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Achievable information rates and coding for MIMO systems over ISI channels and frequency-selective fading channels

IEEE TRANSACTIONS ON COMMUNICATIONS 2004年第10期52卷 1698-1710页

作者： Zhang, Z Duman, TM Kurtas, EA Arizona State Univ Dept Elect Engn Tempe AZ 85287 USA Seagate Technol Pittsburgh PA 15222 USA

We propose a simulation-based method to compute the achievable information rates for general multiple-input multiple-output (MIMO) intersymbol interference (ISI) channels with inputs chosen from a finite alphabet. This method is applicable to both deterministic and stochastic channels. As an example of the stochastic MIMO ISI channels, we consider the multiantenna systems over frequency-selective fading channels, and quantify the improvement in the achievable information rates provided by the additional frequency diversity (for both ergodic and nonergodic cases). In addition, we consider the multiaccess multiantenna system and present some results on the achievable information-rate region. As for the deterministic MIMO ISI channels, we use the binary-input multitrack magnetic recording system as an example, which employs multiple write and read heads for data storage. Our results show that the multitrack recording channels have significant advantages over the single-track channels, in terms of the achievable information rates when the inter-track interference is considered. We further consider practical coding schemes over both stochastic and deterministic MIMO ISI channels, and compare their performance with the information-theoretical limits. Specifically, we demonstrate that the performance of the turbo coding/decoding scheme is only about 1.0 dB away from the information-theoretical limits at a bit-error rate of 10(-5) for large interleaver lengths.

关键词： channel capacity frequency-selective fading information rates intersymbol interference (ISI) iterative decoding multiantenna systems multiple-input multiple-output (MIMO) systems multitrack recording turbo coding

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Statistical decision making in adaptive modulation and coding for 3G wireless systems

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2005年第6期54卷 2066-2073页

作者： Yang, J Khandani, AK Tin, N Univ Waterloo Dept Elect & Comp Engn Coding & Signal Transmiss Lab Waterloo ON N2L 3G1 Canada Bell Mobil Mississauga ON L4W 5N2 Canada

In this paper, we address the application of adaptive modulation and coding (AMC) for 3rd-generation (3G) wireless systems. We propose a new method for selecting the appropriate modulation and coding schemes (MCS) according to the estimated channel condition. In this method, we take a statistical decision making approach to maximize the average throughput while maintaining an acceptable frame error rate (FER). We use a first order finite state Markov model to approximate the time variations of the average channel signal to noise ratio (SNR) in subsequent frames. The MCS is selected in each state of this Markov model (among the choices proposed in the 3G standards proposals) to maximize the statistical average of the throughput in that state. Using this decision making approach, we also propose a simplified Markov model with fewer parameters, which is suitable in systems where changes in the fading characteristics need to be accounted for in an adaptive fashion. Numerical results are presented showing that both of our models substantially outperform the conventional techniques that use a memoryless threshold based decision making.

关键词： adaptive modulation and coding (AMC) first-order finite-state Markov model 3rd-generation (3G) code division multiple access (CDMA) lognormal shadowing spectral efficiency turbo coding

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Unidirectional distributed video coding for low cost video encoding

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IEEE TRANSACTIONS ON CONSUMER ELECTRONICS 2007年第2期53卷 788-795页

作者： Weerakkody, W. A. R. J. Fernando, W. A. C. Adikari, A. B. B. Brunel Univ Uxbridge UB8 3TY Middx England

Distributed Video coding (DVC) is an emerging video coding approach in the new era, particularly attractive due to its flexibility to introduce very simple encoder structures. This feature could be very effectively utilized in the design of low cost video. cameras. However, the DVC architecture commonly discussed in research literature has a fundamental drawback of involving a feedback channel between the encoder and the decoder, which restrains itself from being used in video storage based applications. In this paper, we discuss a solution to the above problem in DVC, with a novel unidirectional architecture. In the proposed design, the feedback channel is suppressed and the encoded (compressed) bit stream can be transferred onto storage media for offline processing. The proposed decoder uses the spatial and temporal properties of the video sequence to refine the side information for iterative decoding, with the repeated use of same parity bit stream. The simulation results depict a significantly improved performance over other conventional video coding techniques proposed for use in low to middle end video equipments, while involving a very low encoder complexity.

