On the physical layer performance with rank indicator selection in LTE/LTE-Advanced system

The 3GPP (Third Generation Partnership Project) LTE (Long Term Evolution) and LTE-Advanced activities work toward the evolved UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access (E-UTRA), and the solution of IMT-Advanced (International Mobile Telecommunications) and systems beyond. The combination of OFDM (orthogonal frequency division multiplexing) and MIMO (multiple-input multiple-output) has been introduced into LTE and LTE-Advanced systems for achieving high system capacity. Furthermore, the closed-loop concept with codebook based precoding MIMO and transmission layers selection, termed as RI (rank indicator) selection have also been included to provide robust transmission in mobile wireless communication scenarios and increase the cell coverage. This manuscript focuses on the RI selection study and implementation in LTE and LTE-Advanced systems and illustrates the downlink performance evaluation and comparison with different RI selection schemes. According to the analytical and numerical results from an LTE and LTE-Advanced compliant simulator, the mutual information based scheme is chosen as the best candidate for RI selection.