In the Shannon-theoretic analysis of joint source-channelcoding problems, achievability is usually established via a two-stage approach: The sources are compressed into bits' and these bits are reliably communica...
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ISBN:
(纸本)9781424415632
In the Shannon-theoretic analysis of joint source-channelcoding problems, achievability is usually established via a two-stage approach: The sources are compressed into bits' and these bits are reliably communicated across the noisy channels. Random coding arguments are the backbone of both stages of the proof. This strategy not only establishes the optimal performance for stationary ergodic point-to-point problems, but also for a number of simple network situations, such as independent sources that are communicated with respect to separate fidelity criteria across a multiple-access channel. Beyond such simple cases, for general networks, unstructured random coding arguments are not sufficient. This was first realized for sourcecoding by Korner and Marton, who showed that for a distributed sourcecoding problem where one only needs to recover a function of the sources random linear codes are necessary. The goal of this note is to extend this insight to pure channelcoding as well as to joint source-channelcoding problems, such as the problem of reliable computation over a multiple-access channel and a multi-access network with relays.
Compressed video bitstreams require protection from channel errors in a wireless channel and protection from packet loss in a wired ATM channel. The three-dimensional (3-D) SPIHT coder has proved its efficiency and it...
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ISBN:
(纸本)0819437603
Compressed video bitstreams require protection from channel errors in a wireless channel and protection from packet loss in a wired ATM 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(1) combined with a single ARQ (automatic-repeat-request) proved to be an effective means for protecting the bitstream. There were two problems with this scheme: the noiseless reverse channel ARQ may not be feasible in practice;and, in the absence of channelcoding and ARQ, the decoded sequence was hopelessly corrupted even for relatively clean channels. In this paper, we first show how to make the 3-D SPIHT bitstream more robust to channel errors by breaking the wavelet transform into a number of spatio-temporal tree blocks which can be encoded and decoded independently. This procedure brings the added benefit of parallelization of the compression and decompression algorithms. Then we demonstrate the packetization of the bit stream and the reorganization of these packets to achieve scalability in bit rate and/or resolution in addition to robustness. Then we encode each packet with a channel code. Not only does this protect the integrity of the packets in most cases, but it also allows detection of packet decoding failures, so that only the cleanly recovered packets are reconstructed. This procedure obviates ARQ, because the performance is only about 1 dB worse than normal 3-D SPIHT with FEC and ARQ. Furthermore, the parallelization makes possible real-time implementation in hardware and software.
Arikan and Merhav proved joint source-channelcoding theorems for guessing decoders based on Gallager's method. But, in this paper, only channelcoding is considered to derive a stronger channelcoding theorem for...
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ISBN:
(纸本)9781457705953
Arikan and Merhav proved joint source-channelcoding theorems for guessing decoders based on Gallager's method. But, in this paper, only channelcoding is considered to derive a stronger channelcoding theorem for constant composition universal codes based on the method of types. Furthermore, the coding theorem is applied to the wiretap channelcoding problem.
Recently DFT codes have been considered for use as joint source-channel codes in order to provide robustness against packet loss in IP networks. In this paper, we propose a recursive syndrome decoding algorithm of DFT...
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ISBN:
(纸本)0780374029
Recently DFT codes have been considered for use as joint source-channel codes in order to provide robustness against packet loss in IP networks. In this paper, we propose a recursive syndrome decoding algorithm of DFT codes for bursty erasure patterns. The algorithm is based on the statistical properties of the quantization error and the codevector. The statistical analysis of the codevector is independent of the proposed algorithm. We also analyze the error performance of the proposed decoding scheme, and show that it can perform better than the conventional syndrome decoding of DFT codes if the message signal model and quantization error model assumptions are valid. Simulation results with a Gauss-Markov source are presented.
Distributed coding is a new paradigm for video compression based on Slepian-Wolf (1973) and Wyner-Ziv (1976) theorems. In this paper, we propose a new pixel-domain Distributed Video coding (DVC) scheme, in which both ...
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ISBN:
(纸本)9780769543529
Distributed coding is a new paradigm for video compression based on Slepian-Wolf (1973) and Wyner-Ziv (1976) theorems. In this paper, we propose a new pixel-domain Distributed Video coding (DVC) scheme, in which both the temporal and the spatial correlations are exploited only at the decoder. A joint source-channel decoding is implemented to exploit the source statistics. Iterations between the Map channel decoder and the BCJR source decoder are made to improve the global decoder performance. Simulations results show that a gain is obtained, in term of rate, with iterative joint source-channel decoding, compared to the basic decoding.
