Path Selection Based Feedback Reduction for FDD Massive MIMO Systems

Massive multi-input multi-output systems with large-scale transmit antenna arrays can bring significant improvements in the spectral efficiency and energy efficiency. To fully enjoy the benefits of the massive MIMO systems, acquisition of accurate downlink channel state information (CSI) at the basestation is crucial. While the CSI acquisition is relatively easy for the time division duplexing (TDD) systems, it is quite burdensome for the frequency division duplexing (FDD) systems due to the CSI feedback overhead. In this paper, we propose a path selection based feedback reduction technique for the FDD-based massive MIMO systems. The key idea of the proposed scheme is to exploit the property that the spatial characteristics of the propagation channel can be represented by a small number of multi-path components (e.g., path angle and path gain). By quantizing the multi-path component information instead of the channel information, the number of bits required for the channel vector quantization scales linearly with the number of dominant paths, not the number of transmit antennas. From the simulation results, we demonstrate that the proposed scheme is very effective in achieving the feedback overhead reduction compare to the conventional scheme relying on the CSI feedback.