The Research Of Channel Estimation And Link Designation In LTE Downlink

With the rapid development of WIMAX, the3GPP proposes long-term evolution (LTE) project. Compared with the traditional communication services, LTE has many advantages,such as improving data transfer rate and spectrum efficiency,increasing the system capacity, enhancing the ability of anti-interference, reducing commercial cost and so on, and has much breakthrough.So it is very valuable to study. There are many key technologies,which are OFDM,multiple antennas and channel coding in downlink.These advanced technologies greatly improve the performance of the transmitter, realize treliable and stable transmission of the system, and the receiver can more accurately restored the data which is passed random and complex space channelIn LTE downlink, there are OFDM technology, in order to obtain high frequency spectrum efficiency, this system needs to adopt multilevel and constant amplitude modulation mode (such as16QAM) by coherent demodulation.And coherent demodulation need to estimate and track the parameters of the fading channel. So it is very important for OFDM system to obtain the accurate parameters of channel.Therefore, in order to get as accurate as possible parameters of the channel at the receiver, it is necessary to study all kinds of channel estimation technology. Based on the LS channel estimation algorithm and DFT channel estimation algorithm, which is studied and analysed, this paper proposes the improved algorithm of DFT channel estimation algorithm, and then simulate the three channel estimation algorithm. The result of simulation indicates that the improved algorithm can obtain more accurate channel information.According to the3GPP physical layer related protocol and actual project,this paper designs LTE downlink with downlink Shared channel, this paper studies and designs transmitter scheme, which is including channel coding and the process of symbols. According to the TS36physical series agreement about FDD mode, and referring to the standard agreement, there set up a complete downlink Shared channel and realize the FDD receiver system, which is including channel decoding and the process of symbols. In this paper, there is to study resources mapping module,which is the mapping of the distributed virtual resource blocks to physical resource blocks.In protocol, there are formulas for this mapping,but the process is very complex and the result is unordered, for completing the mapping, it must sort the result,so greatly adding the time of the hardware realization.Then this paper studies the calculation method and puts forward to a more simple calculation method, so as to save the time of FPGA or DSP realization. Finally, for the technical difficulties in LTE downlink, based on this paper, there are the key points for further studies.