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© 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED A Frequency Assignment Strategy for Common Data Link (CDL) Users An Inspection of USCENTCOM.

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Presentation on theme: "© 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED A Frequency Assignment Strategy for Common Data Link (CDL) Users An Inspection of USCENTCOM."— Presentation transcript:

1 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED A Frequency Assignment Strategy for Common Data Link (CDL) Users An Inspection of USCENTCOM Operations in Afghanistan Rob Moser, The MITRE Corporation Jeff Bench, L-3 Communications 16 March 2011

2 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED Provide a Frequency Allocation Strategy for CDL Links supporting ISR Operations in Afghan Theater ■Problem Statement ■USCENTCOM Study Guidance ■CDL Background Information ■Approach to Problem ■Study Limitations ■Options Availability ■Option 1: Limited Airspace Management ■Option 2: Managing Airspace, More CDL Links ■Further Study ■Summary ■Recommendations Page 2 Purpose and Agenda (U)

3 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Demand for Ku-band CDL assignments exceeds allocation by 300% –700% in “hot spot” regions of Combined Joint Operations Area Afghanistan (CJOA-A) ■New Wide Area Surveillance (WAS) aircraft consume 75% of allocation by themselves ■Aircraft using overlapping frequency assignments will interfere with one another without a solid deconfliction plan –Interference causes loss of data or loss of UAV control ■No pre-mission or real-time spectrum deconfliction tools are currently available for frequency managers or ISR planners in the CJOA-A –Current approach to frequency assignment is best effort ■A frequency plan is needed that can mitigate interference and still support ISR operations Page 3 Problem Statement (U)

4 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Many studies produce “academic” recommendations –Current situation is a growing problem; need actionable results now ■Operational Guidance –Use no formulas! –Allow operators/planners to apply guidance within 5 seconds (from question to answer) –Be based on situational data already available to the operators/planners –Rely on tools, maps, software, etc. already available to the operators/planners Page 4 USCENTCOM Study Guidance (U)

5 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Common Data Link (CDL) operates in Ku-band –14.4 – GHz Air to Ground Downlink (430 MHz bandwidth) –15.15 – GHz Ground to Air Uplink (200 MHz bandwidth) ■OSD Policy & Public Law require CDL to be incorporated in all manned & unmanned ISR platforms (circa 2005) –Affects the acquisition pipeline for every UAV Program of Record –Influences QRC development activities –OSD Waiver (Feb 2011) authorizes 15.7 – 17.3 GHz for CDL in AOR ■14 unique models of CDL-enabled ISR aircraft were deployed to CJOA-A as of Jan 2011 –Does not include Recce pods on fighter/bomber aircraft ■Data throughput requirements for aerial downlinks has steadily increased due to advances in sensor technology (i.e. WAS, HD FMV, etc.) –Constant Hawk: 21Mbps –Blue Devil / Gorgon Stare / Yellow Jacket / AAA: 274Mbps Page 5 Background (U)

6 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■USCENTCOM J2/J6 tasked MITRE to … –Study the problem –Propose frequency mgt/deconfliction guidance for specific geographic areas of interest in the CJOA-A ■MITRE collaborated with L-3 Communications –Used “FlyPlan” Modeling & Simulation (M&S) software ■ Created by L-3 specifically to solve CDL management problems ■ Developed under contract to CDL PMO, Hanscom AFB (ESC) –Analyzed CDL equipped platforms operating in CJOA-A ■ Platform data provided by the Services via USCENTCOM data call ■ Performed RF analysis of inputs/outputs/results –Developed recommended operational guidelines ■ Identified deconfliction procedures applicable across the CJOA-A ■ Provided focused examples for Regional Command South (RC-S) Page 6 Approaching the Problem (U)

7 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■90% solution delivered ■Analysis is limited to aircraft in USCENTCOM data call –Omits Ku-band microwave towers; ground-based interferers ■Data call is not complete –Not all platform program offices responded ■ PTDS / Canadian King Air –New systems arriving since data call; ■ Inbound systems not included : Yellow Jacket / Fire Scout ■ Operating locations for inbound platforms are still TBD (AAA aircraft) ■ Engineering data not available (platform not included in data call) Page 7 Study Limitations (U)

8 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Minimum frequency separation between 10Mbps channels is 15MHz for currently deployed aircraft –Key factor is the spectral emission mask –May be different for systems not included in the data call ■Minimum angular separation between 274Mbps aircraft –30 Degrees if using the same frequency assignment –15 Degrees if frequencies spaced as far apart as possible ■ & GHz (30 MHz separation – no further separation is possible) ■ May be different for systems not included in the data call ■Minimum angular separation between 10Mbps aircraft is 10 Degrees (if using the same frequency) ■21Mbps users (e.g. Constant Hawk) consume equivalent of two 10Mbps channels Page 8 FlyPlan Software Analysis Key Findings (U) All determinations were made using FlyPlan software and data provided by the respective Program Managers

