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2017 Vol. 39, No. 6
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2017, 39(6): 1271-1277.
doi: 10.11999/JEIT160969
Abstract:
This paper studies physical layer security of the multi-cell cellular networks, where the base stations need to perform cooperation beamforming in selected subcarriers to secure the downlink communication, and eavesdroppers with random location are interfered by inter-cell interference. Firstly, the approximation for the secrecy connection probability with uncertained locations of eavesdroppers is obtained. Then a distributed coalition game based cooperation algorithm is proposed to maximize the secrecy connection probability of downlinks. Specifically, the downlink is modeled as game player, whose payoff is the secrecy connection probability in the selected coalition, the join and quit rules of coalitions are designed to make downlinks self-organizing form cooperative coalition and achieve the effective subcarrier allocation. Moreover, the convergence of the proposed coalition formation game is proved, theoretical analysis and simulation results show that the proposed algorithm can form a stable coalitional structure and results in a notable secure performance advantage relative to the traditional cooperation algorithms.
This paper studies physical layer security of the multi-cell cellular networks, where the base stations need to perform cooperation beamforming in selected subcarriers to secure the downlink communication, and eavesdroppers with random location are interfered by inter-cell interference. Firstly, the approximation for the secrecy connection probability with uncertained locations of eavesdroppers is obtained. Then a distributed coalition game based cooperation algorithm is proposed to maximize the secrecy connection probability of downlinks. Specifically, the downlink is modeled as game player, whose payoff is the secrecy connection probability in the selected coalition, the join and quit rules of coalitions are designed to make downlinks self-organizing form cooperative coalition and achieve the effective subcarrier allocation. Moreover, the convergence of the proposed coalition formation game is proved, theoretical analysis and simulation results show that the proposed algorithm can form a stable coalitional structure and results in a notable secure performance advantage relative to the traditional cooperation algorithms.
2017, 39(6): 1278-1283.
doi: 10.11999/JEIT160967
Abstract:
The self-interference signal to noise ratio in digital domain decreases as the amount of RF self-interference cancellation increases in Co-time Co-frequency Full Duplex (CCFD) communications. The amount of digital self-interference cancellation decreases as the digital self-interference power decreases. The impact of the amount of RF self-interference cancellation on digital self-interference cancellation is analyzed. The digital self-interference cancellation is analyzed in this paper based on LS and MMSE channel estimation. It is shown that the decrease in the amount of digital self-interference cancellation is always less than the increase in RF self- interference cancellation when applying digital cancellation after RF cancellation in full duplex communications. Applying digital cancellation after RF cancellation is more useful when RF cancellation delivers poor suppression. The performance of digital self-interference cancellation will degrade when RF cancellation achieves large suppression.
The self-interference signal to noise ratio in digital domain decreases as the amount of RF self-interference cancellation increases in Co-time Co-frequency Full Duplex (CCFD) communications. The amount of digital self-interference cancellation decreases as the digital self-interference power decreases. The impact of the amount of RF self-interference cancellation on digital self-interference cancellation is analyzed. The digital self-interference cancellation is analyzed in this paper based on LS and MMSE channel estimation. It is shown that the decrease in the amount of digital self-interference cancellation is always less than the increase in RF self- interference cancellation when applying digital cancellation after RF cancellation in full duplex communications. Applying digital cancellation after RF cancellation is more useful when RF cancellation delivers poor suppression. The performance of digital self-interference cancellation will degrade when RF cancellation achieves large suppression.
2017, 39(6): 1284-1290.
doi: 10.11999/JEIT160839
Abstract:
Considering the differences in Quality of Service (QoS) requirements of different application classes in heterogeneous wireless networks, this paper proposes an individualization service oriented fuzzy vertical handover algorithm. The handover performance is improved from the following two aspects. Firstly, in the network discovery phase, the candidate networks are sifted by predicting the network loads in handover execution. Secondly, in the handover decision phase, different membership functions are designed according to the different QoS requirements of each application class. The simulation results show that the proposed algorithm can reduce the blocking probability, improve the system throughput, select the target network reasonably, and meet the QoS requirements of terminal individualization service.
Considering the differences in Quality of Service (QoS) requirements of different application classes in heterogeneous wireless networks, this paper proposes an individualization service oriented fuzzy vertical handover algorithm. The handover performance is improved from the following two aspects. Firstly, in the network discovery phase, the candidate networks are sifted by predicting the network loads in handover execution. Secondly, in the handover decision phase, different membership functions are designed according to the different QoS requirements of each application class. The simulation results show that the proposed algorithm can reduce the blocking probability, improve the system throughput, select the target network reasonably, and meet the QoS requirements of terminal individualization service.
2017, 39(6): 1291-1297.
doi: 10.11999/JEIT160799
Abstract:
In order to overcome the uncertainty of the reward with long-term relay incentive strategy and the degradation of resource utilization efficiency incurred by the short-term incentive scheme, a Cooperative Compound Relay Incentive (CCRI) mechanism is proposed for cooperative downlink communication system. By exploiting the bottleneck resulted from the imbalance of links capability, the rate difference that the first hop exceeds the second is provided as an instant reward for the relay nodes own data transmission. In addition, by taking into account the situations where the short-term reward is insufficient, excessive or the bottleneck exists in the first hop in such a case that the short-term incentive scheme becomes unavailable, a proportional fair based long-term incentive is employed as supplementary, with which the relay nodes scheduling weight is further adjusted. Simulation results show that the proposed scheme can provide rational reward to the relay and achieve improvements of systems spectral efficiency and lifetime, as well as relays energy efficiency.
In order to overcome the uncertainty of the reward with long-term relay incentive strategy and the degradation of resource utilization efficiency incurred by the short-term incentive scheme, a Cooperative Compound Relay Incentive (CCRI) mechanism is proposed for cooperative downlink communication system. By exploiting the bottleneck resulted from the imbalance of links capability, the rate difference that the first hop exceeds the second is provided as an instant reward for the relay nodes own data transmission. In addition, by taking into account the situations where the short-term reward is insufficient, excessive or the bottleneck exists in the first hop in such a case that the short-term incentive scheme becomes unavailable, a proportional fair based long-term incentive is employed as supplementary, with which the relay nodes scheduling weight is further adjusted. Simulation results show that the proposed scheme can provide rational reward to the relay and achieve improvements of systems spectral efficiency and lifetime, as well as relays energy efficiency.
2017, 39(6): 1298-1304.
doi: 10.11999/JEIT160745
Abstract:
The existing methods about fine classification of video traffic suffer from a couple of serious limitations: content dependency and feature dependency. Then, theory of fractals is introduced in this paper, and in wavelet domain, a classification model named Fractals is presented based on Hurst exponent. For this purpose, fractal properties of video flows are described, the corresponding Hurst exponent is defined, and the estimated value of Hurst exponent in wavelet domain is derived. Then, the optimum segments based on cost function is analyzed, the statistical differential level is calculated with the method of clustering, and the classification results are deduced with maximum between-cluster variance threshold. The result shows that the classification method with Fractals, which takes data variability as the content, makes up for the defect of content dependency and feature dependency, and demonstrates wonderful performance when classifying video flows.
