1. A method of predicting the performance of a communication system on a transmission channel, the system comprising: a transmitter suitable for applying bit interleaved coded modulation to information bits issued by a source so as to generate coded symbols, these coded symbols being transmitted by the transmitter over the transmission channel, the coded modulation being based on a turbo-code comprising at least two constituent codes; and an iterative receiver, suitable for performing an iterative interference cancellation technique in order to process the coded symbols received from the transmission channel, the iterative receiver comprising an equalizer, a demodulator, and a turbo-decoder that are activated during each iteration performed by the iterative receiver, the turbo-decoder comprising at least two decoders suitable for decoding the respective constituent codes of the turbo-code, the decoders being suitable for interchanging probabilistic quantities in an iterative manner; the prediction method comprising, for each iteration i of the iterative receiver: a first determination process of determining a value γ Eq (i) representative of a signal to interference plus noise ratio at the output from the equalizer from an estimate of the transmission channel and from an estimate v of the variance of the coded symbols at the input to the equalizer at iteration i, this determination being performed by using a preestablished function characterizing the behavior of the equalizer; and a second determination process of determining: a transmission error probability P e (i) on the channel; a variance v i of the coded symbols at the output from the turbo-decoder; and mean mutual information I E,DEC (i) between the information bits issued by the source and probabilistic quantities representative of extrinsic probabilities on those information bits supplied at the output from the turbo-decoder; this determination being done from the value γ Eq (i) and from “a priori” mean mutual information I A,DEC (i) between the information bits issued by the source and probabilistic quantities representative of a priori probabilities on these information bits available at the input of the turbo-decoder at iteration i, by using preestablished functions characterizing the behavior of the demodulator and of the turbo-decoder for a predetermined number (NDEC) of decoding iterations performed by the turbo-decoder; the variance v i being used during the first determination process of the following iteration i+1 of the iterative receiver to estimate the variance v of the coded symbols at the input of the equalizer, and the mean mutual information I E,DEC (i) being used during the second determination process of iteration i+1 as a priori mean mutual information I A,DEC (i+1) .