We show that the channel distortion for maximum-entropy encoders, due to noise on a binary-symmetric channel, is minimized if the vector quantizer can be expressed as a linear transform of a hypercube, The index assig...
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We show that the channel distortion for maximum-entropy encoders, due to noise on a binary-symmetric channel, is minimized if the vector quantizer can be expressed as a linear transform of a hypercube, The index assignment problem is regarded as a problem of linearizing the vector quantizer, We define classes of index assignments with related properties, within which the best index assignment is found by sorting, not searching, Two powerful algorithms for assigning indices to the codevectors of nonredundant coding systems are presented, One algorithm finds the optimal solution in terms of linearity, whereas the other finds a very good, but suboptimal, solution in a very short time.
In linear predictive speech coding algorithms, transmission of linear predictive coding (LPC) parameters-often transformed to the line spectrum frequencies (LSF) representation-consumes' a large part of the total ...
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In linear predictive speech coding algorithms, transmission of linear predictive coding (LPC) parameters-often transformed to the line spectrum frequencies (LSF) representation-consumes' a large part of the total bit rate of the coder. Typically, the LSF parameters are highly correlated from one frame to the next, and a considerable reduction in bit rate can be achieved by exploiting this interframe correlation. However, interframe coding leads to error propagation if the channel is noisy, which possibly cancels the achievable gain. In this paper, several algorithms for exploiting interframe correlation of LSF parameters are compared. Especially, performance for transmission over noisy channels is examined, and methods to improve noisy channel performance are proposed, By combining an interframe quantizer and a memoryless "safety-net" quantizer, we demonstrate that the advantages of both quantization strategies can be utilized, and the performance for both noiseless and noisy channels improves. The results indicate that the best interframe method performs as good as a memoryless quantizing scheme, with 4 bits less per frame. Subjective listening tests have been employed that verify the results from the objective measurements.
In this study, based on the view of statistical inference, we investigate the robustness of neural codes, i.e., the sensitivity of neural responses to noise, and its implication on the construction of neural coding. W...
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In this study, based on the view of statistical inference, we investigate the robustness of neural codes, i.e., the sensitivity of neural responses to noise, and its implication on the construction of neural coding. We first identify the key factors that influence the sensitivity of neural responses, and find that the overlap between neural receptive fields plays a critical role. We then construct a robust coding scheme, which enforces the neural responses not only to encode external inputs well, but also to have small variability. Based on this scheme, we find that the optimal basis functions for encoding natural images resemble the receptive fields of simple cells in the striate cortex. We also apply this scheme to identify the important features in the representation of face images and Chinese characters.
A standard assumption in network information theory is that all nodes are informed at all times of the operations carried out (e.g., of the codebooks used) by any other terminal in the network. In this paper, informat...
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A standard assumption in network information theory is that all nodes are informed at all times of the operations carried out (e.g., of the codebooks used) by any other terminal in the network. In this paper, information theoretic limits are sought under the assumption that, instead, some nodes are not informed about the codebooks used by other terminals. Specifically, capacity results are derived for a relay channel in which the relay is oblivious to the codebook used by the source (oblivious relaying), and an interference relay channel with oblivious relaying and in which each destination is possibly unaware of the codebook used by the interfering source (interference-oblivious decoding). Extensions are also discussed for a related scenario with standard codebook-aware relaying but interference-oblivious decoding. The class of channels under study is limited to out-of-band (or "primitive") relaying: Relay-to-destinations links use orthogonal resources with respect to the transmission from the source encoders. Conclusions are obtained under a rigorous definition of oblivious processing that is related to the idea of randomized encoding. The framework and results discussed in this paper suggest that imperfect codebook information can be included as a source of uncertainty in network design along with, e.g., imperfect channel and topology information.
The work promotes reliable dynamical validations for transmitted e-documents using session wise randomly hidden secret multi-signatures. Client triggers this protocol by deriving the random circular sequencing of such...
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ISBN:
(纸本)9781538636244
The work promotes reliable dynamical validations for transmitted e-documents using session wise randomly hidden secret multi-signatures. Client triggers this protocol by deriving the random circular sequencing of such invisible signatures onto the cover image e-document. Additional security and authenticity criteria met with dynamical orientations of hidden signature bits on concern sub block pixel bytes of the cover image. Vitally both these dynamical fabrications are fully governed by the respective mathematical operations executed on client-server based mutual secret key and session random challenge. Hence, same dynamical authentications for those valid copyright signatures can also be complied at the server end. Apart from that multi-copy signature dispersing with hosting of each individual signature copy on each separate regions of the cover image serves better authenticity and robustness under attacks. Further region wise varied transforms on sub image blocks with variable threshold range driven sign bit encoding on separate transformed pixel bytes of such sub blocks ensures excellent robustness and recovery of signatures. Finally, exhaustive experimental results also confirmed strong superiority of this scheme over existing works with significant enhancements on standard evaluation parameters. Overall, this protocol reflects better trusted authentication, confidentiality and non-repudiation for wireless digital transmissions in contrast to the current ideas.
We propose a packet loss recovery method that uses an incomplete secondary encoding as redundancy. The recovery is performed by minimum mean squared error estimation. The method adapts to the loss scenario and is rate...
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ISBN:
(纸本)1424407281
We propose a packet loss recovery method that uses an incomplete secondary encoding as redundancy. The recovery is performed by minimum mean squared error estimation. The method adapts to the loss scenario and is rate scalable. It incorporates a statistical model for the quantizers to facilitate real-time adaptation. We apply the method to the encoding of line-spectral frequencies, which are commonly used in speech coding, illustrating the good performance of the method.
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