短帧长Turbo编译码的FPGA实现研究

Implementation of Short Frame Length Turbo Encoding and Decoding on FPGA

对深空通信中短帧长信息的Turbo编译码FPGA实现进行了研究。设计了Turbo编译码方法,编码由两个分量编码器并行级联组成,选择递归系统卷积码,编码采用特殊行列交织器;译码由两个独立的软输入软输出译码器串行联级联组成,采用近似Log-Map算法。给出了Turbo编译码的现场可编程逻辑阵列(FPGA)实现,给出了Turbo编译码单元的接口和顶层接口时序,以及Map译码单元流程。仿真结果表明:对帧长小于500b、码率为1/2的Turbo编译码器的FPGA实现了编码数据实时输出,译码延时0.45ms,满足输入数据速率要求。实测结果验证了仿真结果与理论性能相符。

The realization in FPGA of Turbo coding and decoding of short frame information for deep space communication was studied in this paper.The Turbo coding and decoding were designed.The coding part was composed of two sub parallel cascaded coders.The recurrence convolutional code was selected and the special row column interleaver was used.The decoding part was composed of two independent soft input soft output series cascaded decoders.The approximate Log-Map algorithm was applied.The FPGA realization of Turbo coder and decoder was given out.The interface and timing sequence of Turbo coding and decoding and the flowchart of Map decoding unit were presented.The simulation results showed that the coding data was output in real time,and decoding delay was 0.45 ms which met the requirement of input data rate for the frame length was less than 500 b and the rate was 1/2.The experiment proved that the simulation result was agreed with the theory.