Patent ID: 6990092

Claim:
Process for radiomobile communication of the time division multiple access type, in which timeslots are allocated to several users for transmission and reception of radioelectric signals, and in which: on transmission, data symbols and reference symbols are created in each allocated timeslot, a radioelectric signal containing these data symbols and reference symbols is transmitted, this signal being sent along a multi-path radiomobile channel, on reception, matched filtering is applied to the received signal, the filtered signal is sampled at the rate of the symbols, an estimate of the radiomobile channel is made, the samples are processed using this channel estimate and data symbols specific to the allocated timeslot are restored, this process being characterized in that: on transmission, several reference sequences possessing appropriate time correlation properties are built up for each allocated timeslot, and these sequences are distributed in each timeslot, on reception: i) in order to estimate the radiomobile channel, this channel is represented by a mesh comprising branches symbolizing transitions between two successive states of the channel and characterizing possible sequences at the channel output, ii) the probabilities of these branches are calculated using an iterative algorithm in which an estimate of a representation {G 1(D) } l= 0 L−1 of L paths of this channel is calculated using a finite number (D+1) of iterations using the maximum a posteriori probability criterion, the iteration rank (d+1) ( d+1) being used to obtain a re-estimate {G 1(d+1) } l=0 L−1 starting from the estimate {G 1(d) } l=0 L−1 obtained in the previous iteration ( d), and in each iteration ( d+1), the vectors {G 1(d+1) } l=0, 1, . . . , L−1 are calculated in L steps from vectors {G m(d+1) } m=0 1−1 and {G m(d) } m=1 L−1 calculated in the previous step, the estimate {C 1(D) } l=0 L−1 of L channel paths finally being obtained from the estimate of its representation {G 1(D) } l=0 L−1 .