A linear technique for combining equalization and coset codes on partial response channels with additive white Gaussian noise is developed. The technique, vector coding, uses a set of transmit filters or 'vectors&...
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A linear technique for combining equalization and coset codes on partial response channels with additive white Gaussian noise is developed. The technique, vector coding, uses a set of transmit filters or 'vectors' to partition the channel into an independent set of parallel intersymbol interference (ISI)-free channels for any given finite (or infinite) block length. The optimal transmit vectors for such channel partitioning are shown to be the eigenvectors of the channel covariance matrix for the specified block length, and the gains of the individual channels are the eigenvalues. An optimal bit allocation and energy distribution, are derived for the set of parallel channels, under an accurate extension of the continuous approximation for power in optimal multidimensional signal sets for constellations with unequal signal spacing in different dimensions. Examples are presented that demonstrate performance advantages with respect to zero-forcing decision feedback methods that use the same coset code on the same partial response channel. Only resampling the channel at an optimal rate and assuming no errors in the feedback path will bring the performance of the decision feedback methods up to the level of the vector coded system.
The quasi-static nature of the optical wireless channel means that the channel state information (CSI) can be readily available at the transmitter and receiver prior to data transmission. This implies that electricall...
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The quasi-static nature of the optical wireless channel means that the channel state information (CSI) can be readily available at the transmitter and receiver prior to data transmission. This implies that electrically band-limited optical wireless communication (OWC) systems can make use of optimal channel partitioning or vector coding based multi-channel modulation (MCM) to achieve high throughput by mitigating the non-linearities arising from the optical and electrical channel. This paper proposes a pulse amplitude modulation (PAM) based DC-biased optical vector coding (DCO-VC) MCM scheme for OWC. The throughput performance of DCO-VC is evaluated and compared to the well known DC-biased optical orthogonal frequency division multiplexing (DCO-OFDM) over hybrid (line-of-sight and diffuse) and diffuse (non line-of-sight only) visible light communication (VLC) channels with additive white Gaussian noise. For the completeness of the VLC physical layer, the performance comparison is based on an uncoded and a forward error correction transmission mode using well-known convolutional codes with Viterbi decoder. The results show that the coded DCO-VC outperforms DCO-OFDM system by achieving up to 2 and 3 dB signal to noise ratio gains over hybrid and diffuse VLC channels, respectively.
A new fast algorithm is presented for the multidimensional discrete Fourier transform (DFT). This algorithm is derived using an interesting technique called "vector coding" (VC), and we call it the vector-co...
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A new fast algorithm is presented for the multidimensional discrete Fourier transform (DFT). This algorithm is derived using an interesting technique called "vector coding" (VC), and we call it the vector-coding fast Fourier transform (VC-FFT) algorithm. Since the VC-FFT is an extension of the Cooley-Tukey algorithm from I-D to multidimensional form, the structure of the program is as simple as the Cooley-Tukey fast Fourier transform (FFT). The new algorithm significantly reduces the number of multiplications and recursive stages. The VC-FFT therefore comprehensively reduces the complexity of the algorithm as compared with other current multidimensional DFT algorithms. (c) 2006 Elsevier B.V. All rights reserved.
作者：
Muta, O.Kyushu Univ
Grad Sch Informat Sci & Elect Engn Ctr Japan Egypt Cooperat Sci & Technol Nishi Ku Fukuoka 8190395 Japan
As a solution to high peak-to-average power ratio (PAPR) problems in vector coding (VC) systems, phase control-based methods such as selected mapping (SLM) and partial transmit sequence have been investigated. As desc...
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As a solution to high peak-to-average power ratio (PAPR) problems in vector coding (VC) systems, phase control-based methods such as selected mapping (SLM) and partial transmit sequence have been investigated. As described in this study, a phase sequence blind estimation method is presented for PAPR reduction based on phase control in multi-input multi-output (MIMO) adaptive modulated VC systems, where turbo code is employed. On the receiver side, the phase sequence component is estimated using a maximum likelihood method that selects the most likely sequence among all candidate sequences by exploiting soft-output information of the decoder. Computer simulation results show that when the number of candidate sequences in SLM is M = 16, instantaneous power of the transmit signal at the complementary cumulative distribution function of 10(-5) can be reduced by about 4.0 and 3.5 dB for single-input single-output and MIMO cases as compared with the case without PAPR reduction, although almost identical block error rate performance and the same throughput performance as in the case of perfect phase sequence estimation are achieved in an attenuated six-path Rayleigh fading condition.
vector coding (VC) is a novel vector modulation scheme that partitions a SISO (Single-Input Single-Output) channel into orthogonal subchannels by singular value decomposition (SVD). Because the orthogonal transmission...
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vector coding (VC) is a novel vector modulation scheme that partitions a SISO (Single-Input Single-Output) channel into orthogonal subchannels by singular value decomposition (SVD). Because the orthogonal transmissions enabled by VC cannot cope with inter block interference (IBI) that is inevitable in delay spread channels, this paper proposes an IBI cancelling demodulator which can remove IBI by an iterative technique. We also show that code elimination in which insignificant eigencodes with lowermost eigenvalues are intentionally removed from transmission vectors greatly reduces BER (Bit Error Rate). The VC which utilizes the IBI cancelling demodulator and code elimination to reduce BER is compared with the original VC in not only delay spread SISO channels but also delay spread MIMO (Multi-Input Multi-Output) channels while emphasis is placed on the MIMO cases. Simulation results show that, under a predetermined BER, the enhanced MIMO-VC can improve effective transmission rate than the natural extension of VC to delay spread MIMO channels.
