| The development of wireless communication has profoundly changed the way of people’s life, but the pursuit of higher performance of wireless communication has never stopped. The rapid development of Mobile Internet and Internet of Things promotes the research of the 5th generation mobile communication (5G).5G not only demands comparable access rate of optical fiber but also enjoys the local operating real-time experience and own the ability of broadband wireless access at anytime and anywhere. It puts forward a huge challenge to the network capacity, connection reliability, network coverage and capacity efficiency of the 5G communication system, which can’t be met by merely improving the transmission bandwidth and increasing cell density. Therefore, there is an urgent need for innovative wireless transmission technology. Massive MIMO as one of the potential candidate key technology for the 5th generation, breakthroughs the limitation of traditional multiple antenna and smart antenna technologies, as it can rap infinite space resources to achieve a smaller power consumption, as well as improve the spectrum efficiency and the reliability of the channel.The wireless channel characteristics be considered in the research of design, deployment and optimization process of communication system. As the basic instrument of communication system development, channel model urgently needs support from real data. Based on this background, this paper utilizes the real data which is captured by the self-developed channel sounder in different scenarios to analyze and model massive MIMO wideband wireless channels.Firstly, the paper briefly reviews the parameters that represent the characteristics of broadband wireless channels, the basic methods and principles of channel measurement and selection criterion of excitation signal. In the measurement data extraction, the noise-floor decision was introduced, the methods of how to search the multipath and how to remove system response were proposed. After which the software and hardware of the self-development channel sounding platform and its corresponding functional principle are explained in detail.The massive MIMO wideband wireless channel propagation characteristics were investigated in this paper, based on the realistic massive MIMO channel measurement in typical stadiums and meeting halls in 1.4725GHz and 4.450GHz respectively, and. the small scale fading properties and angle spread properties were investigated.Finally the stationary properties over the antenna structure were investigated by using the reverse arrangements test. Real measurement data show that channel behaviors in our high frequency band are stationary over the linear antenna array, whereas this appears untrue at the low frequency band. Due to the low propagation loss of signal at low frequency, the antenna array is longer and is more affected by the surrounding scattering, the multipath number at the receiver is larger, which can’t meet the generalized stationary characteristics.Due to the large size antenna array, the channel behavior differs from that usually experienced on conventional compact arrays. In this paper, an extended large scale attenuation matrix is proposed, by which the large scale losses over the antenna array can be considered when establishing the massive MIMO channel. Based on realistic experimental data, we extracted the large scale fading attenuation results. The experimental results reveal that the large scale attenuation over the linear antenna array is essentially determined by the transmission distance between the user and the nearest antenna element, and the angle with respect to the antenna.By selecting the typical scenarios for realistic channel measurements and analyzing the measurement data, we can achieve the channel behaviors in two frequency bands. At the same time we can also obtain the general channel model through the analysis of the statistical properties, which offers references when deploy network and establish Massive MIMO 5G wireless communication system... |
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