MAP Decoder Research Articles

Embedded human control of robots using myoelectric interfaces.

Myoelectric controlled interfaces have become a research interest for use in advanced prostheses, exoskeletons, and robot teleoperation. Current research focuses on improving a user's initial performance, either by training a decoding function for a specific user or implementing "intuitive" mapping functions as decoders. However, both approaches are limiting, with the former being subject specific, and the latter task specific. This paper proposes a paradigm shift on myoelectric interfaces by embedding the human as controller of the system to be operated. Using abstract mapping functions between myoelectric activity and control actions for a task, this study shows that human subjects are able to control an artificial system with increasing efficiency by just learning how to control it. The method efficacy is tested by using two different control tasks and four different abstract mappings relating upper limb muscle activity to control actions for those tasks. The results show that all subjects were able to learn the mappings and improve their performance over time. More interestingly, a chronological evaluation across trials reveals that the learning curves transfer across subsequent trials having the same mapping, independent of the tasks to be executed. This implies that new muscle synergies are developed and refined relative to the mapping used by the control task, suggesting that maximal performance may be achieved by learning a constant, arbitrary mapping function rather than dynamic subject- or task-specific functions. Moreover, the results indicate that the method may extend to the neural control of any device or robot, without limitations for anthropomorphism or human-related counterparts.

A modified MAP decoder architecture for low power consumption using folded technique

A modified MAP decoder architecture to reduce the power using folded technique is presented in this article. Firstly, the folded technique is applied in the interleaving and deinterleaving unit and then in the MAP decoder unit. The number of latches is reduced by using folded technique in the interleaving and deinterleaving unit. Here the end-to-end delay by using the proposed folded technique in the interleaving block is 2 M. But existing reports reveal that end-to-end delay is 2MN − 2 M + 2 for BI and M(N − 1) for FCI. In addition to the end-to-end delay, the number of latches is also reduced by using folded technique. We have used only M − 2 latches, whereas for other methods the number of latches utilised is more. The proposed MAP decoder reduce the memory elements up to 88% for the block interleaver, when M = NJ. In addition to that we achieved a memory element of 2 K −1 + 4 when calculating LLR by applying folded technique in the MAP decoder. Total power consumption is 160.3mW when folded technique is used in the interleaving block and the MAP decoder section. This ratio is less than the existing reported values for K = 5, code rate ½ and k = 4.

Sensory Population Decoding for Visually Guided Movements

We have used a new approach to study the neural decoding function that converts the population response in extrastriate area MT into estimates of target motion to drive smooth pursuit eye movement. Experiments reveal significant trial-by-trial correlations between the responses of MT neurons and the initiation of pursuit. The preponderance of significant correlations and the relatively low reduction in noise between MT and the behavioral output support the hypothesis of a sensory origin for at least some of the trial-by-trial variation in pursuit initiation. The finding of mainly positive MT-pursuit correlations, whether the target speed is faster or slower than the neuron's preferred speed, places strong constraints on the neural decoding computation. We propose that decoding is based on normalizing a weighted population vector of opponent motion responses; normalization comes from neurons uncorrelated with those used to compute the weighted population vector.

The Design of the Dynamic Detection System for the Screw’s Lead Precision Testing

For the screw’s lead precision dynamic testing needs, the hardware of the design includes two parts: the motion control card and the data acquisition card. We use the motion control card (GT200-SV) as the circular grating and long grating motor controller, and the data acquisition card is consist of FPGA and DSP. FPGA is the core device to realize the synchronous dynamic grating signal and inductive signal data acquisition and DSP is used to realize the function of decoding and communicating to PC by the USB bus protocol. Finally data are evaluated by the software on the computer. The acquisition speed of Screw’s lead precision dynamic detection system can reach 20 KHZ, and it has been successfully applied to a certain type of screw’s lead precision dynamic detection device in a company.

A GPU Implementation of a MAP Decoder for Synchronization Error Correcting Codes

In this paper we present a parallel implementation of a MAP decoder for synchronization error correcting codes. For a modest implementation effort, we demonstrate a considerable decoding speedup, up to two orders of magnitude even on consumer GPUs. This enables the analysis of much larger codes and worse channel conditions than previously possible, and makes applications of such codes feasible for software implementations.

