**APPENDIX A**

**ASSESSMENT OF POTENTIAL INTERFERENCE TO RADAR**

**SYSTEMS IN THE 5725-5875 MHz BAND FROM HIGHER-POWERED UNLICENSED
DEVICES EMPLOYING DYNAMIC**

**FREQUENCY SELECTION**

## 

## INTRODUCTION

In the Notice of Proposed Rulemaking (NPRM) the Federal Communications
Commission (Commission) proposed to permit higher-powered unlicensed
device operation in the 5725-5875 MHz band.[^1] Under the Commission's
proposal, this higher-powered unlicensed device operations would be
limited to rural areas or areas where it is determined that spectrum use
is limited.[^2] The Commission proposed that the unlicensed devices
operating in these rural or unused areas employ dynamic frequency
selection (DFS)[^3] with a detection threshold of 30 dB above the
thermal noise floor within a measurement bandwidth of 1.25 MHz.[^4]

The Federal Government users in the 5725-5875 MHz band are fixed,
transportable, and mobile radar systems operated by the Department of
Defense (DoD) that are used primarily for surveillance, test range
instrumentation and experimental testing.[^5] These radar systems are
used extensively in support of national and military test range
operations in the tracking and control of manned and unmanned airborne
vehicles. As pointed out in the NPRM, many of the installations where
these radar systems operate are located in rural areas to avoid
interference with other systems.[^6] There is also a growing concern
regarding potential interference to these radar systems related to their
expanding role in support of homeland defense. This expanded role could
result in a requirement to deploy radar systems in areas close to cities
and highways, potentially increasing interference to the radar systems
from unlicensed devices operating at the higher power levels. The
potential interference between military radar systems operating in the
5250-5350 MHz and 5470-5725 MHz and Unlicensed National Information
Infrastructure (U-NII) devices employing DFS was addressed as part of
another Commission rulemaking proceeding.[^7] A similar analysis must be
performed in the 5725-5875 MHz band in order to assess whether the power
levels and detection threshold proposed by the Commission are adequate
to protect these radar systems.

This appendix describes: the operational scenario for the unlicensed
devices and the military radar systems used in the assessment; the
technical characteristics of the radar systems and unlicensed devices
used in the assessment; and the engineering algorithms used to assess
the potential for interference to the radar systems from the DFS
equipped unlicensed devices. The analysis will assess whether the
proposed power levels and detection threshold is adequate to protect the
radar systems.

## 

## DESCRIPTION OF UNLICENSED DEVICE DEPLOYMENT

The NPRM does not propose a specific higher powered unlicensed device
application in the 5725-5875 MHz band. However, it does indicate that
local area networks and Wireless Internet Service Providers (WISP) would
benefit from the proposed higher power levels.[^8] In another rulemaking
the Commission expects that the primary use of unlicensed devices in
rural areas would be to provide wireless Internet services such as those
provided by WISPs.[^9] The higher power levels proposed by the
Commission will in all likelihood not be used in hand-held or laptop
unlicensed device application because of radiation hazard and battery
life issues.

In this assessment, the number of unlicensed devices will be varied and
the locations of the unlicensed devices will be randomly distributed in
a circular region defined by a radius of 25 kilometers. It is assumed
that all of the unlicensed devices are transmitting and are co-channel
with the radar system. The antenna heights will be randomly assigned to
each unlicensed device, using a uniform probability distribution. The
range of the antenna heights considered in the analyses are: 6 to 10
meters; 10 to 40 meters, or 40 to 100 meters.

### DESCRIPTION OF RADAR DEPLOYMENT

Two aspects are considered when positioning the radar with time, one
taking into account the physical location of the radar and the other
taking into account the scanning ability of the radar beam. The radars
operating in the 5725-5875 MHz band include: ground-based (scanning and
tracking), airborne, and maritime systems.[^10] In the technical studies
examining interference from DFS equipped U-NII devices, it was
determined that radars employing tracking beam scans were the most
susceptible to interference. A tracking beam scan was defined as a beam
pointing at the horizon in any direction that then moves directly
overhead and opposite to the starting location to the horizon. The
location of the tracking radar and the azimuth of the beam will be
varied to determine where the highest interference level occurs.[^11]

