Research And Implementation Of Physical Downlink Cortrol Link Of TD-LTE Based On Software-defined Radio Platform

As the main trend of communication technology after 3G era,LTE has been adopted by countries worldwide and been networking widely.TD-LTE is the time division duplex model of LTE,which is used as the standard of our country.The software-defined radio is a kind of technology which is flexible,highly-configurable,and can adapt to different communication standards and environments.Buliding the communication system on the platform of software-defined radio is a trend.The main content of this essay is the simulation and implementation of LTE downlink control link.The LTE downlink control link includes three channels of PCFICH,PHICH,PDCCH,which is the important part of the LTE downlink,It carrys the control information from the top which determing wether the users can receive or transmit the signals rightly.The organization structure of LTE network and the basic specification of physical layer are studied in the essay firstly,and the contents of the three control channels are introduced.On the basis of in-depth study of the three control channels,the algorithms used in the eNodeb and the ue part are studied: the algorithm of the transmitting diversity is studied,and then the formulation of the data sending and reciving in the UE and the eNodeb in the case of 2 ?1 MIMO is derivated;the process of sub-block interleaving and bit-collection when doing the rate matching in the sending part is studied;the process of data recovery in the recving part when doing the re-rate matching in the case of the input length of 40 bits is provided.The steps when doing the resource mapping in the time-frequency resource grid of the three control channels are provided.The simulation on the channel estimation part using different algorithms is done;the simulation on the performance curve of channel decoding when using the soft or hard judement is done;the blind detection process of PHICH channel and PDCCH channel is studied;the decoding algorithm of each channel and compare the advantages and disadvantages of different algorithms used in the decoding of the PDCCH tail biting convolutional codes are studied.And then the simulation design on the level of the link is provided,which is to build the transmission model of three control channels in MATLAB.The baseband data produced by the sending part goes through different noise environments and fading channel environment,and the channel analysis in the receving part is done.The information analyzed by the receving part with the information sended by the sending part is compared;the statistics of the channel block error rate are achived.At last the GNU Radio software radio platform is used to build a downlink control link receiver model.The C++ signal processing module of each part of the downlink control link is written,and the channel performance curve of the downlink control link is given.The test with the data from the real air interface is done,and the results show that the downlink control link can successfully resolve the downlink control information.