-axis angle, and

o denotes the antenna diameter.)

Signal Power (dBW)

¢

(degrees) D=D.6 m 1.0 1. 5 2.0 22.41

20 -138.3 -140.5 -142.2 -143.5 -143.8

15 -135.2 -137.4 -139.1 -140.4 -141 .2

10 -130.8 -133.0 -134.7 -136.0 -136.8

Table 3. ~1aximum Value of the BSS Signal Power Received by an

FS Receiver (The ¢ denotes the off-axis angle, and

o denotes the antenna diameter.)

Signal Power (dBW)

¢

(degrees) 0=0.6 m 1.0 1.5 2.0 ~2.41

20 -134.5 -136.7 -138.4 -139.7 -140.0

15 -131 .4 -133.6 -135.3 -136.6 -137.4

I 10 -127.0 -129.2 -130.9 -132.2 -133.0

4
The NF (noise figure) of the receiver in the 12 GHz range is considered to range

between 4 dB and 6 dB with a preamplifier, and between 8 dB and 25 dB without a

preamplifier. These NF values are at the input of the receiver excluding the

intervening circuits. To convert these values to the values referenced at the

receiving antenna output~ the loss of the intervening circuits must be added (in

decibels} to the NF values at the receiver input. We will take a value of 10 dB as a

typical value of the NF at the reference point.

The noise power is proportional to the bandwidth. The spectral density of the

noise power is represented by NF - 204 dBW/Hz. With the assumed NF value and with

1 MHz as the unit of the bandwidth, it becomes -134 dBW/MHz. This value will be used

as the noise-power spectral density of a typical FS receiver in the following

discussions.

2.4. Interference to an FDM-FM Telephony System

~1any short-range FDM-FM telephony systems are in operation as FS systems in this

band in the United States. Typical receiver bandwidths are 12 MHz and 20 MHz. In an

FDM-FM telephony system, degradation of the system performance caused by an interfering signal depends on the power spectral density of the interfering signal as well

as the total power of the interfering signal. Even if the total interfering-signal

power is so small that the wanted FDM-FM system continues to operate above its

threshold, ,some telephone channels may be degraded severely if the power spectral

density of the interfering signal is very high in these channels.

First, we will compare the total power of the interfering BSS signal with that

of the noise. The total noise power is -123 dBW in a 12-MHz bandwidth, and -121 dBW

in a 20-MHz bandwidth. These values are several decibels higher than -127 dBW, which

is the interfering BSS signal power in the worst case given in Table 3. The total

power of noise plus interfering signal is only one decibel higher, at most, than the

noise power alone in this case. Therefore, the operation of the wanted FDM-FM system

should remain above the threshold in all cases if the system is designed with a

reasonabie margin in SNR.

Next, we will compare the power spectral density of the interfering signal with

that of noise. Since the 1977 WARe-BS specifies the power (or energy) dispersal that

corresponds to a peak-to-peak deviation of 600 kHz for BSS (ITU, 1977, p. l04)~ the

power of a BSS signal is considered to be uniformly distributed in a 600-kHz bandwidth in the worst case. Therefore, the comparison of the power spectral density can

be made equivalently by comparing the total power of the interfering signal with the

noise power contained in a 600-kHz bandwidth.

5
The noise power in a 600-kHz bandwidth is estimated to be

-134 + 10 log 0.6 = -136.2 dBW. Since this value is about the same order as the

values of the BSS signal power given in Tables 2 and 3, the effect of the interfering

BSS signal is not considered negligible. The post-demodulation baseband noise power

in a telephone channel is 3 dB higher with the noise plus interference than with the

noise alone if the power spectral density of the interfering signal is equal to that

of the noise. Tables 4 and 5 show the increases in the baseband noise power caused

by the interfering BSS signal, calculated with Tables 2 and 3. These tables show the

relation among the off-axis angle of the BSS satellite from the main beam of the FS

receiving antenna, the FS receiving antenna diameter, and the required system margin

against the interference in the design of the FS system. In the worst case of

¢ = 100 and D = 0.6 m considered in Table 5, a margin of 10 dB is required. The

required system margin decreases as the off-axis angle and/or the antenna diameter

increases. In the receiving site where the elevation angle of the BSS satellite is

200 , the required system margin is less than 4 dB regardless of the antenna diameter.

When the antenna diameter is equal to or greater than 2.41 m, the required system

margin is less than 5 dB even if the elevation angle is 10°.

2.5. Interference to an FM TV System

An FM TV relay system of a small number of hops (not more than five hops) is

considered as an FS system in this band in France (CeIR, 1978c). The channel bandwidth considered in this system is 27 MHz. ~e fS system considered in the preceding

se~tion is used also to transmit an FM TV signal in the United States. Consideration

of interference to an FM TV system is essentially the same as that of interference to

an FDM-FM telephony system in that both the total power and the power spectral

density of the interfering signal must be considered.

Insofar as the total interfering-signal power is concerned, the discussion on

the FDM-FM telephony system given in the preceding section also applies. Even with

the interfering signal, the system remains operating above its threshold.

Since the power spectrum of the BSS signal is considered to be uniform in a

600-kHz bandwidth for the purpose of interference analysis, the discussion of the

interference to the FDM-FM telephone system given in the preceding section also

applies to the interference to an FM TV system. The interfering BSS signal causes

the baseband noise power spectral density in the victim FM TV system to increase in a

part of the baseband by the ratio given in Tables 4 and 5. If the system margin is

greater than this ratio, the interference is considered tolerable.

6
Table 4. Increase in the Baseband Noise Power Due to the Interfering BSS

Signal (Typical values of BSS signal power shown in Table 2 are

used. The ¢ denotes the off-axis angle, and 0 denotes the

antenna diameter.)

Increase in Baseband Noise Power (dB)

¢

(degrees) 0=0.6 m 1.0 1.5 2.0 2:2. 41

20 2.1 1.4 1.0 0.7 0.7

15 3.5 2.4 1.. 8 1.4 1.2

10 6.5 4.9 3.8 3.1 2.7

Table 5. Increase in the Baseband Noise Power Due to the Interfering BSS

Signal (Maximum values of BSS signal power shown in Table 3 are

used. The ¢ denotes the off-axis angle, and 0 denotes the

antenna diameter.)

Increase in Baseband Noise Power (dB)

<P

(degrees) 0=0.6 m 1.'0 1.5 2.0 2:2.41

20 3.9 2.8 2.0 1.6 1.5

15 5.3 4.5 3.5 2.8 2.5

10 9.3 7.8 6.4 5.5 4.9

7
2.6. Interference to a Wideband Digital System

A trunking-type coast-to-coast application of a wideband digital system is

considered as an FSsystem in this band in Canada (CeIR, 1978b). The receiver bandwidth considered i~ 240 MHz. In this FS system, degradation of the system performance caused by interfering signals depends on the ratio of total interferingsignal power to total noise power in the receiver bandwidth.

Since the bandwidth of the FS system is 240 MHz and the minimum spacing between

BSS assignments in a BSS service area is 2x19.18 = 38.36 MHz (ITU, 1977, Article 11),

up to six BSS signals may interfere with the FS system simultaneously. In the worst

case of ¢ = 100 and 0 = 0.6 m considered in Table 3, the total ass interfering-signal

power can be as high as -127.0 + 10 log 6 = -119.2 dBW. On the other hand, the total

noise power is -134 + 10 log 240 = -110.2 dBW for the bandwidth of 240 MHz. Therefore, the total interfering-signal power is 9 dB less than the total noise power even

for the assumed worst-case conditions. It can be concluded from this result that

degradation of the performance of this FS system caused by the BSS interfering

signals is negligible.

2.7. Summary

8y comparing the interfering BSS signal power with the FS receiver noise power,

we have studied interference from the BSS to the FS. The FS systems considered

include an FDM-FM telephony system used in the United States, an FM TV system used in

France and the United States, and a wideband digital system envisioned in Canada.

The results of the study indicate that i·nterference from the BSS to the FSis,

in general, not a serious problem. The signal power from a broadcasting satellite

received by an FS receiving antenna is usually smaller than the FS receiver noise

power. The total power of noise plus interfering signal is not more than one decibel

higher than the noise power alone in most cases. Therefore, the operation of the FS

system should remain above the threshold in all cases if the system is des~gned with

a reasonable margin in the SNR.

The interfering BSS signal will increase the baseband noise power in some

telephone channels in the FDM-FM telephony system and the noise power spectral

density in some part of the baseband in the FM TV system. These increases, however,

will be less than 10 dB even in the worst case. These increases can be controlled to

an acceptable level by properly designing the FS system.