The Development of Soft PLC Running and Simulation System Based on RTX

For the traditional PLC compatibility and poor scalability problems, this article developed a soft PLC running and simulation system. The system compatible with Mitsubishi FX2N series PLC instruction set. RTX was used to serve as the real-time kernel, ensured the real-time performance of the control, introduced the using method of RTX timer, multithreading and shared memory, emphasized the decoding function realization, also developed a soft PLC simulation system. Finally, through an example program verify the correctness of the running and simulation system.

회전로크 구조의 차분 선부호화 기법의 성능 분석

LTE (long term evolution) 및 LTE-A (LTE-Advanced) 시스템에서는 폐회로 기반의 다중 안테나 기술이 적용되었으며, 최대 비 전송 방식 (maximum ratio transmission, MRT) 보다 성능은 감소되지만, 동 이득 (equal gain) 특성을 유지할 수 있는 동 이득 전송 (equal gain transmission, EGT) 코드북을 채택하고 있다. 본 논문에서는 LTE 및 LTE-A 시스템에서 사용되는 코드북보다 성능을 향상시킬 수 있는 차분 코드북을 제안한다. 특히 동 이득 특성을 그대로 유지하면서 LTE 시스템의 코드북 요구조건을 모두 만족시키는 코드북을 제안한다. 코드북을 구성하는 코드워드들의 인자들 (elements)이 8-PSK(phase-shift keying) 성운 (constellation) 만을 사용하므로, 선부호화 및 복호 시 계산량이 낮아지는 LTE 코드북의 장점을 그대로 유지할 수 있다. 동 이득 성질은 특히 상향 링크에서 첨두 전력 대 평균 전력비 (PAPR)에 상당한 영향을 미치므로 매우 중요하다. 본 논문에서는 각 송신 안테나에 동 이득을 유지하는 성질을 이용한 새로운 차분 코드북을 제안하고, 동작원리를 회전 로크 구조로 설명한다. 컴퓨터 시뮬레이션을 통한 성능 분석에서, 동일한 피드백 비트 수를 갖는 같은 크기의 코드북에서 제안하는 차분 코드북은 기존 LTE 코드북보다 최소 0.9dB 성능 향상을 보인다.

25 Tb/s transmission over 5,530 km using 16QAM at 52 b/s/Hz spectral efficiency

We transmit 250x100G PDM RZ-16QAM channels with 5.2 b/s/Hz spectral efficiency over 5,530 km using single-stage C-band EDFAs equalized to 40 nm. We use single parity check coded modulation and all channels are decoded with no errors after iterative decoding between a MAP decoder and an LDPC based FEC algorithm. We also observe that the optimum power spectral density is nearly independent of SE, signal baud rate or modulation format in a dispersion uncompensated system.

The Performance Evaluation of Recon_Gurable Random Interleavers with MAP Decoding for MPEG-4Medical Image Transmission Systems over Indoor Wireless Channels

The Performance Evaluation of Recon_Gurable Random Interleavers with MAP Decoding for MPEG-4Medical Image Transmission Systems over Indoor Wireless Channels

Area-Efficient QC-LDPC Decoder Architecture Based on Stride Scheduling and Memory Bank Division

In this paper, an area-efficient decoder architecture is proposed for the quasi-cyclic low-density parity check (QC-LDPC) codes specified in the IEEE 802.16e WiMAX standard. The decoder supports all the code rates and codeword lengths defined in the standard. In order to achieve low area and maximize hardware utilization, the decoder utilizes 4 decoding function units, which is the greatest common divisor of the expansion factors. In addition, the decoder adopts a novel scheduling scheme named stride scheduling, which stores the extrinsic messages in non-sequential order to replace the conventional complex flexible permutation network with simple small-sized cyclic shifters and also minimize the number of memory accesses. To further minimize the complexity, the number of extrinsic memory instances for 24 block columns is reduced to 5 banks by identifying independent sets. All the memory instances used in the decoder are single-port memories which cost less area and price compared to dual-port ones. Finally, the decoding function units have partially parallel structure to make the decoding throughput sufficiently over the requirement of the WiMAX standard. The proposed decoder is synthesized with 49K equivalent gates and 54,144bits of memory, and the implementation occupies 0.40mm2 in a 65nm CMOS technology.