## UNLICENSED DEVICE TECHNICAL CHARACTERISTICS

## Unlicensed Device Power Levels

## 

##  The Commission proposed two emission levels for the higher-powered unlicensed devices operating in the 5725-5875 MHz band: 1) transmitter power of 6 watts and 2) a field strength limit of 125 milliVolts per meter (mV/m) at a reference distance of 3 meters.[^12] Converting these emission levels to equivalent isotropically radiated power (EIRP) levels results in 38 dBm (6 watts) and 6.6 dBm (125 mV/m). In this assessment, two transmitter power distributions are considered: 1) 50% of the unlicensed devices operating at the higher EIRP level of 38 dBm and 50% operating at the lower EIRP level of 6 dBm; and 2) 100% of the unlicensed devices operating at the higher EIRP level of 38 dBm.

### Unlicensed Device Transmitter and DFS Detection Bandwidths

There are two bandwidths of concern for unlicensed devices employing
DFS. The first bandwidth is the transmitter bandwidth used by the
unlicensed device. The second is the bandwidth used to measure the DFS
detection threshold. The Commission did not define the bandwidth for the
unlicensed device. In this assessment, three transmitter bandwidths are
considered for the unlicensed devices: 1 MHz, 6 MHz, and 18 MHz. The 1
MHz bandwidth of the unlicensed device is matched to the radar receiver
bandwidth of 1 MHz, which represents a worst case from an interference
perspective. The 6 MHz bandwidth is representative of the transmit
bandwidth used by fixed wireless access systems. The 18 MHz bandwidth is
consistent with that employed by U-NII devices.

As discussed in the NPRM, the Commission defined the measurement
bandwidth for the DFS detection to be 1.25 MHz.

### Unlicensed Device Antenna Gain Patterns

In another rulemaking, the Commission stated that in rural areas
unlicensed devices would typically employ omnidirectional antennas in
order to achieve the most uniform coverage of a particular geographic
area.[^13] The unlicensed device antenna pattern used in this assessment
is omnidirectional in the azimuth plane.

The unlicensed device antenna pattern in elevation orientations was
determined by examination of unlicensed device antenna patterns. The
unlicensed device antenna elevation pattern is defined in terms of the
antenna gain in dBi as a function of the elevation angle (ϕ) in degrees.
The antenna elevation pattern used in this analysis is described below
in Table A-1.

Table A-1. Unlicensed Device Elevation Antenna Pattern

  -------------------------------------- --------------------------------
  Elevation angle\                       Gain\
  (degrees)                              (dBi)

  45 \< ϕ ≤ 90                           --4

  35 \< ϕ ≤ 45                           --3

  0 \< ϕ ≤ 35                            0

  --15 \< ϕ ≤ 0                          --1

  --30 \< ϕ ≤ --15                       --4

  --60 \< ϕ ≤ --30                       --6

  --90 \< ϕ ≤ --60                       --5
  -------------------------------------- --------------------------------

### RADAR TECHNICAL CHARACTERISTICS

### Radar Transmitter and Receiver Characteristics

Representative technical and operational characteristics of the radar
systems used in this analysis are provided in Recommendation ITU-R
M.1638. The ITU-R Recommendation provides the transmitter power level,
mainbeam antenna gain, transmitter and receiver bandwidths, and receiver
noise figure for each type of radar included in the analysis. Table A-2
provides the characteristics of the radar transmitter and receiver used
in this analysis.

Table A-2. Radar Transmitter and Receiver Characteristics

  ----------------------------------- -----------------------------------
  **Parameter**                       **Value**

  **Frequency**                       5725 MHz

  **Transmitter Power**               250,000 Watts

  **Transmitter Bandwidth**           1 MHz

  **Receiver Bandwidth**              1 MHz

  **Receiver Noise Figure**           6 dB

  **Transmitter and Receiver          2 dB
  Insertion Losses**                  

  **Mainbeam Antenna Gain**           38.3 dBi

  **Antenna Height**                  20 meters
  ----------------------------------- -----------------------------------

### Radar Antenna Gain Pattern

A model representing the envelope of the gain of typical directional
antennas is used to determine the radar antenna gain in the azimuth and
elevation orientations.[^14] The model gives the antenna gain as a
function of off-axis angle (θ) for a given main beam antenna gain (*G*).
Figure A-1 illustrates the general form of the antenna gain
distribution. The equations for the angles θ*~M~* (first side-lobe
shelf), θ*~R~* (near side-lobe region), and θ*~B~* (far side-lobe
region) are given in Table A-3. The antenna gains, as a function of
off-axis angle, are given in Table A-4. The angle θ is in degrees and
all gain values are given in terms of decibels relative to an isotropic
antenna (dBi).

