中文摘要：

为了避免交织器产生的时延，通过改进的渐进边增长（PEG）算法和循环中国剩余定理构造了一种不规则重复累积（IRA）码。与常规的IRA码相比，提出的码字具有半随机半结构化形式，不需要设计交织器，且码长选择更加灵活。仿真结果显示，在码率为1／2的条件下，当误码率为10“时，构造的IRA（1000，500）码与PEG—IRA（1000，500）码和基于剩余类数对的IRA（1000，500）码相比，在对应的相同条件下分别取得了0．2dB和0．1dB左右的净编码增益提升；且在码率为3／4时，所构造的IRA（16200，11880）码比相同码长和码率的DVB—S2标准LDPC码净编码增益提高了约0．1dB左右。

英文摘要：

In order to avoid the delay generated by the interleaver, a kind of irregular repeat accumulation （IRA） code is built by the improved progressive edge growth （PEG） algorithm and the cyclic Chinese remainder theorem. Compared with regular IRA codes, the proposed code has the quasi-randomized and semi-structured forms, and does not need to design the interleaver, and the code length selection is more flexible. The simulation results show that when the bit error rate is 104, the net coding gain （NCG） of the proposed IRA（ 1 000,500） code with the code rate of 1/2 is about 0.2 dB and 0.1 dB higher than those of the PEG-IRA（ 1 000,500） code and the IRA（ 1 000,500） code based on residue class respectively. In addition, the NCG of the proposed IRA（ 16 200, 11 880） code is about 0.1 dB more than that of the DVB-S2 standard LDPC code with the same conditions correspondingly with the code rate of 3/4 and the bit error rate（BER） of 10^-6.