Attachment Response to Inquiry SAT-MOD-20031118-00333

Attachment Response to Inquiry

This document pretains to SAT-MOD-20031118-00333 for Modification on a Satellite Space Stations filing.

IBFS_SATMOD2003111800333_357078

MSV Responses to FCC’s Request for Additional Information

Background:

On January 21, 2004 the Commission requested additional information in order to assess
MSV’s request for waivers of provisions in Paragraphs (a)(2), (c), (d)(1), (d)(2), (d)(3),
(d)(4), (d)(5), and (e) of Section 25.253 of the Commission’s rules. The Commission
requested the following additional information:

Item 1: An analysis of the potential interference from MSV ATC base stations to
airborne AMS(R)S terminals from both a statistical basis and a worst case basis using
proposed antenna and EIRP values (see Table 2.2.3.1.A in Appendix C2 of the ATC
Order), with a description of all assumptions that are used.

Item 2: An analysis of the coordination distance that should apply to SARSAT receive
terminals operating in the 1525-1559 MHz band, including a description of all
assumptions and propagation models that are used. Results should be presented in a
manner similar to Table 3.3B in Appendix C2 of the ATC Order.

Item 3: A link budget from the ATC handset to the satellite for the -4.0 dBW EIRP
terminal and average power reduction due to vocoder ½-rate operation for both the
current satellite and the next generation satellite.

Item 4: An analysis of the potential for AMS(R)S airborne terminal overload similar to
that contained in Table 2.2.3.2.A in Appendix C2 of the ATC Order using the proposed
values of EIRP and antenna gain changes.

Item 5: In evaluating your waiver request for section 25.253(a)(2), we reviewed the
relevant GSM specifications, and it appears that the specified burst duration is the same
for both the full-rate and half-rate vocoders. It would appear based on this information
that the additional 0.5 dB reduction in average power would not apply to this situation.
Please clarify how you intend to maintain the same transmitter power and GSM burst
duration. In addition, your analysis only addresses a TDMA system. Provide a similar
analysis showing how the vocoder factor would be applied to a CDMA system.

MSV Responses

Items 1 & 4:

Introduction: The computer simulations and statistical analyses presented in this section
take into account the proposed base station antenna with the relaxed overhead gain
suppression (as specified in MSV’s ATC Application Appendix L, Table 2). In addition,
the aggregate Out-of-Band-Emissions (OOBE) EIRP density per base station sector has
been constrained to not exceed -101.9 dBW/Hz irrespective of the EIRP per carrier and
the number of carriers being radiated by a sector. This constraint (aggregate OOBE

1

density ≤ -101.9 dBW/Hz EIRP per sector, at the base station antenna output, irrespective
of the number of carriers being radiated per sector and the EIRP thereof), equates to an
aggregate OOBE density ≤ -57.9 dBW/MHz per sector at the base station antenna input
(the base station antenna gain is 16 dBi).

In this study, the worst-case simulations that MSV has conducted for a number of ATC
base station deployment scenarios indicate that, for at least some deployment scenarios,
the aggregate per sector OOBE EIRP density limit, as proposed above, is necessary to
maintain consistency with the Commission’s conclusions (as presented in the ATC
Order) regarding the ATC’s ∆T/T impact potential to airborne and non-airborne METs.

Worst-Case and Statistical Analysis – ∆T/T Impact Potential and Overload Margin
of Airborne METs: A computer simulation has been developed to address the worst-
case scenario of an airborne MET, at the minimum-allowed altitude, over a densely-
populated city. The computer simulation populates the city with a specified number of
ATC base stations (1000 maximum) by creating a compact contiguous lattice of base
stations with a distance from base station tower to base station tower calculated, in
accordance with the specified EIRP per carrier, to provide contiguous service – no gaps
in service are allowed. This is in sharp contrast with the statistical analysis approach
whereby the specified number of base stations (1000 maximum) is randomly and
uniformly distributed over a “city” (an area visible to the airborne MET from 304 m
altitude – approximately 80 km in radius). For a specified number of base stations, the
statistical analysis approach addresses the average impact of the ensemble of base station
deployment geometries – one of which is the compact contiguous lattice addressed by the
computer simulation described herein. As such, it is expected (on intuitive grounds) that
any statistical analysis approach (e.g., Monte Carlo simulation as presented by the
Commission in the ATC Order, or the analytical averaging approach presented by MSV
in its ATC Application; Addendum to Appendix L) will yield more optimistic (average)
results than the worst-case computer simulation described herein (as is verified below).