![](media/image1.png){width="4.504861111111111in"
height="2.7506944444444446in"}

Figure A-1.

**Table A-3. Angle Definitions**

+-----------------------------------------------------------------------+
| θ*~M~* = 50 (0.25 *G* + 7)^0.5^/10^*G*/20^                            |
|                                                                       |
| θ*~R~* = 250/10^*G*/20^                                               |
|                                                                       |
| θ~*B*~ = 48                                                           |
+-----------------------------------------------------------------------+

Table A-4. Equations for Radar Antenna Gain

+-----------------------------------+-----------------------------------+
| Angular interval\                 | Gain\                             |
| (degrees)                         | (dBi)                             |
+-----------------------------------+-----------------------------------+
| 0 to θ*~M~*                       | *G* -- 4 × 10^--4^ (10^*G*/10^)   |
|                                   | θ^2^                              |
| θ*~M~* to θ*~R~*                  |                                   |
|                                   | 0.75 *G* -- 7                     |
| θ*~R~* to θ*~B~*                  |                                   |
|                                   | 53 -- (*G*/2) -- 25 log (θ)       |
| θ~*B*~ to 180                     |                                   |
|                                   | 11 -- *G*/2                       |
+-----------------------------------+-----------------------------------+

This model will employ a far-field antenna pattern for the radar
systems, even though the unlicensed devices will sometimes be located
within the antenna near-field. This approach is used because of the
complexity of modeling the radar antenna in the near-field, and will
provide results that may be more conservative than those that would be
expected if the near-field effects could be easily modeled.

## DESCRIPTION OF ANALYSIS METHODOLOGY

This section describes the engineering algorithms that are used in the
model. Radar systems and unlicensed devices operating co-channel in
proximity could produce a scenario where mutual interference is
experienced. The methodology provided in ITU-R recommendation M.1461 is
used to compute the received interference power levels at the radar and
unlicensed device receivers.[^15] A DFS algorithm may provide a means of
mitigating this interference by causing the unlicensed devices to
migrate to another channel once a radar system has been detected on the
currently active channel. This model first considers the interference
caused by the radar to the unlicensed device at the output of the
unlicensed device antenna. If the received interference power level at
the output of the unlicensed device antenna exceeds the DFS detection
threshold, the unlicensed device will cease transmissions and move to
another channel. The model then computes the aggregate interference to
the radar from the remaining unlicensed devices. Each of the technical
parameters used in the model and the radar interference criteria will
also be described.

This received signal level from the radar at the output of the
unlicensed device antenna is evaluated by using Equation A-1.

$I^{U} = P_{\text{Radar}} + G_{\text{Radar}} + G_{U} - L_{\text{Radar}} - L_{U} - L_{P} - L_{L} - \text{FDR}$
(A-1)

Where:

*I^U^* = Received interference power at the output of the unlicensed
device antenna (dBm);

*P~Radar~* = Peak power of the radar (dBm);

*G~Radar\ ~*= Antenna gain of the radar in direction of the unlicensed
device (dBi);

*G~U~* = Antenna gain of the unlicensed device in direction of the radar
(dBi);

*L~Radar~*= Radar transmit insertion loss (dB);

*L~U~* = Unlicensed device receive insertion loss (dB);

*L~P~* = Propagation loss (dB);

*L~L~*= Building and non-specific terrain losses (dB);

*FDR* = Frequency dependent rejection (dB).

Equation A-1 is calculated for each unlicensed device in the
distribution. The value obtained is then compared to the DFS detection
threshold under investigation. Any unlicensed device for which the
threshold has been exceeded will begin to move to another channel, and
thus is not considered (for the remainder of the analysis) in the
calculation of interference to the radar, as given by Equation A-2.