A modified vector coding (VC) technique was used to quantify lumbar-pelvic coordination during gait. The outcome measure from the modified VC technique is known as the coupling angle (CA) which can be classified into ...
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A modified vector coding (VC) technique was used to quantify lumbar-pelvic coordination during gait. The outcome measure from the modified VC technique is known as the coupling angle (CA) which can be classified into one of four coordination patterns. This study introduces a new classification for this coordination pattern that expands on a current data analysis technique by introducing the terms in-phase with proximal dominancy, in-phase with distal dominancy, anti-phase with proximal dominancy and anti-phase with distal dominancy. This proposed coordination pattern classification can offer an interpretation of the CA that provides either in-phase or anti-phase coordination information, along with an understanding of the direction of segmental rotations and the segment that is the dominant mover at each point in time. Classifying the CA against the new defined coordination patterns and presenting this information in a traditional time-series format in this study has offered an insight into segmental range of motion. A new illustration is also presented which details the distribution of the CA within each of the coordination patterns and allows for the quantification of segmental dominancy. The proposed illustration technique can have important implications in demonstrating gait coordination data in an easily comprehensible fashion by clinicians and scientists alike. (C) 2015 Elsevier Ltd. All rights reserved.
Aircraft detection in remote sensing images has become an attractive research topic, which plays an essential role in various military and civil applications. In this letter, we develop a novel method for aircraft det...
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Aircraft detection in remote sensing images has become an attractive research topic, which plays an essential role in various military and civil applications. In this letter, we develop a novel method for aircraft detection in remote sensing images based on deep residual network (ResNet) and Super-vector (SV) coding. First, a variant of ResNet with fewer layers is designed to increase the resolution of the feature map, and multi-level convolutional features are merged into an informative feature description for region proposal. Meanwhile, we extract histogram of oriented gradient (HOG) with SV coding from each region of interest, which assists convolutional features to complete object classification. We comprehensively evaluate the proposed method on our remote sensing image dataset. The experimental results show that our method outperforms top-performing aircraft detection methods with higher accuracy even when the backgrounds are complicated.
vector coding (VC) is a kind of eigen mode transmission scheme which is typically considered in MIMO systems. In VC systems, several code channels corresponding to the eigenvalues of the channel matrix are created. Ho...
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vector coding (VC) is a kind of eigen mode transmission scheme which is typically considered in MIMO systems. In VC systems, several code channels corresponding to the eigenvalues of the channel matrix are created. However, any code channels with low eigenvalues will cause a degradation in performance. In this paper, adaptive modulation and coding (AMC) for a VC system is proposed. In addition to AMC, the number of code channels is adaptively changed by code channel elimination. We show that the BER performance of VC is better than that of MMSE. Secondly, we also show the throughput performance of the proposed scheme is improved compared with the maximum throughput of each individual MCS.
The complexity of human gait patterns has become a topic of major interest in motor control and biomechanics. Range of motion is still the preferred method to quantify movement impairment, however, within these tradit...
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The complexity of human gait patterns has become a topic of major interest in motor control and biomechanics. Range of motion is still the preferred method to quantify movement impairment, however, within these traditional linear measures, the inter-segmental coordination and movement variability is normally ignored. A dynamical systems approach using vector coding and circular statistics provides non-linear techniques to quantify coordination and variability. This study provides comprehensive vector coding and circular statistics calculations. Additionally, pelvis–lumbar coordination and coordination variability data obtained from ten healthy young male participants during five walking trials using an optoelectronic system is provided. This novel data can form the baseline information for future studies in this area of research. Finally, a new illustration to present coordination and coordination variability information of gait kinematics, combining the output from the modified vector coding technique with traditional time-series segmental angle data is presented. This technique, when applied to single patients can be beneficial to assess the effect of an intervention on the patient-specific inter-segmental coordination pattern with implications to the clinical setting.
Variability in the spatio-temporal coordination of human movement kinematics is often assessed by vector coding and continuous relative phase (CRP). To facilitate appropriate comparisons between the findings of studie...
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Variability in the spatio-temporal coordination of human movement kinematics is often assessed by vector coding and continuous relative phase (CRP). To facilitate appropriate comparisons between the findings of studies that have used different techniques to assess variability, the purposes of this study were: (1) to determine if both vector coding and CRP behave according to dynamical systems theories on variability and state space transitions;and (2) to determine if trends in coordination variability during movement are consistent when using either vector coding or CRP. We present both a theoretical case (the Lorenz Attractor) and two experimental cases (rearfoot-forefoot coupling during overground walking for 22 subjects;the effect of treadmill speed on thigh-leg coupling for five subjects). In the theoretical case, variability quantified by CRP agreed with dynamical systems theory on state space transitions more so than variability quantified by vector coding. In experimental cases, this distinction was less clear, although CRP appeared to be a more conservative metric for variability. The magnitudes (all p < 0.001) and timings (all p < 0.04) of peaks in variability during the stance phase of overground walking depended on whether vector coding or CRP was used for two couplings. Similar distinctions were observed for peaks during the stride cycle of treadmill locomotion (all effect sizes > 2.8). However, changes in the average variability during the stride cycle as speed increased were consistent for both methods (all effect sizes < 0.2). The results suggest that comparisons between the findings of studies that have quantified variability using CRP and those that have used vector coding should be made with caution. (C) 2010 Elsevier Ltd. All rights reserved.
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