Method for processing digital symbols in a communication system and transmitter and receiver for carrying out the method

A transmission device for a digital communication system, comprising:

• means for generating a sequence of digital symbols;
• means for assigning the symbols of the sequence to respective positions in successive timeslots, according to a predetermined slot format;
• substitution means for replacing, in a plurality of timeslots, at least one symbol of the sequence by a substitution symbol carrying additional information;
• and
• means for transmitting, on a communication channel, a signal representing the sequence of symbols which is divided into the timeslots, in which the means for generating the sequence include at least one interleaver having an interleaving period longer than a timeslot, and in which the substitution means are designed to vary the position of the substitution symbols in the slots where symbols of the sequence are replaced.

A reception device for a digital communication system, the reception device comprising:

• means for receiving, on a communication channel, a signal representing a sequence of digital symbols which is divided into successive timeslots;
• means for extracting additional information from only part of the timeslots, by reading at least one respective symbol carrying additional information in each of the timeslots of said part;
• and
• means for processing of the sequence of symbols which is stripped of the symbols carrying additional information, the processed symbols being obtained at defined positions in the timeslots according to a predetermined slot format;
• in which the means for processing of the sequence include at least one deinterleaver having a deinterleaving period longer than a timeslot, and in which said extraction means are designed to read said symbols carrying additional information at variable positions from one slot to another slot in said part.