论文部分内容阅读
在LTE移动通信系统中信道质量指示参数(Channel Quality Indicator,CQI)是自适应调制编码(AdaptiveModulation and Coding,AMC)技术的一项重要参数。由于GEO卫星信道存在较长的传输时延,为保证有效的AMC调整,对CQI进行预测是非常必要的。但是大多数预测算法的可预测时长受到输入序列的相关时间限制,而含有小尺度衰落影响的信号的CQI序列的相关时间远远小于所需预测时长,对获得的CQI序列进行预测是不现实的。针对这一问题,提出了一种使用仅含有大尺度衰落的CQI数据进行预测的近似方法。将获得的CQI序列平滑后去掉小尺度衰落的影响,余下的数据可以认为是只受大尺度衰落影响,其相关时间可以大大延长。通过对GEO卫星信道信道质量进行建模分析,对使用近似方法处理前后的CQI序列数据差距以及相关时间的变化进行了数值仿真,结果表明所提出的近似方法不会导致CQI数据产生较大的偏差,且近似后的序列具有较长相关时间。在此种近似方法处理下的CQI数据相关时间能够满足预测模型的需要,从而为保证GEO卫星移动通信系统中使用AMC的可行性和可靠性提供可能。
Channel Quality Indicator (CQI) is an important parameter of Adaptive Modulation and Coding (AMC) in LTE mobile communication system. Due to the long transmission delay of GEO satellite channels, it is necessary to predict the CQI in order to ensure effective AMC adjustment. However, the predictable duration of most prediction algorithms is limited by the relevant time of the input sequence. However, the correlation time of the CQI sequence of the signal containing the influence of small-scale fading is far less than the required prediction duration. It is unrealistic to predict the obtained CQI sequence . In response to this problem, an approximate method for predicting using only CQI data with large-scale fading is proposed. Smoothing the obtained CQI sequence removes the effect of small-scale fading. The remaining data can be considered as being influenced only by large-scale fading, and the correlation time can be greatly prolonged. By modeling and analyzing the channel quality of GEO satellite channels, the numerical simulation of the difference of CQI sequence data and the correlation time before and after using the approximate method is carried out. The results show that the proposed approximation method will not cause large deviation of CQI data , And the approximate sequence has a longer correlation time. The correlation time of CQI data processed by such approximate method can meet the requirement of prediction model, so as to ensure the feasibility and reliability of using AMC in GEO satellite mobile communication system.