To improve the spectrum utilization of a system with fading channels, researchers have designed adaptive coding and modulation (ACM) technology. This technology can decide the channel-coding and modulation modes according to the traffic volume, average signal-to-noise ratio, average delay, interruption probability, and data rate. Adaptive coding and modulation technology can effectively improve the spectrum utilization, increase the system throughput, and inhibit the impact of atmospheric turbulence on system transmission performance.