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[Keyword] weighted QAM transmission technique(1hit)

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  • Companded PCM Weighted QAM Transmission with the Erasure Zone

    Seung Choon AHN  Moon Ho LEE  

     
    PAPER

      Vol:
    E75-B No:8
      Page(s):
    733-738

    The transmission of 8-bit µ-law PCM signals using 16-level weighted QAM over Gaussian channels is examined. The weighting process modifies the positions of the QAM constellation points so that the overall distortion in the recovered information-bearing source signal is reduced. The PCM bits are mapped to the weighted QAM points such that the most significant bits have a lower probability of being in error than the least significant bits. The weighted QAM systems have been optimized for the same energy signal energy per transmitted symbol as for unweighted QAM. Also, the erasure zone is established at the detector, such that if the output falls into the erasure zone, the regenerated sample is replaced by interpolation. The theoretical results indicates that 16-level weighted QAM have a gain of 5dB over unweighted QAM.