The existing methods about fine classification of video traffic suffer from a couple of serious limitations: content dependency and feature dependency. Then, theory of fractals is introduced in this paper, and in wavelet domain, a classification model named Fractals is presented based on Hurst exponent. For this purpose, fractal properties of video flows are described, the corresponding Hurst exponent is defined, and the estimated value of Hurst exponent in wavelet domain is derived. Then, the optimum segments based on cost function is analyzed, the statistical differential level is calculated with the method of clustering, and the classification results are deduced with maximum between-cluster variance threshold. The result shows that the classification method with Fractals, which takes data variability as the content, makes up for the defect of content dependency and feature dependency, and demonstrates wonderful performance when classifying video flows.
2017, 39(6): 1305-1312.
doi: 10.11999/JEIT160821
Abstract:
The order of the modulation used in existing adaptive demodulation schemes is no higher than 16, and the decoding of channel codes is not taken into consideration in the analysis and design. In this paper, an adaptive demodulation algorithm used for higher order Quadrature Amplitude Modulation (QAM) is studied. A rate adaptive scheme at receiver is proposed which combines this algorithm and rateless error correcting codes. The bits in received symbols with absolute log-likelihood ratio value higher than demodulation threshold are demodulated, otherwise, deleted. In the scheme, the length of the codeword for the rateless codes decoding is fixed, and error performance is achieved by adjusting the demodulation threshold. Based on the analysis of the average mutual information of the demodulation bits, the calculation method is given of the log-likelihood ratio demodulation threshold and demodulation bits ratio under different signal-to-noise ratio. A sample design scheme employing 256-QAM constellations and Raptor codes is provided, and the simulation results of this sample are consistent well with those of the theoretical analysis, which confirms the effectiveness of the scheme.
The order of the modulation used in existing adaptive demodulation schemes is no higher than 16, and the decoding of channel codes is not taken into consideration in the analysis and design. In this paper, an adaptive demodulation algorithm used for higher order Quadrature Amplitude Modulation (QAM) is studied. A rate adaptive scheme at receiver is proposed which combines this algorithm and rateless error correcting codes. The bits in received symbols with absolute log-likelihood ratio value higher than demodulation threshold are demodulated, otherwise, deleted. In the scheme, the length of the codeword for the rateless codes decoding is fixed, and error performance is achieved by adjusting the demodulation threshold. Based on the analysis of the average mutual information of the demodulation bits, the calculation method is given of the log-likelihood ratio demodulation threshold and demodulation bits ratio under different signal-to-noise ratio. A sample design scheme employing 256-QAM constellations and Raptor codes is provided, and the simulation results of this sample are consistent well with those of the theoretical analysis, which confirms the effectiveness of the scheme.
2017, 39(6): 1313-1318.
doi: 10.11999/JEIT160918
Abstract:
With the development of satellite communication technology, the demand for communication capacity is increasing. Broadening existing communication bandwidth is a key technology of satellite communication antenna. In order to extend the C band satellite communication, covering the receiving band 3.625~4.800 GHz and the transmitting band 5.850~7.025 GHz, a compact broadband four-port dual linear polarization feed network is designed. The broadband characteristics are achieved by employing a broadband orthomode transducer and two identical E-plane side coupling T-junction duplexers. The extended C band exceeds the bandwidth of a standard rectangular waveguide, so an octave bandwidth concept for compact waveguide transitions based on the use of octagonal-shaped sections is presented. A prototype of the feed network is developed. Simulated and measured results show good agreements. Measurements show that, this compact 4-port network provides Voltage Standing Wave Ratio (VSWR) better than 1.35 in all ports, insertion losses less than 0.5 dB, isolation Tx/Rx greater than 95 dB.
With the development of satellite communication technology, the demand for communication capacity is increasing. Broadening existing communication bandwidth is a key technology of satellite communication antenna. In order to extend the C band satellite communication, covering the receiving band 3.625~4.800 GHz and the transmitting band 5.850~7.025 GHz, a compact broadband four-port dual linear polarization feed network is designed. The broadband characteristics are achieved by employing a broadband orthomode transducer and two identical E-plane side coupling T-junction duplexers. The extended C band exceeds the bandwidth of a standard rectangular waveguide, so an octave bandwidth concept for compact waveguide transitions based on the use of octagonal-shaped sections is presented. A prototype of the feed network is developed. Simulated and measured results show good agreements. Measurements show that, this compact 4-port network provides Voltage Standing Wave Ratio (VSWR) better than 1.35 in all ports, insertion losses less than 0.5 dB, isolation Tx/Rx greater than 95 dB.
2017, 39(6): 1319-1325.
doi: 10.11999/JEIT160877
Abstract:
This paper introduces the cross-terms in Wigner-Ville distribution to explore the time-frequency mechanism and regular of interaction between Prolate Spheroidal Wave Function (PSWF). By establishing the relationship between time-frequency characteristics of cross-terms and the excellent characteristics of PSWF and its Hilbert signal, the relationship between the cross-terms of PSWF signal and the characteristics of PSWF signal is mainly studied, such as parity feature and the best energy clustering, and the regular of the energy density of cross-terms in time domain, frequency domain, and time-frequency domain is studied. Both the mathematical deduction and simulation result show that the time-frequency characteristics of cross-terms have good symmetry and energy clustering. Meanwhile, the time-frequency localization characteristics of Wigner-Ville distribution have close relationship with the order and power spectrum density of PSWF signal, reflecting the degree of coherence between PSWF signals. Furthermore, those characteristics of cross-terms which are found can provide reference basis for the research on efficient time-frequency detection method for PSWF signal.
This paper introduces the cross-terms in Wigner-Ville distribution to explore the time-frequency mechanism and regular of interaction between Prolate Spheroidal Wave Function (PSWF). By establishing the relationship between time-frequency characteristics of cross-terms and the excellent characteristics of PSWF and its Hilbert signal, the relationship between the cross-terms of PSWF signal and the characteristics of PSWF signal is mainly studied, such as parity feature and the best energy clustering, and the regular of the energy density of cross-terms in time domain, frequency domain, and time-frequency domain is studied. Both the mathematical deduction and simulation result show that the time-frequency characteristics of cross-terms have good symmetry and energy clustering. Meanwhile, the time-frequency localization characteristics of Wigner-Ville distribution have close relationship with the order and power spectrum density of PSWF signal, reflecting the degree of coherence between PSWF signals. Furthermore, those characteristics of cross-terms which are found can provide reference basis for the research on efficient time-frequency detection method for PSWF signal.
2017, 39(6): 1326-1332.
doi: 10.11999/JEIT160776
Abstract:
Based on ray tracing, a real-time method of tropospheric scatter slant delay estimation is proposed to estimate the low-elevation tropospheric delay in the absence of meteorological data. The model uses the UNB3m model to obtain atmospheric meteorological parameters, establishes the tropospheric atmospheric refractive index profile model, and overcomes the limitation of meteorological data on the refractive index calculation in the ray tracing method. The atmospheric refractive index profile of the troposphere is calculated by using the meteorological data of the International GNSS Service (IGS) stations in Asia in 2012, and the accuracy of the tropospheric delay model is verified to be less than 25 mm. The three stations with the baseline distance are selected and divided into three sets of scatter correspondence comparison stations. The oblique delay at0--5 incident angle is calculated by ray tracing method. The results show that the maximum one-way propagation delay is 22.38--48.37 m for the three groups, and 3.73--8.07 ns for the two-way time offset 95%.
