| 摘要 |
PURPOSE: A multi-carrier direction number sequence CDMA system using a turbo code on the basis of a nonuniform repetition code is provided to heighten a speech quality in a mobile communication environment when adopted for a base station and a terminal by giving more diversity degree to odd-even check symbol in coding and decoding a data bit. CONSTITUTION: A turbo coder(10) encodes a data bit, an input signal. A repeater/symbol corresponding unit(20) converts a turbo code symbol output after being coded from the turbo coder(10) into a repetition code symbol in a frequency domain and suitably separates the converted repetition code symbol signal. Insertions(30,31,32) change a channel for the turbo code symbol output from the repeater/symbol corresponding unit so that an influence in case of a severe attenuation can be suitably distributed to symbols of a codeword. The first multipliers(40,41,l42) multiply the turbo code symbols which have been suitably out of order by a signature number sequence, and make a spread spectrum. Impact modulator(50,51,52) modulate the spectrum-spread signal to an impulse form. Chip wave shaping filters(60,61,62) converts a waveform of a signal output from the impact modulator smoothly and cancels interference between symbols. Second multipliers assign the signal output from the chip wave shaping filter into each frequency band. The first adder(80) adds all signals output from the second multipliers and transmits it.
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