In zero-delay joint source-channelcoding each source sample is mapped to a channel input, and the samples are directly estimated at the receiver based on the corresponding channel output. Despite its simplicity, unco...
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ISBN:
(纸本)9781479948772
In zero-delay joint source-channelcoding each source sample is mapped to a channel input, and the samples are directly estimated at the receiver based on the corresponding channel output. Despite its simplicity, uncoded transmission achieves the optimal end-to-end distortion performance in some communication scenarios, significantly simplifying the encoding and decoding operations, and reducing the coding delay. Three different communication scenarios are considered here, for which uncoded transmission is shown to achieve either optimal or near-optimal performance. First, the problem of transmitting a Gaussian source over a block-fading channel with block-fading side information is considered. In this problem, uncoded linear transmission is shown to achieve the optimal performance for certain side information distributions, while separate source and channelcoding fails to achieve the optimal performance. Then, uncoded transmission is shown to be optimal for transmitting correlated multivariate Gaussian sources over a multiple-input multiple-output (MIMO) channel in the low signal to noise ratio (SNR) regime. Finally, motivated by practical systems a peak-power constraint (PPC) is imposed on the transmitter's channel input. Since linear transmission is not possible in this case, non-linear transmission schemes are proposed and shown to perform very close to the lower bound.
We study the transmission of a single random variable across the Poisson channel, which takes a continuous-time waveform {lambda(t) : 0 <= lambda(t) <= T} as an input, where 0 <= lambda(t) <= A, for all 0 ...
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ISBN:
(纸本)9781467325790
We study the transmission of a single random variable across the Poisson channel, which takes a continuous-time waveform {lambda(t) : 0 <= lambda(t) <= T} as an input, where 0 <= lambda(t) <= A, for all 0 <= t <= T. The output of the channel is a non-homogeneous Poisson arrival process with rate lambda(T). We explore the class of schemes that are optimal in the distortion exponent sense under mean squared loss. We determine a family of optimal encoders for this channel which achieves the minimum mean squared error. In addition, we characterize the distortion exponent for 'separation' based schemes, and also provide an upper bound for the maximal distortion exponent across all joint sourcechannel strategies under this setting.
We present two access schemes for the transmission of discrete-time analog symbols over a block fading MIMO Multiple Access channel (MAC). We first describe a CDMA-like strategy employed to allow the orthogonal transm...
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ISBN:
(纸本)9781479914814
We present two access schemes for the transmission of discrete-time analog symbols over a block fading MIMO Multiple Access channel (MAC). We first describe a CDMA-like strategy employed to allow the orthogonal transmission of the information of the multiple users. When the channel State Information (CSI) is available at the transmitters, we propose to exploit such a knowledge to obtain the optimal linear access codes that minimize the sum-MSE. Both schemes provide a flexible framework where the access codes of the MAC users can be designed for any distribution of the user rates. We also show that the performance of the proposed systems closely approach the theoretical limits when the source information is transmitted over the MIMO MAC using analog Joint sourcechannelcoding (JSCC).
In this paper, we propose a joint source-channel (JSC) decoding scheme for 3D ESCOT-based video coders, such as Vidwav. The embedded bitstream generated by such coders is very sensitive to transmission errors unavoida...
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ISBN:
(纸本)9781424479948
In this paper, we propose a joint source-channel (JSC) decoding scheme for 3D ESCOT-based video coders, such as Vidwav. The embedded bitstream generated by such coders is very sensitive to transmission errors unavoidable on wireless channels. The proposed JSC decoder employs the residual redundancy left in the bitstream by the source coder combined with bit reliability information provided by the channel or channel decoder to correct transmission errors. When considering an AWGN channel, the performance gains are in average 4 dB in terms of PSNR of the reconstructed frames, and 0.7 dB in terms of channel SNR. When considering individual frames, the obtained gain is up to 15 dB in PSNR.
We investigate channel code rates for communication of finite-dimensional analog sources over a multiple-antenna multiple access channel (MAC) so that the average end-to-end distortions are minimized. Our analysis use...
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ISBN:
(纸本)9781457705953
We investigate channel code rates for communication of finite-dimensional analog sources over a multiple-antenna multiple access channel (MAC) so that the average end-to-end distortions are minimized. Our analysis uses the high-resolution quantization theory for the sources and the high-SNR diversity-multiplexing tradeoff for the MAC. We prove that carefully balanced channelcoding rates, usually far from the boundary of the MAC capacity region, are necessary to achieve the optimal distortion exponent in a separated architecture. In particular, for the case of source vectors of equal dimension, we show that the channel interference from multiple users becomes crucial in characterizing the optimal channelcoding rates if individual minimization of distortion for each user leads to a heavily loaded regime for the MAC.
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