Space-Frequency Scheduling in TDD Based LTE-Advanced MIMO-OFDMA Systems

Space-frequency resource allocation and multiuser beamforming are crucial techniques to obtain high spectral efficiency requirements of IMT-A technologies. In this paper, we consider system level evaluation results of downlink TDD based LTE-A MIMO-OFDMA networks in ITU-R specific IMT-A evaluation environments. Efficient multiuser MIMO beamforming with and without intra-site coordinated multipoint (CoMP) and proportional fair space-frequency scheduling algorithms are particularly investigated. The system level results indicate that MU-MIMO and CoMP are needed in urban micro (UMi) environment to achieve the ITU-R specific spectral efficiency requirements. In ITU specific indoor scenario, MU-MIMO system is able to provide very high spectral efficiency because intercell interference is not limiting performance so strongly. The considered MU-MIMO CoMP seems to work also in rural macro environment with high mobility users and outdated CSI.