In the computer simulation, the trajectory taken by the aircraft (airborne MET) over the
city, at the lowest allowable altitude of 304 meters, is as shown in Figure 1 below. The
compact contiguous lattice of base stations begins at the lower left (LL) corner (at the
origin) and extends along the X and Y dimensions, forming an approximate square. As is
depicted in Figure 1, the aircraft trajectory follows a diagonal path over this square
(worst-case trajectory).

2

Figure 1 – Airborne MET Trajectory over City

Airborne Receiver Trajectory
(View From Top)

60

50
Y, Distance from LL Corner (km)

40

30

20

10

0
0 5 10 15 20 25 30 35 40 45 50
X, Distance from L.L. Corner (km)

Table 1 below illustrates input parameters to the computer simulation for evaluating the
∆T/T impact potential of an airborne MET as it traverses a city as specified above.

3

Table 1 – Example of Input Parameters to Computer Simulation to Evaluate the
∆T/T Impact on an Airborne MET

BTS Input Parameter Values
Base Station Tower Height 30 m
Frequency 1550 MHz
Number of ATC Base Stations 1000

Base Station Service Radius 1 km

Base Station Antenna Down-Tilt 5 deg

Other Parameters
Aggregate OOBE EIRP per Sector (Maximum) -101.9 dBW/Hz
Impact of Sectors Facing Away from Airborne MET 0 dB
Number of Sectors per Base Station Facing Toward Airborne MET 1 --
Variable Vocoder Reduction 0 dB
Voice Activity Reduction 4 dB
Closed Loop Power Control Reduction 5.2 dB
Polarization Discrimination 0 dB
Effective OOBE EIRP per Sector -111.1 dBW/Hz
MET Receiver Noise Temperature 316.2 K

Aircraft Trajectory and GNSS Antenna Values
Airborne MET Trajectory (km) X Y
Starting Point 1 1
Ending Point 48 52
Airborne MET Antenna Gain in Direction of Base Station 0 dBi
Airborne MET Antenna Gain Reduction due to Aircraft Shielding 0 dB
Aircraft Altitude 304 m

Table 2 below illustrates input parameters to the computer simulation for evaluating the
overload margin of an airborne MET as it traverses a city that is densely-populated (as
discussed earlier) with a number of ATC base stations.

4

Table 2 – Example of Input Parameters to Computer Simulation to Evaluate the
Overload Margin on an Airborne MET

BTS Input Parameter Values
Base Station Tower Height 30 m
Frequency 1550 MHz
Number of Base Stations 1000

Base Station Service Radius 1 km

Base Station Antenna Down-Tilt 5 deg

Other Parameters
Base Station EIRP per Carrier 19.1 dBW
Contribution from Sectors Facing Away from Airborne MET 0 dB
Carriers per Base Station Sector 3 --
Variable Vocoder Reduction 0 dB
Voice Activity Reduction 4 dB
Closed Loop Power Control Reduction 5.2 dB
Polarization Discrimination 0 dB
Aggregate Effective EIRP per Sector 14.7 dBW
Overload Threshold of Airborne MET Receiver -50.0 dBm

Aircraft Trajectory and GNSS Antenna Values
Airborne Receiver Trajectory (km) X Y
Starting Point -10 -10
Ending Point 48 52
Antenna Gain of Airborne MET in Direction of Base Station 0 dBi
Shielding of MET Antenna by Aircraft 0 dB
Aircraft Altitude 304 m

The following several Figures (Figures 2 through 8) show the ∆T/T impact potential and
the overload margin potential of the airborne MET, for various different ATC base
station deployment scenarios as a function of the MET’s trajectory over a city. For each
point on the MET trajectory, the ∆T/T impact potential and the overload margin potential
is calculated taking into account the impact from each ATC base station. Free-space line-
of-sight propagation is assumed (from the base stations to the airborne MET) and the
proposed base station antenna pattern with the relaxed overhead gain suppression is taken
into account.

5

Figure 2 – The “Baseline” Case Addressed in the ATC Order: 1000 Base Stations;
3 Carriers per Sector; 19.1 dBW EIRP per Carrier; 1 km Service Radius
(Aggregate Directional Inband EIRP = 19.1 + 10log(3) + 10log(1000) = 53.9)

(a) Worst-Case ∆T/T Impact
Delta-T/T

40.0%

30.0%
Delta T/T

20.0%

10.0%

0.0%
0 5 10 15 20 25 30 35 40 45 50
X, Distance From L.L. Corner (km)

(b) Worst-Case Overload Margin
Overload Margin

12.00

10.00

8.00
Margin (dB)

6.00

4.00

2.00

0.00
0 5 10 15 20 25 30 35 40 45 50
X, Distance From L.L. Corner (km)

