UHF SATCOM Frequency Reuse Planning Tool Developed

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DEVELOPMENT OF UHF SATCOM FREQUENCY REUSE PLANNING TOOL
Junghoon Lee*1
, Anthony Vescio*1
, Tony Puzio*1
, George Elmasry*1
,
Richard Ardolino*2
, and Austin Mroczek*3
*1. XPRT Solutions, Inc., Eatontown, NJ
*2. Space and Naval Warfare Systems Command, San Diego, CA
*3. SBG Technology Solutions, Inc., Stafford, VA
ABSTRACT
U.S. Navy’s UHF SATCOM operation needs a tool to au-
tomate the frequency planning process, maximizing the
efficiency of the spectrum use. This paper presents a UHF
SATCOM frequency reuse planning tool developed for the
operational needs. The design concept of the Tool is ex-
plained in consideration of the technical analyses needs
and usability of the software for the UHF SATCOM opera-
tion. The multi-tier architecture of the software application
is described. The analytical functions are programmed
using MATLAB for ease of the software development. The
major capabilities and features of the Tool are described
with its benefits to the SATCOM operation.
Analyses results with reference to an illustrative opera-
tional scenario demonstrate that the Tool can provide
technical analyses needed for the UHF SATCOM opera-
tion. Having reviewed by UHF SATCOM community in-
cluding GSSC, the Tool has shown the applicability to the
operation.
I. INTRODUCTION
Frequency planning for UHF SATCOM is an increasingly
complex and important issue for the Navy‟s operation, as
the demand for the communications capacity has conti-
nuously been growing while the spectrum resources are
limited. In particular, the SATCOM operation needs to
reuse (in fact, has been reusing in some cases) the UHF
frequency channels to accommodate the communications
demand. Currently, such a UHF SATCOM channel fre-
quency planning has been manually performed by
SATCOM engineers. This paper 1
presents a UHF
SATCOM Frequency Reuse Planning Tool (UFPT), which
can automate the frequency planning process, maximizing
the efficiency of the spectrum use.
1
This paper is based on a research conducted under SBIR titled “Ultra
High Frequency (UHF) Reuse Planning Tool for Increasing Capacity
in Geo-Synchronous Satellite Communications (SATCOM) Sys-
tems” [1][2], sponsored by Space and Naval Warfare Systems Com-
mand (SPAWAR).
While the concept of maximizing the spectrum efficiency
is not new, the planning process for the UHF SATCOM
not only takes a lot of time and effort but also requires
technical expertise, if the tasks are manually performed by
engineers. In some circumstances, the operation may have
to be content with a suboptimum solution due to a con-
straint on time and engineering cost. UFPT has been de-
veloped to provide technical analyses required for the UHF
SATCOM frequency planning, thus saving the time, effort,
and cost.
One of the primary objectives of developing UFPT is to
support SATCOM operation for Global SATCOM Support
Center (GSSC). Currently, processing Satellite Access Re-
quest (SAR), which asks for a SATCOM channel, GSSC
personnel often look into a large amount of satellite confi-
guration data typically given in spreadsheets. Searching
the SATCOM channel, they must take into account variety
of information such as the user‟s location or operational
area, required carrier bandwidth or data rate, priority, ex-
isting channel allocation, etc., to identify the most appro-
priate channel to satisfy the request. The planner must
also analyze link margins for potential channels. They
even have to consider if a channel frequency is reused at
adjacent satellites. This is a very tedious and time-
consuming task. The purpose of developing UFPT is to
help automate the frequency planning process by provid-
ing the technical analyses for searching and identifying a
channel, which satisfies the operational needs.
Section II explains the design concept of the Tool. The
software architecture of the Tool is described in section III.
Section IV presents the capabilities and features of the
Tool and discusses on how it supports the SATCOM oper-
ation.
II. DESIGN CONCEPT OF THE TOOL
This section discusses technical analyses needed to support
the SATCOM planning and usability of the Tool for the
operation. The major analytical capabilities of the Tool are
explained as follows:

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Satellite Beam Coverage and Overlap: In searching a
channel for an access request, the SATCOM operation
needs to investigate if a particular UHF channel can cover
the user‟s operational area. That is, the satellite beam cov-
erage area should be analyzed. In practice, searching for
reusable frequencies, the operation also needs to analyze
what and how much portion of the operational area is over-
lapped with an adjacent satellite beam coverage area, in
consideration of interference when a UHF channel is
reused between a pair of adjacent satellites.
Link Analysis: Link performance or link margin needs to
be analyzed for each and every potential UHF channel to
be allocated. The link analysis should take into account
any possible interference from adjacent satellites for the
case that a same channel is used among the satellites. Also
the Tool needs to support link analysis for hypothetical
operational parameter variations as the operation wants to
answer what-if cases for the planning purposes.
Searching and Identifying Reusable Channels The Tool
should be capable of finding a channel, which not only
satisfies the communications user‟s needs but also uses the
SATCOM spectrum resource most efficiently.
Establishing and Evaluating Hypothetical Scenarios:
The Tool should enable the operation to establish and eva-
luate potential SATCOM operations scenarios,
representing various satellite channel configurations.
The following is a list of the Tool features considering the
usability for the SATCOM operation:
Internet-based Access: Internet-based application allows
users to access the Tool anywhere, retrieving common op-
erational data and scenarios. The server-client architecture
allows the operation to easily maintain and upgrade the
Tool software.
Modular Structure: The Tool would need modification
and enhancement as the operational requirements evolve
and new functionalities are demanded. The Tool should be
based on modular architecture so that the future modifica-
tions can be made without affecting the reliability and in-
tegrity of the Tool.
Default Scenario Management: The Tool maintains cur-
rent channel configuration and allocation for the users to
retrieve and investigate. The default scenario will be ma-
naged users with privileged access to the Tool.
Other Utilities will include: validating input data, forced
logging-out on user inactivity for security, and printer-
friendly pages for downloading and reporting the results.
III. SOFTWARE ARCHITECTURE OF THE TOOL
The software of the Tool (or the “Application”) is based on
a standard multi-tier architecture. The objective of this
architecture is to clearly separate the user presentation, the
application processing, and the data manipulation and sto-
rage. This multi-tier design provides a flexible and reusa-
ble application, and is intended to allow any of the tiers to
be upgraded independently as the requirements or technol-
ogies change. Each Application tier, or layer, is comprised
of components and services specific to that layer, as shown
in Figure 1.
Figure 1: Software Architecture of the Tool
The MATLAB Layer is comprised of components devel-
oped with the MATLAB® software product [3]. The
components contain MATLAB functions (m-Files) and
MATLAB data storage (mat-files). They represent the Ap-
plication‟s analytical and computational engine and sto-
rage repository, respectively. The MATLAB functions
are compiled into a deployable component using the
MATLAB Builder JA® software product [4]. The Builder
creates a „wrapper‟ class that can be integrated into the
Server Layer‟s JAVA programs. The MATLAB functions
provide analytical and computational services for the Ap-
plication. For example, the Application software includes
MATLAB functions to calculate link margins and generate
the link margin contour maps. The Application uses
MATLAB data files, i.e. „mat-files‟, as the Application‟s
central repository. The data includes scenarios, which
consist of satellites and the channel configurations, as well
as the analysis results to be presented.
Use of MATLAB® facilitates the overall Tool develop-
ment. With MATLAB®, technical analyses formulas and
processes are easily programmed, reviewed, and validated.
The programs are compiled and used in the production
software without any modification or adaptation. The
Builder JA® also enables the MATLAB programs to be
Presentation Layer
MATLAB Layer
Server Layer
MATLAB Functions MATLAB Data Storage
JAVA Beans JAVA Servlets Web Services
JAVA Server Pages
(JSP)
JavaScript AJAX