$I^{\text{RADAR}} = P_{U} + G_{U} + G_{\text{Radar}} - L_{U} - L_{\text{Radar}} - L_{P} - L_{L} - \text{FDR}$
(A-2)

Where:

*I^RADAR^* = Received interference power at the input of the radar
receiver (dBm);

*P~U~* = Power of the unlicensed device (dBm);

*G~U\ ~*= Antenna gain of the unlicensed device in the direction of the
radar (dBi);

*G~Radar~* = Antenna gain of the radar in the direction of the
unlicensed device (dBi);

*L~U~* = Unlicensed device transmit insertion loss (dB);

*L~Radar~* = Radar receive insertion loss (dB);

*L~P~* = Radiowave Propagation loss (dB);

*L~L~*= Building and non-specific terrain losses (dB);

*FDR* = Frequency dependent rejection (dB).

Using Equation A-2, the values are calculated for each unlicensed device
being considered in the analysis that has not detected energy from the
radar in excess of the DFS detection threshold. These values are then
used in the calculation of the aggregate interference to the radar by
the unlicensed devices using Equation A-3.

$I = \sum_{j = 1}^{N}I_{j}^{\text{RADAR}}$ (A-3)

Where:

*I^AGG^* = Aggregate interference to the radar from the unlicensed
devices (Watts);

*N* = Number of unlicensed devices remaining in the simulation;

*I^RADAR^* = Interference into the radar from an individual unlicensed
device (Watts).

It is necessary to convert the interference power calculated in Equation
A-2 from dBm to Watts before calculating the aggregate interference seen
by the radar using Equation A-3.

### DESCRIPTION OF ANALYSIS PARAMETERS

The following subsections discuss each of the parameters used in the
analysis model. These parameters include: unlicensed device and radar
technical characteristics such as power and antenna gain, the radiowave
propagation models, and frequency dependent rejection.

**Radar Peak Power Level (*P~Radar~*)**

The peak power levels of the radar that is used in this analysis is
provided in Table A-2.

Radar Antenna Gain (*G~Radar~*)

The azimuth and elevation antenna pattern models for the radar are
described earlier. The models give the antenna gain as a function of
off-axis angle for a given main beam antenna gain. The radar mainbean
antenna gain used in this assessment is provided in Table A-2.

**Unlicensed Device Power Level (*P~U~*)**

As discussed earlier, the EIRP levels of the unlicensed devices
considered in this analysis are 38 dBm and 6.6 dBm.

**Unlicensed Device Antenna Gain (***G~U~*)

The unlicensed device azimuth antenna pattern is omnidirectional and
elevation antenna pattern model is provided in Table A-1.

**Building and Non-Specific Terrain Losses (***L~L~*)

The building and non-specific terrain losses include building blockage,
terrain features, multipath. In the analysis this loss will treated as a
uniformly distributed random variable between 1 and 10 dB for each radar
unlicensed device path.

**Radar and Unlicensed Device Transmit and Receive Insertion Losses
(*L~Radar~* and *L~U~*)**

The analysis includes a nominal 2 dB for the insertion losses between
the transmitter and receiver antenna and the transmitter and receiver
inputs for the radar and the unlicensed device.

**Radiowave Propagation Loss (***L~P~*)

To compute the radiowave propagation loss the NTIA Institute for
Telecommunication Sciences Irregular Terrain Model (ITM) was used.[^16]
The ITM model computes radiowave propagation based on electromagnetic
theory and on statistical analysis of both terrain features and radio
measurements to predict the median attenuation as a function of distance
and variability of the signal in time and space. The parameter values
used in the ITM propagation model are provided in Table A-5.

Table A-5. Description of ITM Parameter Values

+--------------------------+-------------------------------------------+
| **Parameter**            | **Description**                           |
+--------------------------+-------------------------------------------+
| Transmitter/Receiver     | The unlicensed device antenna height      |
| Antenna Height           | varies based on a uniform distribution    |
|                          | and the radar antenna height is 20 meters |
|                          | for this type of radar                    |
+--------------------------+-------------------------------------------+
| Frequency                | A nominal frequency of 5725 MHz           |
+--------------------------+-------------------------------------------+
| Polarization             | Vertical polarization is used for the     |
|                          | radar and unlicensed device.              |
+--------------------------+-------------------------------------------+
| Transmitter/Receiver     | Random for the unlicensed device location |
| Site Criteria            |                                           |
|                          | Careful for the radar location            |
+--------------------------+-------------------------------------------+
| Delta H                  | 90 m                                      |
+--------------------------+-------------------------------------------+
| Surface Refractivity     | 301                                       |
+--------------------------+-------------------------------------------+
| Dielectric Constant      | 15                                        |
+--------------------------+-------------------------------------------+
| Conductivity             | 0.005                                     |
+--------------------------+-------------------------------------------+
| Radio Climate            | Continental Temperate                     |
+--------------------------+-------------------------------------------+
| Percent                  | Variable between 1 to 99 % based on a     |
| T                        | uniform distribution                      |
| ime/Location/Variability |                                           |
+--------------------------+-------------------------------------------+
| Mode of Variability      | Single message mode, which combines       |
|                          | location and time variability into a      |
|                          | single variability                        |
+--------------------------+-------------------------------------------+
| Distance                 | Variable depending on the path under      |
|                          | consideration which is determined by the  |
|                          | random placement of the unlicensed device |
|                          | and radar locations                       |
+--------------------------+-------------------------------------------+

