Research And Implementation Of LTE Physical Layer

Long Term Evolution(LTE)is a standard set for high-speed wireless communications in mobile devices and data terminals.The 3rd Generation Partnership Project(3GPP)is responsible for the entire standardization effort.LTE adopts Orthogonal Frequency Division Multiplexing(OFDM)technology and Multiple-Input Multiple-Output(MIMO)to improve spectrum utilization,data rate,and communication quality.At the same time,LTE supports multiple bandwidth configurations,provides more flexible spectrum allocation and significantly improves system capacity.LTE adopts all-IP and network flattening methods to seamlessly and flexibly support high-speed multimedia services,reducing overall system latency and reducing the cost of network setup and infrastructure maintenance.This paper firstly studies the related technology of the uplink and downlink physical layer in the LTE multimode(TDD LTE and FDD LTE)base station.It focuses on the LTE physical layer cell search and channel estimation theory and implementation and has carried on the simulation verification.In terms of the channel estimation,there is a problem of higher complexity and larger delay among existing windowed DFT transform domain estimation algorithm.To solve this problem,this paper proposes a method of energy accounted window with memory function;This method uses the window length of the previous moment to reduce the range of the estimation of the current moment window length.Obtained by simulation,this method is guaranteed that without sacrificing the quality of channel estimation,It can reduce system processing delay.Afterwards,this project realizes all the physical layers and its key technologies of LTE system on the DSP platform.The code of this optimized at three levels such as the C/C++ language,internal streamlining instructions and assembly language.The results show that the optimized program runs more than 12 times faster than the pre optimized program.It greatly improves the speed of the system and the capacity of the system in unit time.