In this paper, we use a stochastic expectation-maximization method to illustrate how to come close to achieving the capacity of the noisy (0, k) constrained additive white Gaussian noise (AWGN) channels. We use the bi...
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In this paper, we use a stochastic expectation-maximization method to illustrate how to come close to achieving the capacity of the noisy (0, k) constrained additive white Gaussian noise (AWGN) channels. We use the bit-flipping-based constrained coding system proposed by Vasic and Pedagani, to transmit (0, k) constrained low-density parity check (LDPC) codewords over an AWGN channel. In the original approach of Vasic and Pedagani, if the number of flipped bits is large, the message-passing decoder of the LDPC codes fails to correct all the errors, and the system is prone to an error floor. We propose a flip decoder that exploits the information from the message-passing decoder to correct the flipped bits. We illustrate that the message-passing decoder and the flip decoder together correct both the channel and flip errors and achieve rates close to the noisy (0, k) channel capacity.
In this letter, we propose a novel approach of constructing low-density parity-check convolutional codes (LDPC-CCs), based on the progressive edge-growth (PEG) algorithm. LDPC-CC related modifications are made upon th...
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In this letter, we propose a novel approach of constructing low-density parity-check convolutional codes (LDPC-CCs), based on the progressive edge-growth (PEG) algorithm. LDPC-CC related modifications are made upon the original PEG algorithm to generate the time-varying parity-check matrix. The proposed method can generate LDPC-CCs with large girth, and is flexible in handling codes with different parameters. Simulation results show that such codes have good performance.
This paper provides performance results through analysis and simulation for key error control problems encountered in using wireless links to transport asynchronous transfer mode (ATM) cells, Problems considered inclu...
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This paper provides performance results through analysis and simulation for key error control problems encountered in using wireless links to transport asynchronous transfer mode (ATM) cells, Problems considered include the forward-errorcorrection (FEC) and interleaving at the physical layer, the impact of wireless links on the ATM cell header-error control (HEC) and cell delineation (CD) functions, the application of data link automatic repeat-request (ARQ) for traffic requiring reliable transport, and the impact of the choice of end-to-end ARQ protocol for reliable service, We conclude that it is very important to make the physical layer as SONET-like as possible through the use of powerful FEC, interleaving, and ARQ, These additional error control measures are especially necessary for disturbed channels because of the degrading effects of the channel on higher-layer functions, A recommended error control architecture is given with tradeoffs.
In this letter, we extend the class of deterministic pi-rotation low-density parity-check codes to a more flexible irregular pattern. The extended codes maintain the advantages of the classic pi-rotation pattern with ...
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In this letter, we extend the class of deterministic pi-rotation low-density parity-check codes to a more flexible irregular pattern. The extended codes maintain the advantages of the classic pi-rotation pattern with easy implementation based on a single vector while providing superb performance.
In this letter, the performance of an ultra-wideband (UWB)-over-fiber system with low-density parity-check (LDPC) coding is experimentally investigated and supported by a simulation study. The results show that short ...
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In this letter, the performance of an ultra-wideband (UWB)-over-fiber system with low-density parity-check (LDPC) coding is experimentally investigated and supported by a simulation study. The results show that short block length LDPC coding provides a coding gain between 5.75 and 8.5 dB for a code rate of 50% and 93.3%, respectively, compared to an uncoded UWB-over-fiber system at a bit-error rate of 10(-8) after errorcorrection.
We give a method of finding convolutional codes with minimum bit-error rate (BER) that combines ideas of importance sampling, Monte Carlo integration, and maximum a posteriori probability decoding. The method is appli...
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We give a method of finding convolutional codes with minimum bit-error rate (BER) that combines ideas of importance sampling, Monte Carlo integration, and maximum a posteriori probability decoding. The method is applied to rate 1/2 tailbiting convolutional coding, both feedforward and feedback systematic. Tables of BER-minimizing encoders are given for memories 2-5 and tailbiting size 5-40, over a range of good and bad binary symmetric and additive white Gaussian noise channels. The best generators for these cases are in general all different and are not necessarily the generators that optimize distance. The best generators for bad channels are always systematic. The best when the channel quality is known are usually feedforward, but when it is unknown, they are feedback systematic. The best generators in good channels are predicted by a union bound technique.