Deviation influences on sectional image reconstruction in optical scanning holography using a random-phase pupil

In this paper, we analyze the influence of two kinds of deviation errors on sectional image reconstruction for an optical scanning holography system using a random-phase pupil. The first deviation occurs in the lateral pixel position while the second occurs in the pixel value of the decoding function. Theoretical analysis and numerical simulation show that these two deviations may lead to noise in the reconstructed image. Additional discussions include the signal-to-noise ratio of the reconstructed image.

Distributed Source Coding via Linear Block Codes: A General Framework for Multiple Sources

In this paper, we propose a general framework for Distributed Source Coding (DSC) of multiple sequentially correlated information sources. In particular, we modularize the joint decoding function into a conceptually simple structure by utilizing a notion of complementarity on the code space. Assuming a constrained Hamming-distance based correlation, our general framework of DSC achieves arbitrary non-asymmetric-rate compression of multiple sources with a same overall compression rate as asymmetric compression schemes. This DSC framework does not only have flexibility with respect to compression rates, but also accommodates the use of any linear block code and any of its corresponding complements. By investigating the unique connection between syndromes and complementary codewords, we translate the major steps of DSC joint decoding into syndrome decoding followed by channel encoding via a linear block code and also via its complement code. Our aim is to achieve transparency which facilitates practical implementation.

4-Demethylwyosine Synthase from Pyrococcus abyssi Is a Radical-S-adenosyl-l-methionine Enzyme with an Additional [4Fe-4S]+2 Cluster That Interacts with the Pyruvate Co-substrate

Wybutosine and its derivatives are found in position 37 of tRNA encoding Phe in eukaryotes and archaea. They are believed to play a key role in the decoding function of the ribosome. The second step in the biosynthesis of wybutosine is catalyzed by TYW1 protein, which is a member of the well established class of metalloenzymes called "Radical-SAM." These enzymes use a [4Fe-4S] cluster, chelated by three cysteines in a CX(3)CX(2)C motif, and S-adenosyl-L-methionine (SAM) to generate a 5'-deoxyadenosyl radical that initiates various chemically challenging reactions. Sequence analysis of TYW1 proteins revealed, in the N-terminal half of the enzyme beside the Radical-SAM cysteine triad, an additional highly conserved cysteine motif. In this study we show by combining analytical and spectroscopic methods including UV-visible absorption, Mössbauer, EPR, and HYSCORE spectroscopies that these additional cysteines are involved in the coordination of a second [4Fe-4S] cluster displaying a free coordination site that interacts with pyruvate, the second substrate of the reaction. The presence of two distinct iron-sulfur clusters on TYW1 is reminiscent of MiaB, another tRNA-modifying metalloenzyme whose active form was shown to bind two iron-sulfur clusters. A possible role for the second [4Fe-4S] cluster in the enzyme activity is discussed.

Low-complexity iterative receiver design for mobile OFDM systems

Iterative receivers with minimum mean square error turbo equalization are computationally involved, as they require some form of matrix inversion. In this article, we propose a low complexity iterative receiver that implements successive interference cancelation-based MAP decoding (SIC-MAP) in doubly dispersive channels for orthogonal frequency division multiplexing systems. SIC-MAP leverages the soft feedback symbol estimates to remove the intercarrier interference from the received data. Numerical simulation results show that the proposed scheme achieves BER performance comparable to that of the equalization schemes proposed in Schniter et al. and Fang et al. but with significant computational savings. A low-complexity least squares-based iterative channel estimation scheme using soft feedback information is also proposed. This scheme is especially suitable when the number of significant channel taps is higher than the number of pilots, a phenomenon that is encountered by receivers in Single Frequency Networks (for example, DVB deployments in Europe).

