Mimo Technology Research Based On Limited Feedback In LTE And Next-Generation Communications Systems

MIMO (Multiple Input Multiple Output, MIMO) technology is one of the key technologies of the LTE system, which utilizes spatial diversity significantly improve spectrum utilization. In order to avoid mutual interference between the data stream in MIMO system, we introduce the receiver equalization technology, but receive equalization technique increases the complexity of the receiving end, the user equipment performance requirements. Instead, the pre-coding technique transfer the signal processing from the receiving side to the transmitter, thereby eliminating the inter-symbol interference and inter-channel interference in a received signal to improve the overall performance of the MIMO system.The paper discuss deeply LTE system based on limited feedback precoding MIMO systems, the main work is as follows:I. A systematic research on LTE system standards, Finally, in-depth study on the indoor hotpot scenes standardized channel models.Based on the above research, the paper built a standards-based downlink physical layer simulation platform, with detailed description of the system architecture and design details;II. As a key technology, the paper study MIMO technology, pre-coding technology and limited feedback principle in-depth. And the pre-coding is divided into linear and nonlinear precoding. Linear precoding main discuss ZF beamforming scheme and minimum mean square error (MMSE) solution. The non-linear pre-coding aims at Tomlinson-Harashima precoding;III. The different transmission modes, different modulation and coding schemes, different pre-coding is thought to show their strengths under different environments. This paper proposes an adaptive thinking, that is, linear and non-linear precoding is selected adaptively based on user feedback channel state information. And the problem caused by the different SINR calculation under different pre-encoding method is solved;IV. Most programs can only handle for that the current user has only one data stream, the case of multi-stream user feedback process is complex, requires a linear flow of independent information for each question. This article also designed a receiver processing method is equivalent to the user single multi-stream flow, with a low complexity user selection method on the basis of the overall improved performance.