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[Keyword] multi-level QAM(1hit)

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  • Adaptive Modulation/TDMA Scheme for Large Capacity Personal Multi-Media Communication Systems

    Seiichi SAMPEI  Shozo KOMAKI  Norihiko MORINAGA  

     
    PAPER

      Vol:
    E77-B No:9
      Page(s):
    1096-1103

    This paper proposes an adaptive modulation/TDMA scheme to achieve high capacity personal multi-media communication systems. TDMA is employed to cope with various bit rate for multi-media services. The modulation scheme is selected from 1/4-rate QPSK, 1/2-rate QPSK, QPSK, 16QAM and 64QAM according to the received C/IC (power ratio of the desired signal to the co-channel interference) and the delay spread. The spectral efficiency is evaluated by using the simulated bit error rate (BER) performance as well as the cumulative distribution of the C/IC with parameters of cell configurations. The results show that the spectral efficiency of the proposed scheme is 3.5 times higher than that of the conventional QPSK systems at the outage probability of 10%, and the effect is more remarkable at lower outage probability. The results also show that the proposed adaptive modulation is effective in improving delay spread immunity.