  Satellite communication is one of the key technologies that is enabling
next-generation networks. However, nearest-satellite-supported downlink
transmission may not meet a user's requirements due to limited signal strength,
especially in emergent scenarios. In this paper, we investigate a coordinated
multi-satellite joint transmission system from a system-level perspective,
where a user can be served by multiple satellites to improve its
quality-of-service (QoS). Furthermore, we analyze the coverage and rate of a
typical user in the joint transmission system. Simulation and numerical results
show that the introduced system achieves a higher coverage probability than the
traditional nearest-satellite-supported network. Moreover, a user's ergodic
rate can be maximized by selecting an appropriate number of serving satellites.
