Iterative source-channel decoding (IS CD) exploits the residual redundancy of the source by iteratively exchanging extrinsic information with the channel codecs to achieve robust transmission. In this treatise we prop...
详细信息
ISBN:
(纸本)9781467359399;9781467359382
Iterative source-channel decoding (IS CD) exploits the residual redundancy of the source by iteratively exchanging extrinsic information with the channel codecs to achieve robust transmission. In this treatise we propose a video codec suitable for lossless video compression and IS CD. At the encoder the spatio-temporal redundancy is partially removed at a low complexity by simply evaluating the frame difference (FD), which is then variable-length encoded (VLC). At the receiver we invoke a three-stage concatenated IS CD scheme for exploiting the residual redundancy of the FD. A Markov Random Field (MRF) model based soft-in-soft-out (SISO) module is proposed for exploiting the spatial correlations amongst the adjacent video pixels, using intra-frame coding. More explicitly, the VLC SISO decoder operates by exchanging soft information with both the MRF module and the soft channel decoder. The convergence of the three-stage iterative decoding process is examined using 3D extrinsic information transfer (EXIT) charts. Finally, we show that our system exhibits a substantial E-b/N-O improvement of about 5.2 dB compared to the corresponding benchmarker schemes.
In cooperative networks, despite its simplicity, the decode-and-forward protocol suffers from the problem of error propagation when the source-relay channel is noisy. By forwarding erroneous decoded messages, the rela...
详细信息
ISBN:
(纸本)9781467361873
In cooperative networks, despite its simplicity, the decode-and-forward protocol suffers from the problem of error propagation when the source-relay channel is noisy. By forwarding erroneous decoded messages, the relay significantly degrades the diversity order of the system. One trivial solution was to restrict the use of decode-and-forward protocol to reliable source-relay transmissions. However, the forwarded messages from the relay can be seen as data correlated with that transmitted by the source. This property can be exploited in order to allievate the error propagation phenomenon. The problem of joint decoding of correlated sources is then directly transposed to the relay network. In this paper, we propose to exploit the potential correlation existing between the source and the relay messages in order to achieve enhanced end-to-end performance. Performance comparison with classical decoding of the decode-and-forward protocol is conducted especially under degraded source-relay channel conditions. We derive an analytical upper bound on the probability of error at the destination, which is verified by simulation results.
The aim of the 3rd generation networks is to combine the multimedia services over Internet and provide them on wireless mobile platforms. The stability, interoperability and robustness offered by MPEG-4 (Moving Pictur...
详细信息
ISBN:
(纸本)078039335X
The aim of the 3rd generation networks is to combine the multimedia services over Internet and provide them on wireless mobile platforms. The stability, interoperability and robustness offered by MPEG-4 (Moving Picture Experts Group) make it an ideal solution for mobile networks, and it has been selected by 3GPP (the 3rd Generation Partnership) and 3GPP2 for 3G phones. Burst and random bit errors introduced by fading channels will degrade MPEG-4 streams. Conventional error correcting techniques cannot correct these errors. In this paper, a JSCC (joint source-channelcoding) method based on MPEG-4 system and Turbo coder has been proposed. The critical important MPEG-4 streams such as the BIFS (Binary Format for Scenes), OD (Object Descriptors) and IOD (Initial Object Descriptors) streams are transmitted by using TCP (Transmission Control Protocol), and MPEG-4 audio/video ES (Elementary Streams) are transmitted by using UDP (User Datagram Protocol) over 3G channels. Transmission UDP packets is adopted UEP (Unequal Error Protection) Turbo codes according to MPEG-4 audio/video data partitioning. Simulation results show that this method can effectively improve the performance.
We consider the transmission of a complex Gaussian source over a single-input multiple-output (SIMO) quasi-static fading channel. The goal is to minimize the expected distortion of the reconstructed signal at the rece...
详细信息
ISBN:
(纸本)9781424415632
We consider the transmission of a complex Gaussian source over a single-input multiple-output (SIMO) quasi-static fading channel. The goal is to minimize the expected distortion of the reconstructed signal at the receiver. A delay-limited scenario is assumed where channelcoding is restricted to a single realization of the channel. Quantized channel state information at the transmitter (CSIT) is obtained using a noisy, fixed-rate feedback link and is used to adjust the transmission rate and power. A channel optimized scaler quantizer (COSQ) is designed to incorporate the effects of the errors in the feedback link. For a high quality feedback channel, the proposed COSQ performs close to the noiseless feedback case, while its performance converges to the no-feedback scenario as the feedback channel quality degrades. We show that noisy feedback does not improve the performance at asymptotically high signal to noise ratios (SNRs). Nevertheless, the numerical results for a Rayleigh fading channel show that noisy feedback provides significant gains for practical values of the SNR.
We describe techniques for joint source-channelcoding of hidden Markov sources using a modified turbo decoding algorithm. This avoids the need to perform any explicit sourcecoding prior to transmission, and instead ...
详细信息
ISBN:
(纸本)0818684062
We describe techniques for joint source-channelcoding of hidden Markov sources using a modified turbo decoding algorithm. This avoids the need to perform any explicit sourcecoding prior to transmission, and instead allows the decoder to utilize the a priori structure due to the hidden Markov source. In addition, we present methods that allow the decoder to estimate the parameters of the Markov model. In combination, these techniques allow the decoder to identify, estimate, and exploit the source structure. The estimation does not degrade the performance of the system, i.e. the joint estimation/decoding allows convergence at the same noise levels as a system in which the decoder has perfect a priori knowledge of the source parameters.
