The problem of computing sum of sources over a multiple access channel (MAC) is considered. Building on the technique of linear computation coding (LCC) proposed by Nazer and Gastpar [1], we employ the ensemble of nes...
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ISBN:
(纸本)9781479904464
The problem of computing sum of sources over a multiple access channel (MAC) is considered. Building on the technique of linear computation coding (LCC) proposed by Nazer and Gastpar [1], we employ the ensemble of nested coset codes to derive a new set of sufficient conditions for computing sum of sources over an arbitrary MAC. The optimality of nested coset codes [2] enables this technique outperform LCC even for linear MAC with a structural match. Examples of non-additive MAC for which the technique proposed herein outperforms separation and systematic based computation are also presented. Finally, this technique is enhanced by incorporating separation based strategy, leading to a new set of sufficient conditions for computing sum over a MAC.
作者：
Mitter, S. K.MIT
Informat & Decis Syst Lab Cambridge MA 02139 USA
Technological advances in the control of processes over a communication network have necessitated the development of a unified theory of communication and control. This is currently not available in full generality bu...
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ISBN:
(纸本)9781424471379
Technological advances in the control of processes over a communication network have necessitated the development of a unified theory of communication and control. This is currently not available in full generality but steps towards this can and have been taken. In this lecture, I attempt to present, in summary form, some of these developments.
In this work, the problem of transmitting an i.i.d Gaussian source over an i.i.d Gaussian wiretap channel with an i.i.d Gaussian side information at the intended receiver is considered. The intended receiver is assume...
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ISBN:
(纸本)9781457713484
In this work, the problem of transmitting an i.i.d Gaussian source over an i.i.d Gaussian wiretap channel with an i.i.d Gaussian side information at the intended receiver is considered. The intended receiver is assumed to have a certain minimum SNR and the eavesdropper is assumed to have a strictly lower SNR compared to the intended receiver. The objective is minimizing the distortion of source reconstruction at the intended receiver. In this work, it is shown that the source-channel separation coding scheme is optimum in the sense of achieving the minimum distortion. A hybrid digital-analog Wyner-Ziv coding scheme is then proposed which achieve the minimum distortion. This secure joint sourcechannelcoding scheme is based on Wyner-Ziv coding scheme and wiretap channelcoding scheme when the analog source is not explicitly quantized. The proposed secure hybrid digital-analog scheme is analyzed under the main channel SNR mismatch. It is proven that the proposed scheme can give a graceful degradation of distortion with SNR under SNR mismatch, i.e., when the actual SNR is larger than the designed SNR.
Compressed video bitstreams require protection from channel errors in a wireless channel. The three-dimensional (3-D) SPIHT coder has proved its efficiency and its real-time capability in compression of video. A forwa...
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ISBN:
(纸本)0819441880
Compressed video bitstreams require protection from channel errors in a wireless channel. The three-dimensional (3-D) SPIHT coder has proved its efficiency and its real-time capability in compression of video. A forward-error-correcting (FEC) channel (RCPC) code combined with a single ARQ (automatic-repeat-request) proved to be an effective means for protecting the bitstream. In this paper, the need for ARQ is eliminated by making the 3-D SPIHT bitstream more robust and resistant to channel errors. Packetization of the bitstream and the reorganization of these packets to achieve scalability in bit rate and/or resolution in addition to robustness is demonstrated and combined with channelcoding to not only protect the integrity of the packets, but also allow detection of packet decoding failures, so that only the cleanly recovered packets are reconstructed. In extensive comparative tests, the reconstructed video is shown to be superior to that of MPEG-2, with the margin of superiority growing substantially as the channel becomes noisier.
A new JSCCM scheme based on Multi-layer Feed-forward network is proposed. The coding and modulation of traditional system is replaced by a neural network. At the receive end, a network maps the deteriorated modulation...
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ISBN:
(纸本)0780377028
A new JSCCM scheme based on Multi-layer Feed-forward network is proposed. The coding and modulation of traditional system is replaced by a neural network. At the receive end, a network maps the deteriorated modulation signals to reconstructed signals, the demodulation and decoding of traditional system is replaced. Simulation results show that the performance of neural networks is superior to traditional system. The result is a useful basis for applying neural networks to transmitter and receiver of communication system.
Quantized frame expansions based on block transforms and oversampled filter banks (OFBs) have been considered recently as joint source-channel codes (JSCCs) for erasure and error-resilient signal transmission over noi...
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Quantized frame expansions based on block transforms and oversampled filter banks (OFBs) have been considered recently as joint source-channel codes (JSCCs) for erasure and error-resilient signal transmission over noisy channels. In this paper, we consider a coding chain involving an OFB-based signal decomposition followed by scalar quantization and a variable-length code (VLC) or a fixed-length code (FLC). This paper first examines the problem of channel error localization and correction in quantized OFB signal expansions. The error localization problem is treated as an M-ary hypothesis testing problem. The likelihood values are derived from the joint pdf of the syndrome vectors under various hypotheses of impulse noise positions, and in a number of consecutive windows of the received samples. The error amplitudes are then estimated by solving the syndrome equations in the least-square sense. The message signal is reconstructed from the corrected received signal by a pseudoinverse receiver. We then improve the error localization procedure by introducing a per-symbol reliability information in the hypothesis testing procedure of the OFB syndrome decoder. The per-symbol reliability information is produced by the soft-input soft-output (SISO) VLC/FLC decoders. This leads to the design of an iterative algorithm for joint decoding of an FLC and an OFB code. The performance of the algorithms developed is evaluated in a wavelet-based image coding system. Copyright (C) 2006 Hindawi Publishing Corporation. All rights reserved.