It is interesting to observe, for the above “baseline” case, that the Commission’s Monte
Carlo statistical analysis predicts a ∆T/T impact of 16.5% and an overload margin of 10.4
dB (see ATC Order Appendix C2, Tables 2.2.3.1.A and 2.2.3.2.A). MSV’s worst-case
computer simulation yields more conservative (pessimistic) results. As can be seen,
Figure 2(b) predicts a worst-case overload margin of 7.5 dB at the point where the
airborne MET is over the city center, increasing to about 11 dB at the city edges. For the
∆T/T impact (Figure 2(a)) MSV’s computer simulation predicts 12% at the center of the
city. This value would have been 36% if the “spurious EIRP density” (OOBE EIRP
density limit) were allowed to be -101.9 dBW/Hz per carrier (as the Commission assumes
in its statistical analysis; Table 2.2.3.1.A of the ATC Order). By constraining the
aggregate per sector “spurious EIRP density” (aggregate per sector OOBE EIRP density
limit) to be no greater than -101.9 dBW/Hz (as MSV is proposing based on this study)

6

the worst-case ∆T/T stays within the bound authorized by the Commission in the ATC
Order and, furthermore, allows the number of carriers per sector to be increased1 while all
∆T/T conclusions reached by the Commission in the ATC Order, for both airborne and
non-airborne METs, continue to hold and in fact improve as is demonstrated below. The
left portion of the Table below (columns A, B) is a reproduction of Table 2.2.3.1.A of the
ATC Order. Columns C and D are new. Column C reflects MSV’s analytical (non
Monte Carlo based) statistical analysis approach (see MSV’s ATC Application,
Addendum to Appendix L) while Column D reflects the Commission’s Monte Carlo
statistical analysis approach. Both approaches of columns C and D have been adjusted to
take into account 1) the proposed base station antenna pattern with the relaxed overhead
gain suppression and 2) an aggregate spurious EIRP density per sector of -101.9 dBW/Hz
(as discussed above). As such, the first numerical entry of column C and/or D “-101.9”
denotes the aggregate (from all carriers that may be deployed in a sector) spurious EIRP
density limit (aggregate per sector OOBE EIRP density limit).2 The second numerical
entry of column C and/or D “1” denotes the number of sectors per base station assumed
to impact an airborne MET. Every other entry of column C and/or D maintains its
original meaning. It is seen from column D that the Commission’s statistical analysis
predicts ∆T/T = 5.5% whereas the computer simulation results of Figure 2(a) are more
pessimistic predicting a worst-case ∆T/T of 12% at the point where the airborne MET is
over the center of the ATC base station cluster.

A B C D
Modified Table 2.2.3.1.A: Potential Adjusted For Proposed BTS
Interference to Inmarsat Airborne Antenna Gain and EIRP
Receiver from ATC Base Stations As shown in ATC Order Limits
1000 Base stations 1000 Base stations
FCC's Monte
Carlo
Item Units MSV Approach MSV (adjusted) FCC (adjusted)
EIRP per Carrier (dBW) 19.1
Bandwidth (kHz/ch) 200.0
EIRP Density/carrier (dBW/Hz) -33.9
Spurious EIRP density (dBW/Hz) -101.9 -101.9 -101.9 -101.9
Assumed spurious limit (out-of-band suppression) (dB) -68.0 -68.0
Carriers per sector (#) 3.0 3 1.0 1
Voice activation (dB) 4.0 4 4.0 4
Power control (dB) 6.0 5.2 6.0 5.2
Polarization (dB) 8.0 0 8.0 0
Spurious emissions average (dBW/Hz) -115.1 -106.3 -119.9 -111.1

Gain discrim. Inmarsat MES to Base Station (dB) 0.0 0.0 0.0 0.0
Calculated Isolation (dB) -101.6 -105.1 -105.4 -105.1
Received interference power (dBW/Hz) -216.7 -211.4 -225.3 -216.2

Receiver Noise Temperature (dBK) 25.0 25.0 25.0 25.0
Receiver Noise Temperature (K) 316.2 316.2 316.2 316.2
Receiver Noise Density (dBW/Hz) -203.6 -203.6 -203.6 -203.6
Interference Temperature (T) 15.4 52.1 2.1 17.4
Delta-T/T (%) 4.9% 16.5% 0.7% 5.5%
Interference to Noise Ratio (Io/No) (dBW/Hz) -13.1 -7.8 -21.7 -12.6

1
As MSV is requesting subject to the upper bound of 38.9 dBW aggregate EIRP per sector (see MSV’s
ATC Application Appendix J).
2
This means that as a function of the number of carriers deployed by a sector and as a function of the in-
band EIRP per carrier, the filtering requirements of the sector may vary. Alternatively, a single filter
design may be developed based on a “maximal” deployment scenario (e. g., 6 carriers per sector, 29.1 dBW
EIRP per carrier) and such filter (with 13 dB more out-of-band rejection relative to a filter designed for the
baseline case; 3 carriers per sector, 19.1 dBW EIRP per carrier) could be used everywhere.

