Development Of Virtual Massive MIMO Channel Measurement System And Analysis Of Large Scale Fading

This thesis takes the researching on test method and measurement system developing about wireless propagate channel of wide-band virtual Massive Multi-Input Multi-Output (Massive MIMO) system as the center. And then using the system to do two field channel measurement campaigns in 2014 and 2015 respectively, acquiring the data of wireless propagate channel of anechoic chamber and sports ground in Beijing Jiaotong University. Applications in algorithm about channel measurement and parameter estimation, likes LS (Least Square) and MUSIC (Multiple Signal Classification), extract all kinds of channel parameters. First introduced the system realization principle and the function of each module, and the verifications in lab show that the emulating data extracted from this system are accurate. In the time delay domain, the extracted results match the pre-defined parameters in the channel emulator. In the angle spread domain, the relative error of the AOA (Angle of Arrival) in 1×2 MIMO is less than 0.6°. At last, analysis the data in the actual measurements and get the corresponding channel characteristics, so that lay a solid foundation for the research and application of 5G technology and system.First of all, the propagation characteristics of wireless channel are introduced. Summarizes the characteristics of wireless channel and the characteristic parameter of Large scale fading and small scale fading which can embody the transmission capacity of channel. Elaborating the research point and research method of Massive MIMO system. Then, a comprehensive analysis of the wireless channel fading model and wireless channel measurement methods is made. Basic requirements for wideband channel measurement, classification of channel measurement and application scenario for channel measurement also are summarized. All the ever-emerged channel measurement, are summarized. Based on the existing literature, making a classification and analysis about the principles and method of channel measurement.Secondly, elaborated the development of virtual Massive MIMO channel measurement equipment. First step, analysis of Massive MIMO channel sounding technology and summarizes it’s principle. The second step, according to the proposed channel measurement technology and principle, reference the basic structure of the communication system, based on the detailed consideration of signal source, antenna array, synchronization unit, RF receiving unit and a data acquisition and storage units in the relevant parameters, different hardware equipment was designed or buy to build a set of applicable to massive MIMO channel measurement system, then Performance analysis is performed on the system. Compared with the existing commercial channel measurement, the advantage of this system lies in its low cost and simple realization. In order to ensure the continuous phase in the process of detecting signal of the channel measurement, using the optical fiber devices to ensure that the homologous synchronization of the whole system, so as to guarantee the system phase synchronization. In data acquisition and storage process, the use of virtual storage method, reduced the data storage drive pressure without destroying the useful information in data.it also can enhance the performance of the system. By using the channel simulation instrument, the system has been calibrated in laboratory, it is proved that the stability and effectiveness of this system.Finally, an overview of the scheme about Massive MIMO channel sounding is presented. For two kinds of panoramic scenarios have been descripted and analyzed. The strategy of placement about the test point and antenna array, the basic parameters of the test, the properties of the test and the items of the antenna array are introduced. Through field channel measurement, channel impulse response can be acquired, and the effective algorithm to learn channel parameters have been put forward. A comprehensive analysis of the various characteristics of MIMO Massive wireless communication channels has been done, such as channel impulse response matrix, path loss, shadow fading, correlation about array, and so on. Studies have shown that for fixed user, the different array element on same array has different communication link, whish shadow fading correlation is existence, and this source of correlation is different array elements, which may be keep out by the same occlusions.