Digital signal transmission system based on partitioning of a coded modulation with concatenated codings

Claim 1

Digital signal transmission system which operates by coded modulation of a constellation, the system comprising a transmitting station including an encoder (5) which includes a modulator (13) installed in the transmitting station, a receiving station comprising a decoder (105) which includes a demodulator (113) installed in the receiving station, and a channel (15), the encoder (5) and the decoder (105) communicating together through the channel (15); the encoder (5) comprising a plurality (12) of multi-stage channel sub-encoders (31); each multi-stage channel subencoder (31) combining a channel coding, for protecting data bits to transmit, with the coded modulation, the whole channel coding being subdivided and assigned to several successive partitioning levels of the constellation, each multi-stage channel sub-encoder (31) further comprising an assigning element (32) for assigning the encoded signals to one partitioning level and for supplying symbols which modulate a carrier, each multi-stage channel sub-encoder (31) having its own carrier with a unique carrier frequency; a frequency interleaver (37) for interleaving together said symbols from all the sub-encoders (31) to form a modulating signal; a modulator (13) for receiving the carriers and modulating signal and for modulating the carriers in the modulator (13), the carrier modulation being performed according to an orthogonal carrier frequency-division multiplexing technique for obtaining modulated carrier signals which are transmitted through the channel (15); the decoder (105) comprising a demodulator (113) for demodulating the received transmitted modulated carrier signals, the decoder (105) further comprising a frequency de-interleaver (137) which operates in the reverse manner to the frequency interleaver (37); at least one of the multi-stage channel sub-encoders (31) comprising: at least one internal encoder (34 1 34 2 ) which performs an internal block coding constituted of a series of codeword blocks, each codeword being a series of data bits, at least one external encoder (35 1 35 2 ) which performs an external coding of the codeword blocks delivered to it by the internal encoder, the internal and external codings being concatenated to divide a binary protection redundancy between the internal encoder and the external encoder; the decoder (105) further comprising a plurality of multi-stage channel sub-decoders (112) each of which includes at least one multi-stage channel sub-decoder comprising: at least one internal decoder which performs an internal block decoding corresponding but in the reverse manner to the internal coding performed by the internal encoder, at least one external decoder which performs an external block decoding corresponding but in the reverse manner to the external coding performed by the internal encoder; the decoder (105) further including detectors (40 1 , 40 2 ) which performs a detection on said partitioning levels of the constellation.