Spread spectrum communication system

Low rate data D1-D4 and middle rate data D5 and D6 are time division multiplexed independently according to their rates by a time division multiplexer TDM(A) (110) so that their rates are converted into the rate of high rate data D7 and D8 which are not passed through the time division multiplexer TDM(A) (110). Subsequently, the entire data are converted into biorthogonal signals by biorthogonal signal generators BORTs (121, 122a-125a), and code division multiplexed by a code division multiplexer CDM(A) (130a). The code division multiplexed signal undergoes modulation by a spreading modulator (20) and a carrier modulator (30), and transmitted.