Performance Evaluation of Closed Loop Transmission for LTE-A Uplink MIMO

Single carrier frequency division multiple access has been adopted as uplink multiple access scheme for next generation cellular system. This paper deals with the closed loop transmission for Long Term Evolution-Advanced (LTE-A) uplink. In the uplink, the feedback for support of uplink data transmission consists of rank indicator (RI), precoding matrix indicator (PMI) and channel quality indicator (CQI). The expression for the received signal-to-interference-plus-noise ratio (SINR) of uplink MIMO has been derived. The joint selection method of RI and PMI which maximizes the mutual information associated with the derived SINR is presented. The CQI selection scheme based on the exponential effective SNR mapping is proposed to maximize the spectral efficiency under a given block error ratio (BLER) target. Simulation results for LTE-A uplink scenario shows that the presented closed loop transmission scheme can significantly improve spectral efficiency under a given BLER constraint.