9 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Signals are not “Lego Bricks”; they are complex functions –FlyPlan assesses interference as signals overlap; finds the breaking point regardless of how bandwidth is defined (e.g. 3 dB, Necessary, etc) ■10Mbps links require 15MHz frequency separation to share the same airspace without interference Page 9 Minimum Frequency Separation Explained (U) 3 dB BW (10.1MHz) 90% of the Power (11.5MHz) Necessary BW (18.2MHz) As used by: Vader MARSS Harvest Hawk Constant Hawk Hunter AAA

10 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■All GCS antennas in the data call are highly directional (4 ft parabolic) –Example: 5 Degrees offset has a 31 dB drop in antenna gain ■FlyPlan assesses interference at off-axis angles; finds breaking point –Takes into account GCS pointing stability and A/C power outputs Page 10 Minimum Angle Separation Explained (U)

11 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■10Mbps Narrowband Aircraft fall into one of two categories –Narrowband aircraft using only Omni Antennas –Narrowband aircraft using Directional Antennas ■Omni-Only Narrowband Aircraft –Omni antennas broadcast everywhere, in all directions –Broadcast reach GCS & Remote Video Terminals (RVT) simultaneously ■Directional Narrowband Aircraft –Focuses a radio beam at the GCS with directional antenna –Directional radio beam does not illuminate dismounted soldier RVT’s –Most A/C in data call require support to dismounted soldiers; therefore –Directional narrowband aircraft require a second CDL link ■ RVT links typically use an omni so as to reach all soldiers on the ground ■The term “Links” is used throughout this briefing –If referring to omni-only aircraft, then # Aircraft = # Links –If referring to directional aircraft, then # Aircraft = Half the # Links Page 11 Links vs. Aircraft (U)

12 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED Page 12 Data Call CDL-Platform Summary for Afghanistan (U)

13 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Develop frequency plans requiring little or no airspace management or tasking considerations –Aircraft can fly anywhere without regard to frequency considerations ■Use airspace management to expand the number of CDL links –Requires disciplined airspace management ■ Airspace management tied directly to aircraft tasking in support of ISR collection requirements –Aircraft cannot fly “anywhere” –Coordination must occur before an A/C can change from one geographical sector to another –Frequencies may need to be centrally or regionally assigned (perhaps daily) to manage channels Page 13 Two Frequency Mgt Option Approaches Available (U)

14 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED Page 14 Option 1: Little to No Airspace Management (U) ■Max number of CDL links that fit into Ku-band (each base) –27 10Mbps (15 MHz separation) –1 274Mbps Mbps (15 MHz separation) ■Aircraft can fly anywhere within LOS range of base (200NM) –Useful if you do not want to manage airspace & frequencies

15 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■There is not enough spectrum to separate two wideband A/C that share the same airspace ■Minimum angular separation between two wideband A/C measured from operating location is 30° –A/C use same frequency ■Depending on orbit size, airspace can handle upwards of 9 wideband A/C –Each separated by 30° –Spread out around the base ■Twelve 10Mbps CDL links can operate simultaneously anywhere within range of base Page Mbps Wideband Considerations (U) 12 10Mbps can fly anywhere Co-located GCS on same base

16 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■There is insufficient spectrum available for use to separate two wideband A/C to share the same airspace; but, ■Spacing two wideband A/C channels as far as possible reduces the minimum angular separation –From 30° to 15° ■ Channel assignments of & GHz ■ 30 MHz max separation possible –Huge cost; Number of 10Mbps links drops from 12 to 4 ■The 4 10Mbps can be anywhere in the airspace Page 16 Bringing Wideband A/C Closer Together (U)

17 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Minimum separation angle between 10Mbps platforms is 10° ■Result –Wedge containing wideband A/C can support 4 10Mbps (shown in green) –Larger wedge (shown in red) can reuse frequencies with normal 10Mbps pattern (below) supporting 27 links Page 17 Overcoming Cost of 2 Wideband A/C Close Together (U) 27 Links 4 Links

18 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Divide airspace into 4 sectors ■Alternate frequency patterns ■Results –13 Links (10Mbps) in “A” –14 Links (10Mbps) in “B” –54 10Mbps) ■Freedom of Movement: –A/C in “B” can move into “A” & vice versa –Provides 270° of freedom Page 18 Option 2: Managing Airspace to Increase CDL Links (U) A B B A

19 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Dividing airspace into more sectors yields more links –4 Sectors: 54 10Mbps –6 Sectors: 81 10Mbps –8 Sectors: Mbps –12 Sectors: Mbps ■Alternate Even/Odd frequencies –A/C have freedom to move into adjacent sector Page 19 Further Link Increases => More Sectors (U)