7

Figure 3 - 500 Base Stations; 6 Carriers per Sector; 19.1 dBW EIRP per Carrier;
1 km Service Radius per Base Station
(Aggregate Directional Inband EIRP = 19.1 + 10log(6) + 10log(500) = 53.9)

(a) Worst-Case ∆T/T Impact
Delta-T/T

40.0%

30.0%
Delta T/T

20.0%

10.0%

0.0%
-20 -10 0 10 20 30 40 50
X, Distance From L.L. Corner (km)

(b) Worst-Case Overload Margin
Overload Margin

16.00
14.00
12.00
Margin (dB)

10.00
8.00
6.00
4.00
2.00
0.00
-20 -10 0 10 20 30 40 50
X, Distance From L.L. Corner (km)

The computer simulation results for overload margin (Figure 3(b) above) can now be
compared with the overload value that the Commission’s Monte Carlo statistical analysis
predicts for this case. The Table below is a reproduction of Table 2.2.3.2.A of the ATC
Order (first two columns). The right-most column in new and addresses the
Commission’s statistical analysis approach adjusted to take into account the base station
antenna pattern with the relaxed overhead gain suppression and the new base station
deployment scenario of Figure 3 (500 base stations, 19.1 dBW EIRP per carrier, 6
carriers per sector).

8

A B C
Modified Table 2.2.3.2.A: Evaluation Adjusted For Proposed BTS
of Potential for AMS(R)S Airborne Antenna Gain and EIRP
Terminal Overload As shown in ATC Order Limits
1000 Base stations 500 Base stations

Parameter Units MSV Value FCC Analysis FCC (adjusted)
BS EIRP per carrier (dBW) 19.1 19.1 19.1
Carriers per sector (#) 3.0 3.0 6.0
Voice activation (dB) 4.0 4.0 4.0
BS power control (dB) 6.0 5.2 5.2
EIRP per sector (dBW) 13.9 14.7 17.7
Polarization isolation (dB) 8.0 0.0 0.0
Gain discrimination MES to base station (dB) 0.0 0.0 0.0
Calculated base station isolation (dB) -101.6 -105.1 -108.1
Effective power per sector at A/C (dBW) -95.7 -90.4 -90.4
Power at A/C receiver (dBm) -65.7 -60.4 -60.4
Overload level (dBm) -50.0 -50.0 -50.0
Margin (dB) 15.7 10.4 10.4

It is seen from the above Table (right-most column) that the Commission’s Monte Carlo
statistical analysis, when adjusted to reflect the deployment scenario of Figure 3 (500
base stations, 19.1 dBW EIRP per carrier, 6 carriers per sector) and the proposed base
station antenna with the relaxed overhead gain suppression, predicts the same (as for the
baseline case) overload margin of 10.4 dB.3 In contrast, MSV’s “worst-case” computer
simulation (Figure 3(b) above) predicts an overload margin of 6 dB when the airborne
MET is over the center of the city (over the center of the base station cluster), increasing
to 14 dB at the edges of the city. It is evident that the statistical analysis approach
predicts an “ensemble average” overload margin and is not able to predict variations
about this average as a function of specific base station deployment scenarios. Clearly
the base station deployment scenarios of Figures 2 and 3 differ. Figure 2 reflects the
baseline case of 1000 base stations, 19.1 dBW EIRP per carrier, and 3 carriers per sector.
Figure 3 is based on 500 base stations, 19.1 dBW EIRP per carrier, and 6 carriers per
sector. Intuitively, the deployment scenario of Figure 3 may be expected to yield lower
worst-case overload margin given the higher aggregate EIRP per base station sector. The
computer simulation results of Figure 3(b) bear this out. While the statistical analysis
predicts the same overload margin for both deployment scenarios, the computer
simulation results of Figures 2(b) and 3(b) differ and reflect the impact of reducing the
number of base stations (to half the original number) while at the same time the aggregate
EIRP per sector is doubled. As seen from Figures 2(b) and 3(b) the overall effect is to
reduce the worst-case overload margin from 7.5 dB to 6 dB (a value that is still consistent
with RTCA and ITU recommendations; see RTCA Document DO-235; ITU-R M.1477).