### 

For each transmitter/receiver path, the ITM model is used to compute the
propagation loss as a function of three random variables: distance,
antenna height for the unlicensed device and mode variability. The
distance depends on the random placement of the unlicensed devices with
respect to the radar. The antenna height for each unlicensed device is
randomly selected using a uniform probability distribution. The
time/location variability is chosen randomly for each path based on a
uniform probability distribution.

### Frequency Dependent Rejection 

Frequency Dependent Rejection (FDR) accounts for the fact that not all
of the undesired transmitter energy at the receiver input will be
available at the detector. FDR is a calculation of the amount of
undesired transmitter energy that is rejected by a victim receiver. This
can be found in Recommendation ITU-R SM.337-4 Annex 1.[^17]

FDR can be stated mathematically as:

$\text{FDR} = \text{10}\text{log}_{\text{10}}\left\lbrack \frac{\int_{0}^{\infty}{p(f - f_{\text{tx}})\text{df}}}{\int_{0}^{\infty}{p(f - f_{\text{tx}})h(f - f_{\text{rx}})\text{df}}} \right\rbrack$
(A-4)

Where

$f_{\text{tx}}$= Undesired transmitter tuned frequency;

$f_{\text{rx}}$= Victim receiver tuned frequency;

$p(f - f_{\text{tx}})$= Normalized emission spectrum of the undesired
transmitter;

$h(f - f_{\text{rx}})$= Normalized transfer function of the victim
receiver;

$f$= Absolute frequency.

Numerical integration and convolution routines can be used to solve
equation A-4.

In the special case of an undesired transmitter operating co-channel to
a victim receiver, the following simplified form may be used:

$\text{FDR} = \text{max}\left( 0,\text{10}\text{log}_{\text{10}}\left( \frac{B_{\text{tx}}}{B_{\text{rx}}} \right) \right)$
(A-5)

Where

$B_{\text{tx}}$= Emission bandwidth of the undesired transmitter;

$B_{\text{rx}}$= Input bandwidth of the victim receiver.

The analysis model only considers co-channel operation of the radar and
unlicensed devices, therefore Equation A-5 is used to compute the FDR.

#### RADAR INTERFERENCE PROTECTION CRITERIA

The desensitizing effect, on a radar system from other services of a
noise-like type modulation such as those from the unlicensed devices is
predictably related to its intensity. In any azimuth sectors in which
such interference arrives, its power spectral density can, to within a
reasonable approximation, simply be added to the power density of the
radar receiver thermal noise.

The interference-to-noise (*I/N*) ratio is determined by comparing the
interference power (I) to the receiver noise power, which is given by:

$N = - \text{114}\text{ dBm} + \text{10}\text{log}\left( B_{\text{IF}} \right) + \text{NF}$
(A-6)

Where:

*N =* Receiver noise level (dBm);

*B~IF~* = Receiver bandwidth (MHz);

*NF* = Receiver noise figure (dB).

Recommendation ITU-R M.1461 states that if no specific *I/N* ratio is
provided for a given radar, the protection criterion of *I/N* = --6 dB
should be used. This protection criterion applies 100% of the time. The
contribution of the output from an unlicensed device that has detected
the radar and has begun to move from the affected channel should not be
considered in calculating the aggregate interference power at the radar
receiver input.

**DFS DETECTION THRESHOLD**

As discussed earlier, the Commission is proposing to use a detection
threshold based on a level that is 30 dB above the thermal noise
measured in a 1.25 MHz bandwidth. Using Equation A-6, the thermal noise
is:

N = -114 + 10 Log (1.25) + 0 = -113 dBm

The detection threshold is then found to be: -113 + 30 = -83 dBm. This
detection threshold will be used in the assessment.

