Design And Performance Research Of Massive MIMO Relaying Cooperation Scheme

With the continuous improvement of the social informatization,the current fourth-generation mobile communication systems have been unable to meet people's further demands for high speed and huge capacity.In order to meet the increasing needs of users in the next ten years,and provide ubiquitous links requests as much as possible,both academia and industry have sped up the research of the next generation communication systems that is the fifth-generation mobile communication system(5G).Massive multiple input multiple output(MIMO)and relay cooperation are considered as the core technologies of 5G,because they can significantly increase the spectral efficiency(SE)of the system.Although the massive MIMO technology can enormously reduce the system additive noise,inter-user interference,and can effectively depress the source' transmitting power.However,there are still many problems that to be solved urgently.Therefore,in the view of the key features of massive MIMO and relay cooperation technologies,different researchers of massive MIMO relaying cooperative systems are performed in this dissertation.The specific contents are as follows:Firstly,aiming at the huge energy loss caused by large scale antenna array,based on the maximal ratio combining/ maximal ratio transmission(MRC/MRT)and zero forcing reception/ zero forcing transmission(ZFR/ZFT)two kinds of linear preprocessing schemes,this thesis proposes the full duplex massive MIMO amplify and forward relaying systems for low-resolution analog to digital converters(ADCs).The exact closed-form expressions of the SE are obtained firstly.Then,the asymptotic analyses of three different power scaling laws are also carried out.The results show that the low-resolution ADCs quantizers impose more performance loss on ZFR/ZFT than MRC/MRT ones.In particular,the system can simultaneously suppress the impact of both loop interference and quantization noise only under the relay's transmission power of the system is scaled down the number of transmit antennas and the sources' transmission power is fixed.Secondly,although the low-resolution ADCs technology can significantly improve the energy efficiency of the massive MIMO relaying systems,however,the latest research shows that the quantization of low-resolution ADCs will cause several other problems including phase/ frequency synchronization and multi-user detection errors at high signal to interference plus noise ratio(SINR).In addition,the emergence of quantum computers and supercomputers in recent years has brought severe challenges to the physical layer security of the systems.Different from the traditional way of key encryption,information theory shows that it can also improve the system security by using the noise and quantization error of system channel.Therefore,this dissertation studies the massive MIMO relaying cooperative scheme with mixed-resolution ADCs.Besides,an optimized performance design is performed.The SE and secrecy outage rate are obtained firstly,and then the secrecy energy efficiency(SEE)is obtained according to the constructed energy consumption model.The results show that,when using medium resolution ADCs instead of high resolution ADCs,the SEE can be improved effectively without affecting the SE of the system.Besides,the research shows that when the SEE is maximum,there is an optimal source transmitting power.At the same time,the ratio of the medium resolution antenna M0 and the low-resolution antenna M1 is also an important parameter that affects the system performance.Finally,in order to further improve the SE and energy efficiency of the system,and at the same time promote the quality of service of cell-edge users effectively,this dissertation studies the two-tier massive MIMO relaying cooperation heterogeneous networks(Het Nets),in which the macro cells configured with a large scale antenna array is covered by the dense small cells.The macrocell base stations are mainly used for user scheduling and resource allocation as well as the needs of high mobility users,while the dense small cell base stations are mainly providing higher Qo S link requests for low mobility users.Assumed that the base station adopts MRC/MRT and ZFR/ZFT processing schemes respectively,this thesis first formulates the SINR for a user pair as well as the expression of power amplification factor.By using the stochastic geometry theorem,then the closed-form expressions of SE are obtained.To acquire optimal system performance,we find that only the radius of the small cell should be less than the guard radius.In addition,there is an optimal lower limit for the radius of the macro cell,and only if the radius of the macro cell is less than the optimal lower limit,the aggregate SE of the system is increasing with the radius of macro cell.