Research On Pre-coding Technology Of Broadcast Channel For MU-MIMO System

With the development of the mobile communication system, the wireless communicationtechnology has entered the era of the4G and is forwarding the era5G with the fast speed,especially MIMO technology, which is the key technology of4G and5G. In order to improve thedensity of user and the capacity of the system, MIMO LTE-Advanced system enhancementtechnology plays an important role in the4G technology. This technology uses theSDMA technology to transmit more user data, though it obtains a high efficient of thefrequency resource in space, the multi user co-channel interference (CCI) is introduced in thewireless system. How to design effective MU-MIMO system to eliminate the CCI is the prioritygoal.Using the Multi user MIMO pre-coding channel state information to eliminate the co-channelinterference is becoming the hot topic. It can eliminate the co-channel interference and improvethe performance of the system in the effectively way. Facing the broadcast channel in multi userMIMO scene, this paper studies the linear precoding technology. First we analyzesthe classic SLNR precoding algorithm, although this algorithm has some advantages insuppressing the user interference, the performance of the system has not been greatly improved.In order to solve this problem, this paper designed a stream selection based on sub data SLNRpre-coding algorithm, which analysis the sub-stream selection and the simulation verifies theimproved algorithm is effective. In addition, we also analyse the ZF algorithm, MMSE algorithmand the improved MZF algorithm, while the complexity is low, the application scope is limited.Aiming at this problem, this paper presents the designing of a combined pre-coding scheme, thisalgorithm combined the advantage of the MZF and the SLNR, on one hand, it inherits theMZF algorithm advantage which is simple and low complexity, on the other hand, it enlarges thescope of the algorithm application scene. In order to eliminate the residual interference betweenthe user and the antenna, we also introduced the parameterθ. This paper used the software VS2008to build the system level simulation test based on theLTE RRM system level simulation platform. By mixed programming of VC++and MATLAB totest the performance of the algorithm above. The simulation shows that the improved SLNR,based on the selected sub data streaming has achieve a better SNR when the system capacity is notloss much, what’s more, the improved algorithm also has a better system capacity, low SNR andlow complexity compared to the classical algorithm.