1. PI: Will Ivancic/GRC Co-PI: Don Sullivan/ARC
Real-Time and Store-and-Forward Delivery of Unmanned Airborne Vehicle Sensor Data
PI: Will Ivancic/GRC
Co-PI: Don Sullivan/ARC
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4. Goals
Develop and deploy a mobile communication architecture based on Internet Technologies that will be utilized on the Global Hawk Unmanned Arial Vehicle (UAV) for atmospheric research.
Improve the data throughput and utilization of current UAV remote sensing by developing and deploying technologies that enable efficient use of the available communications links.
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5. Approach
Use and/or Develop Standard Store and Forward Disruption Tolerant Networking Technology
Implement improvements to the Saratoga transport protocol to include rate-limiting and, if needed, congestion control features
Develop a protocol that advertises link properties from an RF modem to an end node
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6. Missions
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7. Global Hawk Operational Capability Four Mission Regions, with Arcs of Constant On-Station Times
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8. GloPac Mission
Conducted in support of the Aura Validation Experiment (AVE).
Aura is one of the A-train satellites supported by NASA Earth Observation System.
Will encompass the entire offshore Pacific region with four to five 30 hour flights.
Will fly over the Pacific ocean, from the North Pole to the equator for its first Atmospheric Chemistry experiment.
The flights are designed to address various science objectives:
Validation and scientific collaboration with NASA earth-monitoring satellite missions, principally the Aura satellite,
Observations of stratospheric trace gases in the upper troposphere and lower stratosphere from the mid-latitudes into the tropics,
Sampling of polar stratospheric air and the break-up fragments of the air that move into the mid-latitudes,
Measurements of dust, smoke, and pollution that cross the Pacific from Asia and Siberia,
Measurements of streamers of moist air from the central tropical Pacific that move onto the West Coast of the United States (atmospheric rivers).
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9. Genesis and Rapid Intensification Processes (GRIP)
Better understand how tropical storms form and develop into major hurricanes.
Deployment of new remote sensing instruments for wind and temperature that can lead to improved characterization of storm structure and environment.
NASA plans to use the DC-8 aircraft and the Global Hawk Unmanned Airborne System (UAS)
The spaceborne, suborbital, and airborne observational capabilities of NASA put it in a unique position to assist the hurricane research community in addressing shortcomings in the current state of the science.
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10. Mobile Communications Architectures
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11. GloPac Communication Network
Reconnected around
+/- 70 Degrees Latitude
Disconnection Over the North Pole
GE 23
Store
Forward
3 Mbps
Bidirectional
Link
NASA Dryden
L3-Com
Ku-Band
Transportable
Terminal
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12. GRIP Communication Network
Ku Band
Satellite - A
Ku Band
Satellite - B
> 3 Mbps
Bidirectional
Link
NASA Dryden
Disconnection During Satellite Handover
Due to Repointing
L3-Com
Ku-Band Terminal
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13. Future Communication Network
Ku Band
Satellite
Disconnection During Handover Between
Service Providers
NASA Dryden
Service
Provider A
Service
Provider B
Internet
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14. Why Store and Forward
Global Hawk has large periods of disconnection from the network and needs to store data during disconnection and transmit data during times of connectivity
Store and forward can break control loops
Allows for link by link transport protocol optimization.
NASA Dryden
Control Loop
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15. Layer-2 Triggers
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16. Smart Modems
Modem's transmitting and receiving link rates can be varied over time due to the following:
Adaptive coding
Changes in Modulation to suit the channel characteristics.
Changes in transmission rate to suit the channel characteristics
Rate mismatch between RF link and local area network.
Serial connections are less of a problem as clocks can be controlled by modem (at least the receiving clock)
Ethernet connections are becoming standard and result in rate mismatch between the LAN interface and the RF link. RF
3 Mbps
Ethernet
100 Mbps
Ethernet
1 Gbps
Application
Modem
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17. Issue / Problem
In order to condition traffic and get the most out of the RF link, applications need to know the modem's link status (e.g. Link Up/Down, Link Unreliable, Data Rates).
Figure 1 corresponds to existing commercial imaging satellites
Figure 2 is more generic
A standard method is needed for applications to understand the down stream modem’s RF link status and adjust that application traffic pattern accordingly.
Modem RF
3 Mbps
Serial
Link
Application
Figure 1
Modem RF
3 Mbps
Ethernet
100 Mbps
1 Gbps
Application
Figure 2
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18. Solution
Develop a standard protocol that provides link status conditions
Should be able to provide wide area network (WAN) radio reachback link status to applications that may be multiple hops away.
Uses
Applications can adjust to link state
Route Optimization
Useful for multi-homed systems RF
256 kbps
Modem
Ethernet
100 Mbps
Application RF
3 Mbps
Modem
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