Virtual Routing Areas for NGSO Satellite Handover
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Solution Overview
Problem
Current routing techniques for non-geostationary orbit (NGSO) satellite systems face scalability issues and are not performant enough to handle the high number of handovers required, especially due to user terminal mobility, leading to inefficient network management and increased calculations.
Innovation Solution
The method involves generating time-sliced routing graphs for virtual routing areas (VRAs) that cover specific geographical regions, establishing connectivity between satellites and terminals, and allocating IP addresses, allowing for efficient and scalable routing by representing satellite-to-satellite and satellite-to-ground connectivity as static graphs, reducing the complexity of path management and handover calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If link-state routing using on-board narrowband IP routers is employed, then real-time routing decisions can be made, but the system does not scale beyond a few hundred satellites due to scalability issues and excessive calculation requirements
Solution Approach 1:
The patent divides the satellite network into multiple Virtual Routing Areas (VRAs), each managed independently with its own routing graph. This segmentation allows the overall network to scale beyond the limitations of a single link-state routing domain, as each VRA can be managed separately without requiring updates across the entire network for every handover event.
Solution Approach 2:
The patent pre-generates routing graphs for each VRA covering specific time periods and geographical areas before handover events occur. These routing graphs are computed offline or in advance, containing pre-calculated paths and connectivity information. When handovers occur, the system simply looks up pre-computed routes rather than performing real-time calculations across the entire network, dramatically reducing computational burden.
2Reliability
If the entire network is updated for each handover event, then routing accuracy is maintained, but the number of calculations increases excessively, reducing system performance
Solution Approach 1:
The patent implements localized routing management where each VRA maintains its own routing graph and updates only affect local areas. When a handover occurs within a specific VRA, only that VRA's routing graph needs updating, not the entire network. This local quality approach maintains routing accuracy for affected areas while avoiding unnecessary recalculations in other parts of the network.
Solution Approach 2:
Routing graphs are pre-computed for various scenarios and time periods before handover events occur. The system prepares multiple routing graphs covering different time intervals and geographical regions in advance. During operation, the appropriate pre-computed graph is selected and applied, eliminating the need for real-time recalculation and maintaining routing accuracy without excessive computational overhead.
3Ease of operation
If on-board routers modulate/demodulate and inspect data packets at run-time, then routing decisions can be made, but scalability is limited due to the computational burden on satellite hardware
Solution Approach 1:
The patent extracts the complex routing computation functions from the satellite on-board hardware and relocates them to ground-based network management systems. The on-board narrowband IP routers on satellites are simplified to basic forwarding devices that use pre-computed routing information, while the complex graph generation and routing optimization are performed on the ground where computational resources are abundant.
Solution Approach 2:
The patent uses virtual routing areas that create virtual copies of routing functionality on the ground to manage satellite communications. Instead of requiring complex real-time routing computations on satellite hardware, the system uses pre-computed routing graphs that are copied and distributed to relevant nodes, allowing simplified on-board routers to operate efficiently with pre-determined routing tables.
Data Source
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AI summary
Systems, methods, and apparatus for mobile routing for non-geostationary orbit (NGSO) systems using virtual routing areas (VRAs) are disclosed. A disclosed method comprises generating a plurality of routing graphs for each of a plurality of VRAs. Each of the routing graphs is for a different period of time, and comprises a gateway and satellites that are within view of each other and of the gateway during the period of time associated with the routing graph. The method further comprises generating at least one time-sliced graph for each of the routing graphs, where each of the time-sliced graphs shows connectivity between at least some of the satellites, which are on the routing graph associated with the time-sliced graph, with each other. Further, the method comprises, during each of the periods of the time, establishing communications between the satellites according to each of the time-sliced graphs for the period of time.