Intermediate symbols expanding window raptor codes for unequal error protection

A new design to provide unequal error protection (UEP) using Raptor codes over erasure channels, named Intermediate Symbols Expanding Window Raptor (ISEW Raptor) codes using windowing techniques, is developed and discussed. ISEW Raptor encodes intermediate symbols with EWF approach, possessing UEP property while keeping systematic code characteristics. ISEW Raptor is improved based on standard Raptor (adopted by the third generation partnership project, namely 3GPP), and of which the core codec algorithms are also compatible with standard Raptor. ISEW Raptor introduces an additional parameter in the UEP code design, making it more general and flexible in application. Furthermore, the proposed approach shows excellent UEP performance that MIB could be decoded successfully with high probabilities even for less than number of source symbols received, and which is confirmed experimentally.