Near-Far Resistance of Multicarrier CDMA Systems
CINCINNATI UNIV OH DEPT OF ELECTRICAL AND COMPUTER ENGINEERING AND COMPUTER SCIENCE
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Multicarrier MG CDMA systems have been developed and rapidly gained popularity as they capitalize on both MCM multicarrier modulations resilience to MUI and direct-sequence DS CDMAs robustness against frequency selectivity to mitigate both MUI and the inter-symbol interference ISI caused by time dispersive channels. However, the well-known near-far problem in a multiuser setting still places fundamental limitations on the performance of MC-CDMA communication systems, and this issue has been considered by very few papers. In this paper the theoretical near far resistance of the MMSE detector in the uplink MC-CDMA with and without cyclic prefix CP setting is derived. It turns out that the near-far resistance of MC-CDMA without CP has the same form as that of the DS-CDMA except that the user codes are IFFT transformed. Our formulation for the near-far resistance is applied to either blind or non-blind MMSE detectors. Computer simulations confirm theoretical findings.
- Radio Communications