  Leveraging the advantage of satellite and terrestrial networks, the
integrated satellite terrestrial networks (ISTNs) can help to achieve seamless
global access and eliminate the digital divide. However, the dense deployment
and frequent handover of satellites aggravate intra- and inter-system
interference, resulting in a decrease in downlink sum rate. To address this
issue, we propose a coordinated intra- and inter-system interference management
algorithm for ISTN. This algorithm coordinates multidimensional interference
through a joint design of inter-satellite handover and resource allocation
method. On the one hand, we take inter-system interference between low earth
orbit (LEO) and geostationary orbit (GEO) satellites as a constraint, and
reduce interference to GEO satellite ground stations (GEO-GS) while ensuring
system capacity through inter-satellite handover. On the other hand, satellite
and terrestrial resource allocation schemes are designed based on the matching
idea, and channel gain and interference to other channels are considered during
the matching process to coordinate co-channel interference. In order to avoid
too many unnecessary handovers, we consider handover scenarios related to
service capabilities and service time to determine the optimal handover target
satellite. Numerical results show that the gap between the results on the
system sum rate obtained by the proposed method and the upper bound is reduced
as the user density increases, and the handover frequency can be significantly
reduced.
