Joint Adaptive Modulation and MIMO Transmission for Non-Ideal OFDMA Cellular Systems

In this paper, a joint adaptive modulation and multiple-input multiple-output (MIMO) transmission scheme is considered. An efficient use of radio resources shall be based on channel state information at the transmitter (CSIT) to adjust the modulation order and MIMO transmission mode. A new suboptimal algorithm is proposed for link adaptation in a MIMO-OFDMA cellular system under spatially correlated fading and imperfect CSIT due to user mobility. Performance results are provided for the proposed solution under a long term evolution (LTE) downlink scenario. A substantial spectral efficiency gain is observed in contrast to the standalone transmission schemes.