Research On Channel Estimation Of Long Term Evolution Downlink

LTE is one of the most influential broadband mobile communication standards in the next 10 years. In order to increase data transmission efficiency and spectral efficiency, LTE systems adopted orthogonal frequency division multiplexing (OFDM) technology as the downlink transmission technology. Channel estimation is the key technology of OFDM systems, the estimated accuracy directly affects the system performance. This paper mainly studied the application of common channel estimation algorithm in LTE downlink.Firstly, the start background and the physical layer of LTE are introduced briefly, and the basic principles of OFDM and MIMO technologies are described. The discussion of the basic characteristics and some important parameters of wireless channel are made in this paper, and their impact on the wireless communication systems is analyzed. Then a detailed description of the common channel estimation is made, including the LS estimation algorithm, DFT-based channel estimation algorithm and LMMSE estimation algorithm. Some common interpolation algorithms are also introduced in this paper. The performance of these common channel estimation algorithms is analyzed through computer simulation.The application of DFT-based channel estimation algorithm in downlink of LTE systems is the focus of this paper, that is, the contents of Chapter 4.An application of DFT-based channel estimation algorithm in the downlink of LTE systems is devised in chapter 4, then the analysis and improvement about the shortcomings of DFT-based channel estimation algorithm is made. Two methods to reduce edge effect (edge value repetition method and part of subcarriers replacement method) are compared by computer simulation, the result shows edge value repetition is better, and it is applied to the downlink of LTE. Then an algorithm for time domain windowing operation is improved. The simulation results show that the performance of the improved algorithm is better than traditional algorithm. The improved algorithm is easy to implement by hardware, and is suitable for the downlink of LTE systems. Finally, the performance of multi-antenna systems of LTE is analyzed through computer simulation, and the simulation results further verify the feasibility of the proposed scheme.