The next Table shows that according to the Commission’s statistical analysis relating to
∆T/T for this case, a ∆T/T of 2.8% is predicted. The worst-case computer simulation
result of Figure 3(a) predicts a ∆T/T of 8%.

3
The effect of the proposed base station antenna with the relaxed overhead gain suppression (see MSV’s
ATC Application, Appendix L, Table 2) is completely negligible. As has been shown previously, and also
verified by the present study, the effect of the proposed antenna is to increase the “calculated base station
isolation” by less than 0.03 dB (see MSV’s ATC Application, Addendum to Appendix L).

9

A B C D
Modified Table 2.2.3.1.A: Potential Adjusted For Proposed BTS
Interference to Inmarsat Airborne Antenna Gain and EIRP
Receiver from ATC Base Stations As shown in ATC Order Limits
1000 Base stations 500 Base stations
FCC's Monte
Carlo
Item Units MSV Approach MSV (adjusted) FCC (adjusted)
EIRP per Carrier (dBW) 19.1
Bandwidth (kHz/ch) 200.0
EIRP Density/carrier (dBW/Hz) -33.9
Spurious EIRP density (dBW/Hz) -101.9 -101.9 -101.9 -101.9 Per Sector Aggregate Limit
Assumed spurious limit (out-of-band suppression) (dB) -68.0 -68.0 (for Columns C and D)
Carriers per sector (#) 3.0 3 1.0 1 Sectors/BTS Seen by MET
Voice activation (dB) 4.0 4 4.0 4
Power control (dB) 6.0 5.2 6.0 5.2
Polarization (dB) 8.0 0 8.0 0
Spurious emissions average (dBW/Hz) -115.1 -106.3 -119.9 -111.1

Gain discrim. Inmarsat MES to Base Station (dB) 0.0 0.0 0.0 0.0
Calculated Isolation (dB) -101.6 -105.1 -108.4 -108.1
Received interference power (dBW/Hz) -216.7 -211.4 -228.3 -219.2

Receiver Noise Temperature (dBK) 25.0 25.0 25.0 25.0
Receiver Noise Temperature (K) 316.2 316.2 316.2 316.2
Receiver Noise Density (dBW/Hz) -203.6 -203.6 -203.6 -203.6
Interference Temperature (T) 15.4 52.1 1.1 8.7
Delta-T/T (%) 4.9% 16.5% 0.3% 2.8%
Interference to Noise Ratio (Io/No) (dBW/Hz) -13.1 -7.8 -24.7 -15.6

We conclude that, in general, a computer simulation that takes into account the specific
deployment geometry of a given base station cluster (compactness, lattice regularity, and
service radius per base station) yields more pessimistic results in both overload margin
potential and ∆T/T potential than a statistical analysis (Monte Carlo based or not) which
can only address the impact of the ensemble average of all deployment geometries of a
given number of base stations. The computer simulations presented herein (Figures 2
through 8) evaluate the worst-case values for overload margin potential and ∆T/T
potential, for various different ATC base station deployment scenarios, as the airborne
MET traverses a city at the minimum allowed altitude (304 m).4

The specific deployment scenarios identified in Figures 2 through 8 are illustrative.
However, at least some of these scenarios (or variations thereof) may be deployed in
MSV’s nation-wide ATC depending on the specific requirements of particular markets
(cities) such as geographic area to be covered, existing cellular/PCS infrastructure (base
station towers) to be reused by the ATC, and traffic densities. In certain cases, other
scenarios (not addressed herein) may prove necessary. For each specific deployment
scenario that becomes necessary for a specific geographic area, MSV will evaluate the
worst-case overload margin and ∆T/T impact potential to airborne METs in accordance
with the worst-case simulation tool presented herein. As such, the Commission need not
a priori authorize specific deployment architectures of ATC base stations; the
Commission need only remove the present restrictions on carrier EIRP and number of
carriers per sector. As the present worst-case analysis clearly demonstrates, such
restrictions are unnecessary for the protection of airborne METs.

4
Furthermore, as the Commission has recognized, zero polarization discrimination benefit in conjunction
with 0 dBi MET antenna gain in the direction of a base station tower represent conservative parameter
choices (See ATC Order, Appendix C2, §§ 2.2.3.2). This further underscores the conservative and worst-
case nature of the results presented in Figures 3 through 8.

