A novel link adaptive transmission scheme in higher-order MIMO systems

This paper proposes a novel cascaded precoding scheme at the base station to adapt to both long-term and short-term channel variations in higher-order MIMO systems which are supported in 3GPP LTE-Advanced. The proposed precoding scheme includes a long-term precoding followed by a short-term precoding, where the former bases on the channel statistical eigenmodes, adapting to the long-term channel variations and the latter bases on the LTE Rel. 8 codebook, adapting to the short-term channel variations. Simulation results show that the proposed scheme can achieve a high spectral efficiency while guaranteeing a given codeword error ratio target. And when compared with the precoding scheme using the codebook for LTE-Advanced which is finally fixed recently in one of the 3GPP´s proposals, the proposed scheme has a comparable performance but a reduced complexity due to the codebook size and long-term feedback interval.