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AssigneeAlcatel
InventorsEMMANUEL LEMOIS, FABIEN BUDA, JOEL RICHARD
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The invention provides a spread-spectrum transmission system with multiple carrier modulation in which the signals for transmission over each of the subcarriers are filtered prior to being transmitted over the subcarrier, thereby making it possible on reception to synchronize the various subcarriers in time, and in which each subcarrier carries a plurality of chips that result from spreading a single symbol. With coherent modulation, the number of chips resulting from spreading a single symbol and transmitted over each subcarrier is selected so as to enable the various subcarriers to be put into phase alignment by recombining the chips coming from the same symbol on each subcarrier. With differential modulation, the transmission over each subcarrier of chips resulting from spreading a single symbol provides resistance to jamming by limiting recombination losses because of the differential modulation.
1/ A spread-spectrum transmission system with multiple carrier modulation in which the signals for transmission over each of the subcarriers are filtered prior to being transmitted over the subcarrier, thereby making it possible on reception to synchronize the various subcarriers in time, and in which each subcarrier carries a plurality of chips that result from spreading a single symbol.
2/ The system of claim 1, in which the various subcarriers are subjected to coherent modulation, and in which each subcarrier carries a number of chips that result from spreading a single symbol, which number is sufficient to enable the various subcarriers to be brought into phase alignment by recombining chips coming from a single symbol on each subcarrier.
3/ The system of claim 1, in which the various subcarriers are subjected to differential modulation, and in which each subcarrier carries a number of chips resulting from spreading a single symbol, which number is sufficient to provide resistance to jamming by limiting recombination losses because of the differential modulation.
4/ The system according to claim 1, in which said signals are filtered by lowpass filters ensuring that the spectra of the subcarriers remain distinct.
5/ The system according to claim 1, in which said signals are filtered by Nyquist root filters.