In this work we consider the problem of combined source-channel coding for H.263 coded video transmitted over a wireless channel modeled as a slow-fading Rician channel. We use non-binary bandwidth-efficient trellis-c...
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In this work we consider the problem of combined source-channel coding for H.263 coded video transmitted over a wireless channel modeled as a slow-fading Rician channel. We use non-binary bandwidth-efficient trellis-coded modulation (TCM) employing appropriate phase-shift keyed modulation, and determine the optimal tradeoff between source and channel coding for the Rician channel as a function of the specular-to-diffuse energy ratio and the channel SNR. We show that if feedback on channel parameters is available, the video information can be optimally coded according to channel characteristics.
A combined source coding and multicarrier modulation scheme for transmitting image over noisy channels is proposed. The source image is divided into several layers which are transmitted in parallel, each occupying a n...
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A combined source coding and multicarrier modulation scheme for transmitting image over noisy channels is proposed. The source image is divided into several layers which are transmitted in parallel, each occupying a number of subchannels. For spectrally shaped channels, the existing loading algorithms try to remove the property that channel gain and noisy variance are quite different across the subchannels, and use the power and rate allocation to provide an uniform error performance at the usable subchannels. In contrast, we deem the above property as an advantage and develop a new loading algorithm to provide unequal error protection as well as achieve better power efficiency. For subband coded images transmission, simulations show that the proposed algorithm achieves significant performance improvement, especially, 4-10 dB improvement over the existing algorithms for typical spectrally shaped channels.
In this paper, we propose a complete transmission system for still images which minimizes the distortion introduced by residual transmission errors. This system comprises a source encoder combining DCT (discrete cosin...
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In this paper, we propose a complete transmission system for still images which minimizes the distortion introduced by residual transmission errors. This system comprises a source encoder combining DCT (discrete cosine transform) and VQ (vector quantization). The compression rate is equal to 16.7 for an average PSNR (peak signal to noise ratio) of 29.2 dB. The data are then encoded by a BCH (63,57,3) block code and mapped on a 64-QAM constellation. The parameters of the code book and channel encoder have been optimized for 64-QAM. For channel decoding, we use maximum likelihood sequence decoding. The PSNR of the reconstructed image in the receiver is equal to 28.6 dB for a channel SNR of 11 dB. This represents a very small degradation of the PSNR (0.6 dB) in presence of a SER (symbol error rate) of 10% at the input of the receiver.
Concatenated coding schemes with Reed-Solomon (RS) coding in the outer stage and trellis coded modulation (TCM) in the inner stage are analyzed. The TCM decoder incorporates a Viterbi decoder compliant with ITU-T Reco...
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Concatenated coding schemes with Reed-Solomon (RS) coding in the outer stage and trellis coded modulation (TCM) in the inner stage are analyzed. The TCM decoder incorporates a Viterbi decoder compliant with ITU-T Recommendation J.83, Annex B (north American digital video transmission specifications for multimedia cable network system (MCNS)). The module is suitable as the inner stage for a concatenated decoding scheme. A triple-error-correcting extended RS (128,122,7) code is used in the outer stage. Union bounds on the bit error performance of concatenated coding schemes, over 64- and 256-QAM signal constellations over AWGN channels are derived and verified by computer simulations. The effects of quantization of input symbols and of trace-back depth in the Viterbi decoder are simulated as well.
The capacity of a wireless communication system based on the OFDM transmission technique is analysed. The considered system, which includes a TDMA approach, is designed for mobile access to different multimedia servic...
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The capacity of a wireless communication system based on the OFDM transmission technique is analysed. The considered system, which includes a TDMA approach, is designed for mobile access to different multimedia services, such as speech, video, e-mail and file transfer. In order to support a variety of services on the one hand and to take into account the behaviour of the frequency-selective radio channel on the other hand, an adaptive allocation of modulation and coding scheme is supplied. For this purpose, an optimal combination of modulation scheme and code rate is determined in a first step. Using these results, the capacity of such a system is analysed by calculating the number of supported users within a cell and comparing these numbers to a system with fixed modulation/coding.
