Differential quantization of eigenmodes for MIMO eigenmode transmission systems

In this letter, a generic quantization scheme for MIMO eigenmode transmission system in temporally and spatially correlated channels which allocates different number of quantization bits to the various eigenmodes is proposed. By transmitting the difference between the previous eigenbeamformer and the present eigenbeamformer to the transmitter, we show that the variances in the difference for eigenmodes with higher gains are smaller than that for eigenmodes with lower gains. Simulation results proved that the proposed scheme requires lower number of quantization bits than the conventional method of quantizing the channel matrix, especially when temporal and spatial correlations are high.