Research On Hybrid Precoding Algorithm For Large Scale Antenna System

In order to meet the ever growing demand for wireless communications, utilizing the underutilized spectrum in the millimeter-wave frequency bands can be an effective way to solve the bottleneck in transmission rate and limited spectrum resources.Currently,millimeter-wave (mm Wave) MI MO with large-scale antenna array has attracted considerable interests from academic and industry, as it can simultaneously provide wider bandwidth and higher spectrum efficiency. Combined with the characteristic of millimeter-wave propagation and Massive MIMO, hybrid precoding technology becomes an important signal processing method in millimeter-wave MIMO system, it can effectively compensate multipath fading,reduce the interference between the transmission data streams, thus the spectral efficiency will be greatly improved.Conventional MIMO systems are configured with one radio frequency (RF) chain for each antenna,and the precoding process is performed only at the digital baseband.With the increase of the number of antenna, this will produce huge hardware overhead and energy consumption, so the traditional precoding scheme is no longer suitable for millimeter-wave MIMO system. To reduce the RF complexity of the millimeter-wave MIMO system, the hybrid precoding scheme divides the signal processing into two stages, which are analog precoding and digital baseband precoding. Through analog precoder processing, the number of RF chains can be decreased greatly, thus the RP overhead and energy consumption will be reduced. Coupled with low-dimension digital precoder, it can realize comparable performance with traditional all-digital precoding scheme.Firstly, this paper reviews the MIMO structure in millimeter-wave communication system, analyzes the characteristics of traditional MIMO structure, mainly focuses on the analog-digital hybrid MIMO structure and the lens array antenna mm Wave MIMO structure. Then, the design of precoding algorithms for different structures is studied.For analog-digital hybrid MIMO structure,several hybrid precoding algorithms are studied for single-user and multi-user scenarios. In addition, for the partially connected structure with lower complexity in the hybrid structure, the newest algorithm is introduced,and its performance and algorithm complexity are analyzed. Based on that,we propose improved hybrid precoding algorithm. The simulation results show that the improved algorithm can achieve satisfied performance with lower complexity. Finally,for the lens array antenna mm Wave MIMO structure, a detailed analysis of the system structure, modeling and precoding algorithm design are studied. We also compare the performance with algorithm under analog-digital hybrid MIMO structure, which further demonstrates that the structure can effectively reduce the RF complexity of millimeter-wave MIMO system.