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21st Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Kahraman, Sinan Celebi, Mehmet Ertugrul T&#x00FC bitak-Uekae Turkey

ISBN: (纸本)9781424480166

In this paper, we propose a technique which is efficient in reducing the required computational complexity of the maximum-likelihood decoding for BLAST system. Our technique is based on the determination of reducible computational complexity for any given BLAST system. In this fashion a specialized decoding can be defined. Our idea is based on the determination of zero entries of the upper-triangular matrix R which occurs in QR-decomposition step of the sphere decoding algorithm. Through the determined zero at kth row of the matrix R, at least 8 arithmetic operations can be canceled for every time of node visiting in the search tree at level k. Furthermore, properties of the matrix structure can be exploited in sphere decoding in order to reduce complexity of the metric computations for each branch. For this case, considerable saving in the computational complexity can be obtained.

关键词： BLAST decoding complexity MIMO ML estimation QR-decomposition sphere decoder

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Exponential error bounds and decoding complexity for block concatenated codes with tail biting trellis inner codes

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JOURNAL OF DISCRETE MATHEMATICAL SCIENCES & CRYPTOGRAPHY 2006年第2期9卷 307-320页

作者： Hirasawa, Shigeichi Kasahara, Masao Waseda Univ Sch Sci & Engn Dept Ind & Management Syst Engn Shinjuku Ku 3-4-1Ohkubo Tokyo 1698555 Japan Osaka Gakuin Univ Fac Informat Suita Osaka 5648511 Japan

Tail biting trellis codes and block concatenated codes are discussed from random coding arguments. An error exponent and decoding complexity for tail biting random trellis codes are shown. We then propose a block concatenated code constructed by a tail biting trellis inner code and derive an error exponent and decoding complexity for the proposed code. The results obtained by the proposed code show that we can attain a larger error exponent at all rates except for low rates with the same decoding complexity compared with the original concatenated code.

关键词： Block codes concatenated codes error exponent tail biting convolutional codes decoding complexity asymptotic results

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High-Rate, Multisymbol-Decodable STBCs From Clifford Algebras

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IEEE TRANSACTIONS ON INFORMATION THEORY 2009年第6期55卷 2682-2695页

作者： Karmakar, Sanjay Rajan, B. Sundar Univ Colorado Elect & Comp Sci Engn Dept Boulder CO 80309 USA Indian Inst Sci Dept Elect Commun Engn Bangalore 560012 Karnataka India

It is well known that space-time block codes (STBCs) obtained from orthogonal designs (ODs) are single-symbol decodable (SSD) and from quasi-orthogonal designs (QODs) are double-symbol decodable (DSD). However, there are SSD codes that are not obtainable from ODs and DSD codes that are not obtainable from QODs. In this paper, a method of constructing g-symbol decodable (g-SD) STBCs using representations of Clifford algebras are presented which when specialized to g = 1, 2 gives SSD and DSD codes, respectively. For the number of transmit antennas 2(a) the rate (in complex symbols per channel use) of the g-SD codes presented in this paper is a+1-g/2(a-9). The maximum rate of the DSD STBCs from QODs reported in the literature is a/2(a-1) which is smaller than the rate a-1/2(a-2) of the DSD codes of this paper, for 2(a) transmit antennas. In particular, the reported DSD codes for 8 and 16 transmit antennas offer rates 1 and 3/4, respectively, whereas the known STBCs from QODs offer only 3/4 and 1/2, respectively. The construction of this paper is applicable for any number of transmit antennas. The diversity sum and diversity product of the new DSD codes are studied. It is shown that the diversity sum is larger than that of all known QODs and hence the new codes perform better than the comparable QODs at low signal-to-noise ratios (SNRs) for identical spectral efficiency. Simulation results for DSD codes at various spectral efficiencies are provided.

