The Technology Research On Synchronization Of Long Term Evolution Downlink

3GPP LTE(Long Term Evolution)is one of the dominant wireless communication technology.LTE down-link adopts OFDM technology, where the sensitivity of synchronization performance isthe worst defect which affects the performance of whole OFDM system. Synchronization is thepremise for the following baseband signal processing. This paper researches on timingsynchronization as well as the carrier frequency offset estimation for LTE down-link in order toavoid above defects. The concrete works are:Chapter 1 briefly introduces the background of LTE, key technology, target requirement, theadvantage of LTE adopted OFDM and its synchronization problem, analysis the research status ofOFDM synchronization estimation.Chapter 2 introduces the synchronous process of LTE down-link OFDM systems, analyzes theinfluence on the system performances which result from timing error, carrier frequency offset, andsampling clock offset.Chapter 3 researches on the coarse synchronization performance over primary synchronouschannel. Analyze the process of primary synchronous channel, indicate the shortage of both timingestimation and carrier frequency offset estimation, present a improved algorithm. Simulation resultsshow that the new algorithm can achieve better performance compared with its original one.Chapter 4 investigates synchronization algorithm based on training sequence. Firstly, weintroduce several existing classic algorithms and reconstruct training sequence according to abovealgorithm adnvantage, propose a synchronization algorithm based on novel training sequence.Finally, the simulation results show that the new proposed algorithm can achieve much betterperformance when compared with original algorithm not only in gaussian channel but also inmultipath fading channel.Chapter 5 investigates synchronization algorithm based on the cyclic prefix—maximumlikelihood (ML) algorithm. Owing to treat the key coefficient as a constant which is decided bysignal to noise ratio, estimation error is increased in the derivation of ML algorithm. In this paper,based on this algorithm, we achieve more accurate timing synchronization through the accurateestimate of coefficient. Finally, we propose the improvement measures of the carrier frequencyoffset to overcome the poor performance of the ML algorithm in multi-path environments.Simulation results show that the improved algorithm can achieve much better performancecompared with the original one.At last, the paper concludes the whole work, points out the deficiency and puts forward the next research direction.