关键词： distributed video coding turbo coding Wyner-Ziv coding

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Informed watermarking by means of orthogonal and quasi-orthogonal dirty paper coding

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2005年第2期53卷 824-833页

作者： Abrardo, A Barni, M Univ Siena Dept Informat Engn I-53100 Siena Italy

A new dirty paper coding technique that is robust against the gain attack is presented. Such a robustness is obtained by Adopting a set of (orthogonal) equi-energetic codewords and a correlation-based decoder. Due to the simple structure of orthogonal codes, we developed a simple yet powerful technique to embed the hidden message within the host signal. The proposed technique is an optimal one, in that the embedding distortion is minimized for a given robustness level, where robustness is measured through the maximum pairwise error probability in the presence of an additive Gaussian attack of given strength. The performance of the dirty coding algorithm is further. improved by replacing orthogonal with quasi- orthogonal codes, namely, Gold sequences, and by concatenating them with an outer turbo code. To this aim, the inner decoder is modified to produce a soft estimate of the embedded message. Performance analysis is carried out by means of extensive simulations proving the validity of the novel watermarking scheme.

关键词： dirty paper coding informed embedding informed watermarking orthogonal codes spherical codes turbo coding

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Lossless source coding using nested error correcting codes

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2007年第6期55卷 2583-2592页

作者： Haghighat, Javad Hamouda, Walaa Soleymani, Mohammad Reza Concordia Univ Dept Elect & Comp Engn Montreal PQ H3G 1M8 Canada

We propose a tree-structured variable-length random binning scheme for lossless source coding. The existing source coding schemes based on turbo codes, low-density parity check codes, and repeat accumulate codes can be regarded as practical implementations of this random binning scheme. For sufficiently large data blocks, we show that the proposed scheme asymptotically achieves the entropy limit. We also derive the distribution of the compression rate achieved by the tree-structured random binning scheme. Comparing this distribution with the distribution obtained using a library of random binning schemes, we show that a nested code can achieve rates close to a library of codes but with much lower encoding/decoding complexity. With lossless turbo source coding being one of the most powerful source compression techniques, we investigate its performance relative to the proposed tree-structured random binning scheme. Our numerical results show that the compression rate achieved by lossless turbo source coding is far from the tree-structured random binning bound. In that, we suggest improvements to enable short-block-length turbo source codes to achieve compression rates close to the tree-structured random binning bound.

关键词： entropy nested codes random binning source coding turbo coding

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Adaptive Channel coding to Enhance the Performance in Rayleigh Channel

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INTERNATIONAL JOURNAL OF ADVANCED COMPUTER SCIENCE AND APPLICATIONS 2024年第6期15卷 504-511页

作者： Srividya, L. Sudha, P. N. Dayananda Sagar Coll Engn Dept Elect & Commun Engn Bangalore India KS Inst Technol Dept Elect & Commun Engn Bangalore India

Rayleigh fading channel model is usually used to model real time wireless mobile communication as it has the potential to emulate the multipath scattering effect, dispersion, fading, reflection, refraction and Doppler shift. Mobility and interferences, will change the channel conditions over the time and so will the error environment and results in variable bit error rates (BER). Fixed channel coding schemes have proven in providing reliability of the data despite of poor channel conditions, but fails to contend with time varying channel conditions. Hence they suffer loss in the information rate during good channel conditions. There is need for adaptive scheme that adapts dynamically to channel conditions improving the overall performance and reliability in communication. An adaptive channel coding technique(ACC) is proposed in this paper which requires a simple statistics from the receiver and switches two channel coding schemes dynamically to the changing environment and makes it different from other schemes which deals dynamic tuning of parameters of one Error control coding (ECC) scheme. This strategy not only guarantees reliability but also spectral efficiency as channel capacity is utilized effectively by switching between two ECCs, less robust (high data rate) Convolutional ECC is used when the channel conditions are good and more robust (low data rate) turbo ECC is used when the channel conditions degraded. Proposed concept is implemented using MATLAB and results outperforms the conventional fixed ECC schemes, an effective reduction of Eb/N0 requirement is obtained for a target BER compared to the fixed or predetermined ECCs. ACC is tested under various mobile channel environment and proven resilient to varying channel conditions. It is beneficial in providing flexibility in QoS by changing the switching criteria according to the application.

关键词： Adaptive error control coding turbo coding convolutional coding bit error rate throughput Rayleigh channel

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A full-rate complex orthogonal space-time block coding scheme for multiple antennas

A full-rate complex orthogonal space-time block coding schem...

