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RAP opportunity at Air Force Science and Technology Fellowship Program     AF STFP

Nontraditional and Resilient Satellite Navigation and Timing


Space Vehicles Directorate, RV/Space and Planetary Sciences

opportunity location
13.40.01.C0467 Kirtland Air Force Base, NM 871175776


name email phone
Khanh Dai Pham 505.846.4823


Part of the core dominance in space resilience is the ability to effectively position, navigate and synchronize all space assets in contested, degraded, and operationally-limited (CDO) environments. Future resilient satellite navigation and timing (PNT) is expected to be rapidly tailorable to execute in any geographical region, orbital regime, and adaptable to support the full range of missions. The objective of this topic is to identify innovative solutions, nontraditional approaches, and out-of-the-box concepts of operations that can be feasibly leveraged for applicability in CDO environments. More specifically, adaptive multi-flow carrier aggregation (a.k.a. multi-flow CA) and advanced link layer structures are envisioned to be enable a persistent PNT capability of rapidly, redundantly and securely connecting geographically separated all-domain sensors, actuators, and end-effectors that are being served simultaneously using distinct component GPS frequence carriers. Also of interest are innovative packet scheduling and responsive load balancing strategies allocating incoming PNT packets based on link capacities and fill rates of the aggregated carriers among multiple serving PNT platforms from different tiers of missions. Expected metrics and attributes may include queuing delay, packet loss probability, out-of-order delivery, and spectral usage. Many of the existing techniques authenticate satellite navigation requirements based on the corresponding signatures received and appropriate public keys available. This research opportunity also explores potential scientific breakthroughs of the so-called "covert authentication," where the transmission of signatures cannot be detected by radio meters; only legitimate receivers would be able to obtain them for authenticating the intended satellite navigation messages. Last but not least, PNT system accuracy and integrity are sought during CDO operations, where scientific foundations and design principles are of concerns to networking and fusion of line-of-sight and non-line-of-sight radio frequency platforms inside and outside of GPS denied areas, in order to diffuse the fused PNT results to all-domain platforms in the PNT network and/or theater operations. Some research efforts, including social learning, belief propagation, spanning trees, optimal edge selection, etc. may have relevant benefits in impacting PNT system accuracy, complexity, fault tolerance, and real-time convergence.


1. K. D. Pham, "Resilient Synchronization of Radio Networks: A Pursuit-Evasion Graphical Game Approach," IEEE Aerospace Conference, 2019

2. Z. Khan, et. al., "Carrier aggregation/channel bonding next generation cellular networks: methods and challenges," IEEE Network, vol. 28, no. 6, pp. 34-40, 2014

key words
Satellite Position, Navigation and Timing; Covert Authentication; Networking; Fusion; Multi-flow Carrier Aggregation; Packet Scheduling; Load Balancing; Link Capacity; Fill Rate; Queuing Delay; Packet Loss Probability; Out-of-Order Delivery; Spectral Usage


Citizenship:  Open to U.S. citizens
Level:  Open to Postdoctoral and Senior applicants


Base Stipend Travel Allotment Supplementation
$95,000.00 $5,000.00

Experience Supplement:
Postdoctoral and Senior Associates will receive an appropriately higher stipend based on the number of years of experience past their PhD.

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