Dual Threshold Mode Switching Criteria with Diversity and Spatial Multiplexing in LTE

This paper presents a dual threshold mode switching criteria to optimize the performance of multiple-input multiple-output (MIMO) in Long Term Evolution (LTE) downlink. Transmit diversity (TD) and spatial multiplexing (SM) is the basic MIMO transmission modes in LTE-A standards. General method for mode switching based on Signal-to-Noise-and-Interference Ratio (SINR) or CQI is merely a single threshold. However, that can result in significant throughput loss. We exploit the statistical properties of the CQI value under TD and SM scheme respectively and propose a dual threshold mode switching method. This approach is implemented in different switching criteria to verify its effectiveness and robustness. We provide simulation data to show that such an algorithm can improve the downlink throughput by 2-30% on an average compared with the conventional single threshold method.