8
3. INTERFERENCE FROM FS TO BSS

3.1. Introduction

Interference from FS to BSS (i.e., interference caused by an FS transmitter on a

BSS receiver) is not uniform in a service area of the BSS. Severity of the interference largely depends on the location of the BSS receiver relative to the location

and the main-beam direction of the FS transmitting antenna. Since a sidelobe

envelope pattern better than that of an isotropic antenna (i.e., sidelobe envelope

gain of less than 0 dB) cannot be expected for either an FS transmitting antenna or a

BSS receiving antenna, there always exists an area around an FS transmitting antenna,

where the interfering FS signal power received by a BSS receiver exceeds its maximum

permissible limit. If such areas occupy a large portion of the BSS service area,

sharing between BSS and FS must be judged impossible because of interference from the

FS to the BSS. Therefore, the dimension of such areas must be determined before one

can discuss whether or not sharing between the two services is feasible.

3.2. Permissible Limit of Interfering FS Signal Power

The maximum permissible limit of the interfering FS signal power received by a

BSS receiver depends on the wanted BSS signal power and the signal-to-interference

protection ratio. We will examine each of the last two parameters separately and

determine the maximum permissible limit.

We will first determine the wanted BSS signal power received at the BSS

receiver. The PFD of a BSS signal to be exceeded for 99% of the worst month at the

edge of the service area is specified to be -105 dBW/m2 in Region 2 (ITU, 1977,

p. 82). The received signal power is calculated with thi~ PFD and the effective area

of the receiving antenna. For individual reception of a BSS signal in Region 2, the

half-power (or 3 dB) beamwidth of a receiving antenna is specified to be 1.80 (ITU,

1977, p. 97). This corresponds to an on-axis' (main-beam) gain of 39.33 dB (ITU,

1977, p. 101). At a frequency of 12.45 GHz, it corresponds to an effective area of

0.40 m

2, or -4 dBm2. (If the antenna efficiency is assumed to be 55%, this effective

area corresponds to a circular-aperture parabolic antenna diameter of 0.96 m.)

Therefore, the wanted BSS signal power received by a BSS receiving antenna at the

edge of the BSS service area is -109 dBW.

We will next examine the signal-to-interference protection ratio. The signalto-interference protection ratio against all types of terrestrial transmissions is

35 dB for carrier frequency differences between the wanted and interfering signals of

up to 10 MHz, decreasing linearly from 35 dB to 0 dB for carrier frequency differences between 10 MHz and 35 MHz, and 0 dB for frequency differences in excess of,

9
35 MHz (ITU, 1977, p. 82). Therefore, the protection ratio is 35 dB when the

interfering FS signal is situated at the center of the BSS channel in question,

22.1 dB when the interfering FS signal is at the center of the adjacent BSS channel

(i.e., 19.18 MHz apart), and 0 dB when the interfering FS signal is two or more BSS

channels (i .e., 38.36 MHz or more) apart.

However, it ;s specified in the Final Acts of the WARC-BS (ITU, 1977-, p. 82)

that "a signal from a terrestrial station should be considered only if its necessary

bandwidth overlaps the necessary bandwidth of the broadcasting-satellite assignment. II

For this reason, we will consider only the co-channel and adjacent-channel interfering FS signals in this study and exclude the case where the interfering FS signal

is two or more BSS channels apart.

The permissible limits of the interfering FS signal power are obtained by

subtracting (in decibels) the protection ratio values from, the wanted BSS signal

power. They are -144 dBW and -131.1 dBW for the co-channel and adjacent-channel

interfering FS signals, respectively.

3.3. FS Signal Power Received by a BSS Receiver

The interfering FS signal power received by a BSS receiver is a function of the

FS transmitting power, the FS transmitting antenna gain in the direction of the BSS

receiver, the propagation loss, and the BSS receiving antenna gain in the direction

of _the FS transmitter. We will examine these parameters in this section.

The FS transmitter power varies from system to system. It ranges from -20dBW

to 10 dBW. When the fS signal bandwidth is wider than the BSS receiver bandwidth,

only the power in the latter is taken as the FS transmitter power.

The reference radiation patterns for circular antennas used in radio-relay

systems are given in CCIR Report 614 (CCrR, 1974). The report gives the on-axis gain

as a function of 0/\ and the sidelobe envelope pattern as a function of 0/\ and ¢,

where 0 is the diameter of the antenna, \ ts the wavelength, and ¢ is the off-axis

angle. The report selects a value of 0 dB as the residual gain, which is the gain in

the distant sidelobes. The sidelobe envelope pattern given there is applicable

between the position of the first sidelobe and the angle at which the sidelobe

envelope equals the residual gain. For simplicity we assume that the gain near the

main-lobe axis expressed in decibels is parabolic with respect to the off-axis angle

in the range where the gain is greater than the sidelobe envelope gain at the

location of the first sidelobe and that the gain is constant outside the above range

but inside th~ first sidelobe location. We will use these reference radiation

patterns for all FS transmitting antennas considered in this study.

10
The relation among the propagation loss, path length, and type of path is given'

in the Final Acts of the 1977 WARC~BS (ITU, 1977, pp. 85-86}. With this relation,

the propagation loss can be calculated from the path length, and vice versa. In this

study we assume all overland paths.

The reference pattern for the BSS recelvlng antenna in Region 2 is given in the

Final Acts (ITU, 1977, p. 84). This pattern is given in the form of off-axis gain

relative to the on-axis gain, which is equal to 39.33 dB in. Region 2, as calculated

in the preceding section. The absolute off-axis gain of the BSS receiving antenn~ is

equal to 12.2 dB, 7.8 dB, 4.7 dB, and 0 dB when the off-axis· angle is 100 , 150 , 200 ,

and 270 or greater, respectively.

With these relations, we can calculate the FS signal power received by a BSS

receiver when the FS transmitter power and the relative locations of the two antennas

are known. Conversely, we can calculate the minimum distance between the two

antennas necessary to keep the received FS signal power below its maximum permissible

limit when all other parameters are known.

3.4. Areas Where Interference is Intolerable

For each FS transmitter, we can plot "the minimum distance between the two

antennas against the off-axis angle of the FS transmitting antenna on a polar

coordinate with the location of the FS transmitter as its origin and with the mainbeam direction as the zero-angle direction (i.e., the x-axis direction in the

associated Cartesian coordinate). The resulting curve is the contour line on which

the received interfering FS signal power is equal to its maximum permissible limit.

The area inside the contour represents the area where the interference from the FS to

the BSS is intolerable. Figures 1 and 2 show some examples of such contours.

Figure 1 shows contours plotted for the case of a U.S. high-power FS system.

The FS transmitter power is 1 W(or 0 dBW), which is typical for such a system. The

antenna diameter is 1.8 m. The upper half (A) of the figure is for the co-channel

interference, and the lower half (B) is for the adjacent-channel interference.

Therefore, the difference between the upper half and the lower half represents the

effect of moving the interfering FS signal from the co-channel position to the

adjacent-channel position.

Figure 2 shows contours plotted for the case of a wideband FS system envisioned

in Canada (CCIR, 1978b). The antenna diameter is 2 m. Only the co-channel interference is considered here. In the upper half (A), the FS transmitter power is

-7.8 dBW per 20 MHz of bandwidth, which is the nominal power of the system. In the

lower half (B), the power is -0.8 dBW in the same bandwidth, which is the maximum

11
100

u.s. High-Power System

Transmitter Power: 0 dBW (Typical)

100km

( A) Co-channel Interference

40 km

'200 km 260

40 ,.....-----1100

40

200 km

( B) Adjacent - Channel Interference

Figure 1. Contours on which the received interfering FS signal power is

equal to its maximum permissible limi'ts for a U.S. high-power

FS system. The outer contour is for the worst case, and the

inner contour is for the most favorable case.

12
Canadian FS System

Co-channel Interference

60km

60

60

(A) Transmitter Power: -18 dBW (Nominal)

100 km

100 200 km

100

100

(B) Transmitter Power: -O.8dBW (Maximum)

200km

Figure 2. Contours on which the received interfering FS signal power is

equal to its maximum permissible limits for a Canadian FS

system. The outer contour is for the worst case, and the

inner contour is for the most favorable case.

13
power of the system. Therefore, the, difference between the upper half and the lower

half represents the effect of increasing the transmitter power by 7 dB.

In each half of Figures 1 and 2, the outer contour is for the worst case in

which the elevation angle of the BSS receiving antenna is 150 and the azimuths of the

FS transmitter and the BSS satellite seen from the BSS receiver coincide with each

other. The inner contour is for the most favorable case in which the elevation angle

of the BSS receiving antenna is so large that the antenna gain in the direction of

the FS transmitter is equal to the residual gain regardless of the azimuthal

relations. Therefore, the difference between the inner and the outer contours

represents the effect of the discrimination of the interfering FS signal by the BSS

receiving antenna.

