New Cross-correlation Results for Multi-rate CDMA

ABSTRACT Support of multiple data services can be accomplished via code division multiple access (CDMA) with a constant chip rate, but variable data rates. We present exact equations for the cross-correlation of codes in a multiple-data rate system, and thus equations for the multiple access interference (MAI) and bit error rate (BER). Previous analysis has found the BER using the mean of the MAI assuming codes are truly random sequences. We show that Gold and Kasami sequences have a cross-correlation with a distribution closely approximated by a Gaussian one, and present confidence intervals to quantify the performance under the random code assumption.