LT codes with block duplication and ring type constellation for unequal error protection

This work describes an unequal error protection using a rateless code namely Luby transform codes (LT codes), with block duplication, over Additive White Gaussian Noise (AWGN) channel. Ring type constellation is used as modulation technique to encode the different levels of data independently. In noisy channels, the index replacing concept cannot be used because all the bits are corrupted by noise; symbols are no more either correctly received or completely lost. In this work, a new method has been proposed to circumvent the need for index replacing in block duplication. This is called Index Averaging. It is found that block duplication applied to the Most Important Bits (MIB) leads to a better performance than previous Unequal Error Protection (UEP) based schemes.