Each contour has a sharp peak in the main-beam direction of the FS transmitting

antenna, while it is a circular arc for distant angles. Roughly speaking, therefore,

each contour can be represented reasonably well by two distances corresponding to the

main-beam direction and to a distant angle. We have calculated the two distances for

each of. various FS systems and present them in Tables 6 and 7 for the co~channel and

adjacent-channel interference, respectively.

So far we have calculated the size of the area where reception of a BSS signal

is intolerably interfered with by only one FS transmitter. The next step is to

calculate the size of the area interfered with by a number of FS transmitters

operating simultaneously and to discuss feasibility of sharing between BSS and FS.

This calculation depends on the usage of FS transmitters or the type of applications

of the FS systems.

3.5. Sharing With FS of U.S. Applications

In the United States, most FS systems in the band 12.2-12.7 GHz are independent

short-hop links. The bandwidth, which is on the order of 10 MHz or 20 MHz, is about

the same as the BSS channel spacing, which is equal to 19.18 MHz in Regions 1 and 3.

(Long-haul, very wideband, trunking-type applications are not considered in this band

in the United States.) There are over 1500 frequency assignments to the FS systems

in the United States. Most FS system links are concentrated in or around big cities.

Since most links are mutuallY independent, there is no general rule or trend in

the direction of the link paths. According to the results presented in Tables 6 and

7, therefore, it is safe to consider that, inside the circle with a radius of 100 km

and possibly up to 250 km around the center of a big city, reception of a BSS signal

would be intolerably interfered with by FS transmitters to which co-channel or

adjacent-channel frequencies are assigned. The area of such a circle is in the same

order as the area of many western states of the United States.

14
Table 6. Minimum Separation Distances Required for the Co-channel Interference

from FS to BSS

Antenna Transmitter Distance (km)

Diameter Power Worst Case Most Favorable Case

FS System em) (dBW) On-Axis Distant On-Axis Distant

U.S. 0.6 Typical -20.0 126.8 13.0 100.0 5.3

Low-Power Max. - 3.0 200.0 92.2 166.4 37.6

U.S. 1.8 Typical 0.0 254.0 100.0 220.4 53.1

High-Power Max. 10.0 297.0 104. 1 263.4 100.0 -- - --

French 1.5 Min. -41.7 100.0 1. 1 63.4 0.4

Nominal -35.7 100.0 2.1 100.0 0.9

Canadian 2.0 Nominal - 7.8 224.3 53.1 190.8 21.6

Max. - 0.8 254.4 100.0 220.9 48.4

Table 7. Minimum Separation Distances Required for the Adjacent-Channel

Interference from FS to BSS

Antenna Transmitter Distance (km)

Diameter Power Worst Case Most Favorable Case

FS System (m) (dBW) On-Axis Distant On-Axis . Distant

U.S. 0.6 Typi cal -20.0 100.0 3.0 69.8 1.2

Low-Power Max. - 3.0 144.5 20.9 110.9 8.5

U.S. 1.8 Typical 0.0 198.4 29.5 164.9 12.0

High-Power Max. 10.0 241.5 93.3 207.9 38.0

French 1.5 Min. -41 .7 35.2 0.2 14.3 0.1

Nominal -35.7 70.3 0.5 28.6 0.2

Canadian 2.0 Nominal - 7.8 168.8 12.0 135.3 4.9

Max. - 0.8 198.9 26.9 165.4 11 .0

15
Since the size of the area intolerably interfered with by the FS transmitters is

enormous and since BSS receiving stations are not to be licensed, shared use ofFS

systems in a BSS service area in the same or adjacent channel is not feasible. In

this case, therefore, sharing by frequency division in each BSS service area should

be considered. (In this report the phrase IIfrequency division ll is used in conjunction with frequency assignments ina geographical area as opposed to frequency

allocations in an ITU Reg~on or in a country.)

As described in Appendix C~ only five channels or less each are assigned to most

service areas in the 1977 WARC-BS Plan for Regions 1 and 3. We assume that more than

five. channels will not be assigned to a service area in Region 2. Since the adjacent

channels must also be considered to be occupied by the BSS, however, channel occupancyis much greater than the number of channels with assignments. In the 1977

Plan, the channel occupancy is 12 or less in about one-half of the total service

areas and from 13 to 18 in most of the remaining half of the total service area (see

Appendix C). This large channel occupancy in many service areas arises from the fact

that every fourth BSS channel is assigned to a service area. If every other BSS

channel is assigned to a service area as in some service areas in Region 3, the BSS

channel occupancy is reduced to some extent. For example, the BSS channel occupancy

is 14 or 15 when five assignments are made to a service area in every fourth channel,

while it is 10 or 11 when the same number of assignments are made in every other

channel. If the same channel spacing is used in Region 2 as in Regions 1 and 3 in

the 1977 Plan, a total of 24 BSS channels are available in a 500 MHz band. Therefore, we can consider that one-half of this band is available for the FS systems in a

service area.

On or near the boundary of· two service areas, the BSS channel occupancy depends

on the frequency assignments to both service areas. If cross-polarized beams are

used for the two areas, the two areas can alternate channels. If the two areas are

served from two satellite locations, the two service areas can use the same channels

or alternate channels. In, these cases the BSS channel occupancy is 11 or 12

channels, and one-half of the band is again available to the FS systems.

If co-polarized beams from the same satellite position must be used for both

service areas, on the other hand, the assignments to the two service areas must be

separated in frequency without an overlap. In this case, 20 to 22 BSS channels are

occupied by the BSS,and only a small portion of the band corresponding to two,

three, or four channels remains available to the FS systems.

The study conducted by SBS (Satellite Business Systems) (1978) shows that ~ll

the current FSassignments in the band 12.2-12.7 GHz in the United States can be

rearranged in one-half of the band. Even if the number of FS assignments is assumed

16
to grow at an annual rate of 10% compounded annually, new FS assignments up to the

year 2000 can be accommodated in one-half of the band in most cities of the United

States, the only exceptions being New York, NY; Los Angeles, CA; Chicago, IL;

St. Louis, MO; and Dallas, TX. Since the boundary of two BSS service areas is not

expected to run through big cities, one-half of the band is considered available to

FS, and sharing between BSS and FS by frequency division is considered feasible in or

around big cities.

As mentioned earlier, only a small portion of the band is available to the FS on

or near the boundary of two service areas in some cases. However, as the boundary is

expected to run through sparsely populated areas and the FS systems of this type are

concentrated in or around big cities, demands for the FS systems on or near the

boundary are not considered very intense. It is, therefore, expected that the FS

systems can be accommodated in a small portion of the band on or near the boundary of

two BSS service areas.

3.6. Sharing With FS of Canadian Applications

A very wideband, trunking-type application is envisioned in Canada (CCIR, 1978b).

The long-haul relay system consists of a number of relay stations and can stretch

from coast to coast across the continent. The use of the combined 11 and 13 GHz

band (10.7-11.7 GHz and 12.2-13.25 GHz) is considered. The RF (radiofrequency)

bandwidth is 240 MHz. A high-performance, 2-meter parabolic dish antenna with a

maximum gain of 45 dB is considered, and the nominal hop length is 8 km. The transmitter power is equal to -7.8 dBW (nominal) and -0.8 dBW (maximum) per 20 MHz of

bandwidth.

Since the hop length of the relay system is smaller than the size of a BSS

service area, theFS system uses several frequencies in a BSS service area. If both

frequencies that fall in the band 12.2-12.7 GHz are used by the FS relay system in a

BSS service area, sharing ,between BSS and FS by frequency division in the whole

service area is impossible. We will first discuss this case.

When n frequencies alternate in every set of n hops, the second station receives

from the first station and the (n+21nd station receives from the (n+l)st station on

the same frequency. Therefore, there is a chance for the {n+2)nd station to be

interfered with by the signal from the first station. This intrasystem interference

can be avoided if the path is zigzagged in such a way that the (n+2)nd station does

not lie inside the main beam of the transmitting antenna of the first station and, at

the same time, the first station does not lie in the main beam of the receiving

antenna of the {n+2)nd station.

17
This intrasystem interference is most severe When n=2. In this case, the angle

between the direction of each hop and the general direction of the relay system is

approximately 1.5 times the angle of the first minimum of the antenna pattern. Since

the first minimum of the pattern is considered to take place at approximately twothirds of the position of the first side10be, which is given approximately by the

equation

<P l = 100/CD/A),

the angle between the direction of each hop and the general direction of the relay

system is approximately given by the, above equation for <1>1 (CCIR, 1974, Rept. 614).