Based on ray tracing, a real-time method of tropospheric scatter slant delay estimation is proposed to estimate the low-elevation tropospheric delay in the absence of meteorological data. The model uses the UNB3m model to obtain atmospheric meteorological parameters, establishes the tropospheric atmospheric refractive index profile model, and overcomes the limitation of meteorological data on the refractive index calculation in the ray tracing method. The atmospheric refractive index profile of the troposphere is calculated by using the meteorological data of the International GNSS Service (IGS) stations in Asia in 2012, and the accuracy of the tropospheric delay model is verified to be less than 25 mm. The three stations with the baseline distance are selected and divided into three sets of scatter correspondence comparison stations. The oblique delay at0--5 incident angle is calculated by ray tracing method. The results show that the maximum one-way propagation delay is 22.38--48.37 m for the three groups, and 3.73--8.07 ns for the two-way time offset 95%.
2017, 39(6): 1333-1339.
doi: 10.11999/JEIT160750
Abstract:
To solve the problem of time-frequency interference existing in the multicomponent Polynomial Phase Signal (mc-PPS) Wigner-Ville distribution, a new time-frequency analysis method based on the multi-scale Chirplet sparse decomposition and Wigner-Ville transform is proposed. This method projects mc-PPS onto the multi-scale Chirplet base functions, searching best base functions by the improved FRactional Fourier Transform (FRFT). Through the Wigner-Ville transform and best path pursuit algorithm, the base functions constitute largest energy signals component and power distribution in turns. Simulation results verify that the proposed method can restrain effectively the cross-interference of constant mc-PPS in low Signal-to-Noise Ratio condition, maintain a high time-frequency aggregation, and overcome the large computation of global searching algorithm. Furthermore, this method is suitable for non-stationary signals analysis and processing.
To solve the problem of time-frequency interference existing in the multicomponent Polynomial Phase Signal (mc-PPS) Wigner-Ville distribution, a new time-frequency analysis method based on the multi-scale Chirplet sparse decomposition and Wigner-Ville transform is proposed. This method projects mc-PPS onto the multi-scale Chirplet base functions, searching best base functions by the improved FRactional Fourier Transform (FRFT). Through the Wigner-Ville transform and best path pursuit algorithm, the base functions constitute largest energy signals component and power distribution in turns. Simulation results verify that the proposed method can restrain effectively the cross-interference of constant mc-PPS in low Signal-to-Noise Ratio condition, maintain a high time-frequency aggregation, and overcome the large computation of global searching algorithm. Furthermore, this method is suitable for non-stationary signals analysis and processing.
2017, 39(6): 1340-1347.
doi: 10.11999/JEIT160921
Abstract:
In order to improve underdetermined wideband signals DOA estimation accuracy under low Signal to Noise Ratio (SNR) condition, an off-grid sparse learning via iterative minimization algorithm is proposed. Firstly, the novel algorithm vectorizes the covariance matrix in frequency domain to realize visual array extension, as a result, underdetermined wideband signals are transformed into overdetermined signals. Then linear transform is used to eliminate the noise contained virtual array elements, whitening process is utilized to the estimation error of covariance matrix, as a result, the interference in signals is suppressed. Finally, a Bayesian structure containing the joint sparsity parameter of different frequencies and off-grid parameter is built, the minimization sparse expressions of joint sparsity parameter and off-grid parameter are deduced and corresponding parameters are learned iteratively. Compared with other methods, the proposed method does not rely on any prior information, suppresses the inference in virtual array elements more efficiently, reduces the effects of off-grid problem, and gets higher DOA estimation accuracy and resolution under low SNR condition. Simulation experiments verify the validity of the novel algorithm.
In order to improve underdetermined wideband signals DOA estimation accuracy under low Signal to Noise Ratio (SNR) condition, an off-grid sparse learning via iterative minimization algorithm is proposed. Firstly, the novel algorithm vectorizes the covariance matrix in frequency domain to realize visual array extension, as a result, underdetermined wideband signals are transformed into overdetermined signals. Then linear transform is used to eliminate the noise contained virtual array elements, whitening process is utilized to the estimation error of covariance matrix, as a result, the interference in signals is suppressed. Finally, a Bayesian structure containing the joint sparsity parameter of different frequencies and off-grid parameter is built, the minimization sparse expressions of joint sparsity parameter and off-grid parameter are deduced and corresponding parameters are learned iteratively. Compared with other methods, the proposed method does not rely on any prior information, suppresses the inference in virtual array elements more efficiently, reduces the effects of off-grid problem, and gets higher DOA estimation accuracy and resolution under low SNR condition. Simulation experiments verify the validity of the novel algorithm.
2017, 39(6): 1348-1354.
doi: 10.11999/JEIT160825
Abstract:
To solve the phase-difference ambiguity problem in Ultra-Short BaseLine (USBL) underwater acoustic positioning systems, an ambiguity resolution and localization method based on Multiple Classifier Fusion (MCF) is proposed. Firstly, the multiple classifier system is built. Then, ambiguity resolution problem is formulated as classifying and recognizing the ambiguity integer, and Choquet integral is utilized for fusing the results of multiple classifiers. Finally, the category of ambiguity integer is obtained and the target is located. The unambiguous observation condition of the target position is derived. Without constructing an inter-sensor spacing less than half the wavelength, unambiguous aperture of the array is effectively enlarged. Moreover, as statistical characteristics of the observation data are fully utilized, the positioning accuracy approaches the Cramer-Rao bound. Simulation results verify the effectiveness of the proposed method.
To solve the phase-difference ambiguity problem in Ultra-Short BaseLine (USBL) underwater acoustic positioning systems, an ambiguity resolution and localization method based on Multiple Classifier Fusion (MCF) is proposed. Firstly, the multiple classifier system is built. Then, ambiguity resolution problem is formulated as classifying and recognizing the ambiguity integer, and Choquet integral is utilized for fusing the results of multiple classifiers. Finally, the category of ambiguity integer is obtained and the target is located. The unambiguous observation condition of the target position is derived. Without constructing an inter-sensor spacing less than half the wavelength, unambiguous aperture of the array is effectively enlarged. Moreover, as statistical characteristics of the observation data are fully utilized, the positioning accuracy approaches the Cramer-Rao bound. Simulation results verify the effectiveness of the proposed method.
2017, 39(6): 1355-1362.
doi: 10.11999/JEIT160727
Abstract:
The receiver array of matched field processing usually needs to cover the whole water column, such a large arrangement of array hinders its application seriously. To overcome this shortcoming, an approach called matched field processing based on least squares algorithm is proposed, which decomposes the received fields into depth function matrixes and amplitudes of normal mode at the beginning. Then all the mode amplitudes are estimated using the least squares in the sense of minimum norm. Next, the amplitudes estimated are used to reconstruct the received fields of the short vertical linear array, which makes the reconstructed ones contain more environmental information, therefore the performance of matched field processing with short array is improved. In the end, lots of simulations with three short vertical arrays which are located near by water surface are processed in the classical Pekeris waveguide, and the performance of matched field passive localization is evaluated. Meanwhile, in order to quantify the influence of different kinds of geometrical arrangements to the received fields, the generalized cosine-squared between two vectors is used. The results show that when the received fields of short array are reconstructed using the least squares, the generalized cosine-squared is larger obviously, finally the performance of matched field passive localization with short array is improved and the proposed algorithm is proved to be effective.
