Adaptive coding modulation selection optimisation scheme for Ka-band LEO mobile satellites

To address the problem that Ka-band satellite communication signal transmission is easily affected by rainfall and terminal environment, combining the characteristics of high-speed movement of LEO satellites and the wave propagation characteristics of satellite-ground links, this paper establishes a Markov synthesis model of four-state satellite channels based on Ka-band that integrates rainfall attenuation and terminal shadow attenuation, and a scheme for adaptive coding and modulation selection based on the DVB-S2 standard is proposed. Based on this, a rainfall fading probability density function (PDF) based on the satellite elevation angle variation is derived, and a more efficient and streamlined set of modulation and coding(MODCOD) is obtained through simulations and calculations. The simulation results show that the proposed scheme not only effectively solves the problem of severe fading of the transmission signal due to rainfall, ground movement environment and satellite mobility but also significantly reduces the system complexity of the original DVB-S2 standard scheme with little loss of efficiency.