With D = 2 m and A = 0.024 m (at f=12.45 GHz), the angle is approximately 1.20.

We can combine this result with the minimum separation distance given earlier in

Figure 2 and Table 6 to determine the size of the area intolerably interfered with by

the FS relay system. We rotate each figure in Figure 2 counterclockwise by 1.20 and

take the maximum value of the ordinate values (y values). The distance thus determined represents the width of the belt area where BSS signals are intolerably interfered with by the FS relay system on each side of the general route of the relay

system when the route is a straight line. In this FS relay system, the minimum

distant-angle separation distance given in Table 6 always dominates and determines

the width of the belt area. It is equal to 53.1 km and 21.6 kmfor the worst case

and the most favorable case, respectively, when the nominal transmitter power

-7.8 dBW is used, and it is equal to 100 km and 48.4 km when the maximum transmitter

power -0.8 dBW is used. When the general direction of the relay system is east-towest, we can very roughly consider that the area within approximately 50 km on the

north side and approximately 20 km on the south side from the general route is

intolerably interfered with by the FS system.

When the general route of the FS relay system is deflected, the area intolerably

interfered with by the FS system includes spikes of the size and shape shown in

Figure 2 in addition to the belt zone described above. When the general route is

gradually curved, the area spreads like the pattern of a snowplow turn in skiing.

The width of the spread depends on the curvature of the route; the greater the

curvature (or the smaller the radius of curvature), the wider the spread.

Assuming that the general routes of the FS relay system are about the same as

the existing analog routes and the planned DRS-8 routes (de Witte, 1978), we have

drawn a rough sketch of the area intolerably interfered with by the FS relay system.

The result is shown in Figure 3. In this sketch, we have assumed the nominal

transmitter power throughout the routes and the worst-case condition regardless of

the route direction for simplicity; i.e., we have assumed the outer contour of Figure

2(A). We have also assumed that both frequencies that fall in the band 12.2-12.7 GHz

18
\

\

\ r __J

I

\ " "V\ \'_ .... ,-.....,

/

/

/

/

/

/

/

( ON I

I

USA

AS

............... ----.-'---,-

I I

I I

I I

! I

I I

I SK I MB

I I

I

I

J

I

J

\.0

Figure 3. A rough sketch of the area in which BSS receivers would be intolerably

interfered with by the Canadian FS relay system.
are used by the FS relay system in every BSS service area. Although the area is not

negligibly small, the area is comparably small if the r-elay system routes are

restricted as assumed here. Unfortunately, the area shown in figure 3 covers much of

densely populated areas of Canada. Therefore, it is impossible to replace the BSS

for the terrestrial BS (broadcasting service) in such areas, if the wideband

trunking-type FS relay system is built across the continent. However, if the BSS is

to be used as a supplement to the terrestrial BS in rural areas, there remain many

areas where the BSS will be effectively used.

So far in this section, we have assumed that the two FS frequencies that fall in

the band 12.2-12.7 GHz are used by the FSrelay system in every BSS service area.

This assumption, however, might not necessarily be valid. Since the total bandwidth

considered for the FS relay system is 2000 MHz and the bandwidth of each FS signal is

240 MHz, there are eight FS frequencies to be assigned to the FS relay system. It is

not certain that all eight frequencies are necessary in a geographical area~ If one

FS frequency can be spared in an area, one-half of the band 12.2-12.7 GHz will become

available for the BSS, and sharing between the BSS and the FS by frequency division

in the area will become feasible. Sharing will impose a constraint on the design of

the FS relay system, but design with such a constraint cannot be considered totally

impossible. Sharing will also impose a constraint on the BSS in that all BSS

channels in a BSS service area must be in either the upper or the lower half of the

band 12.2-12.7 GHz, but the effect of this constraint can be considered minimal.

3.7. Summary

By calculating the minimum separation distance required between the FS transmitting antenna and the BSS receiving antenna from the permissible limit of interfering FS signal power and the FS signal power received by a BSS receiver, we have

studied interference from the FS to the BSS. The FS systems considered include a

short-hop system for transmission of an FDM-FM telephony signal or an FM TV signal

used in the United States and a very wideband, trunking-type digital system

envisioned in Canada.

The results of the study indicate that interference from the FS to the BSS is

not a negligible problem. For successful sharing between the BSS and the FS, the

interference must be controlled by prudent use of both the BSS and FS systems.

To avoid intolerable interference from the FS system currently in use in the

United States, the two services must use two different portions of the band in each

BSS service area. In other words, sharing must be done by frequency division in each

BSS service area. If five BSS channels or less are assigned to a service area in

20
every channel, the BSS will use about one-half of the 500-MHz band and, according to

a study by SBS (1978), the FS systems can be accommodated in the rest of the band in

most areas.

Since the RF signal bandwidth of the trunking-type FS relay system envisioned in

Canada is 240 MHz, interference to the BSS from the FS relay system cannot be

controlled by frequency division if both frequencies that fall in the band

12.2-12.7 GHz are used by the FS relay system in a BSS service area. In this case,

the interference must be controlled by geographical division. This means that only

either BSS or FS, but not both, can be accommodated at a particular geographical

location. Since the route of the FS relay system is expected to run through big

cities, the BSS is available only in rural areas if no constraint is imposed on the

design of the FS relay system.

If this FS relay system can be built under a constraint that at least one FS

frequency (with a 240-MHz bandwidth) that falls in the band 12.2-12.7 GHz is spared

in each BSS service area, the situation will be completely different. Sharing

between the BSS and the FS can be achieved by frequency division in each BSS service

area. Although eight FS frequencies (each with a 240-MHz bandwidth) are available

for the FS relay system, such a constraint on the design of the FS relay system has

investment and economic impact not considered in this report. Sharing will also

impose a constraint on the BSS in that all BSS channels in a BSS service area must be

in either the upper or the lower half of the band 12.2-12.7 GHz.

4. CONCLUSIONS

In conjunction with the U.S. proposal for the 1979 WARe, we have discussed

feasibility of sharing the band 12.2-12.7 GHz between the BSS and FS. As FS systems,

we have considered both the short-hop systems currently used in the United States and

the very wideband, trunking-type system envisioned in Canada. Interference from BSS

to FS is discussed in Section 2, and interference from FS to BSS is discussed in

Section 3.

As discussed in Section 2, interference from BSS to FS is in general not a

serious problem. A BSS signal power from a broadcasting satellite received by an FS

receiving antenna is usually smaller than the FS receiver noise power in the same

band. The interfering BSS signal will increase the baseband noise power in some

telephone channels in the FDM-FM telephony system and the noise power spectral density

in some part of the baseband in the FM TV system, but these increases will be less

than 10 dB even in the worst case. These increases can be controlled to an acceptable level by properly designing the FS system.

21
As discussed in Section 3, on the other hand, interference from FSto BSS is not

a negl igible problem. For successful shari,ng betwee,n the BSS and FS, the interference of this direction must be controlled by prudent use of both the BSS and FS

systems.

To avoid intolerable interfer>ence from the FS system currently in use in the

United States, the two services must use two different portions of the band in each

BSS service area. If five BSS channels or less are assigned to a service area in

every other channel, the BSS uses about one-half of the 500-MHz band, and the FS

systems can be accommodated in the rest of the band in most areas.

Since the signal bandwidth ofthetrunking-type FS relay system envisioned in

Canada is 240 MHz, interference to the BSS from the FS relay system cannot be

controlled by frequency division if both frequencies that fall in the band

12.2-12.7 GHz are used by the FS relay system in a BSS service area. In this case

the interference must be controlled by geographical division. Since the route of the

FS relay system is expected to run through big cities, the BSS is available only in

rural areas if no constraint is imposed on the design of the FS relay system.

If this FS relay system can be built under a constraint that at least one FS

frequency (with a 240-MHz bandwidth) that falls in the band 12.2-12.7 GHz is spared

in each BSS service area, the situation will be completely different. Sharing

between the BSS and the FS can be achieved by frequency division in each BSS service

area. Although eightFS frequencies (each with a 240-MHz bandwidth) are available

for the FS relay system, designing the FS relay system under such a constraint has

investment and economic impact not considered in this report. Sharing will also

impose a constraint on the BSS in that all BSS channels in a BSS service area must be

in either the upper or the lower half of the band 12.2-12.7 GHz.

5. ACKNOWLEDGMENTS

The study reported on in this report has been supported in part by the FCC

(Federal Communications Commission), Washington, DC 20554. The FCC program monitors

are Messrs. Edward R. Jacobs and Thomas S. Tycz.