The receiver array of matched field processing usually needs to cover the whole water column, such a large arrangement of array hinders its application seriously. To overcome this shortcoming, an approach called matched field processing based on least squares algorithm is proposed, which decomposes the received fields into depth function matrixes and amplitudes of normal mode at the beginning. Then all the mode amplitudes are estimated using the least squares in the sense of minimum norm. Next, the amplitudes estimated are used to reconstruct the received fields of the short vertical linear array, which makes the reconstructed ones contain more environmental information, therefore the performance of matched field processing with short array is improved. In the end, lots of simulations with three short vertical arrays which are located near by water surface are processed in the classical Pekeris waveguide, and the performance of matched field passive localization is evaluated. Meanwhile, in order to quantify the influence of different kinds of geometrical arrangements to the received fields, the generalized cosine-squared between two vectors is used. The results show that when the received fields of short array are reconstructed using the least squares, the generalized cosine-squared is larger obviously, finally the performance of matched field passive localization with short array is improved and the proposed algorithm is proved to be effective.
2017, 39(6): 1363-1370.
doi: 10.11999/JEIT160892
Abstract:
In order to achieve spatial cognition and autonomous navigation, enlightened by the mechanism for biological navigation, a bio-inspired goal-directed navigation model based on a multi-scale spatial representation is proposed. First, a place cell map with different scales is constructed for encoding the space environment. Second, the firing rate of place cells in each layer is calculated by the Gaussian function as the input of Q-learning process. Third, the annealing strategy is used to choose a reasonable action. After training and learning, the robot can succeed to plan an optimal route from the starting point to the goal point. Simulation results show that, the proposed method is feasible for goal-directed navigation. Compared with the spatial cognitive model of single scale place cells, the proposed method not only meets the multi-scale spatial representation nature of place cells in hippocampus, but also has a faster learning speed. Additionally, it has good performance on completing the goal- oriented navigation in the presence of obstacles, and can adapt to the change of obstacles in the environment.
In order to achieve spatial cognition and autonomous navigation, enlightened by the mechanism for biological navigation, a bio-inspired goal-directed navigation model based on a multi-scale spatial representation is proposed. First, a place cell map with different scales is constructed for encoding the space environment. Second, the firing rate of place cells in each layer is calculated by the Gaussian function as the input of Q-learning process. Third, the annealing strategy is used to choose a reasonable action. After training and learning, the robot can succeed to plan an optimal route from the starting point to the goal point. Simulation results show that, the proposed method is feasible for goal-directed navigation. Compared with the spatial cognitive model of single scale place cells, the proposed method not only meets the multi-scale spatial representation nature of place cells in hippocampus, but also has a faster learning speed. Additionally, it has good performance on completing the goal- oriented navigation in the presence of obstacles, and can adapt to the change of obstacles in the environment.
2017, 39(6): 1371-1378.
doi: 10.11999/JEIT160888
Abstract:
The main drawback of sparse representation based Single Channel Blind Source Separation (SCBSS) is the interference between sub-dictionaries. To alleviate this drawback, an extra sub-dictionary, named common sub-dictionary, is proposed to add into traditional union dictionary. The single source is reconstructed by linear combining sparsely activity atoms of its corresponding sub-dictionary and common sub-dictionary. The common sub-dictionary can pure discriminative information in each sources specified sub-dictionary since the common information different sources shared together is gathered in common sub-dictionary. The optimization of objective function involves three steps: sparse representation, dictionary updating and weight coefficients optimization, the three steps are iteratively performed for a specified number of times or until convergence. In test stage, single source separation is achieved by combining atoms in source corresponding sub-dictionary and common sub-dictionary with the sparse coefficients of single mixed signal over union dictionary. Experimental results on speech dataset show that, when compared with traditional and state of art algorithms, the proposed algorithm can improve the performance 1 dB at most.
The main drawback of sparse representation based Single Channel Blind Source Separation (SCBSS) is the interference between sub-dictionaries. To alleviate this drawback, an extra sub-dictionary, named common sub-dictionary, is proposed to add into traditional union dictionary. The single source is reconstructed by linear combining sparsely activity atoms of its corresponding sub-dictionary and common sub-dictionary. The common sub-dictionary can pure discriminative information in each sources specified sub-dictionary since the common information different sources shared together is gathered in common sub-dictionary. The optimization of objective function involves three steps: sparse representation, dictionary updating and weight coefficients optimization, the three steps are iteratively performed for a specified number of times or until convergence. In test stage, single source separation is achieved by combining atoms in source corresponding sub-dictionary and common sub-dictionary with the sparse coefficients of single mixed signal over union dictionary. Experimental results on speech dataset show that, when compared with traditional and state of art algorithms, the proposed algorithm can improve the performance 1 dB at most.
2017, 39(6): 1379-1386.
doi: 10.11999/JEIT160786
Abstract:
To solve the problems about noise sensitivity and unclosed segmentation object boundaries in Fuzzy C-means Method (FCM), this paper proposes a fast image segmentation model combined with FCM and curve evolution, based on the pseudo level set formulations and object boundary curves, which are defined on the membership matrixes of FCM. To get the smooth and closed segmentation object boundaries, the Gaussian filter is performed on the pseudo level sets to approximate the function of the curve length regularization term. To eliminate the influence of Gaussian filter on the results of FCM, the gray values of the noisy points?are corrected, according to a new introduced edge-stop function and the mapping relationship between the gray value and membership degree. The FCM and the smoothing object boundary stage are performed alternately, which improves the robustness of this model. The experimental results show that the proposed model can overcome the influence of noise and get better segmentation results.
To solve the problems about noise sensitivity and unclosed segmentation object boundaries in Fuzzy C-means Method (FCM), this paper proposes a fast image segmentation model combined with FCM and curve evolution, based on the pseudo level set formulations and object boundary curves, which are defined on the membership matrixes of FCM. To get the smooth and closed segmentation object boundaries, the Gaussian filter is performed on the pseudo level sets to approximate the function of the curve length regularization term. To eliminate the influence of Gaussian filter on the results of FCM, the gray values of the noisy points?are corrected, according to a new introduced edge-stop function and the mapping relationship between the gray value and membership degree. The FCM and the smoothing object boundary stage are performed alternately, which improves the robustness of this model. The experimental results show that the proposed model can overcome the influence of noise and get better segmentation results.
2017, 39(6): 1387-1393.
doi: 10.11999/JEIT160955
Abstract:
The star maps acquired by the ground-based cameras are susceptible to the complex background of the starry sky and thus have high noise levels. In addition, the targets in star maps are similar to the noises due to their punctate shapes. As a result, the traditional image denoising method is not applicable to star maps. A new adaptive extremum median filtering denoising algorithm is put forward based on energy function, which can effectively remove the salt and pepper noise of the star maps and keep the small target information at the same time. This method employs a twice-check strategy to reduce the false detection ratio of noisy pixels and uses the improved adaptive median filter and the energy function model to recovery noise imagery. The simulated and real star map experiments show that, the Peak Signal to Noise Ratio (PSNR) is improved about 3 times and the Mean Squared Error (MSE) is reduced by in the terms of objective evaluations, the proposed method can effectively improve the denoising result and thus is applicable to star maps.
