The embodiment of the invention discloses a method and a device which are used for obtaining
symbol mapping diversity, generating a star map and modulating. The modulating method comprises the following steps: a same modulating way is adopted for modulating a bit
stream which is input in each layer, thus obtaining a modulating symbol, and the bit
stream is a
data stream of the same business of the same user; phase deflection of the modulating symbols which are output by at least two
layers is implemented according to different phase deflecting factors; and superposition of the modulating symbols of each layer, which are output after the phase deflection, is implemented. The
symbol mapping diversity obtaining method comprises the following steps: feedback detecting error information of a transmission
signal that is sent by a receiving terminal is received, and
retransmission is launched; angle rotating superposition of the basic modulating symbol corresponding to the transmission
signal is implemented according to the information, thus obtaining a
retransmission signal, and the rotating superposition angle of the
retransmission signal is different from the rotating superposition angle of the transmission signal; and
combined treatment of the transmission signal and the retransmission signal is implemented, thus obtaining the
symbol mapping diversity. The modulating method and the symbol mapping diversity obtaining method of the embodiment can decrease the
block error rate of the receiving terminal and eliminate the interlayer interference during retransmission.