基于无码率码的独立窗不等差错保护方案

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IW LT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。

Independent window UEP scheme based on rateless codes

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 performance of IW-LT codes is derived by the AND-OR tree analysis technique. Moreover, to accurately match the expected 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.