10

Figure 4 - 250 Base Stations; 3 Carriers per Sector; 25.1 dBW EIRP per Carrier;
1.5 km Service Radius per Base Station
(Aggregate Directional Inband EIRP = 25.1 + 10log(3) + 10log(250) = 53.9)

(a) Worst-Case ∆T/T Impact
Delta-T/T

40.0%

30.0%
Delta T/T

20.0%

10.0%

0.0%
-20 -10 0 10 20 30 40 50
X, Distance From L.L. Corner (km)

(b) Worst-Case Overload Margin
Overload Margin

16.00

14.00

12.00
Margin (dB)

10.00

8.00
6.00

4.00

2.00

0.00
-20 -10 0 10 20 30 40 50
X, Distance From L.L. Corner (km)

11

Figure 5 - 125 Base Stations; 6 Carriers per Sector; 25.1 dBW EIRP per Carrier;
2 km Service Radius per Base Station
(Aggregate Directional Inband EIRP = 25.1 + 10log(6) + 10log(125) = 53.9)

(a) Worst-Case ∆T/T Impact
Delta-T/T

40.0%

30.0%
Delta T/T

20.0%

10.0%

0.0%
-30 -20 -10 0 10 20 30 40 50
X, Distance From L.L. Corner (km)

(b) Worst-Case Overload Margin
Overload Margin

18.00
16.00
14.00
12.00
Margin (dB)

10.00
8.00
6.00
4.00
2.00
0.00
-30 -20 -10 0 10 20 30 40 50
X, Distance From L.L. Corner (km)

12

Figure 6 - 100 Base Stations; 3 Carriers per Sector; 29.1 dBW EIRP per Carrier;
2.5 km Service Radius per Base Station
(Aggregate Directional Inband EIRP = 29.1 + 10log(3) + 10log(100) = 53.9)

(a) Worst-Case ∆T/T Impact
Delta-T/T

40.0%

30.0%
Delta T/T

20.0%

10.0%

0.0%
-20 -10 0 10 20 30 40 50
X, Distance From L.L. Corner (km)

(b) Worst-Case Overload Margin
Overload Margin

16.00

14.00

12.00

10.00
Margin (dB)

8.00

6.00

4.00

2.00

0.00
-20 -10 0 10 20 30 40 50
X, Distance From L.L. Corner (km)

13

Figure 7 - 100 Base Stations; 6 Carriers per Sector; 26.1 dBW EIRP per Carrier;
2.7 km Service Radius per Base Station
(Aggregate Directional Inband EIRP = 26.1 + 10log(6) + 10log(100) = 53.9)

(a) Worst-Case ∆T/T Impact
Delta-T/T

40.0%

30.0%
Delta T/T

20.0%

10.0%

0.0%
-30 -20 -10 0 10 20 30 40 50
X, Distance From L.L. Corner (km)

(b) Worst-Case Overload Margin
Overload Margin

18.00
16.00
14.00
12.00
Margin (dB)

10.00
8.00
6.00
4.00
2.00
0.00
-30 -20 -10 0 10 20 30 40 50
X, Distance From L.L. Corner (km)

14

Figure 8 - 87 Base Stations; 1 Carrier per Sector; 38.9 dBW EIRP per Carrier;
5.7 km Service Radius per Base Station
(Aggregate Directional Inband EIRP = 38.9 + 10log(1) + 10log(87) = 58.3)

(a) Worst-Case ∆T/T Impact
Delta-T/T

40.0%

30.0%
Delta T/T

20.0%

10.0%

0.0%
-30 -20 -10 0 10 20 30 40 50
X, Distance From L.L. Corner (km)

(b) Worst-Case Overload Margin
Overload Margin

14.00

12.00

10.00
Margin (dB)

8.00

6.00

4.00

2.00

0.00
-20 -10 0 10 20 30 40 50
X, Distance From L.L. C orne r (km)

15

Item 2:
The Commission requested an analysis of how Table 3.3.B of Appendix C2 to the ATC
Order would change using MSV's proposed values. The table is reproduced below with
changes highlighted in bold. Since MSV is not authorized to provide MSS in the 1544-
1545 MHz band, the potential for interference is strictly an out-of-band case. While
MSV has asked the Commission for an increase in carrier/sector in-band EIRP, it has not
asked for any change in out-of-band emissions density (-57.9 dBW/MHz) into the base
station antenna. On the contrary, MSV is proposing to make the aggregate Out-of-Band-
Emissions (OOBE) density per sector into the base station antenna port no greater than -
57.9 dBW/MHz, irrespective of the number of carriers per sector and in-band EIRP
thereof.

