S Performance Evaluation of MIMO and HARQ Techniques for LTE Uplink System

In this paper, we carry out a performance evaluation of multiple-input multiple-output (MIMO) and Hybrid automatic repeat request (HARQ) techniques for singlecarrier frequency division multiple access (SCFDMA) of the LTE uplink system. Different MIMO schemes such as singleantenna port (SISO or SIMO), transmit diversity (TD) and spatial multiplexing (SM) are described and simulated. In this paper, we propose an advanced soft combining method of HARQ transmissions which is called linear minimum square error soft combining (LMMSE-SC). In this method, the LMMSE equalizer operates jointly the spatial diversity provided by MIMO technique and the temporal diversity provided by the HARQ retransmissions. Simulation results show that the proposed method improves the performance of HARQ with chase combining technique compared to the classical method of combination.