In earlier work, we presented the k-error protocol, a technique for protecting a dynamic dictionary lossless data compression method from error propagation as the result of errors on the communication channel or compr...
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In earlier work, we presented the k-error protocol, a technique for protecting a dynamic dictionary lossless data compression method from error propagation as the result of errors on the communication channel or compressed file. In the worst case, the protocol only protects against k errors total;however, it gives very high probability protection against a sustained error rate. Here, we further develop this protocol and present experiments showing that in practice this approach is both fast and highly effective against a noisy channel or faulty storage medium. We also address the issue of dynamically deleting strings. Although without modification most standard methods used in practice (e.g., LRU strategies) perform poorly with respect to error propagation, we propose and analyze some that are very robust, including a strategy based on leaf pruning.
A novel design approach is proposed for low-density parity-check convolutional codes (LDPC-CCs), that jointly optimizes the code, encoder and decoder to achieve high-throughput parallel encoding and decoding. A series...
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A novel design approach is proposed for low-density parity-check convolutional codes (LDPC-CCs), that jointly optimizes the code, encoder and decoder to achieve high-throughput parallel encoding and decoding. A series of implementation-oriented constraints are applied to construct architecture-aware (AA) codes by introducing algebraic structures into the parity-check matrix. The resulting AA codes have bit error rate performance comparable to other published LDPC-CCs. Given these AA LDPC-CCs, new architectures are proposed for a parallel LDPC-CC encoder with built-in termination and an LDPC-CC decoder that is parallel in the node dimension as well as pipelined in the iteration dimension. ASIC synthesis results for a 90-nm CMOS process show that the proposed encoder and the decoding processor achieve 2.0-Gbps throughputs at 250-MHz clock frequencies within silicon areas of 0.1 mm(2) and 1 mm(2) respectively.
In 1997, the US National Science Foundation recognized the need to unite research communities together to solve mutual problems, overcome challenges, future development and practical applications of cryptography and e...
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In 1997, the US National Science Foundation recognized the need to unite research communities together to solve mutual problems, overcome challenges, future development and practical applications of cryptography and error correction coding. Recent works in this area are connected with turbo codes, which have a special ability to provide errorcorrection characteristics of the information transmission close to theoretically obtained values. Besides, they are used for television (DVB-RCS, DVB-RCT), wireless local networks (WiMAX), software-defined radio systems, mobile (3G, 4G, Inmarsat) and space (CCSDS) communications etc. In this article is presented the crypto coding system based on turbo codes with secret keys used by interleavers. All calculations are performed during data encoding, which reduces the computational complexity of data pre-encryption. The necessary mathematical apparatus was presented, the security level of the communication system was estimated, a simulation of the errorcorrection characteristics was performed, and multimedia information was processed. The working characteristics of the classical and proposed turbo codecs do not differ statistically. The results can be used in communication systems for various functional purposes. (c) 2023 The Authors. Published by Elsevier B.V. on behalf of The Korean Institute of Communications and Information Sciences. This is an open access article under the CC BY license (http://***/licenses/by/4.0/).
In this paper, we describe a novel data transfer scheme that uses the camera in a smart phone as an alternative data channel. The data is encoded as a sequence of 2-D barcode images, displayed on a flat panel display,...
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In this paper, we describe a novel data transfer scheme that uses the camera in a smart phone as an alternative data channel. The data is encoded as a sequence of 2-D barcode images, displayed on a flat panel display, acquired by the camera, and decoded in real time by the software embedded in device. The decoded data is written to a file. Compared with existing data channels, such as CDMA/GPRS, cables, Bluetooth, and Infrared, our method relies on visual communication and does not require special hardware or data plans. Users only need to point the camera at a monitor displaying the VCode to download. Technical challenges to overcome include correction of perspective distortion, compensation for contrast variation, and efficient implementation of small footprint software into a mobile device. We address these challenges and present our solution in detail. We have implemented a prototype which allows users to download various types of files successfully, including pictures, ring tones and Java games onto camera phones running Symbian and Windows Mobile platforms. We discuss the limitations of our solution and outline future work to overcome these limitations.
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