Parallel concatenated codes with unequal error protection

We show how parallel concatenated codes (PCCs, also known as “turbo codes”) can be endowed with unequal error protection (UEP). Given the two component encoders of the PCC encoder and the desired interleaver size, UEP is achieved by: (1) suitably positioning the different importance classes of information symbols into the encoder input frame; (2) puncturing the PCC redundancy symbols with a nonuniform pattern; and (3) choosing the interleaver of the PCC encoder in a class of interleavers that guarantees isolation of the importance classes. By controlling the amount of redundancy assigned to each importance class and the class positioning in the input frame, a whole family of UEP PCCs with different UEP levels can be obtained from the same component encoders and interleaver size. From a practical viewpoint, a family of UEP PCCs can be decoded by the same “turbo” iterative decoder, provided that the decoder hardware implementation allows for programmable puncturing and interleaving