Abstract: We investigate joint source-channel coding for transmission of video over time-varying channels. We assume that the channel state is known at the receiver, but only statistical description of the time varying nature of the channel is available at the transmitter. A multimode coder is proposed to efficiently quantize the input video, and generate a quasi fixed-length bit stream of unequal importance. We vary the error protection offered to the individual bits, by matching it to both its importance, and the channel noise statistics. Based on the channel state, the decoder makes the best estimate of the source vector from the received codeword. We present a design algorithm which optimizes the overall rate- distortion performance of the system. Simulations results show that the proposed system outperforms a reference scheme where the multimode (source) codes and the channel codes were designed separately. Further, both the multimode coding schemes provide substantial gains over fixed length JSCC coding. !7
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