Hybrid Precoding Based on a Switching Network in Millimeter Wave MIMO Systems

Abstract

Aiming at the algorithm difficult optimization of the fully-connected hybrid precoding structure and the complex hardware implementation in millimeter wave multiple-input multiple-output (MIMO) systems, this paper proposes a novel hybrid precoding structure based on a switching network (SNHBP). The structure enables the dynamic grouping of the sub-arrays in three ways by switching the network, which can greatly reduce the hardware complexity, simplify the optimization algorithm, and avoid the performance degradation defect caused by a partially-connected structure. Through simulation of different antenna sizes and different numbers of RF chains, experimental results show that SNHBP can approach the performance of the full digital precoder. Under the condition of more than 2 RF chains, the difference between the unit structure and the full digital precoding is less than 0.13 dB. The spectral efficiency of the low-precision phase optimization algorithm is better than that of the partially-connected structure when the quantization bit of the phase shifter is 3. The feasibility of the three dynamic grouping schemes is verified, which is more beneficial to engineering implementation than the fully-connected structure.