Optimization of CDMA systems with respect to transmission probability, part II: Signal to noise plus interference ratio optimization

Itsik Bergel, Hagit Messer

    Research output: Contribution to journalArticlepeer-review

    4 Scopus citations

    Abstract

    Code division multiple access (CDMA) systems commonly use power control mechanism to reduce the amount of interference between the users. In part I of this paper, we introduced the concept of probability control that optimizes system performance with respect to the users' transmission probabilities. The importance of probability control was demonstrated by proving that probability control alone optimizes the mutual information rates over a frequency-flat slow-fading multiple access channel. In this part we extend this result to the optimization of the average signal-to-noise plus interference ratio (SIR) in a CDMA system over a frequency-selective slow-fading channel model and any network topology. We prove that there is a group of CDMA receivers, in which the average SIR (ASIR) of all users is maximized using probability control (while all users transmit their maximal allowed power). This receivers group includes, among others, the common matched filter (MF) RAKE receiver, as well as the sophisticated minimal mean square error (MMSE) RAKE receiver. Simulations demonstrate for a 2-users scenario that both users achieve significantly higher ASIR using probability-control instead of power-control. Results are applicable both for CDMA and impulse radio (IR) systems.

    Original languageEnglish
    Article number4543061
    Pages (from-to)2084-2093
    Number of pages10
    JournalIEEE Transactions on Wireless Communications
    Volume7
    Issue number6
    DOIs
    StatePublished - Jun 2008

    Keywords

    • CDMA
    • IR
    • Power control
    • Probability control
    • UWB

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