Research On The Millimeter-wave Massive MIMO Transceiver And Key Technology For Fifth Generation Commnications

With the deployment and commercialization of the 4G LTE(Long-Term Evolution)mobile communication systems,many research institutions as well as some international standards organizations(such as 3GPP)turn their focus to the research and development of the fifth-generation(5G)communication.In recent years,the broadband mobile communication services at any time and any where have rapidly changed people's life and work.With the explosive growth of mobile data traffic,a new generation mobile communication system is needed to provide higher data throughput and higher system capacity.At present,5G communication technologies have become the research area of global concern.Compared with the previous generation communication systems,5G communication systems need to meet the requirements of lower delay,higher spectrum efficiency and higher data rate(up to 10 Gbps peak data rate).The millimeter-wave frequency band has a large amount of unutilized spectrum resource,which is able to support the wide signal bandwidth for high capacity and high data rate of 5G mobile communication network.Thus,the millimeter-wave communication is regarded as one of the most promising solutions for 5G communications.In the system architecture,advanced adaptive beamforming technology and multiple-in-multiple-out(MIMO)technology will be adopted for achieving better signal coverage and higher data rate.Under these system architectures,there are many challenges needed to be addressed in the hardware design and implementation of the 5G millimeter-wave MIMO transceiver systems.This dissertation focuses on the research and development of 5G millimeter-wave massive MIMO transceiver systems and key components,several key technologies and design challenges have been solved and a series of 5G millimeter-wave transceiver systems are developed.The developed transceiver systems were applied in air-interface tests and field trials of 5G millimeter-wave mobile communication successfully.The research contents and innovations are illustrated as follows:(1)Focusing on 5G millimeter-wave broadband mobile communication,the effects of the RF transceiver impairments on the millimeter-wave MIMO communication system are studied by using baseband processing and RF performance co-simulation,combined with the baseband Orthogonal-Frequency-Division-Multiplexing(OFDM)modulation and transmission scheme.The research contents include channel gain flatness,I/Q imbalance,nonlinearity distortion,phase noise,carrier frequency offset and transmit-receive reciprocity mismatch.Some relative digital compensation techniques are also studied.The researches on the impact of the RF impairments under MIMO-OFDM architecture have provide valuable references and guidance for the hardware circuit design and optimization of the millimeter-wave MIMO transceiver systems.(2)A metal tapered slot antenna for 5G millimeter-wave massive MIMO communication systems was developed.In this antenna,the substrate integrated waveguide(SIW)feeding is served as wideband balun and a vertical transition between the SIW balun and the tapered slot is firstly introduced.The proposed tapered slot antenna can easily meet the requirement of half-wavelength element spacing in the H-plane and can be integrated with the multi-channel millimeter-wave transceivers on the same substrate.The reflection coefficient of the antenna element is lower than-15 dB and the gain of the antenna element is around 9dBi within the frequency range from 22.5 to 32 GHz,which covers multiple 5G millimeter-wave bands proposed by ITU and FCC.This antenna has achieved excellent performance and has been used for a 4T4 R millimeter-wave MIMO system and a 32-element hybrid beamforming based millimeter-wave communication system,and so on.The work in this part has been authorized to obtain national invention patent,and has been published in the IEEE Transactions on Antenna and Propagation.(3)The fast electromagnetic(EM)design and optimization methods for the substrate integrated waveguide(SIW)filters were studied.The SIW filters are the key components for the millimeter-wave transceivers.To achieving fast optimization of the SIW filters,a general model Jacobian matrix updating based filter optimization method was developed.Focuses on the basic element circuits of the SIW filters,a general model that relates physical geometric variables with the feature parameters(frequency,coupling coefficient,external quality factor)of SIW filters is established.The feature parameter deviations are extracted by fast response approximation of the EM responses based on the coupling matrix perturbation and the BFGS quasi-Newton method.Then,with the parameter deviations,the general model based Jacobian matrix is calculated and used for fast design dimension error estimation and correction.This proposed method has been used for fast optimization of a number of SIW filters,and good optimization results are achieved with few EM simulation times.Compared with aggressive space mapping methods,this method exhibits higher robustness and optimization speed.Moreover,a mixed general model and trust region space mapping based Jacobian matrix updating method is proposed for fast optimization of SIW filters.The optimization performance is further improved by combing the robustness of the general model Jacobian matrix update method and the Jacobian matrix correction ability of the space mapping method.By applying the proposed methods to SIW filter design optimizations,the design periods of millimeter-wave transceiver circuits and systems are shortened effectively.The work in this part has been submitted to the IEEE Transactions on Microwave Theory and Techniques.(4)Focusing on digital beamforming(DBF)precoding based millimeter-wave MIMO communication systems,a fully digital beamforming based Ka-band 64-channel massive MIMO transceiver for 5G millimeter-wave communications was firstly developed.The proposed millimeter-wave massive MIMO transceiver is operated at 28 GHz band with a 500 MHz signal bandwidth,a 2.75 GHz IF carrier frequency and the time division duplex(TDD)mode.The base-station contain 64 complete transceiver chains.The channel gain flatness is better than 1.1dB across 500 MHz signal bandwidth and the maximum linear effective isotropic radiated power(EIRP)is 58 dBm.Excellent RF performance is achieved.The proposed DBF based millimeter-wave massive MIMO transceiver has been used for the over-the-air tests and verifications of the 5G millimeter-wave mobile communications.Using the beam-tracking technique and two streams of QAM-64 signals,the proposed millimeter-wave MIMO transceiver can achieve a steady 5.3 Gbps throughput for a single user.In the multiple-user MIMO scenario,by delivering 20 non-coherent data streams to eight four-channel user terminals,it achieves a downlink peak data rate of 50.73 Gbps with the spectral efficiency of 101.5 bit/s/Hz,which is almost the top level in the industry.The work in this part has been published in the IEEE Transactions on Microwave Theory and Techniques.(5)Focusing on analog-digital hybrid beamforming MIMO communication system architecture,a 28 GHz band low cost and high performance phased array was developed for 5G millimeter-wave communications.The local oscillator(LO)phase shifting approach and the sub-harmonic mixing technique are adopted to achieve a full 360o phase-shifting range with up to 10-bit phase resolution and ultra-low magnitude deviation.Each phase-shifting channel contains a 1-bit 180o IF phase shifter and a LO low-voltage varactor tuned reflective-type phase shifter.The LO phase shifting is used to achieve fine phase-shifting with low magnitude variation.The sub-harmonic mixing enables lower phase-shifting range and lower operation frequency at LO path.The measured root-mean-square(RMS)phase error and magnitude variation of the phase-shifting circuit are around 0.3o and 0.1 dB,respectively.The phase-shifting performance achieves the most advanced technological level in current millimeter-wave phase shifters.Moreover,a fast over-the-air millimeter-wave phased array calibration method with single probe are proposed.The OTA phased array calibration and measurement are also performed.The implemented millimeter-wave phased array achieves +/-50o beam scanning angle and a fine beam resolution less than 1o step.The gain flatness of the phased array is less than +/-1dB across 1 GHz signal bandwidth.The maximum linear EIRP is 41 dBm at 10-dB power back-off.The measured error-vector-magnitude(EVM)is 1.72% under the 500-MHz OFDM QAM-64 signals.The work in this part has been published in the IEEE Transactions on Microwave Theory and Techniques.