Research On Hybrid Beamforming Phased Array Transceiver And Key Technology For Fifth Generation Communication

With the rapid development of wireless communication technology,5G communication technology has become a hotspot of global research.Compared with previous generations of mobile communication,5G communication system has three main performance improvements,including extremely high speed,great capacity(up to 10 Gbps peak rate)and extremely low delay.In 5G communication systems,multiple-input multiple-output(MIMO)systems with large antenna arrays have attracted wide attention from academia and industry.With the increasing of user equipment number and mobile transmission rate,multi-user interference has greatly worsened the signal-to-noise ratio of traditional MIMO systems.In order to improve signal-to-noise ratio and obtain better signal coverage,large-scale MIMO antenna arrays using beamforming precoding technology are considered to be one of the most promising 5G technology directions.In order to give full play to the potential of large-scale MIMO,as well as reduce the total power consumption and cost of communication system,the hybrid beamforming communication system based on high-precision phased array provides the possibility for the commercial application of large-scale MIMO antenna array.With the hybrid beamforming architecture,the hardware implementation of large-scale MIMO transceiver system based on phased array faces many challenges that need to be solved urgently.In this paper,the design of large-scale MIMO transceiver system for hybrid beamforming is studied.Several related technical problems and key designs are solved.Several broadband high performance MIMO transceiver systems and high precision phased array for 5G hybrid beamforming are developed.Test results show that the developed tranceiver system has achieved good practical results.The main research contents and innovations of this thesis are follows:(1)For high performance beamforming phased array used in 5G mobile communication,a high precision shared-aperture transceiver array for multi-user communication is proposed.The designed 8-antenna shared-aperture phased array contains two 8-unit phase-shifting networks operating at 3.5GHz,with 500 MHz bandwidth.Each phase-shifting network has a phase-shifting resolution of 1°,and the root mean square(RMS)magnitude error and phase error are 0.23 dB and 0.84°,respectively.The RF front-end and antenna in the array are shared by two phase-shifting networks,which further reduces the manufacturing cost and power consumption.An improved bow-tie antenna with wider bandwidth and smaller mutual coupling is designed and applied,which is suitable for large-scale array applications.Radio frequency and beam measurement results show that the shared-aperture antenna array can be shaped in the range of 100°,gain fluctuation is less than 2dB,and beam resolution is 0.32°.At the same time,the design has a flat in-band response,which is very suitable for 5G broadband signal communication.Finally,a multi-user communication test is carried out using dual-stream signals to verify that the shared-aperture array has stable communication capability and good system performance in multi-stream and multi-user communication scenarios,and can suppress multi-user interference.(2)For high performance beamforming phased array used in 5G mobile communication,a polarization reconfigurable antenna array based on high precision and low amplitude fluctuation phase shifter is designed and implemented,which integrates the phase shifting unit of beamforming array and polarization reconfigurable antenna feeding network.The polarization reconfigurable antenna applies two cross-placed bow-tie antennas as the radiation elements.In feeding network,the phase difference between the dual-fed ports is adjusted by two phase shifters to realize the linear polarization,left-handed circular polarization and right-handed circular polarization modes.At the same time,the antenna feeding network based on the phase shifter can be combined with the phase shifting units in the beamforming array to reduce the number of phase shifters,so that the polarized reconfigurable antenna has the function of beamforming.The high-precision phase shifter can achieve the phase-shifting accuracy of 0.5° in the range of 360°,and 0.36 dB RMS amplitude error and 0.16° RMS phase error are also realized.The test results show that the reconfigurable antenna array has a 1.2GHz impedance bandwidth and 800 MHz AR bandwidth,and has a high resolution beam steering in the range of ±0.32° in horizontal plane.The measured results are basically consistent with the simulation results,which shows that the antenna array has good performance,can meet the application requirements of 5G communication system,and also has high integration and engineering application value.(3)In view of the development of 5G mobile communication system toward higher frequency band,a single-frequency high-performance oscillator based on substrate integrated waveguide(SIW)filter power splitter and a mechanical adjustable oscillator based on SIW adjustable filter are proposed and designed,based on the advantages of low radiation,high isolation,low loss and easy integration with planar circuit.The power splitter is embedded into the SIW filter by using the SIW filter power splitter.This results lower insertion loss and more compact circuit size.By introducing transmission zeros into the resonator,the designed X-band oscillator can increase the group delay peak of the filter power splitter,thus achieving better phase noise performance.Based on the filter power splitter,a high performance X-band oscillator is designed.The experimental results show that the designed SIW filter power splitter operates at 11 GHz and the output power is-1.8dBm.The phase noise of the oscillator can reach-143.3dBc/Hz at 1MHz offset frequency,and the corresponding FOM value is 211.5dBc/Hz.In order to realize the continuity of tunable oscillator,a continuous tunable oscillator based on multilayer SIW filter is designed.By changing the distance between the center of the SIW cavity and the moving metal screw,the resonant center frequency of the double-layer filter can be tuned simultaneously,thus the output frequency of the oscillator can be changed,and the area of the circuit occupied by the filter can be reduced by half.The oscillator based on the tunable filter works at the center frequency of 7.3GHz and the frequency tuning range is 3.5%.The measured results show that the phase noise of the oscillator is-109.46dBc/Hz and-133.59dBc/Hz at 100 kHz and 1MHz deviations from the central frequency,respectively.The designed single-point frequency oscillator and tunable frequency oscillator are with outstanding performance,which shows that SIW structure devices can be widely used in oscillator design to achieve higher level of planar circuit integration and better phase noise performance.(4)For millimeter-wave large-scale MIMO communication system,a millimeter-wave multi-channel hybrid beamforming transceiver system is proposed and developed.The developed millimeter-wave transceiver system has 32 RF channels,working in the band of 28 GHz,with a signal bandwidth of 500 MHz,using time division duplex(TDD)operation mode.In order to achieve high beamforming accuracy,a millimeter-wave phased array based on intermediate frequency(IF)high precision phase-shifting network is proposed,which can realize the analog precoding matrix of hybrid beamforming in analog domain.The high precision millimeter-wave phased array uses IF phase shifting structure and vector-sum phase shifter with high precision and low cost.It can achieve 8-bit phase shifting accuracy in the range of 360°,and the amplitude fluctuation is only 0.13 dB.The final measurement results show that the beam coverage is more than 90° at 28 GHz and the beam resolution is 0.6°.By carefully designing the millimeter-wave front-end circuit,all 32 RF channels of the proposed transceiver system have achieved good millimeter-wave RF performance,and the channel flatness within 500 MHz bandwidth is only 1.3dB.In addition,the error vector magnitude(EVM)of signals received by two user devices is 2.58% and 2.34% respectively in indoor environment MIMO communication test of two data streams.The high quality data transmission capability of the hybrid beamforming transceiver system is verified by dual-stream air-channel communication performance test.