## SPECIFIC MODELING PARAMETERS FOR TRACKING RADARS

This analysis considers ground-based tracking radars. The analysis model
distributes unlicensed device locations randomly within the circular
region described earlier. Initially the radar will be located along a
straight line starting at the center of the circle (0 km) and extending
to the end of the circle (24 km) in 4 km increments: 4 km, 8 km, 12 km,
16km, 20 km, and 24 km.[^18] The analysis begins by placing the radar at
one of these six locations. At each of the six locations one of five
azimuths: 0, 45, 90, 135, and 180 degrees are used. For each starting
azimuth, the analysis then begins calculating *I^U^* for each unlicensed
device, assuming the main beam of the radar antenna is pointing at 0
degrees elevation in the direction of the starting azimuth. The analysis
then proceeds to compare each individual value of *I^U^* to the DFS
detection threshold. For each *I^U^* that exceeds the DFS detection
threshold, the corresponding unlicensed device is eliminated from
further consideration during the analysis. The probability of DFS
detection is 100% when the detection threshold is exceeded.[^19]
*I^RADAR^* is then calculated for each unlicensed device remaining in
the analysis, and is then used to calculate *I^AGG^*. The radar
elevation angle is then incremented by one degree and the calculations
are repeated. This process is continued until the main beam of the radar
antenna is pointing directly at the zenith (elevation = 90 degrees). The
analysis then continues the calculations by decrementing the elevation
angle one degree at a time. In that way, this process provides
simulation of the radar's tracking of a target from horizon-to-horizon,
passing directly overhead. That is the initial model run for 0 degrees
elevation of the radar antenna, the location and antenna height of each
unlicensed device is selected. Also, the building and non-specific
terrain loss factor and the propagation variability for each
radar-to-unlicensed device propagation path are selected. These factors
do not change as the radar antenna pointing angle is moved from
horizon-to-horizon. Only the antenna gain values change according to
elevation angle. If the DFS threshold is exceeded at a specific
elevation angle, that unlicensed device is moved to another channel for
the remainder of the horizon-to-horizon analysis. These aggregate values
are then used to calculate the I/N ratio and an example are plotted as
shown in Figure A-2.

![](media/image2.wmf){width="4.340972222222222in"
height="3.252083333333333in"}

**Figure A-2.**

Based on the radar locations and starting azimuths described above,
there was very little variation in the analysis results based on the
placement of the radar and the starting azimuth. The I/N values were
found to be slightly higher when the radar was positioned at the edge of
the circle defining the unlicensed environment and the starting azimuth
was 180 degrees (e.g., pointed away from the unlicensed device
environment). This radar position and starting azimuth are used in the
analysis to assess potential interference to the radar system.

The number of co-channel, simultaneously transmitting, unlicensed
devices considered in the analysis was: 100, 500, and 1000. In order to
develop statistics 100 iterations of the model were generated. For each
iteration the following parameters are randomly varied: unlicensed
device location, antenna heights of the unlicensed devices, propagation
losses, and losses due to non-specific terrain effects. Based on the 100
iterations, a mean, median, and standard deviation are computed.

**ANALYSIS RESULTS**

Figures A-3 through A-5 present analysis results with half of the
devices operating at the higher proposed power level of 38 dBm and half
operating at the lower proposed power level of 6 dBm. The antenna
heights of the unlicensed devices are randomly varied between 40 and 100
meters. The transmitter bandwidth of the unlicensed devices is 1 MHz.

> ![](media/image3.jpeg){width="4.125in" height="3.0840277777777776in"}

Figure A-3.

![](media/image4.jpeg){width="4.1625in" height="3.1125in"}

Figure A-4.

![](media/image5.jpeg){width="4.75in" height="3.5625in"}

Figure A-5.

Figures A-6 through A-8 present analysis results with half of the
devices operating at the higher proposed power level of 38 dBm and half
operating at lower proposed power level of 6 dBm. The antenna heights of
the unlicensed devices are randomly varied between 40 and 100 meters.
The transmitter bandwidth of the unlicensed devices is 6 MHz.

![](media/image6.jpeg){width="4.375in" height="3.28125in"}

Figure A-6.

