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Photonics West Conference on Broadband Access Communication Technologies VIII

作者： Kumar, Pravindra Srivastava, Anand Indian Inst Technol Mandi Sch Comp & Elect Engn Mandi 175001 Himachal Prades India

ISBN: (纸本)9780819499202

Passive optical network based on orthogonal frequency division multiplexing (OFDM-PON) exhibits excellent performance in optical access networks due to its greater resistance to fiber dispersion, high spectral efficiency and flexibility on both multiple services and dynamic bandwidth allocation. The major elements of conventional OFDM communication system are two-dimensional (2-D) signal mapper and one-dimensional (1-D) inverse fast fourier transform (IFFT). Three dimensional (3-D) OFDM use the concept of 3-D signal mapper and 2-D IFFT. With 3-D OFDM, minimum Euclidean distance (MED) is increased which results in BER performance improvement. As bit error rate (BER) depends on minimum Euclidean distance (MED) which is 15.46 % more in case of 3-D OFDM as compared to 2-D OFDM. Forward error correction (FEC) coding is a technique where redundancy is added to original bit sequence to increase the reliability of communication system. In this paper, we propose and analytically analyze a new PON architecture based on 3-D OFDM with convolutional coding and Viterbi decoding and is compared with conventional 2-D OFDM under various system impairments for coherent optical orthogonal frequency division multiplexing (CO-OFDM) without using any optical dispersion compensation. Analytical result show that at BER of 10-9, there is 2.7 dB, 3.8 dB and 9.3 dB signal-to-noise ratio (SNR) gain with 3-D OFDM, 3-D OFDM combined with convolutional coding and Viterbi hard decision decoding (CC-HDD) and 3-D OFDM combined with convolutional coding and Viterbi soft decision decoding (CC-SDD) respectively as compared to 2-D OFDM-PON. At BER of 10-9, 3-D OFDM-PON with CC-HDD gives 2.8 dB improvement in optical budget for both upstream and downstream path and gives 5.7 dB improvement in optical budget using 3-D OFDM-PON combined with CC-SDD as compared to conventional OFDM-PON system.

关键词： 3-D OFDM PON 3-D mapping convolutional coding minimum Euclidean distance (MED)

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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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Creeper: An algorithm for decoding convolutional codes 8

Creeper: An algorithm for decoding convolutional codes

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8th International Conference on Communication Systems

作者： Imtawil, V Khon Kaen Univ Fac Engn Dept Elect Engn Khon Kaen 40002 Thailand

ISBN: (纸本)0780375106

There are two main strategies for decoding convolutional codes: the well-known Viterbi algorithm and sequential decoding. This paper presents a comparison of Creeper, an algorithm for sequential decoding, and the Viterbi algorithm. Creeper is an algorithm which combines the best properties of both the stack and the Fano algorithms [1]. It requires less memory than the stack algorithm and has no backward moves as in the Fano algorithm. Some results of simulation show that Creeper is an interesting alternative to the Viterbi algorithm.

关键词： convolutional coding sequential decoding creeper Viterbi algorithm

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A (50,2,4) Nonbinary LDPC convolutional Code Decoder Chip over GF(256) in 90nm CMOS

A (50,2,4) Nonbinary LDPC Convolutional Code Decoder Chip ov...

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IEEE Asian Solid State Circuits Conference (A-SSCC)

作者： Lin, Chia-Lung Chen, Chih-Lung Chang, Hsie-Chia Lee, Chen-Yi Natl Chiao Tung Univ Dept Elect Engn 1001 Ta Hsueh Rd Hsinchu Taiwan Natl Chiao Tung Univ Inst Elect Hsinchu Taiwan

ISBN: (纸本)9781467327718

A memory-based (m(s) = 50, d(v) = 2, d(c) = 4) nonbinary LDPC convolutional code (NB-LDPC-CC) decoder over GF(256) with layered scheduling is presented. The proposed architecture-aware construction features fewer memory banks, low degree, low period, and better performance. To the best of our knowledge, this is the first architecture discussion and implementation for NB-LDPC-CC decoders. We optimized the architecture of message first-in-first-out (M-FIFO), check node unit, and variable node unit in terms of area and throughput. Jointly designing code and architecture, overall normalized area efficiency can be enhanced by more then six times with respect to decoders of nonbinary LDPC block codes (NB-LDPC BCs). After fabricated in 90nm CMOS, our prototype NB-LDPC-CC decoder chip can achieve maximum throughput of 22.8Mbps with frequency of 285MHz. The measured average power is 211mW at a typical operating voltage of 1.0V.

