Analysis of Successive Interference Cancellation Scheme in Multiple Data Rate DS/CDMA Systems

In this paper we propose successive interference cancellers (IC) for variable data rate directsequence code division multiple access (DS/CDMA) systems. The performance under Rayleigh fading is analysed for single modulation systems and different systems for handling multiple data rates. One alternative for handling multi-rate systems is to use mixed modulation, which imply that each user chooses modulation format according to need. Therefore, we first analyse an interference cancellation (IC) scheme for M-level rectangular QAM. Another approach is to use parallel channels. Then each user transmits over one or several channels, which are mutually synchronous. We show that the successive IC, for mixed modulation or parallel channel systems, has a performance close to the single BPSK user bound and, consequently, it gives a considerable increase in performance and flexibility compared to both single modulation systems and mixed modulation or parallel channel systems employing a conventional detector. Table of contents