![](media/image7.jpeg){width="4.625in" height="3.46875in"}

Figure A-7.

![](media/image8.jpeg){width="4.6875in" height="3.515277777777778in"}

Figure A-8.

Figures A-9 through A-11 present analysis results with half of the
devices operating at the higher proposed power level of 38 dBm and half
operating at the lower proposed power level of 6 dBm. The antenna
heights of the unlicensed devices are randomly varied between 40 and 100
meters. The transmitter bandwidth of the unlicensed devices is 18 MHz.

![](media/image9.jpeg){width="4.5in" height="3.375in"}

Figure A-9.

![](media/image10.jpeg){width="4.5625in" height="3.421527777777778in"}

Figure A-10.

![](media/image11.jpeg){width="4.25in" height="3.1875in"}

Figure A-11.

Figures A-12 through A-14 present analysis results with all of the
devices operating at the higher proposed power level of 38 dBm. The
antenna heights of the unlicensed devices are randomly varied between 40
and 100 meters. The transmitter bandwidth of the unlicensed devices is 1
MHz (Figures A-12), 6 MHz (Figures A-13), and 18 MHz (Figures A-14).

![](media/image12.jpeg){width="4.625in" height="3.46875in"}

Figure A-12.

![](media/image13.jpeg){width="4.375in" height="3.28125in"}

Figure A-13.

![](media/image14.jpeg){width="4.625in" height="3.46875in"}

Figure A-14.

Figures A-15 through A-17 present analysis results with all of the
devices operating at the higher proposed power level of 38 dBm. The
antenna heights of the unlicensed devices are randomly varied between 10
and 40 meters. The transmitter bandwidth of the unlicensed devices is 1
MHz (Figures A-15), 6 MHz (Figures A-16), and 18 MHz (Figures A-17).

![](media/image15.jpeg){width="4.375in" height="3.28125in"}

Figure A-15.

![](media/image16.jpeg){width="4.625in" height="3.46875in"}

Figure A-16.

![](media/image17.jpeg){width="4.5in" height="3.375in"}

Figure A-17.

Figures A-18 through A-20 present analysis results with all of the
devices operating at the higher proposed power level of 38 dBm. The
antenna heights of the unlicensed devices are randomly varied between 6
and 10 meters. The transmitter bandwidth of the unlicensed devices is 1
MHz (Figures A-18), 6 MHz (Figures A-19), and 18 MHz (Figures A-20).

![](media/image18.jpeg){width="4.25in" height="3.1875in"}

Figure A-18.

![](media/image19.jpeg){width="4.75in" height="3.5625in"}

Figure A-19.

![](media/image20.jpeg){width="4.625in" height="3.46875in"}

Figure A-20.

A summary of the analysis results in terms of the mean I/N for the 100
iterations and the standard deviation are provided in Table A-6 for each
analysis case considered in this assessment.

**Table A-6. Summary of Analysis Results**

+-----------+-----------+-----------+-----------+-----------+-----------+
| **Number  | **U       | **U       | **U       | **Mean    | *         |
| of        | nlicensed | nlicensed | nlicensed | I/N**     | *Standard |
| U         | Device    | Device    | Device    |           | De        |
| nlicensed | Power     | Transmit  | Antenna   | **(dB)**  | viation** |
| Devices** | Distr     | Ba        | Heights** |           |           |
|           | ibution** | ndwidth** |           |           | **(dB)**  |
|           |           |           | **(       |           |           |
|           |           | **(MHz)** | Meters)** |           |           |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 100       | 50% High  | 1         | 40-100    | -12.1     | 1.8       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 500       | 50% High  | 1         | 40-100    | -5.8      | 0.8       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 50% High  | 1         | 40-100    | -2.8      | 0.6       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 100       | 50% High  | 6         | 40-100    | -21       | 1.5       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 500       | 50% High  | 6         | 40-100    | -13.8     | 0.9       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 50% High  | 6         | 40-100    | -10.7     | 0.5       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 100       | 50% High  | 18        | 40-100    | -25.5     | 1         |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 500       | 50% High  | 18        | 40-100    | -18       | 0.7       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 50% High  | 18        | 40-100    | -16       | 0.6       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 100% High | 1         | 40-100    | 0.2       | 0.6       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 100% High | 6         | 40-100    | -7.5      | 0.5       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 100% High | 18        | 40-100    | -12.5     | 0.5       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 100% High | 1         | 10-40     | -0.6      | 0.3       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 100% High | 6         | 10-40     | -8        | 0.4       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 100% High | 8         | 10-40     | -12.6     | 0.3       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 100% High | 1         | 6-10      | -0.5      | 0.5       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 100% High | 6         | 6-10      | -8.4      | 0.4       |
+-----------+-----------+-----------+-----------+-----------+-----------+
| 1000      | 100% High | 18        | 6-10      | -13       | 0.3       |
+-----------+-----------+-----------+-----------+-----------+-----------+

