近地卫星Ka频段数传链路抗雨衰自适应模式设计

Adaptive mode design of near-earth satellite data transmission link for resistance to rainfall attenuation at Ka band

针对近地卫星数传时的信道时变性和严重的Ka频段雨衰现象,采用自适应编码调制(Adaptive Coding and Modulation, ACM)技术能够充分利用链路资源,相对于传统的固定编码调制方式,进一步提高链路的数据吞吐量。提出近地卫星Ka频段数传链路ACM模式设计方法,在降雨环境下建立Ka频段数传链路模型,根据链路预算的信道状况确定ACM选用模式;采用基于导频符号的最大似然信噪比估计算法结合移动平均的平滑方法实现信道估计,有效地减小了估计值的波动。仿真结果表明,无论晴天还是雨天,采用提出的卫星数传链路ACM模式设计方法,能够在保证系统可靠性的同时获取较高的数据吞吐量。

For channel′s time variability and severe rain attenuation at Ka band when near-earth satellites transmit data, using ACM(adaptive coding and modulation) technology can make full use of link resources, and further improve data throughput relative to traditional constant coding and modulation. The design method of the near-earth satellite data transmission link with ACM mode was proposed. The data transmission link model was established under the rainfall environment, then the ACM selection mode was determined depending on the channel condition. The maximum likelihood signal to noise estimation algorithm based on pilot symbols and the moving average smoothing method were adopted at channel estimation to reduce the fluctuation of the estimated value effectively. Simulation results show that no matter on clear or rainy days, the proposed satellite data transmission link ACM mode design method can obtain high data throughput while ensuring system reliability.