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The following topics are dealt with: adaptive prefix coding; Huffman codes; joint source-channel coding; wireless sensor network; data compression; image sequences; and image coding.
Fix-free codes are variable length codes in which no codeword is the prefix or suffix of another codeword. They are used in video compression standards because their property of efficient decoding in both the forward and backward directions assists with error resilience. This property also potentially halves the average search time for a string in a compressed file relative to unidirectional variable...
In this paper we study the adaptive prefix coding problem in cases where the size of the input alphabet is large. We present an online prefix coding algorithm that uses O(sigma1/lambda+epsiv) bits of space for any constants epsiv > 0, > 1, and encodes the string of symbols in O(loglog sigma) time per symbol in the worst case, where sigma is the size of the alphabet. The upper bound on the encoding...
The word-codeword mapping technique allows words to be managed in PPM modelling when a natural language text file is being compressed. The main idea for managing words is to assign them codes in order to improve the compression. The previous work was focused on proposing several mapping adaptive algorithms and evaluating them. In this paper, we propose a semi-static word-codeword mapping method that...
In Huffman-encoded data a bit error may propagate arbitrarily long. This paper introduces a method for limiting such error propagation to at most L bits, L being a parameter. It is required that the decoder knows the bit number currently being decoded. The method utilizes the inherent tendency of Huffman codes to resynchronize spontaneously and does not introduce any redundancy if such a resynchronization...
This paper describes and evaluates pFPC, a parallel implementation of the lossless FPC compression algorithm for 64-bit floating-point data. pFPC can trade off compression ratio for throughput. For example, on a 4-core 3 GHz Xeon system, it compresses our nine datasets by 18% at a throughput of 1.36 gigabytes per second and by 41% at a throughput of 570 megabytes per second. Decompression is even...
This paper studies the tight rate-distortion bound for K-channel symmetric multiple-description coding for a memory less Gaussian source. We find that the product of a function of the individual side distortions (for single received descriptions) and the central distortion (for K received descriptions) is asymptotically independent of the redundancy among the descriptions. Using this property, we...
Multiple description (MD) source coding is a method to overcome unexpected information loss in a diversity system such as the Internet, or a wireless network. While classic MD coding handles the situation where the rate in some channels drops to zero temporarily, thus causing unexpected packet-loss, it fails to accommodate more subtle changes in link rate such as rate reduction. In such a case, a...
Motivated by the paradigm of event-based monitoring, which can potentially alleviate the inherent bandwidth and energy constraints associated with wireless sensor networks, we consider the problem of joint coding of correlated sources under a cost criterion that is appropriately conditioned on event occurrences. The underlying premise is that individual sensors only have access to partial information...
When transmitting a Gaussian source over an AWGN channel with an input power constraint and a quadratic distortion measure, it is well known that optimal performance can be obtained using an analog joint source-channel scalar scheme which merely scales the input and output signals. In the case of bandwidth expansion, such a joint source-channel analog scheme attaining optimal performance is no longer...
The multicasting of an independent and identically distributed Gaussian source over a binary erasure broadcast channel is considered. This model applies to a one-to-many transmission scenario in which some mechanism at the physical layer delivers information packets with losses represented by erasures, and users are subject to different erasure probabilities. The reconstruction signal-to-noise ratio...
We investigate the performance of a discrete-time all-analog-processing joint source channel coding system for the transmission of i.i.d. Gaussian and Laplacian sources over AWGN channels. In the encoder, two samples of an i.i.d. source are mapped into a channel symbol using a space-filling curve. Different from previous work in the literature, MMSE decoding instead of ML decoding is considered, and...
This paper proposes to use a bipartite graph to represent compressive sensing (CS). The evolution of nodes and edges in the bipartite graph, which is equivalent to the decoding process of compressive sensing, is characterized by a set of differential equations. One of main contributions in this paper is that we derive the close-form formulation of the evolution in statistics, which enable us to more...
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