Modified Table 3.3.B: Analysis of SARSAT Avoidance Distance
Item Units Value Comment
Nominal Center Frequency (MHz) 1554.5
Polarization Note 1
Elevation Angle (Degrees) 0 Note 2
Antenna Diameter (m) 1.8

SARSAT Gain (typical) (dBi) 26.7
SARSAT (G/T) (dB/K) 4.0
SARSAT Noise Temperature (dBºK) 22.7

Receiver Noise Power (dBW/Hz) -205.9
Allowable I/N (dB) -11.32
Maximum Allowable Io (dBW/Hz) -217.2

Receive Gain (dBi) 26.7
Isotropic Area (dBm^2) -25.3
Receive Antenna Effective Area (dBm^2) 1.5
Allowable Power Flux at Antenna (dBW/m^2 Hz) -218.6

Aggregate per Sector OOB Emission (dBW/MHz) -57.9
MSV BS peak Antenna gain dBi 16.0
BS Gain Reduction Toward Horizon dB 5.0
Sectors with LOS to SARSAT (1) dB 0
Power Control dB -2.3
Voice Activation dB -1.8
Polarization Discrimination dB 0
Peak Out-of-band Emission dBW/MHz -53.9
MSV OOB Emission Density (dBW/Hz) -113.9
Required Loss (dBm^2) 130.0

Maximum Interference Distance (km) 48.8
Maximum Interference Distance (mi) 29.3
Note 1: SARSAT System uses both RHCP and LHCP
Note 2: SARSAT receivers typically point to the horizon awaiting an oncoming NGSO
satellite.

16

Even though the maximum interference distance is reduced (from its original value of
85.6 km; see ATC Order Appendix C2, Table 3.3.B) to 48.8 km, the Commission’s
coordination threshold of 27 km still seems appropriate. MSV proposes to coordinate all
ATC base stations that it locates within 27 km of a SARSAT receiver where a line-of-
sight path exists between the ATC base station transmitting antenna and the SARSAT
receiver.

17

Item 3:

Tables 1 and 2 below present the return- and forward-link satellite link budgets for
MSV’s next generation satellite based on the -4 dBW EIRP satellite terminal. (These
link budgets appear in MSV’s satellite application amendment filed on November 18,
2003 (File No. SAT-AMD-20031118-00335)).
Table 1: GMR-2 Return Link Budget

Voice Traffic Channels
Channel Type
→ “1/2-Rate” Robust Mode “1/4-Rate” Basic Mode Units
CARRIER PARAMETERS:
Carrier Noise Bandwidth: 50.0 50.0 kHz
Number of voice channels per
return-link carrier: 4 8
DOWNLINK:
(satellite to Gateway)
Satellite gateway G/T: 36.5 36.5 dB/ºK
Satellite EIRP Per Carrier: 20.5 20.5 dBW
Rain Loss (w/ site diversity): -6.0 -6.0 dB
Path loss: -205.2 -205.2 dB
2-satellite diversity combining: 3.0 3.0 dB
Boltzmann's constant: -228.6 -228.6 dBW/Hz·ºK
Downlink C/No 77.4 77.4 dB·Hz
UPLINK:
User Terminal PA Output Power: 0.0 0.0 dBW
User Terminal Antenna Gain: -4.0 -4.0 dBi
User Terminal EIRP: -4.0 -4.0 dBW
Allocated fading & blockage: -14.3 -10.5 dB
U/L Path Loss: -188.8 -188.8 dB
Polarization Loss (linear to CP) -3.0 -3.0 dB
Dual polarization recombination
gain (at satellite gateway) 4.0 4.0 dB
Satellite G/T: 21.0 21.0 dB/ºK
2-satellite diversity combining: 4.0 4.0 dB
∆T/T interference allowance due
to ATC: -0.2 -0.2 dB
Boltzmann's constant: -228.6 -228.6 dBW/Hz·ºK
Uplink C/No 47.3 51.1 dB·Hz
INTRA-SYSTEM INTERFERENCE:
Effective frequency reuse: 28 28
Voice activity improvement
factor: 2.0 2.0 dB
Avg. adj. beam discrimination: 25.0 25.0 dB
C/I: 12.7 12.7 dB
C/Io: 59.7 59.7 dB·Hz
C/Io: 59.7 59.7 dB·Hz
TOTAL: C/(No+Io): 47.1 50.5 dB·Hz
Per User C/(No+Io): 41.0 41.5 dB·Hz
Required Per User
C/(No+Io): 40.0 40.5 dB·Hz

Link Margin: 1.0 1.0 dB

18

Table 2: GMR-2 Forward Link Budget

Voice Traffic Channels:
Link Type → “1/2-Rate” Robust Mode “1/4-Rate” Basic Mode Units
CARRIER PARAMETERS:
Carrier Noise Bandwidth: 200.0 200.0 kHz
Carrier channel bit rate: 270833.3 270833.3 bps
Number of voice channels per forward link
carrier: 16 32