关键词： decoders operating voltage area efficiency low density parity check codes convolutional coding ARCHITECTURE Building construction Complementary Metal Oxide Semiconductor Computer chips DNA Microarrays

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Layered LDPC convolutional Codes for Compression of Correlated Sources under Adversarial Attacks

Layered LDPC Convolutional Codes for Compression of Correlat...

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International Symposium on Information Theory and its Applications (ISITA)

作者： Naghibi, Farshad Thobaben, Ragnar Salimi, Somayeh Skoglund, Mikael KTH Royal Inst Technol Sch Elect Engn SE-10044 Stockholm Sweden

ISBN: (纸本)9784885522673

We consider the problem of code design for compression of correlated sources under adversarial attacks. A scenario with three correlated sources is considered in which at most one source is compromised by an adversary. The theoretical minimum achievable sum-rate for this scenario was derived by Kosut and Tong. We design layered LDPC convolutional codes for this problem, assuming that one of the sources is available at the common decoder as side information. We demonstrate that layered LDPC convolutional codes constitute a sequence of nested codes where each sub-code is capacity-achieving for the binary symmetric channels used to model the correlation between sources, and therefore, can ideally achieve the theoretical minimum sum-rate. Simulated performance results for moderate block length show a small gap to the theoretical limit, and as the block length increases the gap vanishes.

关键词： convolutional coding low density parity check codes nested codes binary symmetric channel Mesenchyma tong Tung-Yang compression

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DeepEfference: Learning to Predict the Sensory Consequences of Action Through Deep Correspondence 7

DeepEfference: Learning to Predict the Sensory Consequences ...

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7th joint IEEE International Conference on Development Learning and Epigenetic Robotic (IEEE ICDL-EpiRob)

作者： Shamwell, E. Jared Nothwang, William D. Perlis, Donald Univ Maryland Neurosci & Cognit Sci Program College Pk MD 20742 USA US Army Res Lab Adelphi MD 20783 USA US Army Res Lab Micro & Nano Devices & Mat Branch Sensors & Elect Adelphi MD 20783 USA Univ Maryland Comp Sci College Pk MD 20742 USA

ISBN: (纸本)9781538637159

As the human eyeball saccades across the visual scene, humans maintain egocentric visual positional constancy despite retinal motion identical to an egocentric shift of the scene. Characterizing the underlying biological computations enabling visual constancy can inform methods of robotic localization by serving as a model for intelligently integrating complimentary, heterogeneous information. Here we present DeepEfference, a bio-inspired, unsupervised, deep sensorimotor network that learns to predict the sensory consequences of self-generated actions. DeepEfference computes dense image correspondences [1] at over 500 Hz and uses only a single monocular grayscale image and a low-dimensional extra-modal motion estimate as data inputs. Designed for robotic applications, DeepEfference employs multi-level fusion via two parallel pathways to learn dense, pixel-level predictions and correspondences between source and target images. We present quantitative and qualitative results from the SceneNet RGBD [2] and KITTI Odometry [3] datasets and demonstrate an approximate runtime decrease of over 20,000% with only a 12% increase in mean pixel matching error compared to DeepMatching [4] on KITTI Odometry.

关键词： Visualization Robot sensing systems Cameras Image reconstruction convolutional codes Two dimensional displays Manipulator sensing systems convolutional coding image reconstruction Cameras Visualization target image parallel paths odometry Correspondence

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Error-Trellises for Tailbiting convolutional Codes

Error-Trellises for Tailbiting Convolutional Codes

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International Symposium on Information Theory and its Applications (ISITA)

作者： Tajima, Masato Okino, Koji Toyama Univ Grad Sch Sci & Engn 3190 Gofuku Toyama 9308555 Japan Toyama Univ Informat Technol Ctr Toyama 9308555 Japan

ISBN: (纸本)9784885522673

In this paper, we present an error-trellis construction for tailbiting convolutional codes. A tailbiting error-trellis is characterized by the condition that the syndrome former starts and ends in the same state. We clarify the correspondence between code subtrellises in the tailbiting code-trellis and error subtrellises in the tailbiting error-trellis. Also, we obtain the scalar parity-check matrix for a tailbiting convolutional code. Moreover, we show the close relationship between code-trellises for an SST Viterbi decoder and error-trellises for a syndrome decoder. The proposed construction is based on the adjoint-obvious realization of a syndrome former.