The star maps acquired by the ground-based cameras are susceptible to the complex background of the starry sky and thus have high noise levels. In addition, the targets in star maps are similar to the noises due to their punctate shapes. As a result, the traditional image denoising method is not applicable to star maps. A new adaptive extremum median filtering denoising algorithm is put forward based on energy function, which can effectively remove the salt and pepper noise of the star maps and keep the small target information at the same time. This method employs a twice-check strategy to reduce the false detection ratio of noisy pixels and uses the improved adaptive median filter and the energy function model to recovery noise imagery. The simulated and real star map experiments show that, the Peak Signal to Noise Ratio (PSNR) is improved about 3 times and the Mean Squared Error (MSE) is reduced by in the terms of objective evaluations, the proposed method can effectively improve the denoising result and thus is applicable to star maps.
2017, 39(6): 1394-1400.
doi: 10.11999/JEIT160923
Abstract:
A high stability routing mechanism for the dynamic wireless Ad-hoc network is designed. Firstly, the condition of link existing between the dynamic nodes and the condition that packets can successfully transport across the link are analyzed. Based on the above analysis, two key indicators of link duration and congestion probability factor, which guarantee the effectiveness of the link are proposed. Secondly, the method to calculate the link duration based on the current movement states of those nodes, and the method to calculate the congestion probability factor based on the queue length of the buffer are put forward. Then, combining the link duration and the congestion probability factor, an On-Demand Routing Protocol based on link Duration and Reliability (ODRP-DR) is proposed. Finally, simulations are conducted to evaluate the effectiveness of the routing mechanism in NS2. The results show that the proposed routing mechanism can effectively reduce the probability of packet loss and routing reconstruction.
A high stability routing mechanism for the dynamic wireless Ad-hoc network is designed. Firstly, the condition of link existing between the dynamic nodes and the condition that packets can successfully transport across the link are analyzed. Based on the above analysis, two key indicators of link duration and congestion probability factor, which guarantee the effectiveness of the link are proposed. Secondly, the method to calculate the link duration based on the current movement states of those nodes, and the method to calculate the congestion probability factor based on the queue length of the buffer are put forward. Then, combining the link duration and the congestion probability factor, an On-Demand Routing Protocol based on link Duration and Reliability (ODRP-DR) is proposed. Finally, simulations are conducted to evaluate the effectiveness of the routing mechanism in NS2. The results show that the proposed routing mechanism can effectively reduce the probability of packet loss and routing reconstruction.
2017, 39(6): 1401-1408.
doi: 10.11999/JEIT160974
Abstract:
There are mismatches of transmission rates and different service classifications between optical domain and wireless domain in Wireless-Optical Broadband Access Network (WOBAN). To improve the QoS of the integration network and make full use of network resources, a new algorithm based on token bucket traffic shaping policy is proposed. According to the service mapping rules and scheduling of EPON and WiMAX, the selection of token bucket parameters B determined based on the relative service priority of the entire network. This paper also combines with more realistic self-similar network traffic to derive the best formula for token bucket parameters and then proposes a shared buffer strategy on the basis of the service priority. Furthermore, an adaptively dynamically adjust traffic shaping policy is obtained through the change of QoS metrics. The simulation results show that the proposed strategy can effectively reduce traffic shaping network equipment pressure while improving the QoS of whole converged networks.
There are mismatches of transmission rates and different service classifications between optical domain and wireless domain in Wireless-Optical Broadband Access Network (WOBAN). To improve the QoS of the integration network and make full use of network resources, a new algorithm based on token bucket traffic shaping policy is proposed. According to the service mapping rules and scheduling of EPON and WiMAX, the selection of token bucket parameters B determined based on the relative service priority of the entire network. This paper also combines with more realistic self-similar network traffic to derive the best formula for token bucket parameters and then proposes a shared buffer strategy on the basis of the service priority. Furthermore, an adaptively dynamically adjust traffic shaping policy is obtained through the change of QoS metrics. The simulation results show that the proposed strategy can effectively reduce traffic shaping network equipment pressure while improving the QoS of whole converged networks.
2017, 39(6): 1409-1416.
doi: 10.11999/JEIT160731
Abstract:
The integration of optical and wireless technologies, denoted as Fiber-Wireless (FiWi) networks, can provide not only high capacity but also flexible wireless access ability with less infrastructure deployment. Since data traffic generated in FiWi networks usually experiences unstable and unpredictable, it is difficult to perform traffic prediction in advance. An effective and fair Dynamic Bandwidth Allocation (DBA) scheme plays an important role. This paper proposes an upstream fair hierarchical DBA scheme for EPON-WLAN networks. Excess bandwidth proportion factor is introduced to address the unfair issue due to the unmatched problem between the allocated bandwidth resource and the assigned user weight among multiple granting cycles. On the other hand, in order to deal with the QoS guarantee and bandwidth waste issue in bandwidth allocation, we jointly taken into account of different traffic QoS priorities, bandwidth requirement proportion, and actual traffic load. Extensive simulation results show that compared with the existing DBA schemes, the proposed hierarchical DBA scheme can improve proportional fairness, throughput and channel utilization. Moreover, the proposed FiWi DBA scheme does not refer to a specific bandwidth resource types, thus obtains good generality.
The integration of optical and wireless technologies, denoted as Fiber-Wireless (FiWi) networks, can provide not only high capacity but also flexible wireless access ability with less infrastructure deployment. Since data traffic generated in FiWi networks usually experiences unstable and unpredictable, it is difficult to perform traffic prediction in advance. An effective and fair Dynamic Bandwidth Allocation (DBA) scheme plays an important role. This paper proposes an upstream fair hierarchical DBA scheme for EPON-WLAN networks. Excess bandwidth proportion factor is introduced to address the unfair issue due to the unmatched problem between the allocated bandwidth resource and the assigned user weight among multiple granting cycles. On the other hand, in order to deal with the QoS guarantee and bandwidth waste issue in bandwidth allocation, we jointly taken into account of different traffic QoS priorities, bandwidth requirement proportion, and actual traffic load. Extensive simulation results show that compared with the existing DBA schemes, the proposed hierarchical DBA scheme can improve proportional fairness, throughput and channel utilization. Moreover, the proposed FiWi DBA scheme does not refer to a specific bandwidth resource types, thus obtains good generality.
2017, 39(6): 1417-1423.
doi: 10.11999/JEIT160816
Abstract:
As the most important core technology in Content Centric Networking (CCN), caching is widely concerned . In order to improve the network performance and enhance the user satisfaction of data request, a Content-based Level and the Popularity of Caching (CLPC) strategies is proposed . The strategy decides the cache position of data and design method of data replacement by setting the request content level of different users and counting the request frequency, to ensure the optimum request of different users for different data and improve the performance of the network. Experimental results show that compared with the CEE + LRU, Prob (0.7) + LRU and Betw+LRU, the CLPC can increase cache hit ratio, reduce the average delay and the content source hit ratio.
