  The ever-increasing demand for ubiquitous, continuous, and high-quality
services poses a great challenge to the traditional terrestrial network. To
mitigate this problem, the mobile-edge-computing-enhanced low earth orbit (LEO)
satellite network, which provides both communication connectivity and on-board
processing services, has emerged as an effective method. The main issue in LEO
satellites includes finding the optimal locations to host network functions
(NFs) and then making offloading decisions. In this article, we jointly
consider the problem of service chain caching and computation offloading to
minimize the overall cost, which consists of task latency and energy
consumption. In particular, the collaboration among satellites, the network
resource limitations, and the specific operation order of NFs in service chains
are taken into account. Then, the problem is formulated and linearized as an
integer linear programming model. Moreover, to accelerate the solution, we
provide a greedy algorithm with cubic time complexity. Numerical investigations
demonstrate the effectiveness of the proposed scheme, which can reduce the
overall cost by around 20% compared to the nominal case where NFs are served in
data centers.
