Multilevel-DFT based low-complexity hybrid precoding for millimeter wave MIMO systems

The millimeter wave (mmWave) multiple-input multiple-output is a promising technique for next-generation (5G) communication systems. The inherently high path loss in mmWave can be compensated by adopting large antenna array. However, huge cost of radio frequency (RF) chains at high frequencies, as well as large number of antennas, makes full-digital precoding in mmWave-MIMO system infeasible. Hence, hybrid analog/digital precoding techniques are proposed to reduce the hardware cost of RF components while achieving similar performance as full-digital precoder. Usually it requires iterative process and matrix inversion to split full-digital precoder into hybrid structure. In this paper, we propose a low-complexity hybrid precoding algorithm with predefined rotated multilevel-DFT codebook. It can leverage orthogonal mapping process to avoid iterative process and matrix inversion. Simulation results demonstrate that the proposed algorithm can achieve 97.6% spectrum efficiency compared with state-of-the-art low-complexity hybrid precoding algorithm while reducing 99.7% complexity in terms of complex multiplications.