We consider Slepian-Wolf code design (or sourcecoding with side information) based on LDPC codes. We show that density evolution defined in conventional channelcoding can be used in analyzing the Slepian-Wolf coding...
详细信息
ISBN:
(纸本)0780387201
We consider Slepian-Wolf code design (or sourcecoding with side information) based on LDPC codes. We show that density evolution defined in conventional channelcoding can be used in analyzing the Slepian-Wolf coding performance provided that certain symmetry condition, dubbed dual symmetry, is satisfied by the hypothetical channel between the source and the side information. Exploiting such an analysis, we design an efficient LDPC code based Slepian-Wolf coding scheme and apply it to the quadratic Gaussian Wyner-Ziv problems.
In this paper, we study the performances of various layered source-channelcoding schemes over two-way relay networks, where the sources are coded into different layers and transmitted by progressive coding or superpo...
详细信息
ISBN:
(纸本)9781467361873
In this paper, we study the performances of various layered source-channelcoding schemes over two-way relay networks, where the sources are coded into different layers and transmitted by progressive coding or superposition coding. The two-way relay network employs multiple-access-broadcast or time-division-broadcast protocol, and the relay uses decode-and-forward (DF) protocol. We first derive the optimal distortion exponents of different schemes at high signal-to-noise ratios (SNRs). Fast resource allocation algorithms are then developed to optimize the expected distortion of the source at finite SNRs. Simulation results show that layered coding achieves better performance than single rate coding, and the proposed fast resource allocation scheme is near-optimal.
Consider the problem of broadcasting an i.i.d. source sequence X = {X-i}(i=1)(N) (possibly N --> infinity) to n listeners over a discrete broadcast channel, consisting of n channels with capacities C-1 = C-max grea...
详细信息
ISBN:
(纸本)0780387201
Consider the problem of broadcasting an i.i.d. source sequence X = {X-i}(i=1)(N) (possibly N --> infinity) to n listeners over a discrete broadcast channel, consisting of n channels with capacities C-1 = C-max greater than or equal to C-2 greater than or equal to ... greater than or equal to C-n = C-min. Let the tuple D = (D-1, D-2,..., D-n) represent the average distortion in reconstructing sources at the n listerners. The problem of characteriziing all achievable tuples D is till open for a general case. for a fairly general class of discrete channels, we prove the achievability of the tuple Q(n) (rho(1), rho(2),..., rho(n)) = (D-X(rho(1)C(1) - zeta), D-X(rho(1)C(2) - zeta),..., D-X(rho(n)C(n) - zeta)), provided that lambda(i) = (rho(i)C(i) - rho(i+1)C(i+1))/C-i > 0, for 1 less than or equal to i less than or equal to n - 1, lambda(n) = rho(n) and Sigma(i=1)(n-1) lambda(i) less than or equal to 1, where D-X(R) is the distortion rate function of X. The penalty term zeta = 1/2 for a gernal source with real alphabets and is zeta = 0 if X is progressisely refinable. The factor 0 less than or equal to rho(i) less than or equal to 1 is call the utilization of the ith channel. As an example, for n = 2, we show that Q(2)(1/(2 - C-2/C-1), 1/(2 - C-1/C-2)) is achievable for any C-1, C-2. Furthermore , the common utilization of rho = (1 + In(C-max/C-min))(-1) is shown to be achievable for al channels. Conversely, we find examples of channels namely erasure switch-to-talk channels, for which the proposed achievable utilizations are tight. In particular, while Q(3)(2/3, 2/3, 2/3) is achievable for any compatible broadcast channel with capacities C-1 = 2C(2) = 2C(3), for any delta > 0, we find examples of channels for which Q(3)(2/3 + delta, 2/3 + delta, 2/3 + delta) is not achievable.
The deep joint source-channelcoding and modulation (JSCCM) is a promising technology to realize efficient communication over extreme environments such as underwater area. In previous works, it is shown that deep conv...
详细信息
ISBN:
(纸本)9781665435406
The deep joint source-channelcoding and modulation (JSCCM) is a promising technology to realize efficient communication over extreme environments such as underwater area. In previous works, it is shown that deep convolutional neural networks (CNN) can successfully learn JSCCM encoder and decoder, outperforming conventional separation-based coding and modulation schemes in low signal-to-noise ratio settings. This paper proposes a new architecture for deep JSCCM based on the self-attention mechanism. We show that the proposed architecture achieves significant performance improvement compared with the CNN-based schemes while requiring a smaller network size in terms of the number of weight parameters. Furthermore, we present efficient hardware implementation of the proposed JSCCM encoder on a field programmable gate array (FPGA). In particular, we demonstrate that a systolic-array-like structure is effective for FPGA implementation of the proposed JSCCM scheme based on the self-attention mechanism.
This paper continues the investigation of the combinatorial formulation of the joint source-channelcoding problem. In particular, the connections are drawn to error-reducing codes, isometric embeddings and list-decod...
详细信息
ISBN:
(纸本)9781467302234;9781467302241
This paper continues the investigation of the combinatorial formulation of the joint source-channelcoding problem. In particular, the connections are drawn to error-reducing codes, isometric embeddings and list-decodable codes. The optimal performance for the repetition construction is derived and is shown to be achievable by low complexity Markov decoders. The compound variation of the problem is proposed and some initial results are put forward.
暂无评论