Abstract:

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.