基于改进AMC的LTE MIMO模式自适应切换算法

首先针对传统的自动调制编码（adaptive modulation coding, AMC）技术存在映射的调制编码方案等级与实际信道环境不匹配的问题，提出了一种基于ACK/NACK（acknowledge/negative acknowledgement）反馈的信道质量指示(channel quality indicator， CQI)微调技术，此方案能够使上报的CQI等级更好地适应当前环境，确保了传输的可靠性。在此基础上提出了一种基于AMC的多输入多输出模式自适应切换方案，该方案基于信噪比和速率进行自适应的模式切换，可以在不同的传输环境下达到最高系统容量。仿真结果表明，所提方案能够适应多种传输环境，可以显著提高系统容量。

Adaptive MIMO mode switching algorithm based on improved AMC in LTE system

Firstly, aiming at the problem that the mapping modulation and coding scheme level of traditional adaptive modulation coding （AMC does not match actual channel conditions, an improved AMC scheme based on acknowledge/negative acknowledgement (ACK/NACK) is presented, which adjusts the modulation and coding scheme level by user equiment （UE） reporting channel quality indicator （CQI） and ACK/NACK. The AMC algorithm enables the CQI level better adapted to the current environment and ensures the transmission reliability. And then a multi input multi output (MIMO) mode switching algorithm is presented, which selects the optimum MIMO mode according to proper signal to noise ratio and UE move speed. This algorithm can reach the maximum system capcity in different transmission environments. Simulation results show that the algorithm can improve system throughput notably.