Hierarchical Multi-Beam Search for Millimeter-Wave MIMO Systems

In millimeter-wave (mmWave) MIMO systems, while a hybrid digital/analog precoding structure offers the potential to increase the achievable rate, it also faces the challenge to lower channel estimation time due to a large number of antennas at both Tx/Rx sides. In this paper, the channel estimation is realized via multi-beam search, and a new hierarchical multi-beam search scheme, which uses a pre- designed analog hierarchical codebook, is proposed. Performance evaluations show that, compared with a state-of- the-art scheme, the proposed scheme not only achieves a higher success rate to acquired multiple beams under typical system settings, but also greatly reduces the channel estimation time.