As the most important core technology in Content Centric Networking (CCN), caching is widely concerned . In order to improve the network performance and enhance the user satisfaction of data request, a Content-based Level and the Popularity of Caching (CLPC) strategies is proposed . The strategy decides the cache position of data and design method of data replacement by setting the request content level of different users and counting the request frequency, to ensure the optimum request of different users for different data and improve the performance of the network. Experimental results show that compared with the CEE + LRU, Prob (0.7) + LRU and Betw+LRU, the CLPC can increase cache hit ratio, reduce the average delay and the content source hit ratio.
2017, 39(6): 1424-1431.
doi: 10.11999/JEIT160718
Abstract:
It is particularly important to estimate the geometric features of buried pipe cables in urban construction and municipal infrastructure maintenance. For this kind of subsurface thin-wire structure targets, a method for estimation of the length and orientation of a target based on transient electromagnetic responses is proposed. In this method, a time delay difference model of the backscattering responses from such thin-wire structures illuminated by electromagnetic wave at Brewsters angle with horizontal polarization is established. By analyzing the time-frequency distribution of the transient responses, the relationship between the resonant state and the target length is established and the length of the target is estimated. The energy change between the early time responses and late time resonances is applied to determining the time sequence of the arrival of the electromagnetic wave to the target. Then the target orientation is estimated by the time delay difference of early time responses. Numerical simulation results show that the proposed method is effective in the case of the direction of electric field close to the target axial direction. Meanwhile, the proposed method is robust to noise, and can be applied to length estimation forSNR5 dB and orientation estimation for SNR10 dB.
It is particularly important to estimate the geometric features of buried pipe cables in urban construction and municipal infrastructure maintenance. For this kind of subsurface thin-wire structure targets, a method for estimation of the length and orientation of a target based on transient electromagnetic responses is proposed. In this method, a time delay difference model of the backscattering responses from such thin-wire structures illuminated by electromagnetic wave at Brewsters angle with horizontal polarization is established. By analyzing the time-frequency distribution of the transient responses, the relationship between the resonant state and the target length is established and the length of the target is estimated. The energy change between the early time responses and late time resonances is applied to determining the time sequence of the arrival of the electromagnetic wave to the target. Then the target orientation is estimated by the time delay difference of early time responses. Numerical simulation results show that the proposed method is effective in the case of the direction of electric field close to the target axial direction. Meanwhile, the proposed method is robust to noise, and can be applied to length estimation forSNR5 dB and orientation estimation for SNR10 dB.
2017, 39(6): 1432-1438.
doi: 10.11999/JEIT160861
Abstract:
The radar technology used in indoor localization prefers wide bandwidth frequency modulated continuous wave for high accuracy, yet this way needs specific device and suffers from clutters. In order to reduce the bandwidth overhead, the indoor human localization is implemented based on dual frequency continuous wave phase ratio. However, the receive signal spectrum spreads due to the complex indoor environment and the changing moving speed. The spectrum spread will leads to SNR reduction, energy divergence and wrong peak value, which decrease velocity measuring and localization accuracy. To improve the location accuracy, the frequency domain signal is calibrated with the proposed partial velocity deviation compensation algorithm in the dual frequency phase ratio localization. The experiment results show that the root mean square error of the distance measuring is as high as 9 ~ 14 cm in low bandwidth, which is parallel to the state of art. Moreover, the indoor localization and tracking can work in real time by using the proposed low complexity algorithm.
The radar technology used in indoor localization prefers wide bandwidth frequency modulated continuous wave for high accuracy, yet this way needs specific device and suffers from clutters. In order to reduce the bandwidth overhead, the indoor human localization is implemented based on dual frequency continuous wave phase ratio. However, the receive signal spectrum spreads due to the complex indoor environment and the changing moving speed. The spectrum spread will leads to SNR reduction, energy divergence and wrong peak value, which decrease velocity measuring and localization accuracy. To improve the location accuracy, the frequency domain signal is calibrated with the proposed partial velocity deviation compensation algorithm in the dual frequency phase ratio localization. The experiment results show that the root mean square error of the distance measuring is as high as 9 ~ 14 cm in low bandwidth, which is parallel to the state of art. Moreover, the indoor localization and tracking can work in real time by using the proposed low complexity algorithm.
2017, 39(6): 1439-1445.
doi: 10.11999/JEIT160562
Abstract:
This paper proposes a least-squares registration algorithm using Time Differences Of Arrival (TDOA) and Gain Ratios Of Arrival (GROA) measurements to solve the problem of multiple moving observers passive localization under the influence of system error. The proposed algorithm linearizes the nonlinear measurement equation by Taylor expansion, executes least squares algorithm for the joint estimation of target state and system biases, and considers the influence of measurement noise and location errors of observers. Meanwhile Cramr-Rao Lower Bound (CRLB) under the influence of measurement noise, location errors of observers and system biases is derived, and the influence of system error on CRLB is analyzed. Simulations under several different conditions indicate the proposed algorithm is valid, which can effectively estimate the system biases and target state.
This paper proposes a least-squares registration algorithm using Time Differences Of Arrival (TDOA) and Gain Ratios Of Arrival (GROA) measurements to solve the problem of multiple moving observers passive localization under the influence of system error. The proposed algorithm linearizes the nonlinear measurement equation by Taylor expansion, executes least squares algorithm for the joint estimation of target state and system biases, and considers the influence of measurement noise and location errors of observers. Meanwhile Cramr-Rao Lower Bound (CRLB) under the influence of measurement noise, location errors of observers and system biases is derived, and the influence of system error on CRLB is analyzed. Simulations under several different conditions indicate the proposed algorithm is valid, which can effectively estimate the system biases and target state.
2017, 39(6): 1446-1451.
doi: 10.11999/JEIT160854
Abstract:
A dual stop band Frequency Selective Surface (FSS) in windmill-liked shape is proposed, which achieves wide Rader Cross Section (RCS) reduction by applying FSS on the ground of the dualband microstrip antenna. Each corner of the FSS is formed by combining two semi-suqares which have 90 of rotation between each semi-square. The dual stop bands are the results of the resonance of the electric dipole and the higher order mode effect. The simulation and measurement results show that the gain of E plane and H plane at 5.20 GHz is maintained, while the gain of E plane and H plane at 10.41 GHz are increased by 1.8 dBi, simultaneously. The antennas monostatic RCS reduction is obviously observed in a wide frequency band ranging from 1.0 GHz to 16.8 GHz. Whats more, the maximum value is 28.3 dB under x polarization and 36.2 dB under y polarization, respectively.
A dual stop band Frequency Selective Surface (FSS) in windmill-liked shape is proposed, which achieves wide Rader Cross Section (RCS) reduction by applying FSS on the ground of the dualband microstrip antenna. Each corner of the FSS is formed by combining two semi-suqares which have 90 of rotation between each semi-square. The dual stop bands are the results of the resonance of the electric dipole and the higher order mode effect. The simulation and measurement results show that the gain of E plane and H plane at 5.20 GHz is maintained, while the gain of E plane and H plane at 10.41 GHz are increased by 1.8 dBi, simultaneously. The antennas monostatic RCS reduction is obviously observed in a wide frequency band ranging from 1.0 GHz to 16.8 GHz. Whats more, the maximum value is 28.3 dB under x polarization and 36.2 dB under y polarization, respectively.
