Study Of Convolutional Coding-decoding And Adaptive Transmission Technique Based On OFDM

With the rapid development of digital communication, data processing and computer communication networks, the more reliability and efficiency of information transmission is demanded. As an important channel error-correcting code, convolutional code has excellent performance, and plays an important role in many fields, such as mobile communication, satellite communication and space communication.This thesis introduces the principle of convolutional encode. Viterbi decoding is discussed and the performances of convolutional encoding and Viterbi decoding are analyzed by computer simulation, and compared to other decoding methods. This paper discussed the application of Viterbi decoding in real systems, proposed the schemes of Viterbi decoding in FPGA. Viterbi decoding use parallel way, the flow is clear, and it is simple to modify and expand. The encoder and decoder were described in Verilog HDL under the QuartusⅡ6.0.Then the principles of puncture and depuncture are introduced. In the depuncture module, we choose to multiple the base clock as the control of depuncture. Compared to the traditional method that use other control signal and FIFO register, the new measure is easy to complete, and cost less. The received data is in serial according to the system, it can realize the bit rate matching of sending and receiving without other control signal.Finally, as the convolutional puncture has been realized in FPGA, a simple adaptive coding method is proposed based on the puncture.