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arXiv 0704.2659cs.ITmath.IT
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高斯分层广播编码中的最小期望失真

Minimum Expected Distortion in Gaussian Layered Broadcast Coding with Successive Refinement

Chris T. K. Ng, Deniz Gunduz, Andrea J. Goldsmith, Elza Erkip

摘要:

没有信道状态信息(CSI)的发射机希望在慢衰落信道上发送时延受限的高斯信源。源代码是在叠加层中编码的,每一层都连续地细化前一层中的描述。接收器解码由信道实现支持的层,并重建源直到失真。在无限层的连续体的限制下,最小化期望失真的最佳功率分布由一组线性微分方程的解给出,该解是关于衰落分布的密度的。在最佳功率分布中,随着SNR增加,在较高层上的分配保持不变;相反,额外的功率被分配给较低层。另一方面,当带宽比b(每个源符号的信道使用)趋于零时,使预期失真最小化的功率分布收敛到使预期容量最大化的功率分布。虽然可以通过在发射机处获取CSI(CSIT)或通过从独立衰落路径的实现中增加分集来改善预期失真,但是在高SNR下,来自分集的性能益处超过来自CSIT的性能益处,特别是当b较大时。

英文摘要:

A transmitter without channel state information (CSI) wishes to send a delay-limited Gaussian source over a slowly fading channel. The source is coded in superimposed layers, with each layer successively refining the description in the previous one. The receiver decodes the layers that are supported by the channel realization and reconstructs the source up to a distortion. In the limit of a continuum of infinite layers, the optimal power distribution that minimizes the expected distortion is given by the solution to a set of linear differential equations in terms of the density of the fading distribution. In the optimal power distribution, as SNR increases, the allocation over the higher layers remains unchanged; rather the extra power is allocated towards the lower layers. On the other hand, as the bandwidth ratio b (channel uses per source symbol) tends to zero, the power distribution that minimizes expected distortion converges to the power distribution that maximizes expected capacity. While expected distortion can be improved by acquiring CSI at the transmitter (CSIT) or by increasing diversity from the realization of independent fading paths, at high SNR the performance benefit from diversity exceeds that from CSIT, especially when b is large.

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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