| With the fifth-generation mobile communication(5G)extensive research,millimeter-wave massive multi-input multi-output(MIMO)technology has attracted wide attention.The technology combines the characteristics of millimeter-wave communication technology and massive MIMO technology.Wider channel bandwidth makes it easy to get tens of GBPS transmission rate.Because the wavelength is short,the size of the antenna array is small;it is easier to realize massive MIMO technology,obtaining its advantages.The wireless communication characteristic is the base of MIMO technology applica-tion.In the millimeter-wave frequency band,since the frequency has not been widely used in mobile communications and only a small amount of expensive test equipment and very few test methods exist,The MIMO channel model is much less mature than lower frequency band.Channel measurement and modeling is based on channel measurement platform,the performance of the measurement platform directly determines the measure-ment range,the testing means and the results modeling accuracy.Therefore,this paper developed a set of millimeter-wave band broadband MIMO channel measurement plat-form,which can get the most extensive channel test results and the most flexible testing methods.The test platform has been successfully used in millimeter-wave massive MIMO communication test network.The main contents and innovations of this paper are as follows.In the first chapter,the research background,the research status and the research goal and main content of the related field are described.In the second chapter,this paper studies the advantages of MIMO channel,the ba-sic technology of channel modeling,and the basic parameters of channel characteristics.Through the research of the existing technology,the measuring technology and the re-search target of the future millimeter wave channel measurement system are obtained.The paper summarizes the general channel measurement methods,including large-scale fading test methods and small-scale fading test methods.The architecture of the channel measurement system depends mainly on the structure of the transceiver and on the re-ceiver sampling scheme.In order to meet the needs of a variety of test methods,combined with the millimeter-wave channel measurement hardware platform system indicators are given system design,including the division of the module and hardware design.In the third chapter,for large-scale baseband data transmission,a variety of ana-log baseband data acquisition and transmission systems are designed,implemented and applied to wireless communications.The data rate of the baseband processing units in 3D-MIMO scenario and hybrid beam forming scenario are 30.72 MHz,which are general modules to support 20 MHz signal bandwidth.The analog baseband processing unit in the mixed beam forming scenario has a variety of external control interfaces,which can simultaneously control the phase of the radio(RF)phase shifter at the same time as the data acquisition and realize the synchronization of the two actions.The baseband pro-cessing unit in Qlink-Pan scenario supports 540 MHz signal bandwidth,with a sampling rate of 660 MHz.These analog baseband data acquisition and transmission systems are scalable and compact.With multi-channel transceivers and diversified control functions,it has wide RF bandwidth and supports high digital speed.In the fourth chapter,the realization of multi-channel RF system is inseparable from the key hardware modules of RF system.In this paper,three new modules are mainly studied:quadruple-mode filter using a single circular SIW cavity,Ku band tunable circular SIW cavity filter and dynamic gate voltage bias efficient power amplifier.Quadrable-mode filter can effectively reduce the PCB area and the overall size,besides,the bandwidth is wide.Tunable filter is the first proposed mechanical tuning SIW filter,different from the electric tuning and a variety of fixed tuning way,with the continuous linear tuning ability.The advantage of continuous tuning can be applied to different scenes conveniently and more flexible debugging.Dynamic gate bias voltage amplifier can support the signal bandwidth of 184.32 MHz.Compared with the traditional class A amplifier,dynamic gate bias voltage can increase the system efficiency and linearity,improving the class A amplifier's efficiency without reducing the signal quality.In the fifth chapter,this millimeter wave hardware platform can function as data transmission system at the same time which has a baseband data processing unit to support massive baseband data transmission.The unit can achieve the high-speed data transmission between the FPGA and analog to digital conversion chip or digital to analog conversion chip,and at the same time implement high-speed data transmission between local digital signal processor(DSP).Using Aurora protocol and optical fiber communica-tion,the data transmission can be done in a very far physical distance.As the hardware platform of data transmission,the system supports multi-channel synchronous transmis-sion,besides it supports multiple controlling ports with a variety of external interfaces.The difference between this structure and traditional digital baseband transmission sys-tems is that this data transmission is based on high speed serial JESD204B protocol and corresponding hardware interfaces.The interface supports deterministic time delay which can be more effective to ensure synchronization,and a single lane supports 10 GBPS bit rate,which can reduce the FPGA periphery connections.In order to realize the multichannel data sampling and real-time measurement,this system adopts instanta-neous multi-channel structure to realize MIMO system.The multi-channel architecture is more flexible,higher performance,and more difficult,especially for single-channel high-performance,multi-channel synchronization and multi-channel coherence,as compared with the implementation of alternative MIMO channel measurement platform architec-ture.This paper overcomes the technical difficulties of the local technology,the whole structure and massive data transmission.The hardware platform link test results meet the targets;the OTA test is implemented together with the antenna,and can be perfectly decoded in PC.With R.F frequency of 28 GHz,channel bandwidth of 500 MHz,the mil-limeter wave channel measurement hardware platform support 4×4 MIMO transceivers,and can be used in future millimeter-wave communications.At the same time,the system is applied to 5G millimeter-wave massive MIMO digital multi-beam system.Compared with other systems using hybrid beam forming and multi-beam antenna technology,it has the best flexibility and performance,while the highest complexity and difficulty.In the last chapter,the millimeter wave channel measurement hardware platform needs to support 4×4 MIMO transceiver system,using independent and bidirection-al transceiver.The antenna system uses 4 way linear array antennas.Finally,the millimeter-wave MIMO channel measurement is carried out with the millimeter-wave channel measurement hardware platform.The performance and statistical characteristics of the millimeter-wave MIMO-OFDM system are studied experimentally.After the im-pulse response matrixes of Line of sight(LOS)paths and NLOS paths are obtained,path loss and shadow fading model are calculated.The RMS delay spread is tested using high directional antenna indoor,besides,the broadband channel capacity and throughput are calculated.Compared with the existing other channel measurement hardware platfor-m,The main advantages of this channel sounder are as follows:first,the instantaneous multichannel system which helps to do measurement campaigns more conveniently,the independent controls of each channels APC and AGC which may help to utilize water flooding algorithm to improve channel capacity;second,the developed baseband board enables 2.2 GHz sampling rate and have interfaces for easy synchronization and trans-porting data;third,the OFDM signals used in the measurements greatly reduced the time. |
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