The author is grateful to Mr. Thijs de Haas, Dr. Peter M. McManamon,

Dr. Arthur D. Spaulding, and Mr. Paul I. Wells of the NTIA/ITS for their discussions

on this subject and critical reviews of this report.

22
6. REFERENCES

CCIR (International Radio Consultative COl11l1itteel (1974J, Documents of the XIlIth

Plenary Assembly (CCl'R Green Books), ITU (International Telecommunication

Union), Geneva, Switzerland.

CCIR (1978a), Technical bases for the World Administrative Radio Conference 1979,

SPM (Special Preparatory Meeting) of theCCIR, Geneva, Switzerland.

CCIR (1978b), Frequency sharing between the broadcasting-satellite service and

digital fixed services, CCIR SPM Doc. P/146 (a contribution from Canada).

CCIR (1978c), Sharing between the broadcasting-satellite service and the fixed

service in the band 11.7-12.5 GHz in the case of television transmission, CCIR

SPM Doc. P/271 (a contribution from France).

Comsat (Communications Satellite Corporation) (1978), Comments on the Eighth Notice

of Inquiry, FCC Docket No. 20271, July 17, 1978.

de Witte, G.H.M. (1978), DRS-8: System design of a long haul 91 Mb/s digital radio,

Proc. 1978 National Telecommunications Conference (NTC 178), paper number 38.1,

IEEE, New York, NY.

FCC (Federal Communications Commission) (1978), Report and Order, in the matter of

an inquiry to prepare for a General World Administrative Radio Conference of the

International Telecommunication Union to consider the revision of the international Radio Regulations, Docket No. 20271.

ITU (International Telecommunication Union) (1977), Final Acts of the World

Administrative Radio Conference for the Planning of the Broadcasting-Satellite

Service in Frequency Ban~s 11.7-12.2 GHz (jn Regions 2 and 3) and 11.7-12.5 GHz

(in Region 1), ITU, Geneva, Switzerland.

Lee, Lin-shan, S.P. Russell, and J.M. Janky (1979), Impact of various sharing

strategies in the 12.2-12.7 GHz band for broadcasting and terrestrial services,

EDUTEL Communications and Development, Inc., Palo Alto, CA 94304.

SBS (Satellite Business Systems) (1978), Comments on the Eighth Notice of Inquiry,

FCC Docket No. 20271, July 14, 1978.

Western Union (Western Union Telegraph Company) (1978), Comments on the Eighth

Notice of Inquiry, FCC Docket No. 20271, July 14, 1978.

23

APPENDIX A. THE U.S. PROPOSAL OF REVISION OF THE INTERNATIONAL FREQUENCY

ALLOCATION TABLE IN THE BAND BETWEEN 11.7 GHz AND 12.75 GHz

As one of the proposals for the 1979 GWARC (General World Administrative Radio

Conference) (FCC, 1978), the United States Administration proposes to move the

allocation to the BSS (broadcasting-satellite service) from the band 11.7-12.2 GHz to

the band 12.2-12.7 GHz for Region 2 in the International Frequency Allocation Table

(ITU, 1976). Some changes associated with this move are also proposed. The proposed

changes in the band 11.7-12.75 GHz are shown in this appendix.

In the following, underlining indicates new text; hyphens through the text

indicate existing text which is being deleted; and "MOD" means a modification of the

current provisions. If a service is in all Capitals, then it is a primary service.

If a service has a Capital as the first letter and the remainder in lower case, then

it is a secondary service.

A.l. References

FCC (Federal Communications Commission)(1978), Report and Order, in the matter of an

inquiry to prepare for a General World Administrative Radio Conference of the

International Telecommunication Union to consider the revision of the international Radio Regulations, Docket No. 20271.

ITU (International Telecommunication Union)(1976), Radio Regulations, ITU, Geneva,

Switzerland. Article 5 in particular.

25
Table A.l. 11.7-12.75 GHz

Allocation to Services

Region 1

11.7-12.5

FIXED

MOBILE except

aeronautical mobile

BROADCASTING

BROADCASTING-SATELLITE

405BA

12.5-12.75

FIXED-SATELLITE

(Space-to-Earth)

(Earth-to-space)

405BD 405BE

Region 2·

11.7-12.2

~±XE9

FIXED-SATELLLITE

(Space-to-Earth)

~QB±bE Mobile except

aeronautical mobile BRQA9GA~+fNG

BRQA9GA~lfNG-SAlEbbflE

4Q§BB MOD 405BC

12.2-12.5

FIXED

~QBfbl; e)teef3~

aepeRaHtiea~-Me~~~e

BROADCASTING

BROADCASTING-SATELLITE

12.5-t~.7§ -12.7

FIXED

~tXE9-SAlEbb±lE

t~aptA-te-5~aeet

H88±bl: e)Eeef3~

ae~eRa~tieat-~e~~+e

BROADCASTING

BROADCASTING-SATELLITE

12.7-12.75

FIXED

FIXED-SATELLITE

(Earth-to-space)

MOBILE except

aeronautical mobile

Region 3

11.7-12.2

FIXED

MOBILE except

aeronautical mobile

BROADCASTING

BROADCASTING-SATELLITE

12.2-12.5

FIXED

MOBILE except

aeronautical mobile

BROADCASTING

12.5-12.75

FIXED

FIXED-SATELLITE

(Space-to-Earth)

MOBILE except

aeronautical mobile

405BA

Spa2

In the band 11.7-12.2 GHz in Region 3 and in the band 11.7-12.5 GHz in

Region 1, existing and future fixed, mobile and broadcasting services

shall not cause harmful interference to broadcasting-satellite stations

operating in accordance with the decisions of the appropriate broadcasting

frequency assignment planning conference (see Resolution No. Spa2-2) and

this requirement shall be taken into account in the decisions of that

conference.

leppestp~at-pa~~eee~~HR$eatieR-SepY~eeS-~R-tke-~aR~-~+.7-+~.~-6H~-~R

~e§ieR-~-sAa~~-~e-~Atpe~~ee~-eAly-a~tep-tke-e~a~epat~eR-aR~-~f3f3peYa+-e~

~+aRs-~8P-tAe-s~aee-paa~eeeffi~HR~eab~eR-SepYiees,-se-as-be-eRs~~e

eeffif3ati~~t~ty-~etweeR-the-Hses-that-eaek-ee~Atfy-~ee~aes-~ep-t~~s-~aR~~

26
405BC

Spa2

405BD

Spa2

405BE

Spa2

The use of the band 11.7-12.2 GHz in Region 2 by the ~~ea~east~R§­

sate~~~te-aR~ fixed-satellite services is limited to domestic systems

and 'i s subject to previ ous agreement between the admi nistrati ons

concerned and those having services, operating in accordance with the

Table, which may be affected (see Article 9A aRa-~ese+~t~eR-N8.-S~a~-3).

In Bulgaria, Cameroon" Congo (Brazzaville), the Ivory Coast, Gabon, Ghana,

Hungary, Iraq, Israel, Jordon, Kuwait, Libya,.Mali, Niger, Poland, Syria,

the United Arab Republic, Roumania, Senegal, Czechoslovakia, Togo and the

U.S.S.R., the band 12.5-12.75 GHz is also allocated to the fixed service

and the mobile, except aeronautical mobile, service.

In Algeria, Belgium, Denmark, Spain, Ethio/pia, Finland, France, Greece,

Kenya, Liechtenstei n, Luxembourg, Monaco, Norway, 'Uganda, the Nether1ands , Portugal, the F.R. of Germany, Sweden, Switzerland, Tanzania and Tunisia,

the band 12.5-12.75 6Hz is also allocated, on a secondary basis, to the

fixed service and the mobile, except aeronautical mobile, service.

27

APPENDIX B. EXISTING STUDIES ON SHARING BETWEEN BSS AND FS

Some studies already exist on the sharing problems between the BSS and the FS in

the 12 GHz band (CCIR, 1978 a,b,c; Camsat, 1978; SBS, 1978; Western Union, 1978; Lee

et al., 1979). This appendix presents summaries of those studies with some comments

whenever deemed appropriate.

(CIR SPM Report (CCIR, 1978a)

This report states that lIinterference caused by broadcasting satellites to

typical terrestrial systems sharing the same frequencies and locations is generally

acceptable provided that th? elevation angles to the satellite from these locations

are not too small. 1I Regarding the interference of the other direction, this report

states that Ilco-channel interference caused by transmitting stations of the terrestrial fixed service to broadcasting-satellite receiving stations is generally a

very serious problem. 1I These statements seem to be in general agreement with the

results of other studies.