Airborne image service plays an important role in both government and commercial applications. These applications require reliable transmission of compressed images over wireless channels. Various image compression an...
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ISBN:
(纸本)9781467376778
Airborne image service plays an important role in both government and commercial applications. These applications require reliable transmission of compressed images over wireless channels. Various image compression and wireless channelcoding schemes have been separately developed in the past decades. However, the transmission quality supported by the existing algorithms can be attenuated by many atmospheric factors due to wireless channels. In this paper, we design a joint source-channelcoding framework for transmitting compressed image signals over airborne communication channels in order to further improve the quality of image transmission service. When transmitting the compressed image data, not all information bits are equally important. Due to the inherent nature that compressed images are highly correlated, one bit error can lead to a complete failure of reconstruction of the image sources. In the proposed framework, an unequal error protection (UEP) is included based on the importance and correlation of the information bits. We evaluate rate-compatible punctured convo-lutional (RCPC) channelcoding technique combined with both UEP and equal error protection (EEP) for the set partitioning in hierarchical trees (SPIHT) image compression scheme. Comprehensive simulations are performed for the proposed airborne image transmission system, and the results demonstrate a good error robustness of proposed schemes.
We propose a low complexity analog joint sourcechannelcoding Multiple Description (MD) scheme for transmitting the symbols of a Gaussian source across a pair of independent AWGN channels. The outputs of these channe...
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ISBN:
(纸本)9781457705380
We propose a low complexity analog joint sourcechannelcoding Multiple Description (MD) scheme for transmitting the symbols of a Gaussian source across a pair of independent AWGN channels. The outputs of these channels have each a separated receiver, whereas a third receiver has both outputs available. At the transmitter side, a pair of bandwidth-reduction analog mappings are used for joint source-channelcoding. The presented scheme has the inherent advantage over digital MD schemes based on separation, that coding and decoding can be performed by using a single-letter (or symbol), a strategy that is very suitable for applications where latency originated by the digital compression and the error correcting coding can not be tolerated. Our scheme achieves a performance that is competitive as compared to the optimal region while having a very low complexity and delay.
The accuracy of end-to-end distortion (EED) estimation is crucial to achieving effective error resilient video coding. An established solution, the recursive optimal per-pixel estimate (ROPE), does so by tracking the ...
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ISBN:
(纸本)9781467399623
The accuracy of end-to-end distortion (EED) estimation is crucial to achieving effective error resilient video coding. An established solution, the recursive optimal per-pixel estimate (ROPE), does so by tracking the first and second moments of decoder-reconstructed pixels. An alternative estimation approach, the spectral coefficient-wise optimal recursive estimate (SCORE), tracks instead moments of decoder-reconstructed transform coefficients, which enables accounting for transform domain operations. However, the SCORE formulation relies on a fixed transform block size, which is incompatible with recent standards. This paper proposes a non-trivial generalization of the SCORE framework which, in particular, accounts for arbitrary block size combinations involving the current and reference block partitions. This seemingly intractable objective is achieved by a two-step approach: i) Given the fixed block size moments of a reference frame, estimate moments of transform coefficients for the codec-selected current block partition;ii) Convert the current results to transform coefficient moments corresponding to a regular fixed block size grid, to facilitate EED estimation for the next frame. Experimental results first demonstrate the accuracy of the proposed estimate in conjunction with transform domain temporal prediction. Then the estimate is leveraged to optimize the coding mode and yields considerable gains in rate-distortion performance.
Motivated by potential applications in wireless sensor networks, we consider the problem of communicating a large number of correlated analog sources over a Gaussian multiple-access channel using non-orthogonal code-d...
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ISBN:
(纸本)9781479903573
Motivated by potential applications in wireless sensor networks, we consider the problem of communicating a large number of correlated analog sources over a Gaussian multiple-access channel using non-orthogonal code-division multiple-access (CDMA). We present a joint source-channel decoder which exploits the inter-source correlation for interference reduction in the CDMA channel. This decoder uses a linear minimum mean square error (MMSE) multi-user detector (MUD) in tandem with a MMSE joint source decoder for multiple sources to achieve a computational complexity that scales with the number of sources. However, iterative exchange of extrinsic information between the MUD and the joint source decoder leads to improved interference cancellation. Experimental results obtained with decoding observations from Gaussian random fields show that the proposed iterative decoder can achieve a considerable performance gain compared to a non-iterative decoder. The results also show that the iterative decoder is robust against the performance degradation due to correlated interference in a non-orthogonal CDMA channel.
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