We study the use of overcomplete (also known as oversampled) subband expansions for multiple description coding. The system proposed uses an overcomplete subband expansion (a subband expansion in which the number of s...
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ISBN:
(纸本)0819437646
We study the use of overcomplete (also known as oversampled) subband expansions for multiple description coding. The system proposed uses an overcomplete subband expansion (a subband expansion in which the number of subbands is larger than the downsampling factor of each subband) followed by independent coding (quantization and coding) of each of the subbands. The entire coding of each of the subbands is entirely contained within a single description. Using analysis in the polyphase domain, we study finding frequency responses of optimal filterbanks and the rate allocation across the subbands to minimize the end-to-end reconstruction error subject to a transmission rate constraint when a distribution over channel states is known. A general analysis of the problem is given and results are shown for a 3 x 2 expansion of a first-order autoregressive process.
The main purpose of this paper is to show that once the video sourcecoding is dependent on the channel characteristics, better performance can be achieved in terms of reconstructed video quality. Our study considers ...
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ISBN:
(纸本)0780375890
The main purpose of this paper is to show that once the video sourcecoding is dependent on the channel characteristics, better performance can be achieved in terms of reconstructed video quality. Our study considers a fixed overall bit rate transmission of 64 kbit/s over error prone memoryless binary channels and the source coder is the ITU-T H.263 video standard. The variable H.263 sourcecoding rate adapts to a particular channel Bit Error Rate (BER) at any instant of time. Firstly, we investigated the error sensitivities of H.263 syntactical elements and grouped them into several classes of different significance. By identifying the most sensitive elements, we developed a data grouping (DG) technique which by itself, exhibits improved error resilience. Secondly, we design an Unequal Error Protection (UEP) scheme and compare its performance with an equivalent (same sourcecoding bit rate) Equal Error Protection (EEP) scheme, using Rate Compatible Punctured Convolutional (RCPC) codes of different rates for forward error protection. Both forward error correction schemes adopted have resulted in PSNR improvements, over 20 dB for BERs higher than of 4x10(-3). Finally, if during the real time encoding process, the encoder is aware of the channel BER and there is an unlimited number of code rates, this paper shows that UEP and EEP strategies provide quite similar performances.
In this paper, we present a novel algorithm for dynamic quantization in distributed Wyner-Ziv video coding. In contrast with previous work where the quantization parameter is fixed and a feedback channel is used, our ...
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ISBN:
(纸本)9781424416875
In this paper, we present a novel algorithm for dynamic quantization in distributed Wyner-Ziv video coding. In contrast with previous work where the quantization parameter is fixed and a feedback channel is used, our proposed technique relies on theoretical calculations to jointly determine the number of quantization levels along with a suitable compression rate for each video frame. It employs a cross-layer approach that dynamically allocates unequal transmission rates for different users by taking into account the amount of motion in the captured video scenes on one hand and the transmission conditions for each sensor on the other. The application of this algorithm in a wireless video sensor network shows a significant improvement in the system performance when compared to a traditional system that allocates equal channel resources with a fixed quantization parameter.
The problem of reliably reconstructing a function of sources over a multiple-access channel (MAC) is revisited by considering channel feedback. First, a linear feedback scheme is proposed to compute the average of the...
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ISBN:
(纸本)9798350382853;9798350382846
The problem of reliably reconstructing a function of sources over a multiple-access channel (MAC) is revisited by considering channel feedback. First, a linear feedback scheme is proposed to compute the average of the Gaussian sources transmitted over the Gaussian MAC. Next, numerical results show that in some cases, our proposed scheme performs better than the existing ones without using channel feedback. Finally, we show that with a slight modification, our scheme can be directly extended to compute any linear function of the Gaussian sources transmitted over the Gaussian MAC.
An analysis-based approach for unequal loss-protected multiple description coding (packetization) of the scalable (prioritized / progressive) source code streams is proposed. For a given number of packets (description...
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ISBN:
(纸本)9781424456536
An analysis-based approach for unequal loss-protected multiple description coding (packetization) of the scalable (prioritized / progressive) source code streams is proposed. For a given number of packets (descriptions) of the known size, unequal loss-protected packetization leads to segment the scalable code stream, such that the source can be reconstructed with the maximum possible fidelity at the decoder side. Here, we find an analytical relation between optimal sizes of any two consecutive segments. This idea yields a low-complexity progressive solution with a performance close to that of local search [1], which has been approved as an efficient method to solve the segmentation problem. Simulation results are used to confirm the efficiency of the proposed method as compared with the local search algorithm.
