  With the reduction of satellite costs and the enhancement of processing
capabilities, low earth orbit (LEO) satellite constellations can independently
build inter-satellite networks without relying on traditional ground stations
restricted by geographical distribution and can establish inter-satellite links
(ISLs) and complete computing and routing on-board. The characteristics of
frequent on-off ISLs, the highly dynamic network topology of satellite networks
make it face the challenges of routing strategy design as a delay/interruption
tolerant network (DTN). As a deterministic dynamic routing algorithm, contact
graph routing (CGR) uses a contact plan to calculate the path and forward data,
but it still has problems such as high computational overhead, low prediction
accuracy caused by ignoring queue delay, and overbooked problem caused by
limited cache. Therefore, we first start with the time-space resource contact
graph (TSRCG) to accurately characterize the time-varying and predictable
characteristics of the satellite network and the network resource parameters
under multi-tasks. Then, we optimize the route-list computation and dynamic
route computation process to ensure task delivery and reduce the consumption of
various resources, such as contact capacity, computing resources, and storage
resources. And the resource optimization for the multi-task delivery guarantee
algorithm based on CGR (RMDG-CGR) strategy we propose is compared with standard
CGR in ION 4.0.1. Finally, the simulation results show that the RMDG-CGR can
achieve higher task delivery in advance and successful task delivery rate, save
contact volume occupancy rate, computing and storage resource, and the above
effects are more prominent, especially in the task scenario with critical
bundles.
