中文摘要：

无码率码在广播传输中使用时，信道质量突然下降会导致较大突发性错误并使解码器解码效率降低．为改善此情况，文中提出在短码长LT码解码中采用快速信度传播（FBP）解码法．该方法基于交换启发式原理，对接收到的信号立即进行处理，并快速转化为三角矩阵，不仅提高了解码的成功率而且提高了解码速率．由分析和仿真实验可知：FBP解码法的解码成功率较传统的高斯消元解码法和信度传播解码法有极大的提高；当信源信号长度为128b时，FBP解码法的解码成功率较传统的信度传播解码法有大幅提高；FBP解码法的解码计算复杂度与解码耗时都优于高斯消元解码法．

英文摘要：

During the usage of rateless codes in broadcast transmission, sudden declination of channel quality may increase the error percentage and decrease the decoding efficiency of decoders. In order to solve these problems, a fast belief propagation （FBP） decoding algorithm based on the swap heuristic method is proposed for the decoding of LT codes with short length. With this algorithm, the received signals are rapidly processed and transformed into a triangular matrix, thus improving the decoding success proportion and the decoding rate. Analytical and simulated results indicate that, as compared with the conventional Gaussian elimination （GE） and belief propagation methods, the proposed FBP decoding algorithm is of the highest decoding success proportion. When the length of the source symbol is 128 b, the decoding success proportion is remarkably greater than that of the conventional belief propagation decoding. Moreover, it is found that the decoding complexity and time consumption of the proposed algorithm are both less than those of the GE method.