2017, 39(6): 1452-1457.
doi: 10.11999/JEIT160938
Abstract:
Since the traditional Read-Only Memory (ROM) has the problems of low density and high power consumption, a mask ROM based on diode cells and contact-programming process is proposed. With dual-trench isolation process and borderless contact scheme, the diode array can realize ultrahigh density. Based on the proposed novel diode array, a mask ROM macro with 2 Mb capacity is designed, which contains 8 256 kb sub-arrays. The diode arrays are fabricated with 40 nm design rule and the peripheral logic circuits are achieved in 2.5 V CMOS process. The effective area of the diode cell is only 0.017 m2 and the density of the diode array is 0.0268 mm2/Mb. Test results show that the cell feature of diodes is good and the bit yield of the 2 Mb ROM achieves 99.8% under 2.5 V supply voltage.
Since the traditional Read-Only Memory (ROM) has the problems of low density and high power consumption, a mask ROM based on diode cells and contact-programming process is proposed. With dual-trench isolation process and borderless contact scheme, the diode array can realize ultrahigh density. Based on the proposed novel diode array, a mask ROM macro with 2 Mb capacity is designed, which contains 8 256 kb sub-arrays. The diode arrays are fabricated with 40 nm design rule and the peripheral logic circuits are achieved in 2.5 V CMOS process. The effective area of the diode cell is only 0.017 m2 and the density of the diode array is 0.0268 mm2/Mb. Test results show that the cell feature of diodes is good and the bit yield of the 2 Mb ROM achieves 99.8% under 2.5 V supply voltage.
2017, 39(6): 1458-1463.
doi: 10.11999/JEIT160835
Abstract:
An efficient design of truly random seed generator based on SRAM Physical Unclonable Functions (PUFs) is proposed in this paper. Only the noisy cells of high min-entropy are selected to generate full entropy seeds in this design. Therefore, it can reduce the amount of data to be processed significantly and improve the efficiency of seed generation. The oscillating characteristics of the noisy cells inside SRAM are measured, and screening strategies for filtering out the selected noisy cells inside the SRAM are put forward. Finally, based on the strategies, a truly random seed generator is designed, which can generate full entropy seeds. The length of seeds generated by this design is from 128 bit to 256 bit. The number of the selected cells which are used to generate seeds is from 0.5% to 4% of all SRAM cells. Compared to the current design, it is shown that the proposed design in this paper is efficient and widely applicable.
An efficient design of truly random seed generator based on SRAM Physical Unclonable Functions (PUFs) is proposed in this paper. Only the noisy cells of high min-entropy are selected to generate full entropy seeds in this design. Therefore, it can reduce the amount of data to be processed significantly and improve the efficiency of seed generation. The oscillating characteristics of the noisy cells inside SRAM are measured, and screening strategies for filtering out the selected noisy cells inside the SRAM are put forward. Finally, based on the strategies, a truly random seed generator is designed, which can generate full entropy seeds. The length of seeds generated by this design is from 128 bit to 256 bit. The number of the selected cells which are used to generate seeds is from 0.5% to 4% of all SRAM cells. Compared to the current design, it is shown that the proposed design in this paper is efficient and widely applicable.
2017, 39(6): 1464-1471.
doi: 10.11999/JEIT160889
Abstract:
To reduce the soft error rate of the circuit, this paper proposes a low power soft error tolerant latch based on time redundancy technology. The proposed latch can fully tolerate the Single Event Upset (SEU) when particles strike on internal nodes. Furthermore, it can efficiently mask the input Single Event Transient (SET). Its output node will not enter a high impedance state when a particle strikes on internal nodes, so the proposed latch can be applied to clock-gating circuits. Detailed SPICE simulations are done to evaluate the proposed latch circuit and previous latch circuits designed in the literatures. Compared with other soft error tolerant latches, the proposed latch introduces 13.4% delay overhead on average. While it can achieve 44.3% increase in filterable SET pulse width, 48.5% reduction in power, 46.0% reduction in Power Delay Product (PDP), and 9.1% reduction in transistor numbers on average.
To reduce the soft error rate of the circuit, this paper proposes a low power soft error tolerant latch based on time redundancy technology. The proposed latch can fully tolerate the Single Event Upset (SEU) when particles strike on internal nodes. Furthermore, it can efficiently mask the input Single Event Transient (SET). Its output node will not enter a high impedance state when a particle strikes on internal nodes, so the proposed latch can be applied to clock-gating circuits. Detailed SPICE simulations are done to evaluate the proposed latch circuit and previous latch circuits designed in the literatures. Compared with other soft error tolerant latches, the proposed latch introduces 13.4% delay overhead on average. While it can achieve 44.3% increase in filterable SET pulse width, 48.5% reduction in power, 46.0% reduction in Power Delay Product (PDP), and 9.1% reduction in transistor numbers on average.
2017, 39(6): 1472-1478.
doi: 10.11999/JEIT160826
Abstract:
On the basis of the analysis of the structure, operation principle and mechanism of generating spurs of the charge pump, a charge pump with a low static current mismatch and a low timing mismatch is proposed. This charge pump suppresses the jitter and spurs in high-speed Phase-Looked Loops (PLL) by improving the timing mismatch and the current mismatch during switching in the charge pump. Based on the SMIC 0.18 m CMOS radio frequency technology with 1.8 V power supply, the phase noise simulation of the PLLs adopting the proposed charge pump is performed. The simulation results demonstrate that those PLLs achieve a low noise performance: the second-order PLL shows a period jitter of 1.05 ps and the largest reference spur of -121 dBc with the PLL output frequency of 480 MHz.
On the basis of the analysis of the structure, operation principle and mechanism of generating spurs of the charge pump, a charge pump with a low static current mismatch and a low timing mismatch is proposed. This charge pump suppresses the jitter and spurs in high-speed Phase-Looked Loops (PLL) by improving the timing mismatch and the current mismatch during switching in the charge pump. Based on the SMIC 0.18 m CMOS radio frequency technology with 1.8 V power supply, the phase noise simulation of the PLLs adopting the proposed charge pump is performed. The simulation results demonstrate that those PLLs achieve a low noise performance: the second-order PLL shows a period jitter of 1.05 ps and the largest reference spur of -121 dBc with the PLL output frequency of 480 MHz.
2017, 39(6): 1479-1486.
doi: 10.11999/JEIT160752
Abstract:
As the advantages of zero-current-switching and zero-voltage-switching, the LCLC resonant converters are widely used in power supplies of Travelling-Wave Tubes (TWT). However, the problems such as the reverse resonant current and the non-zero resonant current in the converter drop the efficiency. In this paper, the above problems are explained by the working principle of the converter and the solutions to the problems are also given. Based on the simulations, empirical data is given to guide the design of the LCLC resonant converters. Finally, the analysis is validated by the simulations and experiments.