This report summarizes two input documents (CCIR, 1978 b,c) regarding this

subject. The report states that lithe geographical separation required is largest for

high-capacity digital radio-relay systems, and smallest for certain short-haul radiorelay systems whose transmission parameters are carefu11y constrained and whose

frequency plans are carefully aligned with those of the interfering system(s) in the

broadcasting-satellite service. 1I Since the two input documents will be discussed in

more detail, comments on this statement are not given here.

CCIR SPM Document by Canada (CCrR, 1978b)

This document studies the sharing problem between the BSS and an FS system now

envisioned in Canada. The FS system is premised on the use of the combined 11 and

13 GHz band (10.7-11.7 GHz and 12.2-13.25 GHz) to form a long-haul high-capacity

digital trunking system. The nominal value of the transmitter power is 6 dBW, and

its maximum value is 13 dBW. The antenna diameter is 2 m. The nominal hop length is

8 km. The RF (radiofrequency) bandwidth is 240 MHz. The RF spectral power is

assumed to be uniformly distributed over the total RF bandwidth and, therefore, the

transmitter power is equal to -7.8 dBW (nominal) and -0.8 dBW (maximum) per 20 MHz of

bandwidth.

Concerning the interference from the BSS to the FS, this document derives the

condition for necessary discrimination by the BSS transmitting antenna and the FS

receiving antenna. It concludes that the pointing constraints of the FS antenna to

avoid the azimuths of specific BSS transmitters in the geosynchronous orbit will be

minimal. This conclusion seems to be consistent with those of other studies.

Concerning the interference from the FS to the BSS, this document calculates the

minimum separation distance required between an FS station (transmitter) and a BSS

29
earth station (receiver) which is referred to as the coordination distance. The

ca)culated result indicates that separation distances required to meet the co-channel

interference protection allowance for the BSS of individual reception will range from

a minimum of 100 km up to approximately 300 km. Based on these relatively large

coordination distances coupled with unpredictability of all possible locations of BSS

receivers within a given service area, the report concludes that sharing between

these two services would only be feasible on a geographical basis, i.e., the two

services cannot use the same frequency in the same geographical ~rea.

The analysis presented in this document seems to be well-founded insofar as the

calculation of the coordination distance in the direction of the FS transmitting

antenna main beam is concerned. Since the FS system is a long-haul relay system,

however, the coordination distance in the direction normal (perpendicular) to the

main-beam direction is also very important to determining the size of the interference area. Although the coordination distance in the normal direction can be read

from the figures given in th~ document, explicit discussions of this subject are not

presented in the document.

The document concludes that sharing between the BSS and the FS will only be

feasible on a geographical basis. This conclusion may imply that, where the FS

system is constructed, the BSS reception must be given up. This is, however, not

necessarily the £ase. Since the total band considered for the FS system is 2000 MHz

and the bandwidth of each FS signal is 240 MHz, there are eight frequencies to be

assigned to the FS system. If one frequency out of eight can be spared in a geographical area, the BSS can be accommodated in that area. Discussions of this

subject are also not included in the document.

CCIR SPM Document by France (CCIR, 1978c)

This document studies the sharing problem between the BSS and the FS system used

in France in the band 11.7-12.5 GHz. This FS system operates on one hop or on a

small number of hops (not more than five hops) for the transmission of national

television programs. The nominal value of the FS transmitter EIRP (equivalent

isotropically radiated power) is 1.5 dBW, and its maximum value is7.5 dBW. The

antenna diameter is 1.5 m. The length of a hop is 15 to 20 km.

Concerning the interference caused by the BSS transmitter to the FS"radio relay

system receiver, the document shows calculated values of the signal-to-interference

ratio for the minimum power flux density and for the nominal power flux density of

the FS signal. The calculated values range between 33 dB and 46 dB. The document

concludes that this interference is negligible in all channels other than that of the

satellite itself. This conclusion seems to be consistent with those of other studies.

30
Concerning the interference caused by the FS system transmitter to the BSS

receiver, the document shows the calculated areas of interference caused to a BSS

receiver by an FS transmitter operating in the same channel and in the adjacent

channel. The size of the area in the direction of the FS transmitting antenna main

beam ranges from about 10 km in the case of adjacent-channel interference and a

nominal EIRP of 1.5 dBW to over 100 km in the case of co-channel interference and a

maximum EIRP of 7.5 dBW. The document concludes that sharing between the BSS and the

FS is possible subject to certain constraints.

The document assumes an antenna envelope sidelobe pattern that continues to

decrease until the off-axis angle reaches 180°. The antenna envelope sidelobe

pattern, however, usually does not decrease beyond a certain value called the'

residual response. In many cases, the residual response is assumed to be a dB; (ITU,

1977). The areas of interference shown in the document must be modified by taking

into account the residual response. This revision will increase the area in the

direction of distant angles.

The document gives no reasoning that leads from the calculated size of the area

on interference to the possibility of sharing. The calculated area of interference

is not necessarily small, particularly in the case of cochannel interference, yet the

document concludes that sharing is possible. The document lacks the discussion as to

how dense (or sparse) the planned FS system is, whether the same channel, an adjacent

channel, or a further distant channel is planned for the FS system, etc.

The Comsat Study (Comsat, 1978)

In Para. 49 of its comments on the Eighth Notice of Inquiry, FCC Docket No.

20271, Comsat states that lithe BSS would, in general, use only a small part of the

band in anyone service area, .... In the 1977 Geneva Plan for Region 1, for

example, only 12.5% of the band (5 channels out of 40) was assigned to any particular

service area. Even allowing for spillover from adjacent service area, terrestrial

service could use most of any band it shared with the B5S. 11 These statements are in

good agreement with those by SBS (1978) to be discussed later.

These statements, however, overlook two factors. First, since the BSS band is

500 MHz (instead of 800 MHz) in Region 2, only 24 (instead of 40) BSS channels are

available in Region 2 if the 1977 WARC-BS plan for Regions 1 and 3 (ITU, 1977) is

followed. Second, BSS channels adjacent to a channel which is actually assigned to

the BSS cannot be used by the FS systems and, therefore, adjacent channels on both

sides must also be included in the BSS channel occupancy_ If five ass channels are

assigned to a BSS service area, we must consider that about 10 to 15 channels are

occupied by the BSS and that only about one-half of- the 500-MHz band can be utilized

by the FS at best.

31
The SBS Analysis (SBS, 1978)

SBS (Satellite Business Systems) analyzed the sharing problem between the BSS

and the FS systems currently used in the United States in the band 12.2-12.7 GHz.

The conclusions of the analysis are reproduced as follows:

55. If a BSS system were based on community reception, then the FS could

utilize the full 500 MHz band virtually across the country~ subject only to

standard coordination of earth station location. In this case there would be

little or no restriction on the operation and growth of either BSS or FS

systems.

56. Only if BSS systems were based on a direct-to-home configuration would

any sharing complications arise, and even in this case, if the Region 1 Master

Plan (1977 WARe) formula were used, theFS could utilize nearly 7/8 of the

bandwidth in any service area. That formula is based on a multi-beam configuration designed to increase significantly the total number of channels available

through frequency reuse, a goal apparently shared by United States BSS planners.

57. An analysis undertaken by SBS, summarized below in the Attachment,

indicates that in the United States, BSS community reception systems and FS

systems coul dread; ly share a 500 MHz band thrcough the end of thi s century,

including foreseeable growth of each service. If a domestic direct-to-home BSS

system were established, a sharing plan based on a multi-beam formula comparable

to the Region 1 Master Plan would impose no restrictions on the number of

present FS systems in the United States. Furthermore, even anticipating a 10%

compound annual growth rate for the FS, only the Los Angeles metropolitan area

would appear to fall outside such a plan by the year 2000.

58. Even assuming a worst case situation, namely one in which a BSS directto-home system were limited to four beams (time zone division) for the United

States, our studies indicate that the BSS and the FS could reasonably share the

12.2-l2.7GHz band. In brief, even in this situation, present FS links need not

utilize more than 250 MHz except in two, or possibly three, major metropolitan

areas. Even projecting an annual compound growth rate of 10%, the number of

restricted metropolitan areas would appea'r to be between three and six by the

year 2000 (see Attachment).

* * * * * * *

61. Given that the delivery of BSS video services in congested metropolitan areas would be better served by community rather than direct-to-home

antennas, the entire 500 MHz band as presently allocated for terrestrial

services could be retained in those areas. Our studies indicate that the less

interference-sensitive community reception service could be provided anywhere in

32
the United States. In crowded metropolitan areas, the only restriction imposed

would be on the precise location of the BSS community receiver. For example,

even in the most congested area, namely the Los Angeles basin, BSS community

receivers could be located in approximately 90% of the metropolitan area without

harmful interference from existing terrestrial sites.

