  The next generation multibeam satellites open up a new way to design
satellite communication channels with the full flexibility in bandwidth,
transmit power and beam coverage management. In this paper, we exploit the
flexible multibeam satellite capabilities and the geographical distribution of
users to improve the performance of satellite-assisted edge caching systems.
Our aim is to jointly optimize the bandwidth allocation in multibeam and
caching decisions at the edge nodes to address two important problems: i) cache
feeding time minimization and ii) cache hits maximization. To tackle the
non-convexity of the joint optimization problem, we transform the original
problem into a difference-of-convex (DC) form, which is then solved by the
proposed iterative algorithm whose convergence to at least a local optimum is
theoretically guaranteed. Furthermore, the effectiveness of the proposed design
is evaluated under the realistic beams coverage of the satellite SES-14 and
Movielens data set. Numerical results show that our proposed joint design can
reduce the caching feeding time by 50\% and increase the cache hit ratio (CHR)
by 10\% to 20\% compared to existing solutions. Furthermore, we examine the
impact of multispot beam and multicarrier wide-beam on the joint design and
discuss potential research directions.
