Cellular radiotelephone signal which enables synchronisation at a frame of a supplementary channel by means of symbol numbering

Method of generating a signal cellular radiotelephone, of the type comprising: - a symmetrical bidirectional main channel comprising a main uplink path and a main downward path, ensuring in particular transmission at low or medium data rate and signaling information and control; - At least one additional channel assigned solely to the downstream, which particularly ensures the transmission of high speed data, implementing a multicarrier technique that ensures a distribution of the data in the time / frequency space, and having a structure in entities predefined each comprising a predetermined number of symbols, wherein the method comprises a step of inserting at least one symbol of each entity of the additional channel, a location identifier which identifies the position of said symbol in said entity, so that a terminal can read the position identifier of said symbol and thereby deduce the start of the next entity, thereby obtaining synchronization at the level of the considered entity of the additional channel, and that said predefined entities are subframes (SF1, SF2, ...) or frames (N, N + 1) of the additional channel.