A low-complexity cyclic shift codebook design for massive MIMO

In this paper, we develop a novel codebook with low storage and complexity. The proposed codebook is constructed by cyclically shifting certain unit-norm vectors which satisfy the mutually unbiased condition. Moreover, an FFT-based algorithm, whose time complexity increases logarithmically with the number of transmit antennas, is proposed. Simulation results show that the proposed scheme is very suitable in massive MIMO system with only a small performance degradation.