On The Hybrid Beamforming In Millimeter Wave Communication System

Wireless communication technology in people's daily life has become increasingly important because of its simple and convenient and low cost characteristics.Now most of the wireless terminals are working in the 2.4G or 5G band,the available bandwidth is small,at the same time,with the number of wireless terminals increased significantly,the existing wireless communication network has been unable to meet the user's high-speed transmission rate requirements.At this stage,the user's demand for transmission rates up to multiple Gbps.In view of the lack of spectrum resources in the 2.4G and 5G bands,the available bandwidth is small,so it is imperative to develop new frequency bands,and the millimeter band is receiving more and more attention because of its larger bandwidth.Because of its spectral characteristics,millimeter wave has a great loss in the propagation process,so the need to use beamforming technology,the multiplexing gain,diversity gain,antenna gain,array gain and interference cancellation,etc.,to further increase the communication link capacity.In the millimeter-wave communication system such as IEEE802.11ad,the hybrid beamforming technique is adopted,that is,the antenna gain and array gain obtained by array antenna beamforming are effectively compensated for the excessive path loss and penetration loss of the millimeter wave band.The digital beamforming and analog beamforming are cascaded to further utilize their multiplexed gain and diversity gain.This paper focuses on the beamforming training process of IEEE802.11 ad standard,and explains the sector-level sweep and beam refinement protocol process used in millimeter-wave communication system in detail,and analyzes the antenna beam state of the transceiver in each stage.And then simulated the IEEE802.11 ad link-level platform,and gives the simulation curve for calibration.Aiming at the problem that the feedback cost of the hybrid beam is too large,the paper gives a feedback design scheme suitable for IEEE802.11ad beamforming training to effectively meet the beamforming training requirements of millimeter wave communication system.It is easy to configure more antenna elements in millimeter-wave wireless communication systems,and the increase in the number of antennas means that the use of conventional digital beamforming techniques is becoming unacceptable in terms of cost and complexity.In this paper,focuses on the low-complexity partial connection architecture,the relationship between the number of RF links and energy efficiency and spectral efficiency is studied,and the optimal number of RF links is guaranteed under the premise of guaranteeing the gain.In this paper,we first analyze the relationship between energy efficiency,spectral efficiency and RF link number under partial connected architectures.Then we prove that there is an optimal power point,that is,green point(Green Point),considering the power of link device.Secondly,the influence of the number of links on energy efficiency under the condition of given spectral efficiency is analyzed.The analysis shows that there is an optimal number of RF links when the spectral efficiency is determined,which can make the system get the best energy efficiency.Finally,the relationship between the optimal energy efficiency and the number of RF links is analyzed.The results show that the optimal energy efficiency increases monotonically with the number of RF links when the number of RF links is not correlated with the number of antennas.