Exploring PWSA to Optimize Transport Layer Networking

The Space Development Agency (SDA) is currently focusing its efforts on developing the Proliferated Warfighter Space Architecture (PWSA), a network of small, low-cost satellites designed for various purposes: Transport Layer, Battle Management Layer, Tracking Layer, Custody Layer, Emerging Capabilities (Deterrence) Layer, Navigation Layer, and Support Layer. Many decisions must be made across all these layers to optimize mission performance. This proposal addresses an effort to apply optimization of each of the layers across their product lifecycle, and in particular to optimize the Transport Layer with regard to networking and sending messages to reduce the number of hops needed. The proposal will focus on optimization of the Tranche 2 Transport Layer (T2TL) including system design, R&D portfolio allocation, procurement, mission planning, and real-time adaptation. This will be accomplished by the power of a simulation-based Mission Performance Model (MPM). At present, the SDA has a preliminary design of the Tranche 1 Transport Layer (T1TL) with contracted technical spacecraft specifications. The enabling technology is tuning of the Mission Performance Model (MPM). Critical products of the demonstration include the documentation of the MPM comprised of the relatively weighted KPIs including latency, congestion, mean time to access, and mean access time affecting simultaneous users. Design input parameters include orbital elements, network routing algorithms, and processing speed for the satellite network, followed by signal acquisition, pointing, and transmission rates. Other inputs include transmission range and atmospheric height limits for the intersatellite links. The MPM will be leveraged to determine the combination of design inputs to optimize global performance. A sub-layered approach to optimizing each layer will be applied. One element of the design is related to the intersatellite link configuration. The default design connects each satellite in the T1TL to one ahead, one behind, one to the left and one to the right in a Ghost-Busters pattern, so that optical links between satellites do not cross each other. By running the dynamic routing algorithm (subject to physical constraints) one can demonstrate that the theoretical limit could reduce the average number of links required to transport the packets across the network by significant amount by applying combinatorial optimization. This enables one to consider alternate dynamic routing approaches, especially for scenarios related to various hotspots in the world needing to communicate to corresponding command centers. This can be applied in real-time to take into account traffic, risk, and satellite availability as needed. The proposed effort will describe the technology and show how to achieve sampling distributions that can be global, representative, and generalizable.