  Based on the extended binary image of non-binary LDPC codes, we propose a
method for generating extra redundant bits, such as to decreases the coding
rate of a mother code. The proposed method allows for using the same decoder,
regardless of how many extra redundant bits have been produced, which
considerably increases the flexibility of the system without significantly
increasing its complexity. Extended codes are also optimized for the binary
erasure channel, by using density evolution methods. Nevertheless, the results
presented in this paper can easily be extrapolated to more general channel
models.