关键词： Clifford algebra decoding complexity diversity space-time block codes (STBCs)

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On Fast-Decodable Space-Time Block Codes

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IEEE TRANSACTIONS ON INFORMATION THEORY 2009年第2期55卷 524-530页

作者： Biglieri, Ezio Hong, Yi Viterbo, Emanuele UPF DTIC Barcelona Spain Univ Coll Swansea Inst Adv Telecom Swansea SA2 8PP W Glam Wales Univ Calabria DEIS I-87036 Arcavacata Di Rende CS Italy

We focus on full-rate, fast-decodable space-time block codes (STBCs) for 2 x 2 and 4 x 2 multiple-input multiple-output (MIMO) transmission. We first derive conditions and design criteria for reduced-complexity maximum-likelihood (ML) decodable 2 x 2 STBCs, and we apply them to two families of codes that were recently discovered. Next, we derive a novel reduced-complexity 4 x 2 STBC, and show that it outperforms all previously known codes with certain constellations.

关键词： Alamouti code decoding complexity multiple-input multiple-output (MIMO) quasi-orthogonal space-time block codes (STBCs) sphere decoder

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Multigroup Decodable STBCs From Clifford Algebras

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IEEE TRANSACTIONS ON INFORMATION THEORY 2009年第1期55卷 223-231页

作者： Karmakar, Sanjay Rajan, B. Sundar Univ Colorado Dept Comp Sci & Elect Engn Boulder CO 80309 USA Indian Inst Sci Dept Elect Commun Engn Bangalore 560012 Karnataka India

A space-time block code (STBC) in K symbols (Variables) is called a g-group decodable STBC if its maximum-likelihood (ML) decoding metric can be written as a sum of g terms, for some positive integer g greater than one, such that each term is a function of a subset of the K variables and each variable appears in only one term. In this paper, we provide a general structure of the weight matrices of multigroup decodable codes using Clifford algebras. Without assuming that the number of variables in each group is the same, a method of explicitly constructing the weight matrices of full-diversity, delay-optimal multigroup decodable codes is presented for arbitrary number of antennas. For the special case of 2(a) number of transmit antennas, we construct two subclass of codes: 1) a class of 2a-group decodable codes with rate a/2((a-1)), which is, equivalently, a class of single-symbol decodable codes, and 2) a class of (2a - 2)-group decodable codes with rate (a-1)/2((a-2)), i.e., a class of double-symbol decodable codes.

关键词： Clifford algebra decoding complexity diversity space-time block codes (STBCs)

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Convolutional Codes Under a Minimal Trellis complexity Measure

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IEEE TRANSACTIONS ON COMMUNICATIONS 2009年第1期57卷 1-5页

作者： Uchoa-Filho, Bartolomeu F. Souza, Richard Demo Pimentel, Cecilio Jar, Marcel Univ Fed Santa Catarina CTC EEL GPqCom Florianopolis SC Brazil UTFPR CPGEI DAELN Curitiba Parana Brazil Univ Fed Pernambuco DES CODEC Recife PE Brazil

We conduct a code search, restricted to the recently introduced class of generalized punctured convolutional codes, under the minimal trellis complexity measure defined by McEliece and Lin. For the same decoding complexity and the same code rate, new codes are compared to well-known existing classes of convolutional codes. Some of the best convolutional codes (in a distance spectrum sense) of existing and new trellis complexities are tabulated.

关键词： Convolutional codes decoding complexity distance spectrum minimal trellis

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Low complexity Iterative decoding Algorithm for Low-Density Parity-Check (LDPC) codes

Low Complexity Iterative Decoding Algorithm for Low-Density ...

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1st IFIP Wireless Days Conference

作者： Zeidan, Hany R. Elsabrouty, Maha M. Arab Acad Sci Technol & Maritime Transportat Fac Engn Dept Elect & Elect Commun Cairo Egypt

ISBN: (纸本)9781424428281

The reliability ratio weighted based bit-flipping (RRWBF) algorithm for decoding low-density parity-check (LDPC) codes has recently been developed to provide the best performance among all existing bit-flipping based algorithms. The implementation efficient reliability ratio weighted based bit-flipping (IERRWBF) algorithm speedup the original algorithm to decrease the processing time used. A drawback for this;algorithm is the decrease in the improvement as the maximum number of iterations assigned for the algorithm increase as a large percentage of decoding time is spent on the iteration part without any change in the performance. In this paper, a modified version for this algorithm is proposed to solve this drawback by reducing the number of iterations required to achieve the same performance of the existing IERRWBF algorithm using efficient number of iterations instead of using the maximum number of iterations for decoding without any change in the performance of the IERRWBF.

