Research On MU-MIMO Downlink Interference Suppression Technology

MIMO(Multiple Input Multiple Output)technology makes full use of spatial independence of the antenna.It can effectively improve the rate of peak and spectrum utilization,which greatly promoted the development of communication technology.The application of MIMO technology in military field is more and more extensive.This paper is mainly based on a certain type of communication equipment and analyze arounding the system in the presence of unintentional interference and intentional interference in multiuser MIMO downlink model.Based on the improvement of algorithm and technology,we get the pupose of suppressing the interference of communication system.This paper firstly analyzes the multiuser MIMO downlink system model,especially the one joined the enemy artifical jamming in the battlefield environment,and analyzes the unintentional interference and intentional interference causes existing in the system and the influence on the system.Then the paper gives two aspects discusses separately from the suppression of unintentional interference and the suppression of intentional interference.Unintentional interference in multiuser MIMO system,also namely the CCI between multiple users.In case of the CSI being known at the base station,it is mainly throuth precoding the transmitter data by the base station sender to suppress the CCI.This paper mainly focuses on the study of Linear Precoding in consideration of the tradeoff between the performance and complexity of Linear Precoding algorithm and it is easy to system implementation.The paper gives main analysis of precoding algorithm including ZF,MMSE,BD and SLNR,and also analyzes and emulates the principle and performance of this four algorithms.Of which,SLNR precoding algorithm applies to the system when the transmitting antenna number less then the total receiving antenna number,and it overall gives consideration on noise power and leakage power and can effectively suppress co channel interference.However,when the transmitting antenna is less than the total receiving antenna,the performance of the system is deteriorated by SLNR precoding,which is not conducive to the increase of the communication system users.Then this paper analyzes the intentional interference in multiuser MIMO,and introduces the characteristics and classification of communication jamming.Among all kinds of antijamming methods,the SS technology has been widely concerned because of its lack of investigation and strong anti-jamming.This paper emphatically introduces the principle of direct sequence spread spectrum communication technology,and analyzes its antiinterference performance.It can be seen from the results that the DS-SS technology has strong anti-interference ability to the general interference signal,but its performance will be affected when receiving high power blocking interference.Finally,based on the multiuser MIMO downlink system model,the paper presents the application and improvement of the techniques to suppress unintentional interference and intentional interference,and also gives out the improved system structure drawing.Inhibition of unintentional interference,considering of the performance degradation of SLNR precoding algorithm,it gives joint consideration on improved SLNR algorithm and the influence of the receiver filter matrix.According to the mutual coupling characteristics of the filter and precoding matrix and through several iterations,achieves the precoding matrix.The emulation results show that the system BER is reduced when the improved SLNR precoding algorithm compared to the original algorithm,which also with good performance when transmitting antenna number less than the receiving antenna,increasing the system users.Inhibition of intentional interference,based on the DS-SS technology with strong anti-interference ability,spread spectrum processing is before data precoding at base station.In order to further improve the anti-jamming performance of DS-SS system,it removes the jamming signal based on the thoughts of BSS to separate the received signal at the receiver.The emulation results show that the common DS-SS system cannot complete data transmission when existing enemy high power blocking interference.But the improved system still can successfully complete communication,and improves the anti-jamming performance of the system.This paper analyzes and improves the multiuser MIMO downlink interference suppression technology from two aspects: unintentional interference and intentional interference.Once the imporved technology applied to the actual equipment,it can no only effectively improve the transmission performance of communication system and anti-jamming ability,but also better adapt to battlefield electromagnetic environment with complex signal.It is of great significance to the application of battlefield environment.