基于无码率码的独立窗不等差错保护方案

Independent window UEP scheme based on rateless codes

提出一种能够匹配多媒体业务特性的独立窗口LT码(independent window LT,IW-LT)不等差错保护方案,采用无码率LT码对不同重要等级的数据分别进行独立选窗和编码。通过与或树分析法推导了IWLT码的渐近译码性能,并结合多目标进化算法联合优化编码度分布和选窗概率,以精确匹配预设的不等保护增益及译码开销,增加了不等差错保护方案的灵活性。仿真证明,IW-LT码与现有的无码率码不等差错保护方案相比,能在精确匹配不等差错性能参数的前提下,获得更低的译码差错概率。

To match the multimedia service transmission,an unequal error protection （UEP）scheme based on the independent window LT （IW-LT）code is proposed.According to the level of importance,the original data are divided into independent windows and encoded by rateless LT codes.The asymptotic decoding perform-ance of IW-LT codes is derived by the AND-OR tree analysis technique.Moreover,to accurately match the ex-pected UEP gain and decoding overhead,multi-objective genetic algorithms are introduced to optimize the degree distribution and probabilities of selecting windows,which enhance the flexibility of the IW-LT UEP scheme. The simulation results show that,compared with the existing rateless coding UEP scheme,IW-LT codes can obtain a lower decoding error rate under the fixed parameters of UEP property.