Research Of Cell Identificationand Downlink Synchronization On Heterogeneous Network For Lte-a System

Facing the demands of users and responding to the challenges of the market, the Third Generation Partnership Project(3GPP) is working on the research of LTE-Advanced(LTE-A) technology.Theintroduceof a heterogeneous networks(HetNet) in Release10increases the throughput of the system and improves the spectrum efficiency and peak rate. The complexity, however,brings greater challenges tothe cell identification in heterogeneous network environment.LTE terminal onlyidentifies the serving cell through cell search, andit receives the basic information of the system via downlink time acquisitionand frequency synchronization. The macro base stations and micro base stations in a HetNetcould achieve the same coverage, while thetransmission power of a micro base station is much less thanthat of a macro base station, which turnsthe terminal identification at the edge ofa macro cell and a the micro cellmore difficult.Thisarticle gives a study and analysis on cell identification and downlink synchronization in HetNet based on LTE-A system. A link level simulation platform is built and the accomplished work contributions areas follows:(1) LTE downlinkuses the Orthogonal Frequency Division Multiplexing (OFDM) based on cyclic prefix.In this article, it firstdescribes three synchronizations in OFDM system, including symbol synchronization, sampling synchronization and carrier frequency synchronization.Thereafter, our paper analyses the impact of the three synchronization errors to the system.At last, under the condition of the presence of frequency offset ina single-cell,the simulation figures out the main synchronization search, the auxiliary synchronization search and the detection probability in synchronization point in OFDM system, under the condition of the presence of frequency offset ina single-cell.(2) LTE cell identification is deeply investigated in this article, and cell identification for HetNet link level simulation platform is developed in accordance with the recommendedsimulation parameters in3GPP LTE-Advanced technique specifications. The simulation is conductedoverdifferent SNR points and different channel conditions to evaluate the performance of the cell search.(3) The low power nodewith the presence of interference in the HetNet is studiedfor the purpose of reducing the inter-cell interference and enhancing the quality of service of the edge users, and besides a new interference cancellation algorithm is proposed.By searching the cell under strong interference, decodingthe interference signal at the receiving endand reconstructing interference signal, theinterference cancellation is achieved.The simulation structure shows that it shortens the length of the cell search timeeffectively.(4) After the analysis on denoising insufficiencyin the heterogeneous network environment, a new channel denoising method is proposed to cope with the interference in the radio channel. The feasibility of the proposed method is verified by simulationand reachessatisfying results.