Variable rate transmission and blind rate detection for coherent DS-CDMA mobile radio

A variable rate data transmission and blind rate detection scheme is proposed for coherent DS-CDMA mobile radio. The data to be transmitted is first transformed into a QPSK symbol sequence, then multiplied by the rate-matched repetition code of '1, -1', and finally spread over a wide bandwidth. At the receiver, the received signal is despread by a matched filter and non-coherent rate detection is applied. The despread signal sample sequence is then multiplied by a repetition code of detected rate to recover the original transmitted QPSK symbol sequence. The probability of rate detection error for a three-rate case is evaluated by computer simulations in a two-path Rayleigh fading channel.