Due to the time-varying of the channel and the huge round-trip delay

the application of adaptive coding and modulation (ACM) technique is greatly limited in the mobile satellite environment. In order to solve this problem

an ACM method using partial channel information is proposed based on the characteristics of the line-of-sight component between uplink and downlink

which satisfy the approximate reciprocity in mobile satellite communication. This paper presents an optimized ACM strategy and power allocation method with the constraint of the average transmit power and the average bit error rate

which overcome the limitations of existing adaptation. At the same time

the simulation results also show the effectiveness of the proposed method.