IRA码预检测折线修正译码算法设计

Algorithm design of early detection and offset polyline decoding for IRA codes

不规则重复累积码(IRA)的译码通常采用置信传播(BP)译码算法,然而BP译码算法需进行双曲正切函数计算,复杂度高,不利于硬件实现。为此,提出一种基于分段函数修正和预检测机制结合的译码算法,通过对折线近似译码算法进行非均匀误差补偿,使其性能接近BP算法;同时引入预检测机制对校验节点信息传递进行预检测,判断出对后续迭代影响微小的对数似然信息,并将其移出迭代循环,从而减少计算量。仿真结果表明,该算法通过分段函数修正近似双曲正切函数、引入预检测机制能大大降低运算复杂度,并且具有接近BP算法的译码性能。

Irregular Repeat Accumulate （IRA） codes＇ decoding usually adopts Belief Propagation （BP） decoding algorithm, but BP decoding algorithm needs hyperbolic tangent calculation, so its hardware implementation is very difficult because of the high complexity. A decoding algorithm combining the early detection mechanism and offset polyline was put forward. Its performance would approach to BP algorithm via non-uniform error compensation for polyline approximation decoding algorithm. And the early detection method was introduced which observed the transmitted information of check nodes in advance, judged the lines＇ log-likelihood value which had negligible influence on the next iteration and moved it out of the iteration. So the computational complexity of next iterations was reduced. The simulation results show that the proposed algorithm greatly reduces the computational complexity through the offset polyline approximating the hyperbolic tangent, and the decoding performance is close to BP algorithm.