Based On Rs - Ldpc Mobile Video System Synchronization And Channel Estimation And Its Fpga Implementation

Orthogonal frequency division multiplexing (OFDM) is one of the most important transmission technologies in wireless communication field. The OFDM system with RS and LDPC is robust to the multipath fading. However, the OFDM system is very sensitive to time and frequency synchronization errors and channel estimation errors. How to accurately realize the system synchronization and to effectively estimate the channel response in the OFDM receiver are important.In this thesis, taking the narrow-band mobile video transmission system for application background, synchronization and channel estimation for OFDM systems have been studied. By analyzing the transport stream, LDPC code, and the system parameters, the frame structure of the system has been designed. Employing repeated property of cyclic prefix, the symbol timing synchronization and decimal carrier frequency offset estimation have been Implementation. As for the integer carrier frequency offset, the method of applying the pilot structure property has been proposed. In order to save hardware resources as much as possible, the frame synchronization has been achieved with the carrier frequency offset correction at the same time. In the study of the channel estimation algorithms based on pilot-aided, a least-squares channel estimation technique has been selected to estimate transfer functions of pilot subcarriers, meanwhile, the linear interpolation algorithm has been used to estimate transfer functions of data subcarriers. From what have been discussed above, these issues have been implemented on FPGA and have been verified.To save hardware resources, the design has combined system synchronization and channel estimation, which enables the system to achieve the optimal performance. By combining differential encoding and channel estimation, the realization of channel estimation has been simplified. The quasi-coherent demodulation could overcome the disadvantage of the differential demodulation, and reduce accuracy requirements of channel estimation because differential encoding has been used.