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arXiv 1312.0932cs.ITmath.IT
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时变信道和边信息联合信源-信道编码

Joint Source-Channel Coding with Time-Varying Channel and Side-Information

Iñaki Estella Aguerri, Deniz Gündüz

摘要:

研究了在接收端存在时变相关边信息的情况下,高斯信源在时变高斯信道中的传输。一个块衰落模型被认为是信道和边信息,其状态被假定为仅在接收机是已知的。当信道是静态的,而边信息状态遵循离散或连续和准凹分布时,分离的信源和信道编码在平均端到端失真方面的最优性被示出。当信道和边信息状态都是时变的时,分离的信源和信道编码通常是次优的。通过向编码器提供信道状态信息来研究部分通知的编码器下界。提出了几种基于非编码传输、信源和信道编码分离、联合解码以及数模混合传输的传输方案。未编码传输被证明是最佳的一类连续和准凹边信息状态分布,而信道增益可以有一个任意的分布。据我们所知,这是第一个未编码传输由于状态的时变性质而实现最佳性能的例子,而在同一问题的静态版本中,它是次优的。然后,最佳的\emph{distortion exponent},量化的指数衰减率的预期失真在高信噪比制度,其特征在于Nakagami分布式信道和边信息状态,它被证明是通过混合数字模拟和联合解码方案在某些情况下,说明了次优的纯数字或模拟传输一般。

英文摘要:

Transmission of a Gaussian source over a time-varying Gaussian channel is studied in the presence of time-varying correlated side information at the receiver. A block fading model is considered for both the channel and the side information, whose states are assumed to be known only at the receiver. The optimality of separate source and channel coding in terms of average end-to-end distortion is shown when the channel is static while the side information state follows a discrete or a continuous and quasiconcave distribution. When both the channel and side information states are time-varying, separate source and channel coding is suboptimal in general. A partially informed encoder lower bound is studied by providing the channel state information to the encoder. Several achievable transmission schemes are proposed based on uncoded transmission, separate source and channel coding, joint decoding as well as hybrid digital-analog transmission. Uncoded transmission is shown to be optimal for a class of continuous and quasiconcave side information state distributions, while the channel gain may have an arbitrary distribution. To the best of our knowledge, this is the first example in which the uncoded transmission achieves the optimal performance thanks to the time-varying nature of the states, while it is suboptimal in the static version of the same problem. Then, the optimal \emph{distortion exponent}, that quantifies the exponential decay rate of the expected distortion in the high SNR regime, is characterized for Nakagami distributed channel and side information states, and it is shown to be achieved by hybrid digital-analog and joint decoding schemes in certain cases, illustrating the suboptimality of pure digital or analog transmission in general.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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