This paper investigates the validity of Shannon's separation theorem in the finite block length regime. Under optimal tradeoffs between source rate and channel block error probability obtained from finite block le...
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ISBN:
(纸本)9781479906345
This paper investigates the validity of Shannon's separation theorem in the finite block length regime. Under optimal tradeoffs between source rate and channel block error probability obtained from finite block length analysis, noisy channel quantizers based on joint source-channel coding principles are shown to outperform the separate quantizer designed via Lloyd-Max in terms of end-to-end distortion. Numerical results for the scalar case under the binary symmetric channel and discrete-input memoryless channel demonstrate that the separation of source and channelcoding no longer holds in the finite block length regime, but the advantages of joint designs may be large or small depending on the system configuration.
The XOR network code is widely used in the conventional network coding. However, when the channel is noisy, the XOR code is suboptimal in terms of minimizing distortion in the source signal. We propose to use a new ne...
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ISBN:
(纸本)9781424426430
The XOR network code is widely used in the conventional network coding. However, when the channel is noisy, the XOR code is suboptimal in terms of minimizing distortion in the source signal. We propose to use a new network code for the two-way relay channel, designed to minimize signal distortion due to the channel noise. We assume the source signal X is encoded by a source encoder and the sequence of symbols is transmitted over the two-way relay channel with noise. The received sequence of symbols may be corrupted by the channel noise, and X, the estimation of X, may be different from X. We design a new network code which minimizes the distortion between X and X. To provide an algorithm to obtain a network code with minimum distortion, we define the expected distortion associated with a network code. Starting with the XOR network code, we iteratively optimize the network code to obtain smaller expected distortion, while maintaining the Latin square constraint of the network code. New network code achieves substantial performance gain over the XOR network code.
The problem of efficient video communications over MIMO wireless systems is of great significance, due to the high capacity of the multiple antenna system. The high data rates provided by the MIMO system can be traded...
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ISBN:
(纸本)0780385217
The problem of efficient video communications over MIMO wireless systems is of great significance, due to the high capacity of the multiple antenna system. The high data rates provided by the MIMO system can be traded off with diversity gain by using different, channelcoding schemes. Also, by using different video sourcecoding methods, high compression gain can be traded off with the. error resilience gain. One should jointly consider sourcecoding and channelcoding when designing a MIMO wireless video system. However, little is known so far about what. combinations of channelcoding and sourcecoding methods have the best overall performance in a MIMO system. In this paper, by comparing the performances of several different,. typical combinations through both theoretical and simulation studies, we show that, no single combination is the best for the entire range of channel conditions, rather different combinations may be best for a sub-range.
An adaptive joint source-channel coding (JSCC) scheme is presented for transmitting correlated sources over discrete-memoryless two-way channels subject to distortion constraints. The proposed JSCC scheme makes use of...
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ISBN:
(数字)9781728164328
ISBN:
(纸本)9781728164328
An adaptive joint source-channel coding (JSCC) scheme is presented for transmitting correlated sources over discrete-memoryless two-way channels subject to distortion constraints. The proposed JSCC scheme makes use of the previously transmitted and received channel signals as well as the sources' correlation to facilitate coordination between terminals. It is shown that the adaptive scheme strictly subsumes prior lossy coding methods for two-way simultaneous transmission and yields a new adaptive separate source-channelcoding result. Two examples are given to show the scheme's advantages.
This paper extends the well-known sourcecoding problem of multiple descriptions, in its general and basic setting, to analog source-channelcoding scenarios. Encoding-decoding functions that optimally map between the...
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ISBN:
(纸本)9781479999880
This paper extends the well-known sourcecoding problem of multiple descriptions, in its general and basic setting, to analog source-channelcoding scenarios. Encoding-decoding functions that optimally map between the (possibly continuous valued) source and the channel spaces are numerically derived. The main technical tool is a non-convex optimization method, namely, deterministic annealing, which has recently been successfully used in other mapping optimization problems. The obtained functions exhibit several interesting structural properties, map multiple source intervals to the same interval in the channel space, and consistently outperform the known competing mapping techniques.
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