Abstract: In order to improve the communication quality effectively, an approach of changing information transmission rate named VCTRM was proposed. The approach changed the modulation type and the chip transmission rate adaptively according to the current channel status when satellite communicated with ground station. The approach not only overcomes the defect that variable modulation type cannot meet the requirement of Bit Error Rate (BER) in system, but also solves the problem that the variable chip transmission rate can not improve the throughput in bad channel status. Simulation was given on three kinds of information transmission methods with Matlab: variable modulation method, variable chip transmission method and VCTRM method. The simulation results indicate that the proposed approach can not only meet the requirement of the system BER at any time but also get larger throughput than other approaches apparently.

Key words: communication quality, throughput, Bit Error Rate (BER), modulation type, chip transmission rate

摘要： 为有效地提高星地通信系统的通信质量，提出了一种改变信息传输速率的方法VCTRM。该方法根据当前星地信道状况自适应地改变调制方式和码元传输速率，克服了采用变调制方式传输时在低信噪比时不能满足系统误比特率的缺陷，同时又解决了采用变码元传输速率在高信噪比时不能提高系统吞吐量的问题。通过Matlab对变调制方式、变码率及VCTRM三种传输方式进行了仿真，结果表明，VCTRM在不同信道状况下均能满足系统对误比特率(BER)的要求，且获得的系统吞吐量明显高于其他方法。

关键词: 通信质量, 吞吐量, 误比特率, 调制方式, 码元传输速率