TY - GEN

T1 - Minimum expected distortion in Gaussian layered broadcast coding with successive reinement

AU - Ng, Chris T.K.

AU - Gündüz, Deniz

AU - Goldsmith, Andrea J.

AU - Erkipt, Elza

PY - 2007

Y1 - 2007

N2 - 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 arc 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 thai 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.

AB - 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 arc 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 thai 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.

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U2 - 10.1109/ISIT.2007.4557165

DO - 10.1109/ISIT.2007.4557165

M3 - Conference contribution

AN - SCOPUS:46749086945

SN - 1424414296

SN - 9781424414291

T3 - IEEE International Symposium on Information Theory - Proceedings

SP - 2226

EP - 2230

BT - Proceedings - 2007 IEEE International Symposium on Information Theory, ISIT 2007

T2 - 2007 IEEE International Symposium on Information Theory, ISIT 2007

Y2 - 24 June 2007 through 29 June 2007

ER -