中文摘要：

提出了一种适用于低码率应用环境的低复杂度非相干正交调制解调方案.信息比特首先经过一个Zigzag码线性编码器,然后将满足奇偶校验关系的编码比特映射为一个PPM符号发送出去.再根据PPM的软输出解调和正交Hadamard码译码之间的等价关系,就可以在接收端将解调和译码看作一个整体处理,这样不但避免了解调和译码之间的迭代运算,而且可以应用快速Hadamard变换（FHT）和基于FHT的后验概率译码（APP-FHT）来降低译码复杂度.还应用联合设计的线性交织器进一步改善本方案中存在的错误平层问题.仿真结果表明,本方案在降低复杂度的同时具有和其他方案可比的性能.

英文摘要：

A low-complexity orthogonal modulation scheme with non-coherent detection is presented, which is suitable to the low-rate region. Information bits are first encoded by a Zigzag encoder and then the coded bits satisfying a single parity check constraint are mapped into a PPM symbol. According to the equivalence between soft-out demodulation and decoding of orthogonal Hadamard codes, demodulation and decoding can be considered as a whole at the receiver side, so not only can the iterative operations between decoding and demodulation be avoided, but also the fast Hadamard transform（FHT） and the socalled a posteriori probability fast Hadamard transform（APP-FHT） algorithm can be adopted to further decrease decoding complexity. Furthermore, linear interleavers with a joint design are used to improve the error floor problem in our scheme. Simulation results show that our scheme can lead to performance comparable to that of other non-coherent orthogonal modulation schemes.