Centralized Versus Distributed Routing for Large-Scale Satellite Networks

TL;DR

This work contrasts centralized ground-based routing and distributed onboard routing for large-scale satellite networks modeled as a time-varying toroidal grid with Markovian link dynamics. It analyzes SCPR (centralized) and GR (distributed) under scenarios with and without onboard buffering, deriving throughput and delay bounds and validating them via simulations. The results show that distributed routing generally yields higher throughput when link changes occur on timescales comparable to hop delays and achieves lower delays with buffering, while centralized routing can outperform in regimes of high link memory and small controller delay. The findings offer practical design guidance for routing in dense LEO/MEO constellations and point to improved policies that leverage GR as a modular component for performance gains.

Abstract

An important choice in the design of satellite networks is whether the routing decisions are made in a distributed manner onboard the satellite, or centrally on a ground-based controller. We study the tradeoff between centralized and distributed routing in large-scale satellite networks. In particular, we consider a centralized routing scheme that has access to global but delayed network state information and a distributed routing scheme that has access to local but real-time network state information. For both routing schemes, we analyze the throughput and delay performance of shortest-path algorithms in networks with and without buffers onboard the satellites. We show that distributed routing outperforms centralized routing when the rate of changes in the network link state is comparable to the inherent propagation and transmission delays. In particular, we show that in highly dynamic networks without buffers, the distributed scheme achieves higher throughput than a centralized scheme. In networks with buffers, the distributed scheme achieves lower delays with the same throughput.

Figures (8)

• Figure 1: Toroidal Mesh grid of size $N \times M$, where $N = 5$ and $M = 4$. Each node has degree 4.
• Figure 2: Markovian Link dynamics of $l(t)$
• Figure 3: Tradeoffs of the Routing Schemes
• Figure 4: Pictoral representation of the two scenarios of interest.
• Figure 5: Given the network state at $t=0$, the SCPR policy gives us the shortest connected path from source to destination, as highlighted. Here, the red crosses denote links being unavailable for use.

Theorems & Definitions (9)

• Definition 1: Connected Path
• Claim 1: Throughput Under SCPR Policy
• proof : Proof of Claim \ref{['claim:centralized_throughput']}
• Claim 2
• proof : Proof of Claim \ref{['claim:centralized_delay']}
• Claim 3
• proof : Proof of Claim \ref{['claim:distributed_throughput']}
• Claim 4
• proof : Proof of Claim \ref{['claim:distributed_delay']}