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integrated with software written in JAVA, which is a
popular programming language for this kind of Tool de-
velopment.
The Server Layer, or business services layer, provides the
interface between the Presentation Layer and the
MATLAB Layer. When the Presentation Layer requests
data or calculation, the Server Layer packages the request
in a format that is required by the MATLAB functions in
the MATLAB Layer. The Server Layer is also responsi-
ble for converting results that are in MATLAB-specific
data types to standard JAVA data types or classes that the
Presentation Layer can interpret.
The Server Layer is comprised of JAVA Beans, JAVA
Servlets, and Web Services. The JAVA Bean components
provide the core of the business services for the Applica-
tion. The JAVA Beans provide logging services using the
Apache log4j software. The utility class implements log4j
to provide the Application with the facility to record user
activity and system messages to text files on the Server.
A rollingfileappender mechanism manages the log file size
and log file count (currently set by 2 MB and 10 files max-
imum, respectively for the Tool). The log file parameters
are configurable in the log4j.properties file. The JAVA
Beans also handle Application security with a Login Man-
ager Bean component. A List Factory component provides
data to populate selection lists in the Presentation Layer.
For security purposes, the Application has a session time-
out set by 10 minutes. This means that if a web page is not
accessed during that time period, the Application will re-
quire the user to re-login. The session timeout period is
configurable in the Application‟s web.xml file. The Appli-
cation also provides the user with the ability to produce
printer-friendly documents of any web page that displays
information. This service is handled by JAVA Servlets
that are resident in the Server Layer.
The Application utilizes AJAX (Asynchronous JavaScript
and XML) technologies and Web Services to enhance the
user-experience and perform partial-screen updates on web
pages. Web Services, for example, provide the list of sa-
tellites for searching channel. The Web Services are ac-
cessed via asynchronous XMLHHTPRequest calls from
the web pages.
The Presentation Layer is comprised of the JAVA Server
Pages (JSP), which the user can access from a standard
desktop browser. The Application has been designed to
support the Microsoft Internet Explorer v6.0+, Mozilla
Firefox 3.0+ and Safari 4.0+ web browsers. The JSP pages
implement common blocks of code in the form of include
pages, such as page header/footer logic and application
menu logic. This approach eliminates redundant code,
improves maintainability, and provides a consistent look-
and-feel throughout the application. The JSP pages con-
tain JavaScript code to provide client-side validation of
user-input and to provide information to the user, such as
requests to confirm the deletion of any data in the applica-
tion. The JavaScript code also supports the AJAX calls to
reduce round-trip time for requests to web server.
IV. CAPABILITIES AND FEATURES OF
THE TOOL
This section describes major capabilities of UFPT and how
the Tool benefits the operational planner by promptly pro-
viding data necessary to complete their operational analys-
es for a SAR. With just a few clicks, the web-based Tool
enables the SATCOM planner to enter, browse, and modi-
fy the parameters associated with a given operational sce-
nario. Then, the Tool generates and shows on-screen re-
ports for the analysis results. It allows planners to analyze
channel availability, and search and identify available sa-
tellite channels in accordance with the given SAR. Follow-
ing the instructions given by the Tool, user can modify,
save, and search parameters. The Tool enables to manage
hypothetical operational scenarios representing satellite
location and channel configuration. The analysis metho-
dologies and the related formulas are given in [5].
Satellite Channel Availability
The satellite channel availability function allows the op-
erational planner to analyze satellite beam coverage and
overlap with adjacent satellite channels to investigate the
impact of interference. For each channel of every satellite,
the user can analyze whether the channel has interference
from adjacent satellites, and if there is coverage overlap,
the percentage of overlapped area. Figure 2 illustrates the
Tool‟s analysis results for Channel 2 of FSC-8, with refer-
ence to a scenario given for demonstrating the feasibility
of the Tool. The Tool analyzes link margin for every loca-
tion within the coverage area and shows the link margin
contour in colors of gradual shades, on a world map. In
this case, it identifies the interfering satellite channels
(UFO-5 Channel 2 and FCS-8 Channel 2) and provides the
percentage of coverage overlap (37% and 16%, respective-
ly).
The Tool also provides satellite channel availability for an
operation area given by user. It autonomously identifies
which satellite channels are available for the area and
which channels from adjacent channels create interference
to the area. Using the demonstration scenario, Figure 3
illustrates the Tool‟s analysis results for the area bounded
by 114.5° West, 57.3° West, 41.2° North, and 22.5° South.
For the case, user has selected UFO-5 channel 7 among the
list of channels covering the area, given by the Tool. The
Tool analyzes link margin for every location within the
operational area and shows the link margin contour. It also