The SBS analysis concludes that, if the BSS system were based on community

reception, then the FS could utilize the full 500 MHz band, subject only to standard

coordination on earth station locations. This conclusion, however, is given without

any indication of the required minimum separation distance between an FS transmitting

antenna and a BSS receiving antenna. Use of a larger antenna in community reception

than in individual reception can reduce the required distance, but not drastically.

Also since a BSS receiving station is not to be licensed, standard coordination

procedure of earth station locations is not applicable to a BSS receiving station

even if the station is intended for community reception.

The analysis assumes that, if the 1977 WARC-BS formula for Region 1 (ITU, 1977)

were used, the BSS would utilize only one-eighth of the band and the FS could utilize

nearly seven-eighths of the band in any service area. The fraction one-eighth

assumed for the BSS seems to be based on the observation that only five channels at

most out of 40 are assigned to any service area (Comsat, 1978). As discussed

earlier, however, we must consider that, if five BSS channels are assigned to a BSS

service area, about 10 to 15 channels are occupied by the ass and that at best only

about one-half of the 500-MHz band can be utilized by the FS.

In its appendix, the analysis considers the following four cases:

(1) BSS uses community reception - Region 1 type plan;

(2) BSS uses community reception - FS uses entire 12.2-12.7 GHz band;

(3) BSS uses direct-to-home reception - Region 1 type plan; and

(4) BSS uses direct-to-home reception - limited frequency reuse.

The analysis assumes that the FS uses seven-eighths of the band 12.2-12.7 GHz in

Cases (1) and (3), the entire band in Case (2), and one-half of the band in Case (4).

Based on the above observations, we consider that only the result for Case (4) is

useful.

The result of the SBS study for Case (4) is summarized in Para. 14 of the

appendix. It reads:

14. The results of our studies indicate that, as the band restriction imposed

on the FS is increased from one-eighth to one-h.alf of the allocated band, the

first area in the United States that would be seriously constrained is the

Los Angeles basin. Assuming a 10% compound annual growth rate to the year 2000,

several additional major metropolitan areas might be constrained, including

33
New York and Boston. According to the current FS data base, Cleveland is the

next most congested area following los Angeles, Boston and New York. The frequency assignment program was run for the Cleveland area assuming a 10% annual

compound growth rate to the year 2000.

This result is reflected in Para. 58 of the text quoted above. Although this case is

treated as a worst case in theSBS analysis, it must be considered to be a typical

case in the United States because of the above reasons.

The Western Union Study (Western Union, 1978)

In Para. 13 of its comments on the Eighth Notice of Inquiry, FCC Docket-No.

20271, Western Union summari~es the results of its study as follows:

Sharing of the 12.2-12.75 GHz band by _the BSS with Terrestrial services is

feasible, but not on a co-frequency basis. (Papers presented to various CCIR

study groups and service working groups have demonstrated this.) However, since

the BSS ~ill not use the full band in all areas in any case, a frequency

division arrangement alternating by time zones across the country (or region)

would be a viable alternative. We have investigated the present usage of this

band by terrestrial services in the U.S., and have found that only small areas

on the east and west coasts (essentially the New York and Los Angeles metropolitan areas) show significantly heavy usage, with lesser concentrations in the

Chicago, Cleveland and Dallas areas. Since these heavily populated areas are

and will continue to be well served by land-based broadcast transmitters, there

appears to be no conflict with a sharing arrangement with the BSS countrywide.

The areas likely to require BSS service reception (the more lightly populated

areas) will experience minimal interference from terrestrial transmitters.

No quantitative discussions are presented in the comments.

The EDUTEL Report (Le~ et al., 1979)

Pointing out that sharing between BSS and FS is limited by the interference from

FS transmitter into BSS receiver, the report discusses nine different sharing

techniques that would reduce the interference. It calculates improvements in

discriminating the interfering FS signal at the BSS receiver. The nine techniques

discussed in the report are labelled Schemes A to I. They are

A: Frequency interleaving;

B: Split bands and time zone advantage;

C: Power control for terrestrial systems;

0: Increasing terrestrial transmitter antenna size;

E: Avoiding the terrestrial main beam;

F: Larger azimuthal offset angle;

G: Higher elevation angle;

34
H: Terrain protection;

I: Increasing the broadcasting receiver antenna size.

The r~port classifies Schemes A and B as techniques imposing restrictions on both ass

and FS; Schemes C and 0, on FS only; and all the remaining schemes, on BSS only. The

report summarizes the results of the study as follows:

Some techniques are more attractive, significant improvement can be bought at

reasonable prices (like Schemes B, C, E, and H) and some are relatively less

attractive (like Schemes A, 0, F, G, and I).

After presenting some examples of combined use of the nine techniques, the report

concludes as follows:

Nine different sharing techniques, called Schemes A through I, are proposed,

and their improvements and prices are investigated. Examples indicate that

sharing will be possible and even become easy if appropriate combinations of

sharing techniques are chosen although tradeoffs must be made by broadcasting or

terrestrial services or both. This provides a guideline for the consideration

of allocation of broadcasting service to this band.

The report lists Scheme B (split band) as one of more attractive techniques.

However, it does not discuss the number of BSS channels and the number of FS systems

to be accommodated in a particular geographical area.

The report considers only one FS transmitter at a time. In the United States,

however, there are a number of FS systems in this band concentrated in or around a

large city. Although the report discusses Scheme E (avoiding the terrestrial main

beam) as one of the more attractive techniques, it does not treat these FS systems

collectively in its discussion.

The report lists Scheme H (terrain protection) also as one of the more attractive

techniques. However, it does not give any figure about the extra costs of achieving

terrain protection.

B.l. References

CCIR (International Radio Consultative Committee) (1978a), Technical bases for the

World Administrative Radio Conference 1979, SPM (Special Preparatory Meeting) of

the CCIR, Geneva, Switzerland.

CCIR (1978b), Frequency sharing between the broadcasting-satellite service and

digital fixed services, CCIR SPM Doc. P/146 (a contribution from Canada).

CCIR (1978c), Sharing between the broadcasting-satellite service and the fixed

fixed service in the band 11.7-12.5 GHz in the case of television transmission,

CCIR SPM Doc. P/271 ta contribution from France}.

35
Comsat (Communications Satellite Corporation) (1978), Comments on the Eighth Notice

of Inqui ry, FCC Docket No. 20271, July 17, 1978.

ITU (International Telecommunication Union) (1977), Final Acts of the World

Administrative Radio Conference for the Planning of the Broadcasting-Satellite

Service in Frequency Bands 11.7-12.2 GHz(in Regions 2 and 3) and 11.7-12.5 GHz

(in Region 1), ITU, Geneva, Switzerland.

Lee, Lin-shan, S.P. Russell, and J.M. Janky (1979), Impact of various sharing

strategies in the 12.2-12.7 GHz band for broadcasting and terrestrial services,

EDUTEL Communications and Development, Inc., Palo Alto, CA 94304.

SBS (Satellite Business Systems) (1978), Comments on the Eighth Notice of Inquiry,

FCC Docket No. 20271, July 14~ 1978.

Western Union (Western Union Telegraph Company) (1978), Comments on the Eighth

Notice of Inquiry, FCC Docket No. 20271, July 14,1978.

36
APPENDIX C. SOME STATISTICS OF THE 1977 WARC-BS PLAN FOR REGIONS 1 AND 3

In the plan (_ITU, 1977), there are 984 frequency assignments distributed among

247 service areas in 150 countries. Each assignment is identified by an IFRB Serial

Number, which consists of a three-digit number and an alphabetical character. All

assignments with a common three-digit number are made to a country and to a service

area; they differ only in the channel. In the following analyses the IFRB Serial

Number is used to indicate only its numerical part.

Statistics by Country Symbol

Frequency assignments are made to 149 country symbols. These symbols include

IFB (for IFRB), which is used to reserve one service area each to the Republic of

South Africa and to Rhodesia, with five assignments for each area.

The number of assignments per country ranges from 2 (5 countries; BLR, BRU, MLD,

NIU, TKL) to 65 (~ country; URS), with 4 (21 countries) or 5 (96 countries) being

typical. Only 8 countries have more than 10 assignments. They are ARS (11 assignments), AUS (36), CHN (55), IND (48), INS (21}, PAK (11), SON (15), and URS (65).

The number of IFRB serial numbers per country ranges from 1 (121 countries) to

35(1 country; CHN). Only six countries have more than three IFRB serial numbers.

They are AUS (6 numbers), CHN (35), INO (12), INS (5), PAK (5), and URS (21).

