An improved pilot reuse based estimation method for general channel environment in FDD massive MIMO systems

In frequency-division duplexing (FDD) massive multiple-input-multiple-output (MIMO) systems, channel estimation about reducing the training and feedback overhead has always been a hot research area. The previous studies have shown that the method of utilizing channel sparsity in discrete Fourier transform (DFT) domain and angle reciprocity works well in particular channel environment. In this paper, we propose an improved method based on pilot reuse for general channel environment. The proposed method is applied to uplink/downlink channel estimation in FDD massive MIMO systems. Based on practical characteristics of the channel in massive MIMO systems, we modify the original method and propose an improved algorithm in assigning the pilot resources dynamically. The numerical results corroborate that compared to the original method, the improved method is more suitable and performs better in general channel environment. Meanwhile, the proposed algorithm can save the pilot resources and reduce the feedback overhead efficiently.