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satellite-network

LEO satellite network routing

Starlink

SystemTechniques · 4Primitives · 20 satellite-network Bipartite matchinggraphs · medium: Maximum/weighted bipartite matching (Hopcroft-Karp, Hungarian) for assignment problemsTime varying topology routinggraphs · medium: Shortest paths on a graph whose links change predictably over time (contact plans)Orbit propagationnumerics · medium: Propagate satellite orbits (Kepler, SGP4, numerical with perturbations) and frame transformsSpherical harmonic transformnumerics · medium: Fast spherical harmonic transforms via FFT in longitude and Legendre in latitudeDijkstra's algorithmgraphs · low: Single-source shortest paths with non-negative edge weights by settling vertices in order of distance with a priority queue.›BBR congestion controlnetworking · low: Model-based congestion control that paces at the measured bottleneck bandwidth and caps inflight near one BDP, instead of reacting to loss.›Beamformingsignal-processing · low: Phased-array weights that steer radio energy toward a receiver; per-client steering vectorsForward error correctionsignal-processing · low: Add redundancy (LDPC, Reed-Solomon, XOR parity) so receivers repair loss without retransmitHandover managementsignal-processing · low: Moving a session between cells/beams/satellites without dropping itTdma schedulingsignal-processing · low: Time-slot scheduling of shared radio links among users/beamsBFS and DFSgraphs · low: The two basic graph traversals; BFS gives hop distances and levels, DFS gives discovery/finish order for cycles, components and topological order.›Max flow (Dinic)graphs · low: Maximum s-t flow by BFS level graphs and blocking flows; also gives the min cut, bipartite matching and assignment with capacities.›Interval treedata-structures · low: Index of ranges that answers "which intervals overlap this point or range?" in O(log n + k); static sorted-array form is the compact, cache-friendly choice.›Adaptive Runge-Kutta (Dormand-Princ…numerics · low: An embedded 5(4) Runge-Kutta pair estimates each step's error for free and resizes the step to meet a tolerance; the default non-stiff solver.›Rigid-body transforms (SE(3) poses)robotics · low: Represent, compose, invert, integrate and interpolate 3D poses as unit quaternion plus translation, with exp/log maps for small motions and uncertainty.›Calendar date arithmeticsystems · low: Civil dates, time zones (tzdb), DST gaps, month-end anchoring and duration mathFast Fourier transformnumerics · low: Computes the DFT in O(n log n) by recursively splitting into even and odd halves; the basis of fast convolution and spectral methods.›Gaussian quadraturenumerics · low: Approximate an integral by a weighted sum of n function values at roots of orthogonal polynomials; exact for polynomials up to degree 2n-1.›Spherical gridsnumerics · low: Lat-lon, cubed-sphere and icosahedral grids for global models; pole and area issuesd-ary heapdata-structures · low: Array heap with d children per node (d = 4 typical): half the binary heap's depth, siblings in one cache line, faster priority queues.›+ 4 more primitives