The number of satellite locations per country ranges from 1 (140 countries) to 5

(URS). Only two countries use more than 2 satellite locations. They are CHN (3

locations) and URS (5).

The number of service areas per country ranges from 1 (122 countries) to 35 (1

country;CHN). Only six countries have more than three service areas. They are AUS

(6 areas), CHN (35), INO (12), INS (5), PAK (5), URS (21).

Statistics by IFRB Serial Number

The plan uses 252 IFRB serial numbers. These numbers range from 003 to 341.

The number of frequency assignments per IFRB serial number ranges from 1 (37

numbers including 26 numbers assigned to CHN) to 8 (1 number assigned to J), with 4

(53 numbers) or 5 (113 numbers) being typical. Each of 239 IFRB numbers has five

assignments or less, each of other 12 IFRB numbers has six assignments, and the

remaining one IFRB number has more than six assignments. The 13 IFRB numbers that

have more than five assignments each are six numbers for AUS (6 assignments each),

one for J (8), one for KOR (6), and five for URS (6 each).

The number of countries per IFRB serial number is always 1. No IFRB serial

number is shared by two countries or more.

The number of satellite locations per IFRB serial number is also 1. No IFRB

serial number is associated with two satellite locations or more.

37
The number of service areas per IFRB serial number is also 1. No IFRB serial

numb~r is assigned to two service areas or more.

Statistics by Satellite Location

The plan uses 35 satellite locations. Except for the orbit segment between 290 E

and 380E where satellites are 4° and 5° apart, satellites are spaced 6° apart in the

geostationary orbit. There are two potential locations not used in the plan; i.e.,

1160E and 1640E. (The latter might be used for Region 2, depending on the interregional agreement.)

The number of assignments per satellite location ~anges from 3 (152oE) to 69

(190W). Each of 13 satellite locations has 20 assignments or less, each of other 13

locations has 21 to 40 assignments, and each of the remaining nine locations has more

than 40 assignments.

The number of countries per satellite location ranges from 1 (10 locations;

1600W, 340E, etc.) to 13 l310W, 190W). Each of 23 satellite locations serves five

countries or less, each of other eight locations serves from six to ten countries,

and each of the remaining four locations serves more than ten countries.

The number of IFRB serial numbers per satellite location ranges from 1 (5

locations; 1600W, 340E, etc.) to 15 (920E). Each of 13 satellite locations has five

IFRB numbers or less, each of other 14 locations has from six to ten IFRB numbers, /'

and each of the remaining eight locations has more than ten IFRB numbers.

The number of service areas per satellite location ranges from 1 (5 locations;

1600W, 340E, etc.) to 15 (920E). Each of 13 satellite locations serves five service

areas or less, each of other 14 locations serves from six to ten service areas, and

each of the remaining eight locations serves more than ten service areas.

Statistics by Service Area

The plan identifies 247 service areas. Each servi~e area has a one-to-one

correspondence to an IFRB serial number, with the following three exceptions:

°Service area centered "at 19.50Wand 61.0oN that corresponds to two IFRB

serial numbers ~O (ISL) and 91 (DNK);

o Service area centered at 17.00E and 61.50N that corresponds to four IFRB

serial numbers 90 (DNK), 104 (FNL), 121 (NOR), and 139 (S);

° Service area centered at 18.40E and 43.70N that corresponds to two IFRB

serial numbers 148 (YUG) and 149 lYUG) ..

The number of frequency assignments per service area ranges from 1 (37 areas

including 26 areas in CHN) to 10 0 area in YUG), with 4 (53 areas) or 5 (112 areas)

being typical. Each of 232 service areas has five assignments or less, each of other

12 areas has six assignments, and each of the remaining three areas has more than six

assignments. The 15 service areas that have more than five assignments each are six

38
areas for AUS (6 assignments each), one area for J (8), one area for KOR (6), one

area shared by DNK, FNL, NOR, and S (8), five areas for URS (6 each), and one area

for YUG (10).

In 210 service areas where two or more frequency assignments are made, no

assignments are made in consecutive channels in an area. In 24 areas out of such

areas, assignments are made in every other channel. In the remaining 186 areas,

assignments are made in every fourth channel or with wider spacings.

The number of countries per service area ranges from 1 (245 areas) to 4 (1).

Each of 245 areas is designated to a single country, one area is shared by two

countries (DNK and ISL), and the remaining one area is shared by four countries (DNK,

FNL, NOR, and S).

The number of IFRB serial numbers per service area ranges from 1 (244 areas) to

4 (1). Each of 244 areas has one IFRB number, each of other two areas has two IFRB

numbers~ and the remaining one area has four numbers.

The number of satellite locations per service area is always 1. There is no

service area served from two satellite locations or more.

Channel Occupancy in a Service Area

If only the channel with a frequency assignment in a service area is considered

to be occupied by the BSS, the channel occupancy is the same as the number of assignments in the service area. The channel occupancy in a service area ranges from 1 (37

areas) to 10 (1), with 4 (53) or 5 (112) being typical. The channel occupancy is 5

or less in 232 service areas, 6 in other 12 areas, and greater than 6 in the

remaining three areas.

If adjacent channels are also considered to be occupied by the BSS, the channel

occupancy is much greater than the number of channels with assignments. The channel

occupancy in a service area in this case ranges from 2 (1 area) to 21 (1), with 9

(21), 12 (36), 14 (26), and 15 (81) being typical. The channel occupancy is 6 or

less in 50 service areas, from 7 to 12 in other 75 areas, from 13 to 18 in other 121

areas, and greater than 18 in the remaining one area.

PFD (Power-Flux-Density)

The clear-weather PFD at the boresight location of the service area ranges

from -101.7 dBW/m2 to -94.7 dBW/m2. There are 49 assignments with PFD's -100 dBW/m2

or below; 220 assignments, over -100 dBW/m2up to -99 dBW/m2

; 543 assignmenfs, over

-99 dBW/m2 up to -98 dBW/m2

; 119 assignments, over -98 dBW/m2 up to -97 dBW/m2; and

53 assignments over -97 dBW/m2.

39
C.l. References

ITU (International Telecommunication Union)(1977), Final Acts of the World

Administrative Radio Conference for the Planning of the Broadcasting-Satellite

Service in Frequency Band 11.7-12.2 GHz (in Regions 2 and 3) and 11.7-12.5 GHz

(in Region 1), ITU, Geneva, Switzerland. Article 11 in particular.

40
FORM OT-29

(3-73)

u.s. DEPARTMENT OF COMMERCE OFFICE OF TELECOMMUNICATIONS

BIBLIOGRAPHIC DATA SHEET

1. PUBLICATION OR REPORT NO.2. Gov't Accession No.3. Recipient's Accession No.

NTIA Report 80-32

~. TITLE AND SUBTITLE

Sharing of the Band 12.2-12.7 GHz Between the

Broadcasting-Satellite and Fixed Services

7. AUTHOR(S)

Hiroshi Akima

8. PERFORMING ORGANIZATION NAME AND ADDRESS

U. S. Department of Commerce

NTIA/ITS-4

325 Broadway

Boulder, Colorado 80303

11. Sponsorin8 Or8anization Name and Address

U. S. Department of Commerce

National Telecommunications and Information

Administration

1800 G Street, NW; Washington, DC 20504 1~. SUPPLEMENTARY NOTES

s. Publication Date

January 1980

6. Performin~ Or~anization Code

NTIA/ITS-4

9. Project/Task/Work Unit No.

10. Contract/Grant No.

12. Type of keport and Period Covered

13.

15. ABSTRACT (A 200-word or less factual summary of most significant informafion. 1£ document includes a si~nificant

bibliography of literature survey, mentioo it here.)

The United States Administration has proposed for the 1979 WARC (World

Administrative Radio Conference) to move the BSS (broadcasting-satellite

service) in ITU (International Telecommunication Union) Region 2 from the

band 11.7-12.2 GHz to the band 12.2-12.7 GHz~ which is also allocated to the

terrestrial FS (fixed service). This report discusses the potential of sharing

between the BSS and the FS in the band 12.2-12.7 GHz. It is concluded that

sharing is feasible under certain conditions.

16. Key Words (Alphabetical order, separated by semicolons)

1979 WARC (World Administrative Radio Conference); band sharing;. BSS

(broadcasting-satellite service); FS (fixed service); interference.

11. AVAILABILITY STATEMENT

[X)( UNLIMITED.

o FOR OFFICIAL DISTRIBUTION.

18. Securi ty Class (This report)

Unclassified

19. Security Class (This page)

Unclassified

20. Number of pa~es

52

21. Price:

L' SC OMM- DC 2971 fl- P7 3

* U.S. GOVERNMENT PRINTING OFFICE: 1980-0-677-257/239