DOWNLINK:
Satellite EIRP Per Carrier: 61.4 61.6 dBW
Path loss: -188.3 -188.3 dB
Polarization Loss (CP to linear) -3.0 -3.0 dB
Allocated fading & blockage -14.3 -10.5 dB
User Terminal G/T: -31.0 -31.0 dB/ºK
Boltzmann's constant: -228.6 -228.6 dBW/Hz·ºK
Downlink C/No: 53.4 57.4 dB·Hz
UPLINK:
Gateway Uplink EIRP per Carrier: 61.0 61.0 dBW
U/L Rain Loss (assume site diversity): -6.0 -6.0 dB
U/L Path Loss: -206.7 -206.7 dB
Satellite Ku-band feeder link G/T: -3.0 -3.0 dB/ºK
Boltzmann's constant: -228.6 -228.6 dBW/Hz·ºK
Uplink Peak C/No: 73.9 73.9 dB·Hz
INTRA-SYSTEM INTERFERENCE:
Effective frequency reuse: 28.0 28.0
Voice activity improvement factor: 4.0 4.0 dB
Avg. adj. beam discrimination: 25.0 25.0 dB
C/I: 14.7 14.7 dB
C/Io: 67.7 67.7 dB·Hz
Intermodulation C/Imo: 67.0 67.0 dB·Hz
C/Io: 64 64 dB·Hz
TOTAL:
C/(No+Io): 53.0 56.5 dB·Hz
Per User C/(No+Io): 41.0 41.5 dB·Hz
Required per User C/(No+Io): 40.0 40.5 dB·Hz

Link Margin: 1.0 1.0 dB

It is seen from both the return- and forward-link budgets above that more than 10 dB of
link margin is available in the “basic” mode (32 users per 200 kHz carrier) with more
than 14 dB of link margin available in “robust” mode (16 users per 200 kHz carrier).5
(The robust mode trades capacity for link margin by allocating two time slots per frame
to the user as well as more channel coding; see GMR-2 specification.) The satellite link
vocoder assumed in the above link budgets is the DVSI 3.6 kbps vocoder (as used in the
ACeS system). Tables 3 and 4 below present the return- and forward-link budgets for
MSV’s present satellite system. The 2.4 kbps DVSI vocoder is assumed, and the EIRP of
the “link margin booster” to the integrated ATC terminal (see MSV’s ATC Application
Appendix A) is 6 dBW. The available link margin in robust mode is 6 dB.

5
See the “Allocated fading & blockage” entries of the Tables.

19

Item 5:

The Commission is correct. The burst duration is the same for both the full-rate and half-
rate GSM vocoders. When an ATC terminal switches from using the full-rate vocoder to
the half-rate vocoder it switches from transmitting 13 kbps to 4.75 kbps. Just prior to
switching to half-rate mode the terminal radiates one burst per frame. After switching to
half-rate mode the terminal radiates only one burst per two frames. This (once per two
frames bursting) suffices to transmit the information delivered by the half-rate vocoder
since the half-rate vocoder outputs less than half of the information rate of the full-rate
vocoder. It is the “less than half” information rate of the half-rate vocoder that yields at
least an additional 0.5 dB of terminal power reduction during the burst.6 Thus, in forcing
an ATC terminal to switch from the full-rate to the half-rate vocoder two things occur
simultaneously: 1) the terminal transmits one burst per two frames (this is a 3 dB
reduction in average transmitted power), and 2) the power during the burst is reduced by
at least 0.5 dB since the information rate of the “half-rate” vocoder is 4.75 kbps instead of
6.5 kbps.

In general, as a communications link switches from transmitting 13 kbps (full-rate
vocoder) to 4.75 kbps (half-rate vocoder) the average transmitted power required by the
link, assuming the same Bit Error Rate (BER) at the receiver, reduces by 10log(13/4.75)
≈ 4.4 dB. This is a fundamental result and is independent of the multiple access
technology (TDMA or CDMA). We can, therefore, state that as an ATC terminal
(CDMA or TDMA) reaches or exceeds an output power level of (PMax - 3.5 dB) the
vocoder of that terminal will be commanded to switch to half-rate mode. The terminal’s
vocoder (having been switched from full-rate to half-rate) may be switched back to full-
rate as the terminal’s output power level becomes lower than or equal to (PMax - 7 dB).

6
We observe that 10log(6.5/4.75) ≈ 1.4 dB; MSV conservatively uses 0.5 dB. Thus, the once per two
frames bursting of the half-rate vocoder mode yields 3 dB of average power reduction while the less than
half information rate of the half-rate vocoder conservatively yields an additional 0.5 dB of power reduction
for an overall effective average power reduction of 3.5 dB.

22

Document Created: 2004-02-04 15:56:45
Document Modified: 2004-02-04 15:56:45

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