1. A method for emission, by a terminal, of a message to a receiver station of a wireless communication system, the terminal being time synchronized with the receiver station, the message emitted over a channel shared with other terminals and on which the emission of messages to the receiver station is carried out at beginning of predetermined time intervals for the terminal and the receiver station, called predetermined slots, and the method comprising:encoding data to be included in the message to be emitted by a channel encoder;
distributing the encoded data among Nb sub-messages of the message to be emitted, by fragmenting the encoded data into Nb fragments, Nb being an integer greater than or equal to two;
randomly selecting a slot, among the predetermined slots, for the emission of the message by the terminal;
selecting Nb emission frequencies, respectively associated with the Nb sub-messages, by the terminal, wherein the Nb emission frequencies are not known a priori to the receiver station; and
emitting the message at the beginning of the selected slot, by successively emitting the sub-messages on their respective associated emission frequencies.