LTE Physical Layer Uplink Technology Research

In order to maintain the future competitiveness of the Third-generation (3G) in a ten-year, the Third Generation Partnership Project(3GPP) organization passed the 3G long term evolution (LTE)scheme in the end of 2004. The fundamental targets for LTE concern increased data rates, reduced latency, improved system capacity and coverage as well as reduced operator costs. LTE is an important work which is processing in international standard organization, so the study of LTE technology is of great significance.This article focuses on the study of uplink.Firstly, the scheme of physical layer technology is introduced, especially the standard of Single Carrier-Frequency Division Multiple Access (SC-FDMA) and related evolution.Then, the structure of simulation platform as well as part of module principle and parameter are given. The performances in the Additive White Gaussian Noise (AWGN) and Typical Urban (TU) channel are discussed. The performance between ideal channel estimation and Least Squares (LS) channel estimation is compared. Through simulation we conclude that the performance of low code rate and low order modulation is superior to high code rate and high order modulation in the same simulation conditions.The performances of uplink synchronization are evaluated. Through theoretical analysis and the actual simulation, the effects of timing and frequency synchronization errors on the performance are given. The orthogonality among sub-carriers can be broken and Inter-Carrier Interference can be introduced by decimal frequency offset in carrier frequency offset. The system performance can not be seriously effected when FFT window before starting moment in time synchronization error. However, the Inter-Symbol Interference can be introduced and system performance can be seriously effected when FFT window after starting moment.At last, the Acknowledge/Negative (ACK/NACK) controlling signaling is researched. Based on Const Amplitude Zero Auto-Correlation (CAZAC) sequence, the design methods in different conditions are shown. Cyclic prefix added before CAZAC sequence is put forward. The accuracy of detection is increased in the condition of non-coherent detection. Meanwhile, the new sequence which has character like as difference is put forward. It has good performance near coherent detection in the condition of non-coherent detection.