The Multi-Antenna System Research Of LTE High-Speed Moving Environment

As mobile communication technology development and universal application, it is a growing need for communication. In recent years, increasing number of types of communication services, communication, more and more scenes. The era of mobile data services and increased competition give a further development of technology. As the results of the convergence of mobile communications and wireless broadband services, the 3GPP start the research of LTE, and the combination of MIMO and OFDM has been the hot topic in the research of LTE.An extraordinary spectral efficiency can be achieved in MIMO system without increasing the system bandwidth for employing multiple antennas at both sides of wireless links. Also, OFDM can transform the frequency selective channel into flat fading sub-channel in frequency domain which can combat frequency selective fading, so the combination of MIMO and OFDM has been the hot topic in nowadays.High-speed mobile communication scene takes a challenge to the technology. Doppler frequency shift caused by the high-speed moving impacts the quality of communications. In order to guarantee communication quality, we focus on the research of the uplink and downlink physical layer program. According to the high-speed characteristics we improve the existing algorithms.Firstly, the system structure, system requirement and development trend of 3G LTE are introduced; also some key technologies as OFDM, MIMO and framing will be depicted in details.In the scene of high-speed moving, the offset caused some impacts to the quality of communication. In this paper we conducted a study of the offset. For the frequency offset tolerance study, the BLER performances with different MCSs and different offsets are studied here, and then according to the results of simulations, we get the metrics of the frequency offset tolerance. Two kinds of frequency offset estimation are introduced. Frequency offset compensation algorithm to the ML frequency offset estimation is researched.We research the FDD uplink system and TDD uplink system, and design the simulation and analysis of the results. The results show that the throughput performance is very good with using the pre-coding, AMC and HARQ.We research on the downlink system of the LTE high-speed moving scene. Design the MIMO diversity system and Multi-antenna multiplexing system. Through the improving of AMC, we can get more throughputs in the range of SNR than the case with using the fixed MCS. In order to get a better performance, we improve the standard HARQ program by change the modulation. When design the pilot, we analysis of the application problem of the standard four-antenna pilot in the fast-moving scenes, and design to increase the density of the pilot in order to obtain more accurate channel estimation, thereby improving decoding performance.