As the advantages of zero-current-switching and zero-voltage-switching, the LCLC resonant converters are widely used in power supplies of Travelling-Wave Tubes (TWT). However, the problems such as the reverse resonant current and the non-zero resonant current in the converter drop the efficiency. In this paper, the above problems are explained by the working principle of the converter and the solutions to the problems are also given. Based on the simulations, empirical data is given to guide the design of the LCLC resonant converters. Finally, the analysis is validated by the simulations and experiments.
2017, 39(6): 1487-1492.
doi: 10.11999/JEIT160911
Abstract:
Planar transformers are widely used in low-voltage applications because of the advantages of low profile, high power density and excellent thermal characteristics. This paper applies the planar transformer for power supplies to Travelling-Wave Tube Amplifiers (TWTAs). Based on the LCLC topology, which is always used in TWTAs, a planar transformer with an interleaved structure is designed. In addition, the experimental results are in accordance with the simulation results. The input voltage of the converter is 40 V, the output voltage is 4800 V, the output power is 295 W and the switching frequency is 500 kHz. Conclusions can be drawn that with the planar transformers, the switching frequency can be increased and the volume of the power supplies can be reduced.
Planar transformers are widely used in low-voltage applications because of the advantages of low profile, high power density and excellent thermal characteristics. This paper applies the planar transformer for power supplies to Travelling-Wave Tube Amplifiers (TWTAs). Based on the LCLC topology, which is always used in TWTAs, a planar transformer with an interleaved structure is designed. In addition, the experimental results are in accordance with the simulation results. The input voltage of the converter is 40 V, the output voltage is 4800 V, the output power is 295 W and the switching frequency is 500 kHz. Conclusions can be drawn that with the planar transformers, the switching frequency can be increased and the volume of the power supplies can be reduced.
2017, 39(6): 1493-1502.
doi: 10.11999/JEIT161299
Abstract:
Given a graphG and a proper vertex coloring ofG, a 2-coloring induced subgraph ofG is a subgraph induced by all the vertices with one of two colors, a component of a 2-coloring induced subgraph is called a 2-coloring component. To make a Kempe change is to obtain one coloring from another by exchanging the colors of vertices in a 2-coloring component. Since Kempe introduced Kempe changes in his false proof of the Four Color Theorem in 1879, many scholars devote to the research on Kempe changes from different points of view. The main contributions in this paper are as follows: (1) Some basic properties of Kempe changes are summarized; (2) A series of important results with regard to Kempe changes are to be reviewed and analyzed in detail; (3) Another novel and more brief proof method of Meyniel Theorem, that all 5-colorings of a planar graph are Kempe equivalent, is given out; (4) A problem related with types of colorings is proposed here, which intends to explore the relationships between different Kempe equivalent classes, and thus contributes to the further study.
Given a graphG and a proper vertex coloring ofG, a 2-coloring induced subgraph ofG is a subgraph induced by all the vertices with one of two colors, a component of a 2-coloring induced subgraph is called a 2-coloring component. To make a Kempe change is to obtain one coloring from another by exchanging the colors of vertices in a 2-coloring component. Since Kempe introduced Kempe changes in his false proof of the Four Color Theorem in 1879, many scholars devote to the research on Kempe changes from different points of view. The main contributions in this paper are as follows: (1) Some basic properties of Kempe changes are summarized; (2) A series of important results with regard to Kempe changes are to be reviewed and analyzed in detail; (3) Another novel and more brief proof method of Meyniel Theorem, that all 5-colorings of a planar graph are Kempe equivalent, is given out; (4) A problem related with types of colorings is proposed here, which intends to explore the relationships between different Kempe equivalent classes, and thus contributes to the further study.
2017, 39(6): 1503-1514.
doi: 10.11999/JEIT161288
Abstract:
Low Density Parity Check (LDPC) codes are employed in several standards and systems, due to their Shannon limit approaching ability. However, in order to satisfy the communication systems requirements at the aspects of error correction ability, computing complexity, decoding latency, hardware source consumption and power consumption under different application circumstances, the Belief Propagation (BP) algorithm used for decoding LDPC codes needs to be further investigated and improved. In this survey, authors summarize several different Beyond-BP algorithms from the aspects of motivation, methodology, complexity and performance. Moreover, this survey also discusses the optimization of decoding algorithms for iterative receive system, which can provide a reference for further investigation on this topic.
Low Density Parity Check (LDPC) codes are employed in several standards and systems, due to their Shannon limit approaching ability. However, in order to satisfy the communication systems requirements at the aspects of error correction ability, computing complexity, decoding latency, hardware source consumption and power consumption under different application circumstances, the Belief Propagation (BP) algorithm used for decoding LDPC codes needs to be further investigated and improved. In this survey, authors summarize several different Beyond-BP algorithms from the aspects of motivation, methodology, complexity and performance. Moreover, this survey also discusses the optimization of decoding algorithms for iterative receive system, which can provide a reference for further investigation on this topic.
2017, 39(6): 1515-1519.
doi: 10.11999/JEIT161248
Abstract:
Based on the large scale fading channel model in antenna-array domain, this paper investigates the uplink performance for a massive MIMO system, where each antenna is equipped with one-bit Analog-to-Digital Converters (ADCs). A closed-form expression for the uplink achievable rate with Maximum Ratio Combining (MRC) receiver is derived, and the power efficiency performance, as well as the comparison between the one-bit systems and the conventional system with infinite resolution ADCs are investigated. Numerical results are presented to verify the analytical results.
Based on the large scale fading channel model in antenna-array domain, this paper investigates the uplink performance for a massive MIMO system, where each antenna is equipped with one-bit Analog-to-Digital Converters (ADCs). A closed-form expression for the uplink achievable rate with Maximum Ratio Combining (MRC) receiver is derived, and the power efficiency performance, as well as the comparison between the one-bit systems and the conventional system with infinite resolution ADCs are investigated. Numerical results are presented to verify the analytical results.
2017, 39(6): 1520-1524.
doi: 10.11999/JEIT160738
Abstract:
A modified Sierpinski fractal Ultra WideBand (UWB) antenna with band notch characteristic is proposed to refrain the interference from WLAN. The radiating path is the modified fourth order Sierpinski fractal structure. The bandwidth of the antenna is effectively expanded and can cover the bandwidth of UWB band (3.1~10.6 GHz) by using coplanar waveguide feed technology and increasing the number of iterations of Sierpinski fractal. The notch band characteristic in 5.03~5.85 GHz is realized by adding two symmetrical L-shaped stubs on the fractal path, which can effectively suppress the interference of WLAN. The antenna has a compact size, and the simulation and measurement results show that the antenna can be widely used in all kinds of UWB communication systems.
A modified Sierpinski fractal Ultra WideBand (UWB) antenna with band notch characteristic is proposed to refrain the interference from WLAN. The radiating path is the modified fourth order Sierpinski fractal structure. The bandwidth of the antenna is effectively expanded and can cover the bandwidth of UWB band (3.1~10.6 GHz) by using coplanar waveguide feed technology and increasing the number of iterations of Sierpinski fractal. The notch band characteristic in 5.03~5.85 GHz is realized by adding two symmetrical L-shaped stubs on the fractal path, which can effectively suppress the interference of WLAN. The antenna has a compact size, and the simulation and measurement results show that the antenna can be widely used in all kinds of UWB communication systems.