Block codes based on Golay complementary sequences have been proposed for orthogonal frequency division multiplexing (OFDM) transmission to obtain signals with flat envelopes. These codes confine the peak-to-average p...
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Block codes based on Golay complementary sequences have been proposed for orthogonal frequency division multiplexing (OFDM) transmission to obtain signals with flat envelopes. These codes confine the peak-to-average power ratio of multicarrier signals to a favorable value of 3 dB at the cost of a lower code rate. Additionally, the coding employs diversity which renders a performance improvement in frequency-selective fading channels. This paper contains a discussion on the capabilities and the limits of OFDM transmission techniques using such codes. Different coding and modulation schemes are compared and guidelines are provided for the choice of the appropriate transmission scheme. The Magic WAND (wireless ATM network demonstrator) system set-up is used to discuss the requirements of a practical system.
作者：
O'Leary, SRTE
Network Capital Projects Dublin 4 Ireland
The digital terrestrial television standard approved by the European Telecommunications Standards Institute (ETSI) is based upon the work of the Digital Video Broadcasting group (DVB-T). This standard using Coded Orth...
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The digital terrestrial television standard approved by the European Telecommunications Standards Institute (ETSI) is based upon the work of the Digital Video Broadcasting group (DVB-T). This standard using Coded Orthogonal Frequency Division Multiplexing (COFDM) facilities the establishment of Single Frequency Networks (SFN). The first MPEG2 distributed SFN was established by RTE and other partners of the European Commission sponsored project VALIDATE (Verification and Launch of Integrated Digital Advanced Television in Europe) in Ireland. This paper describes the network established and details some of the measurements performed. Two co-channel UHF transmitters were synchronized using the MPEG2 megaframe identification packet (MIP). A 155 Mbit/sec STM-1 microwave link system was used for signal distribution.
Two new signal space detectors designed to take advantage of maximum transition run (MTR) coded modulation are presented. These detectors are designed to perform across a wide range of densities and offer lower error ...
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Two new signal space detectors designed to take advantage of maximum transition run (MTR) coded modulation are presented. These detectors are designed to perform across a wide range of densities and offer lower error rates than a 3D-110 detector at low densities while requiring only modest increases in complexity. The first scheme, 2D-121 alpha employs an equalization constraint that reduces low density noise correlation relative to the 3D-110 target. The second uses a 3D-110 detector but includes a linear noise predictive filter to reduce the effective noise between the minimum distance sequences, Analysis and simulation results indicate that the two detectors perform equally well in terms of bit error rate.
The channel IC described here achieves data rates of 360 Mb/s at performance levels that improve in various directions upon the state of the art, It accomplishes these feats in a mature 1 mu m CBiCMOS techology at a r...
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The channel IC described here achieves data rates of 360 Mb/s at performance levels that improve in various directions upon the state of the art, It accomplishes these feats in a mature 1 mu m CBiCMOS techology at a read-mode power consumption of only 800 mW. The paper discusses some of the underlying architectural concepts.
This article addresses the problem of embedding a robust copyright label into image data for identifying the ownership and distribution of the digitized image. The article first defines a reasonable set of functional ...
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This article addresses the problem of embedding a robust copyright label into image data for identifying the ownership and distribution of the digitized image. The article first defines a reasonable set of functional requirements and design criteria for an image copyright labeling system, and then describes a labeling method using a JPEG model-based, frequency-hopped, randomly sequenced pulse position modulated code (RSPPMC). Our experiments demonstrated that the proposed method meets the requirements for copyright protection, including the robustness of an embedded label against several damaging possibilities such as lossy data compression, low-pass filtering, and color space conversion, as well as printing/scanning, scaling, and cropping.
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