**CONCLUSION**

The analysis results indicate the I/N is dominated by the number of
higher-powered unlicensed devices. The percentage of lower powered
unlicensed devices does not impact the computed I/N values. The antenna
heights of the unlicensed devices have little effect on the computed I/N
values. As expected the increase in calculated I/N follows a 10 Log
(number of unlicensed devices) relationship. In all but one case (100
unlicensed devices with 50% operating at the high power level) the 1 MHz
transmit bandwidth resulted in computed I/N values that exceeded the
threshold of I/N of -6 dB.

[^1]: . *Facilitating Opportunities for Flexible, Efficient, and
    Reliable Spectrum Use Employing Cognitive Radio Technologies*,
    Notice of Proposed Rulemaking, ET Docket No. 03-108, 18 F.C.C. Rcd.
    26859 at ¶ 42 (2003) ("Cognitive Radio NPRM").

[^2]: . *Id.* at ¶ 44.

[^3]: . DFS is a mechanism that dynamically detects signals from other
    systems and avoids co-channel operation with these systems.

[^4]: . Cognitive Radio NPRM at ¶ 44*.*

[^5]: . The frequency bands from 5250-5925 MHz are allocated on a
    primary basis to the government radiolocation service.

[^6]: . Cognitive Radio NPRM at ¶ 43.

[^7]: . *Revision of Parts 2 and 15 of the Commission's Rules to Permit
    Unlicensed National Information Infrastructure (U-NII) Devices in
    the 5 GHz Band*, Report and Order, ET Docket No. 03-122, 18 F.C.C.
    Rcd. 24484 (2003).

[^8]: . Cognitive Radio NPRM at ¶ 38. The proposed power levels would
    increase the coverage of by a factor of 6.

[^9]: . *Additional Spectrum for Unlicensed Services Below 900 MHz and
    in the 3 GHz Band*; *Amendment of the Commission's Rules with Regard
    to the 3650-3700 MHz Government Transfer Band*, Notice of Proposed
    Rulemaking, ET Docket No. 04-151; ET Docket No. 02-380; ET Docket
    No. 98-237, FCC 04-100, 2004 FCC LEXIS 2071, at ¶ 43 (2004)
    ("3650-3700 MHz NPRM").

[^10]: . Recommendation ITU-R M.1638, *Characteristics of and Protection
    Criteria for Sharing Studies for Radiolocation, Aeronautical
    Radionavigation and Meteorological Radars Operating in the Frequency
    Bands Between 5250 and 5850 MHz* (2003).

[^11]: . Each radar location/azimuth location and distribution of
    unlicensed device locations is defined as a trial.

[^12]: . Cognitive Radio NPRM at ¶ 38.

[^13]: . 3650-3700 MHz NPRM at ¶ 43.

[^14]: . Joint Spectrum Center, JSC-CR-96-016B, *JSMS~W~ Interference
    Analysis Algorithms,* at 2-11 (April 1998).

[^15]: . Recommendation ITU-R M.1461, *Procedures for Determining the
    Potential for Interference Between Radars Operating in the
    Radiodetermination Service and Systems in Other Services*, at Annex
    1 (2000).

[^16]: . National Telecommunications and Information Administration,
    NTIA Report 82-100, *A Guide to the Use of the ITS Irregular Terrain
    Model in the Area Prediction Mode* (April 1982).

[^17]: . Recommendation ITU-R SM.337-4, *Frequency and Distance
    Separations* (1948-1951-1953-1963-1970-1974-1990-1992-1997).

[^18]: . Because the unlicensed devices are distributed uniformly, the
    actual location of the tracking radar is not believed to be a
    critical parameter in the analysis provided that a sufficient number
    of radar locations and starting azimuths are considered.

[^19]: . ITU-R M.1652 at Annex 4.