16QAM transmission with 52 bits/s/Hz spectral efficiency over transoceanic distance

We transmit 160 x 100 G PDM RZ 16 QAM channels with 5.2 bits/s/Hz spectral efficiency over 6,860 km. There are more than 3 billion 16 QAM symbols, i.e., 12 billion bits, processed in total. Using coded modulation and iterative decoding between a MAP decoder and an LDPC based FEC all channels are decoded with no remaining errors.

Novel Generalized max* Approximation Method for Simplified Decoding of Turbo and TTCM Codes

A novel method for approximating the optimal max* operator used in Log- MAP decoding of turbo and turbo trellis-coded modulation (TTCM) codes is proposed being derived from a well-known inequality, which has not been published before. The max* operation is generalized, for the first time, and performed on n > 2 rather than n = 2 arguments, as it is the conventional approach. Complexity comparisons reveal a significant reduction in the number of operations required per decoding step for the proposed approximation, as compared with the optimal Log-MAP algorithm. Performance evaluation results are presented for both turbo and TTCM codes, showing the near optimal performance of the novel approximation method in both the additive white Gaussian noise (AWGN) and uncorrelated, i.e. fully interleaved, Rayleigh fading channels.

Linear-constant log-map, a fast accurate algorithm for map decoding

This paper proposes a new approximation to be used for the correction function in the turbo decoding algorithm, called Linear-Constant-log Map. Max-log Map, Linear-log Map and Constant-log Map are the well known simplified versions of Jacobi-log Map (Maximum a Posteriori) algorithm already in use but they cannot meet a proper performance in term of output BER and clock consumption of the CPU decoding encoded bits. The proposed algorithm first breaks the correction function domain of the Jacobi logarithm to three subsections by determining the border points between these sections and then uses a linear function and two constant values as an approximation of this function. Using an AWGN channel model, simulation results show that the new algorithm is almost more than six times faster than Jacobi-log Map algorithm with a Bit Error Rate (BER) very close to it.

Invertible Extractors and Wiretap Protocols

A wiretap protocol is a pair of randomized encoding and decoding functions such that knowledge of a bounded fraction of the encoding of a message reveals essentially no information about the message, while knowledge of the entire encoding reveals the message using the decoder. In this paper, the notion of efficiently invertible extractors is studied and it is shown that a wiretap protocol can be constructed from such an extractor. Then, invertible extractors for symbol-fixing, affine, and general sources are constructed and used to create wiretap protocols with asymptotically optimal trade-offs between their rate (ratio of the length of the message versus its encoding) and resilience (ratio of the observed positions of the encoding and the length of the encoding). The results are further applied to create wiretap protocols for challenging communication problems, such as active intruders who change portions of the encoding, network coding, and intruders observing arbitrary Boolean functions of the encoding.

Complexity Measurement and Fault Detection Techniques for H.264 Optimized Functions

In this paper, we systematically studied the complexity measurement, SIMD (Single Input Multiple Data) fault types and testing methodologies for H.264 codec. To the best of our knowledge, it is the first attempt to address these problems. Firstly, two complexity metrics are calculated for various optimized functions in H.264 reference software. These measures have been found to be strongly correlated to the number of faults in software testing. Secondly, we introduced a new category of SIMD faults. Conformance testing, random testing and manual testing are proposed to deal with these SIMD faults as well as conventional faults. Results have shown that, conformance testing, often used as a mechanism to verify the conformity of a decoder under test (DUT), can also be used to discover faults in the studied optimized functions. Random testing is able to detect simple faults at both encoder and decoder functions. Manual testing is especially effective for difficult faults. In practice, one or more of the three techniques can be chosen as needed to increase fault detection rate and speed for H.264 video codec testing.

LDPC Codes Based on Algebraic Graphs

In this paper we investigate correcting properties of LDPC codes obtained from families of algebraic graphs. The graphs considered in this article come from the infinite incidence structure. We describe how to construct these codes, choose the parameters and present several simulations, done by using the MAP decoder. We describe how error correcting properties are dependent on the graph structure. We compare our results with the currently used codes, obtained by Guinand and Lodge [1] from the family of graphs D(k; q), which were constructed by Ustimenko and Lazebnik [2].