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calculates the percentage of overlap for the operational
area as 49%.
Figure 2: Illustrative Results on Satellite Channel
Analysis (FSC-8, Channel 2)
Analysis (UFO-5 Channel 7)
Customized Link Analysis
This capability is developed for the operation to answer
“what-if” cases, for example, what will be the link margin
if directional antennas are used. For such a purpose, the
Tool provides parametrical link analysis. That is, the Tool
can provide link performances for the operational
parameter variations from the baseline link analysis. The
Tool allows user to modify: terminal type, antenna type
(for communicator and interfering terminals), terminal
platform (including ship, shore, submairne, and aircraft),
and carrier characteristics including modulation, symbol
rate, and Forward Error Correction (FEC) rate. Figure 4
illustrates the link margin contour for the case that
directional antennas with 10 dB gain are used for the
receiver and two interfering terminals accessing UFO-5
and FSC-7, respectively.
Analysis (Use of 10 dB gain antennas)
Channel Search
The Tool allows user to specify a set of search parameters
describing the attributes of communications channel re-
quired to support a SAR. The channel search input is illu-
strated in Figure 5. User can limit the search by specifying
the Service Support Center managing the channel, cover-
age region (ATLANTIC, INDIAN, PACIFIC, or CONUS),
user priority; channel bandwidth, access type (Dedicated,
DAMA, or IW), and the satellite. User also can select
“Any” to search for any applicable channels, except the
coverage region, which must be specified if the operational
area is not configured. When the operational area is en-
tered, the Tool investigates and automatically fills the
menu items by the list of available satellites, which can
cover the area in accordance with the percentage of mini-
mum coverage given.
The search algorithm first identifies all suitable channels,
i.e., ones that meet the specified criteria. For each suitable
channel, the Tool identifies same frequency channels on
other satellites that can cause interference due to the cov-
erage overlap. For each interfering channel, the percent of
area overlap is computed. Then the degree of suitability of
each channel is assessed in part by the sum of the percent

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overlapping areas for all interfering channels. Another fac-
tor in the suitability is priority. If the priority of the chan-
nel‟s current service is lower than the priority of the re-
quested, the channel can be preempted to support the new
request. The Tool defines four classes of suitability:
 Available, which means that the channel is not in use
 Preemptible, which means the channel can be
preempted while the total overlap is less than 50%
 Overlapped, which means that the channel can be
preempted but the total overlap more than 50%
 Not Preemptible, which means that the channel cannot
be preempted
For the Available class, the channels are ranked in increas-
ing order of the percentage of the total overlap area. For all
other classes, channels are ranked in decreasing order of
priority. Table 1 illustrates a channel search results (show-
ing selected channels among the 115 applicable channels)
for the input parameters given in Figure 5, with reference
to the demonstration scenario.
Figure 5: Channel Search Parameter Input
Table 1: Illustration of Channel Search Results
(for the area bounded by 65° West, 0° East, 60° North, and 60° South)
# Satellite
Ch/
Plan
BW
(KHz
)
Uplink
(MHz)
Dnlink
(MHz)
Access
Priori-
ty
Ch.
On/O
ff
Support
Center
Cov.
Over-
lap
(%)
Suitability
1 ATLANTIC FSC-8 15.5W 1/B 25 SHF 250.55 Dedicated None Off GSSC Available
2 ATLANTIC FSC-8 15.5W 13/B 5 317.16 244.06 Dedicated None Off STRATCOM Available
3 ATLANTIC FSC-8 15.5W 15/B 5 317.17 244.07 Dedicated None Off STRATCOM Available


24 ATLANTIC UFO-7 22.5W 16/P 25 295.525 261.925 Dedicated None Off STRATCOM 0 Available
25 ATLANTIC UFO-7 22.5W 16/P 25 295.525 261.925 Dedicated None Off STRATCOM 1 Available
26 ATLANTIC UFO-7 22.5W 8/P 25 307.95 266.95 DAMA 7A On GSSC Preemptible
27 ATLANTIC FSC-8 15.5W 23-17/B 25 295.45 261.85 Dedicated 7A On GSSC 0 Preemptible


