Research On Channel Capacity And Spatial Correlation Based On Measurement For Massive MIMO Systems

With the rapid development of science and technology and the remarkable improvement of people's life quality,mobile communication technology has become an indispensable part in every aspect of our daily life.With the promotion of various emerging applications,the wireless spectrum resources are increasingly tense;the demand for capacity is rapidly expanding.The energy consumption and environmental issues have become ever more prominent and have drawn much attention.The traditional communication system is far from meeting the development needs of present society.In 2012,the International Telecommunication Union(ITU)determined and announced key performance indicators such as spectrum efficiency,energy efficiency,peak data rate and traffic density based on the preliminary studies of 5G standardization in the telecommunications industry to achieve a more comprehensive and better service configuration and user experience.With the deepening of scientific research.Massive MIMO(Massive Multi-input Multi-output)technology came into being.It can significantly improve the capacity of the system and the overall utilization of system spectrum resources to meet the development needs of present society.The characteristic of wireless channel propagation determines the capacity of information theory,that is.the final performance of wireless communication and the performance of a specific wireless system,therefore it is also the primary conditions for the design of the key parameters of a mobile communication system.The most direct and effective way to understand the propagation phenomena and describe the random statistical characteristics of the channel is to measure the channel.At present.research works on Massive MIMO are usually based on the assumption that the channel is favorable propagation.However,the real wireless propagation environment often cannot meet the appropriate propagation conditions,that is.each sub-channel is orthogonal to each other.Therefore,based on the measured data,studying the channel characteristics of Massive MIMO,especially the characteristics of channel capacity and spatial correlation,will provide theoretical basis and technical support for the actual deployment and network optimization of Massive MIMO systems.Taking the above mentioned facts into consideration.the thesis first introduces the basic knowledge of wireless communication theory,clarifies and classifies the theoretical knowledge of wireless communication,and then introduces the principle and equipment of self-developed measurement system in accordance with the research requirements.By comparing singular value spread of the channel matrix of Massive MIMO system on measurement data and the independent and identically distributed Rayleigh channel matrix,the orthogonality between the sub channels cannot be completely orthogonal in real propagation and it is non-favorable.Channel capacity under equal power is calculated and compared.It can be seen from the contrast,as the number of antennas at the base station increases,the singular values spread gradually get close to the singular value spread of the Rayleigh channel,and the value of the capacity gradually approaches.The spatial correlation is an important factor leading to non-favorable conditions,which pose some impact on the system performance of Massive MIMO.Based on the measured data of the outdoor real scene,the correlation of different array types in different scenes is analyzed and summarized regularly.In general,the spatial correlation decreases with the increase of the number of antennas.And based on measurement data in the indoor environment,we compare the spatial correlation between the virtual Massive MIMO and the Massive MIMO based on TDM.The above research in this thesis provides some support and technical reference for the strategic deployment of Massive MIMO technology.