关键词： convolutional coding Syndromes check matrix Viterbi decoders Correspondence

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An Efficient Method for Computing the Weight Spectrum of LDPC convolutional Codes Constructed from Quasi-Cyclic Codes

An Efficient Method for Computing the Weight Spectrum of LDP...

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International Symposium on Information Theory and its Applications (ISITA)

作者： Hirotomo, Masanori Morii, Masakatu Saga Univ Comp & Network Ctr Saga 8408502 Japan Kobe Univ Grad Sch Engn Kobe Hyogo 6578501 Japan

ISBN: (纸本)9784885522673

In this paper, we propose an efficient method for computing the weight spectrum of LDPC convolutional codes constructed from quasi-cyclic block codes. In the proposed method, we reduce the memory size of their parity-check matrices with the same distance profile as original codes, and apply a forward and backward tree search algorithm to the parity-check matrices of reduced memory. We show numerical results of computing the minimum free distance and the low-part weight spectrum of LDPC convolutional codes of memory about 130.

关键词： convolutional coding check matrix cyclic codes low density parity check codes Memory Memory Spectra

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Effects of digital filtering technique in reducing the effects of clipping of an enhanced orthogonal frequency division multiplexing system

Effects of digital filtering technique in reducing the effec...

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1st International Symposium on Wireless Pervasive Computing

作者： Hassan, Wan Hafiza Wan Khatun, Sabira Multimedia Univ Ctr Fdn Educ & Extens Educ Melaka 7450 Malaysia Univ Putra Malaysia Fac Engn Dept Comp & Commun Syst Serdang 43400 Malaysia

ISBN: (纸本)0780394100

Despite of many advantages of OFDM, it has two main drawbacks which are high peak to average power ratio (PAPR) and synchronization problem. High PAPR causes saturation in power amplifiers, leading to intermodulation products among the sub carriers and disturbing out of band energy. Therefore, it is desirable to reduce the PAPR by means of PAPR reduction schemes. However, it caused the degradation of BER and enhanced the growth of out of band radiation which has led to the degradation of OFDM overall performance In this paper, OFDM system with an enhanced clipping technique has been proposed, the effects of clipping have been analyzed and the system is evaluated by integrating with its significant features including convolutional forward error control coding, oversampled inverse fast fourier transform (IFFT) and digital filtering technique in order to minimize the effects of clipping. It is shown that the bit error rate (BER) of the clipped OFDM signal is improved, the PAPR is further reduced and the effect of out of band radiation is minimized. Besides, other effects of filtering technique are also analyzed in order to optimize the overall performance of our proposed system.

关键词： OFDM PAPR convolutional coding clipping oversampled IFFT FIR filter

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Optimal Data Path Widths for Energy- and Area-efficient Max-Log-MAP Based LTE Turbo Decoders 16

Optimal Data Path Widths for Energy- and Area-efficient Max-...

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16th International Symposium on System-on-Chip (SoC)

作者： Broich, Martin Noll, Tobias G. Rhein Westfal TH Aachen Chair Elect Engn & Comp Syst D-52062 Aachen Germany

ISBN: (纸本)9781479968909

Data path widths in state-of-the-art Turbo decoder implementations depend on estimates for the upper bounds of the dynamic ranges of processed metrics. Aiming at highest area and energy efficiency, this paper presents guidelines for designing SISO and Turbo decoder data paths with minimal widths. This is based on least upper bounds for the dynamic ranges of internal metrics within the underlying Max-Log-MAP algorithm. Least upper bounds are presented for the LTE Turbo decoder. Furthermore, a new dynamic branch metric saturation scheme is presented in order to optimize the hardware utilization by proper adjusting the correlated upper state and branch metric bounds. In total, a data path width reduction of two bits is achieved applying radix-4 Max-Log-MAP arithmetic. An overall area-energy complexity reduction of 33% is achieved for the SISO decoder and of 28% for the LTE Turbo decoder.

关键词： convolutional codes Decoding Dynamic range Silicon Systematics Upper bound Upper bound Dynamic range convolutional coding decoders DEcoding Turbo Worm gears channels (data transmission) Silicon Local thermodynamic equilibrium Long Term Evolution Metronidazole

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