98 ATLANTIC FSC-8 15.5W 4/C 25 296.55 255.55 Dedicated 7A On GSSC 52 Overlapped



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The Tool also provides another channel search algorithm,
which is based on the magnitude of link margin rather than
the total coverage overlap, as described in [5].
Management of Operational Scenario
UFPT is designed based on a web-based architecture. This
allows SATCOM planners from anywhere in the world to
gain access with only an internet connection and a browser.
When a planner signs into the tool, an initial scenario is
created from the master default scenario file that holds the
latest satellite configuration. This allows planners the abili-
ty to investigate current operational parameters including
satellite location and channel configuration. Planners can
create “what-if” scenarios representing hypothetical satel-
lite and channel configuration, and then save them on the
Tool‟s bulletin board for other users to access, or save as a
private scenario for the creator only to view. The Tool
allows a “Privileged User” to manage confidential data and
manage default scenarios, i.e., create, archive, delete, or
reinstate past default scenarios as needed. The Tool has
the capability to delete, modify, or add new satellites con-
figurations with just a few clicks of a button. This gives
flexibility to anyone who wants to make changes to chan-
nel pairs and instantly view the changed frequency overlap
interference contour plots. For example, if the planner
wants to create a scenario where UFO-2 is no longer avail-
able and they need to move adjacent satellites to cover the
gap, the planner just needs to delete the UFO-2 satellite
and move the adjacent satellites to new longitude coordi-
nates, modify any channel frequency pairs, and finally
save the scenario to the bulletin board. The operational
planner can now quickly view the operational circums-
tances channel by channel based on the modification.
Applications Software Features
The following is a list of additional software features of
the Tool:
 Input data validation: Checking user‟s input for the
parameter‟s range, the Tool alerts the user to correct if
the value is not valid. For some parameters, the Tool
automatically corrects or enters associated values. For
example, uplink and downlink frequencies of a chan-
nel is automatically entered or corrected in accordance
with the channel number and frequency plan given,
with reference to the associated military standard.
 Forced logging-out on inactivity: To prevent access
from unauthorized user, the Tool forcibly logs out a
user as described in section III.
 Printer-friendly page: For the results generated, the
Tool provides printer-friendly html pages for down-
loading and reporting the results. The contents can eas-
ily be cut and pasted to a Microsoft Word® document.
V. SUMMARY AND DISCUSSION
This paper presents considerations and benefits of UFPT,
developed to automate the UHF SATCOM frequency
planning processes. The design concept of the Tool is ex-
plained in consideration of the technical analyses needs
and usability of the software for the UHF SATCOM op-
eration. The multi-tier architecture of the software applica-
tion is described. The analytical functions are programmed
using MATLAB for ease of the software development.
The major capabilities and features of the Tool are de-
scribed with the benefits to the SATCOM operation.
Analyses results with reference to the illustrative opera-
tional scenario demonstrate that the Tool can provide tech-
nical analyses needed for the UHF SATCOM operation.
Having reviewed by UHF SATCOM community including
GSSC, the Tool has shown the applicability to the opera-
tion.
VII. REFERENCES
[1] “Ultra High Frequency (UHF) Reuse Planning Tool
for Increasing Capacity in Geo-Synchronous Satellite
Communications (SATCOM) Systems”, SBIR N07-
192 Phase I Final Report, XPRT Solutions, Novem-
ber, 2008.
[2] “Ultra High Frequency (UHF) Reuse Planning Tool
for Increasing Capacity in Geo-Synchronous Satellite
Communications (SATCOM) Systems”, SBIR N07-
192 Phase II Final Report, XPRT Solutions, March,
2011.
[3] http://www.mathworks.com/products/matlab/
[4] http://www.mathworks.com/products/javabuilder/
[5] J. Lee, et al, “A Study on UHF SATCOM Frequency
Reuse”, to be submitted in IEEE MILCOM 2011,
October 2011.

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