Srijidtra Mahapakulchai

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— Previously, we proposed a trellis coded modulation system using CPFSK and ring convolutional codes for transmitting the bits generated by an embedded zerotree wavelet encoder. Improved performance is achieved by using maximum a posteriori (MAP) decoding of the zerotree symbols. In this paper, the optimal ring convolutional trellis codes are determined for(More)
In this paper, we design the adaptive MAP source-controlled channel decoding for transmitting MPEG-4 images. The ?rst order Markov model is employed for adaptively computing the source transition probabilities of the zerotree symbol sequences. Those probabilities are required at the receiver for the newly branch metric computation of the Viterbi algorithm.(More)
In this work, the authors design the variable-size random interleavers for the variable length of MPEG-4 packets. In MPEG-4 source encoder, the authors divide the binary sequence of high frequency subband into the packets. To investigate the image transmission system, the authors also employ the rate 1/2 ring convolutional encoder and Rician fading channel(More)
We implement the convolutional interleavers into MPEG-4 image transmission systems for the Rician fading channels. The objective of this paper is to illustrate the performance differences between applying the convolutional interleavers and our previously designed random interleavers. The simulation results show some improvement on the PSNR performance of(More)
We jointly design the reconfigurable ring convolutional encoders and reconfigurable convolutional interleavers for the MPEG-4 medical image transmission system. Our objective is to maintain our desirable system performance due to the variation of channels with the lowest system complexity. In order to gain the performance in burst noise environment, we(More)
In this work, the MAP source-controlled channel decoder with matched and mismatched source transition probability matrix (STPM) is intensively examined for a MPEG-4 video sequence. We attempt to answer whether or not one can use the MAP decoding with a mismatched STPM instead of the MAP decoding with the matched STPM. The matched STPM requires the(More)
In this work, the performance evaluation of low-frequency and high-frequency MPEG-4 images is exclusively summarized. Our designed transmitting system including the convolutional interleaver is examined over the short-term blockfading channels. The signal envelope for the short-term fading can be obtained from the general Chi-Square distribution. When(More)
The novel design of reconfigurable random interleavers is considered here. Our objective is not only to alleviate the effect of Rician block-fading channels but also to be able to efficiently reduce the complexity of the interleavers. Again, we insert the variable length of MPEG-4 packets into the adjustable interleavers and then pass through the rate(More)
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