Channel decoding of Reed Solomon block turbo codes with a priori information : Application to image transmission

In this paper we are interested to the decoding of blocks turbo codes constructed from Reed Solomon (RS) codes. We have modified the iterative algorithm proposed by Chase in order to exploit the a priori information provided by a correlated source. Indeed, some sources such as images have a strong correlation. A simple iterative decoding algorithm does not take this feature into account. The choice of using RS turbo codes has an advantage compared to the BCH turbo codes when we focus on the example of the image, which is a good representative of correlated sources. A bijection between the pixels of the image and the symbols of the codes will be considered to introduce the bidirectional correlation in the iterative decoding of the rows and columns. Simulation results show that a significant performance gain is obtained with this type of decoding, compared to a classical RS turbo decoding, in case of correlated source and also in case of image transmission.