Software Implementation Of Large-Scale Distributed MIMO Base Station Based On GPP

In the current application of mobile communication,4G has proved popular all over the world.With the rapid development of mobile terminals and smart devices,the research of 5G has also begun to receive widespread attention.Massive MIMO technology is one of the key technologies of 5G,which can significantly improve system capacity and energy efficiency.In a large-scale distributed MIMO system,different user signals arrive at the same RRU with different delays,which may cause a symbol time offset(STO)and deteriorate the system performance.From the point of view of base station,this thesis studies the effect of STO on the spectral efficiency of the uplink channel and the corresponding interference suppression method.Finally,based on the large-scale distributed MIMO system,this thesis introduces the software implementation and system optimization of base station of 5G communication test platform based on general purpose processor(GPP).The first part of this thesis introduces the research background,describes the development and application of MIMO technology,and introduces the main research contents and research status of this thesis.The second part of this thesis introduces the system model of 5G communication test platform based on GPP.GPP is the most commonly used core processor in SDR.Therefore,the advantages,structure and main applications of SDR are introduced firstly.Then from the theoretical point of view,this thesis elaborates the system model of 5G communication test platform.Finally,from the engineering point of view,the system parameters and frame structure of 5G communication test platform are introduced in detail.The third part of this thesis studies the impact of STO on the uplink channel spectral efficiency of largescale distributed MIMO systems.Firstly,this thesis derives the capacity of the uplink channel in the absence of STO and analyzes the influence of the number of base station antennas and the channel estimation error on the system performance through simulation.Then the uplink channel capacity of the system in the presence of STO is derived.The simulation results show that as the STO value increases,the system uplink channel capacity will be significantly dropped.The fourth part of this thesis proposes the interference suppression method of large-scale distributed MIMO systems with STO.The main scenarios are divided into two-user scenario and four-user scenario.In the two-user scenario,while the basic interference suppression is performed,the impact of STO can be perfectly eliminated.For four-user scenario,basic interference suppression needs to be performed three times,and each basic interference suppression operation needs to eliminate the STO effect of one user in other users.The results show that this method is better than the basic interference suppression method with the better bit error rate performance;for other multi-user scenarios,similar to the four-user scenario,we can do the corresponding promotion.The fifth part of this thesis describes the realization of 5G communication test platform base station and system optimization.Firstly,this thesis introduces the concrete realization of base station receiver of 5G communication test platform.The receiver mainly includes channel estimation module,interference suppression module,signal detection module of single user,demodulation and decoding module.Finally,the key technologies of system optimization for 5G communication test platform are demonstrated.The main idea is to mine the multi-core resources of GPP and fully use the performance advantages of GPP by the application of parallel technologies such as MKL library function,SIMD instruction set and DPDK technology.DPDK technology includes large pages,NUMA and exclusive thread.