适用于WMSN的联合信源信道迭代译码

Iterative joint source channel decoding for WMSN

提出了一种适用于WMSN的联合信源信道迭代译码(ISCD)方案,基于一种软输入软输出(SISO)后验概率的变长译码算法,不仅可以得到最大似然(ML)变长序列估计,而且可以计算ISCD所必需的比特级的置信信息。此外,把缩放外信息技术引入到ISCD领域,提出了利用外信息交换特性来获得最优常数缩放因子的方法,这可以在几乎不增加运算复杂度的前提下提高ISCD的性能。这种方案的显著特点是运算复杂度低,所需存储空间小,可以被应用于WMSN节点上。仿真结果表明,提出的ISCD方案显著地提高了变长度编码数据在WMSN中传输的抗差错能力。

An iterative joint source channel decoding （ISCD） scheme for WMSN is proposed, based on a soft-input-soft-output （SISO） a posteriori probability decoding algorithm for variable-length coded sources, which leads to not only maximum likelihood （ML） sequence estimation but also the computation of bit-based reliability values which are necessary for ISCD. Another innovation is that the technique of scaling extrinsic information is brought into the field of ISCD, and the optimal constant scaling factors is obtained under the guide of extrinsic information transfer characteristic. This technique improves the ISCD performance with increasing neglectable complexity. The notable feature of the proposed technique is that it requires very low computational complexity and small memory space, and can be applied to WMSN nodes. Simulation results show that the proposed ISCD scheme provides a significant improvement on error protection capability for the variable-length coded data in WMSN.