Research And Implementation Of Downlink Simulation Platform Based On The LTE Protocol

With the rapid development of mobile communications, The global wireless communications displays the traits of Mobility,Broadband and IP-based architecture. To meet the challenges of WiMAX,Wi-Fi and other mobile braodband wireless access tecnology and to improve the 3G broadband wireless access in emerging maket competitiveness. 3GPP initiate UMTS Long Term Evolution tecnolohy research , thus fulfill smoothed transition from 3G to 4G. In this paper,based on the R8 LTE physical layer communication protocol and Mtalab modeling, we mainly design the basic platform of the LTE downlink physical layer system. This can be used to evaluation and verification the performance of key techniques.Firstly, the thesis introduces the LTE system's technical background, evolution objectives and system architecture. Elaborating OFDMA, MIMO and HARQ theory of the key technology of physical layer downlink, analyzing three schemes for MIMO, transmit diversity, spatial multiplexing and beamforming. Secondly, based on the LTE communication protocol and analysis the basic principles of LTE downlink, Research and implement of the simulation platform for LTE downlink.was introduced, the structure of simulation platform as well as part of module principle and design flow chart were given. Based the simulation platform the key technology MIMO was simulation and analysis, the results show that MIMO combination with OFDM can greatly improve the wireless communications system in frequency selective channel. Finally, based on the platform ,we study the LTE downlink channel estimation and interpolation technology, analyze the principle of LS, MMSE channel estiamtion algorithm and interpolation algorithms. The traditional Minimum Mean Square Error(LMMSE)channel estimation algorithm has good performance of the system.But its greatest fault is the trival inverse matrix. In order to reduce the complexity, while preserving the performance of the LMMSE channel estimator,Approximate Linear Minimum Mean Square Error (ALMMSE) channel estimators are also investigated. End, we conducted a detailed analysis of its performance and practicality by combining Matlab simulation. Simulation restults show that,The performance of channel estimation is similar between the proposed algorithem and the MMSE algorithm, reduces the computational complexity and easy to implement.