A method is provided for transmitting a digital signal between at least two transmitters and at least one receiver, using a concatenation of at least two codes. The method includes a first encoding step, in the transmitters, which outputs at least two first code words; a first transmission step of the first code words, via at least two distinct transmission channels; a receiving step, in at least one relay device, of at least two of the first code words, known as intermediate code words; a step of intertwining at least one part of the bits of the intermediate code words that outputs the intertwined bits; a second step of encoding the intertwined bits, in the relay(s), which outputs at least one second code word, taking into consideration the intermediate code words; a second step of transmitting the second code word(s) through the relay device(s), so as to enable, in the receiver(s), an iterative decoding, taking into account the first code words, and then a redundancy formed by the second code word(s).