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International Symposium on Communications and Information Technologies (ISCIT2005)

作者： Yu, XB Xu, WY Xu, DZ Bi, GG Nanjing Univ Aeronaut & Astronaut Coll Informat Sci & Technol Nanjing 210016 Peoples R China

ISBN: (纸本)0780395387

In this paper, a full-rate complex orthogonal space-time block (STB) coding scheme for multiple antennas in time division duplex (TDD) mode is proposed. Meanwhile, we employ turbo code as channel coding to improve the performance of proposed STB code further by utilizing its soft decision information from multiple iterations decoding, random interleaver and good ability to combat the burst error of fading channel. Compared with full-diversity multiple antennas STB code schemes, the proposed code scheme can implement full rate, partial diversity and a smaller complexity. On the condition of same system throughput and concatenation of turbo code, the code has lower bit error rate (BER) than those low-rate and full-diversity codes.

关键词： space-time block code turbo coding full rate multiple antennas transmit diversity

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Capacity enhancement of compressed domain watermarking channel using duo-binary coding

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5th International Workshop on Digital Watermarking

作者： Damnjanovic, Ivan Izquierdo, Ebroul Queen Mary Univ London Dept Elect Engn Mile End Rd London E1 4NS England

ISBN: (纸本)3540488251

One of the main goals of watermarking is to optimize capacity while preserving high video fidelity. This paper describes a watermarking scheme based on the spread spectrum paradigm with capacity enhancement using a state-of-the-art error correction technique - duo-binary turbo coding. A new watermark composition with novel bit-wise watermark bits interleaving scheme and bit-rate control on the macro-block level is proposed. In previous works, the perceptual watermark adjustment was mainly based on Watson Just Noticeable Difference (JND) model. A new JND estimation model based on block classification is presented. In addition, experimental results on perceptibility and robustness to transcoding are reported.

关键词： digital watermarking MPEG2 turbo coding JND model block classification

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Error correction coding of non-linear side-informed watermarking schemes

Error correction coding of non-linear side-informed watermar...

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6th Conference on Watermarking of Multimedia Contents

作者： Whelan, KM Silvestre, GCM Hurley, NJ Univ Coll Dublin Dept Comp Sci Dublin 2 Ireland

ISBN: (纸本)0819452092

The application of error correction coding to side-informed watermarking utilizing polynomial detectors is investigated. The overall system is viewed as a code concatenation in which the outer code is a powerful channel code and the inner code is a low rate repetition code. For the inner code we adopt our previously proposed side-informed embedding scheme in which the watermark direction is set to the gradient of the detection function in order to reduce the effect of host signal interference. turbo codes are employed as the outer code due to their near capacity performance. The overall rate of the concatenation is kept constant while parameters of the constituent codes are varied. For the inner code, the degree of non-linearity of the detector along with repetition rate is varied. For a given embedding and attack strength, we determine empirically the best rate combinations for constituent codes. The performance of the scheme is evaluated in terms of bit error rate when subjected to various attacks such as additive/multiplicative noise and scaling by a constant factor. We compare the performance of the proposed scheme to the Spread Transform Scalar Costa Scheme using the same rates when subjected to the same attacks.

关键词： side-informed watermarking non-linear detection turbo coding spread-spectrum watermarking

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Distributed video coding of Wyner-Ziv frames using trellis coded modulation

Distributed video coding of Wyner-Ziv frames using trellis c...

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19th IEEE Canadian Conference on Electrical and Computer Engineering

作者： Weerakkody, W. A. R. J. Fernando, W. A. C. Adikari, A. B. B. Brunel Univ Sch Engn & Design Uxbridge UB8 3PH Middx England

ISBN: (纸本)9781424400379

Distributed Video coding (DVC) is known as an emerging video coding technique, which primarily has a modified complexity balance in the encoder and decoder, in contrast to its traditional competitors. In DVC we have a very simple low cost encoder which is an ideal feature for applications involving a large number of video capturing points located remotely and a centralized shared decoder. In this paper, we introduce a novel approach for DVC using turbo Trellis Coded Modulation (TTCM) to generate the parity information at the encoder to be sent over the channel and then to decode the parity with the side information at the decoder. The side information is generated using key frames passed to the decoder by the use of a pixel interpolation technique. TCM symbols are formed using the side information and the parity bit stream which are fed to the TTCM decoder. The decoded output is used to reconstruct the final video sequence. The results are compared with a turbo coding based DVC and it is evident that the proposed method outperforms its turbo code based counterpart by a significant margin.

关键词： DVC Wyner-Ziv coding TTCM turbo coding

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