  Channels of satellite communication are usually modeled as Rician fading
channels with very large Rician factor or Gaussian channels. Therefore, when a
legitimate user is close to an eavesdropping user, the legitimate channel is
approximately the same as the eavesdropping channel. The physical layer
security technology of traditional terrestrial wireless communication mainly
takes advantage of the difference be-tween the legitimate channel and the
eaves-dropping channel; thus, it is not suitable for satellite communication.
To implement secure communication in similar channels for satellite
communications, a secure communication mod-el based on collaboration of the
interference relay of the satellite physical layer is proposed. Relay selection
and power allocation are further studied to enhance the security performance of
the satellite communication system based on the model. The relay selection
standard under known instantaneous channel state information (CSI) and
statistical CSI conditions is theoreti-cally derived, thereby accomplishing
minimiza-tion of the probability of secrecy relay. In addi-tion, the power
allocation factor is optimized based on minimization of the secrecy outage
probability. Moreover, a power allocation method based on the statistical CSI
is present-ed. The secrecy outage probability performance of each relay
selection criterion and power al-location scheme are analyzed via a simulation.
