| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 105 === In this thesis, we deal with the problem in the multiple access system that when many users transmit messages simultaneously, there are possibilities that some users use the same signatures. We call this condition as collision in this thesis. While the collision occurs, the system cannot successfully decode the users'' messages and the performance is severely affected. We fist review two multiple access systems, Code Division Multiple Access(CDMA) and Interleave Division Multiple Access(IDMA). In a CDMA system, each user use a unique spreading code for signature. In a IDMA system, the signature is a user-specific interleaver.
Multilevel Detection(MLDT) is a scheme which can recover the collision users’ messages successfully with little performance degradation. In this thesis we review the MLDT from [1] and derive the performance analysis of MLDT over the Rayleigh fading channel. Moreover, we extend the study of MLDT to the multipath fading channel and the multicarrier scenarios.
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