关键词： bit-flipping algorithm decoding complexity error sum low-density parity-check (LDPC) codes implementation efficient reliability ratio weighted bit-flipping (IERRWBF) algorithm

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complexity Modeling of Spatial and Temporal Compensations in H.264/AVC decoding

Complexity Modeling of Spatial and Temporal Compensations in...

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15th IEEE International Conference on Image Processing (ICIP 2008)

作者： Lee, Szu-Wei Kuo, C. -C. Jay Univ Southern Calif Ming Hsieh Dept Elect Engn Los Angeles CA 90089 USA Univ Southern Calif Signal & Image Proc Inst Los Angeles CA 90089 USA

ISBN: (纸本)9781424417650

complexity modeling of spatial-temporal compensations in H.264/AVC decoding is performed by examining a rich set of inter- and intra-prediction modes. Specifically, we study the relationship between motion vectors, frame sizes and properties of reference frames since they are related to cache management efficiency. The proposed models provide good estimation results for test video bit streams over a wide range of bit rates. As an application, an H.264/AVC encoder equipped with these models estimates the decoding complexity and chooses the best inter- or intra-prediction mode to meet the decoding complexity constraint of a target decoding platform. The decoding complexity of the resultant bit stream is reduced at the cost of small PSNR loss.

关键词： H.264/AVC motion compensation decoding complexity rate-distortion optimization (RDO)

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An efficient decoding algorithm for QO-STBCs based on iterative interference cancellation

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IEEE COMMUNICATIONS LETTERS 2008年第4期12卷 292-294页

作者： Kim, Jeongchang Cheun, Kyungwhoon Pohang Univ Sci & Technol Div Elect & Comp Engn Pohang 790784 South Korea

We propose an efficient decoding algorithm targeted for quasi-orthogonal space-time block codes which can be viewed as an iterative extension of the parallel detection algorithm using iterative interference cancellation. The essence of the algorithm is in the realization of the fact that the number of candidate symbols at the end of each interference cancellation iteration reduces very quickly, and that no more than two iterations are required.

关键词： decoding complexity iterative interference cancellation multiple transmit antennas QO-STBCs stopping

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complexity constrained video coding for decoders with limited resources

Complexity constrained video coding for decoders with limite...

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14th Annual Scientific Conference on Web Technology, New Media Communications and Telematics Theory, Methods, Tools and Applications Medical Imaging and D-TV

作者： Cordeiro, Paulo J. Gomez-Pulido, Juan Assuncao, Pedro A. ESTG Inst Politecn Leiria P-2411901 Leiria Portugal Univ Extremadura E-10071 Caceres Spain Inst Telecommun P-2411901 Leiria Portugal

ISBN: (纸本)9789077381380

This paper describes an efficient method to generate compressed video streams with low complexity decoding requirements. This is particularly targeted at portable media. players;where the use of such video streams leads to reduced power consumption thus extending the battery life. The proposed method is based on the fact that motion compensation is the 'most complex operation in standard H.264/AVC video decoders, mainly because of the operations involved in computing sub-pixel predictions. By using a measure of the computational complexity needed to decode a stream and including it in the encoder cost function used to select the type of sub-pixel motion vector, it is shown that the decoding complexity of compressed video streams can be reduced with negligible penalty in rate-distortion performance. The experimental results show that such optimized constrained coding method is capable of achieving significant decoding complexity reduction at the expense of negligible PSNR loss within the range of bit rates with practical interest.

关键词： constrained video coding decoding complexity power-aware coding

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