20 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Conclusions in this study based exclusively on data for aircraft currently operating in CJOA-A –Future A/C may have different transmitter/receive characteristics –Conclusions contained herein may not apply ■Urge all future deployments provide USCENTCOM with completed Data Call worksheet –Can assess impact (if any) fairly quickly (two weeks) –Importance is amplified for wide band assets or narrow band assets operating out of a FOB that supports a wide band asset Page 20 Caution (U)

21 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Due to operational urgency, this study focused exclusively on the here and now ■Mitigation steps for the long term are likely –9 Months estimated to complete a long term study ■Long term study areas: –Waveform improvements ■ Modulation, Coding, Tunability, Power Control –Antenna improvements (Aircraft & Ground Stations) –Diplexer improvements –Cross-Polarization benefits –Improvements to FlyPlan M&S software Page 21 Recommended Further Study (U)

22 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Ku-band spectrum supports… –27 10Mbps, or –1 274Mbps Mbps ■274Mbps A/C require 30° separation if using same channel –12 10Mbps can overlap same area of operations ■274Mbps A/C can operate within 15° w/staggered frequencies –4 10Mbps can overlap same area of operations –Spectrum reuse begins 10° later, provide 27 10Mbps ■Airspace can be divided into sectors to further increase # of Links –Requires airspace management –A/C are restricted to their assigned sector + adjacent sectors (each side) Page 22 Summary (U)

23 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Assign Blue Devil and Gorgon Stare a “shared” wideband channel ( GHz center frequency) and assign narrowband users remaining channel assignments per below ■IJC and RC-S CM&D need to be cognizant that tasking Blue Devil and Gorgon Stare within 30 o of angular separation will result in signal interference (i.e. imagery degradation to PED cell) ■COA supports the minimum number of assets but requires the least day-to-day deconfliction measures by RC-S CM&D. Page 23 COA #1: Assign Frequencies Independent of Airspace

24 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Same as COA#1, but with two pre-planned 10° keep out zones on either side of the wideband aircraft ■Enables 12 narrowband links as with COA#1 co-located with wideband aircraft Page 24 COA#2: Include two “Keep-Out” zones Around Wideband Aircraft 27 Links 12 Links 10° Keep-Out Zone ■Complete frequency re-use beyond the keep-out zones –Enables 27 additional narrowband links to be assigned as needed ■IJC and RC-S CM&D need to be aware that … –A/C in green zone are confined to green sector –A/C in red zone are confined to red sector

25 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Same as COA #2, but change frequency plan for the Green Zone –Enables IJC and RC-S CM&D to bring wideband A/C within 15° of each other –Reduces narrowband assignments from 12 to 4 –Red zone is unaffected ■Wideband center frequencies will be & GHz Page 25 COA#3: Operate Wideband A/C in Close Proximity 27 Links 4 Links 10° Keep-Out Zone

26 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■Use a 4/6/8/10/12-sector approach to divide airspace around the designated RC-S FOB –Permits the frequency re-use of both wideband and narrowband users –Alternate Red/Blue channel assignments with sectors ■Minimizes and/or prevents “accidental” blue-on-blue frequency interference ■Aerial assets communicating with GCS at FOB locations other than the sectors radius but in the general Area of Operations may require dedicated channels ■COA supports the highest number of possible assets (and channel assignments) although requires the RC-S CM&D (or appropriate authority) to have an intimate hand in spectrum coordination based on aircraft tasking requirements Page 26 COA#4: Assign Frequencies by Sector

27 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED Page 27 Backup BACKUP

28 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED ■This briefing (slide 8) showed that… –Min separation angle = 30° for 274Mbps wideband links –Min separation angle = 10° for 10Mbps narrowband links ■In reality, min separation angle is a function of range –CCJ6 guidance (slide 4) was “no formulas”, “5 second decision time” –Therefore, this briefing took worst case separation angle (max range) ■Planners probably need to know that they have options, particularly for the 274Mbps wideband aircraft –See Slide 29 – 31 for examples Page 28 Minimum Separation Angles for Frequency Reuse

29 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED Page Mbps (STD-CDL) Wideband Aircraft (Blue Devil & Gorgon Stare, both with Directional Antennas) 150NM 10 Deg Separation out to 130NM 30 Deg Separation out to 140NM 5 Deg Separation out to 120NM 140NM 130NM 120NM

30 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED Page Mbps (STD-CDL) (Blue Devil [Omni Antenna] & Gorgon Stare [Directional Antenna]) 30 Deg Separation out to 50NM 10 Deg Separation out to 40NM 50NM 40NM

31 © 2011 The MITRE Corporation. All rights reserved. UNCLASSIFIED Page Mbps (STD-CDL) (25,000 Feet Altitude, Directional Antennas) 10 Deg Separation out to 150NM 30 Deg Separation out to 160NM 2.5 Deg Separation out to 140NM 160NM 150NM 140NM


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