Since the existing full-rate cooperative transmission schemes have a serious defect in low Bit Error Rate (BER) performance while the existing high-rate cooperative transmission schemes have a serious defect in low sp...
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Since the existing full-rate cooperative transmission schemes have a serious defect in low Bit Error Rate (BER) performance while the existing high-rate cooperative transmission schemes have a serious defect in low spectral efficiency, a distributed high-rate cooperative relay transmission scheme based on full-rate cooperative communication model is proposed in this paper, in which Cyclic Delay Diversity (CDD) technology and Linear Constellation Precoding (LCP) technology are employed. Moreover, the proposed scheme addresses the issue of obtaining maximum spatial and multipath diversity with low decoding complexity and high transmission reliability. The BER performance of the proposed scheme is contrasted to that of the full-rate transmission scheme where better performance is achieved, and is improved when the number of the multipath or the relay nodes increases.
Since the single-antenna relay cooperative communication systems have a serious defect in reliability of data transmission, while the MIMO communication systems have difficulty in design and decoding, we propose a mix...
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Since the single-antenna relay cooperative communication systems have a serious defect in reliability of data transmission, while the MIMO communication systems have difficulty in design and decoding, we propose a mixed structure of full-rate and low-detection complexity cooperative relay transmission scheme based on full-rate relay cooperative transmission model, which combines the advantages of cyclic delay diversity (CDD) technology and linear constellation precoding (LCP) technology. This scheme can excavation diversity gain by using single antenna terminal and multiple antenna simultaneously, moreover, the decoding complexity is low. The bit error rate (BER) performance is improved with the number of the antenna or the multipath or the relay nodes increases.
Independent Component Analysis (ICA) was often used to separate movement related independent components (MRICs) from Electroencephalogram (EEG) data.?However, to obtain robust spatial filters, complex characteristic f...
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Independent Component Analysis (ICA) was often used to separate movement related independent components (MRICs) from Electroencephalogram (EEG) data.?However, to obtain robust spatial filters, complex characteristic features, which were manually selected in most cases, have been commonly used. This study proposed a new simple algorithm to extract MRICs automatically, which just utilized the spatial distribution pattern of ICs. The main goal of this study was to show the relationship between spatial filters performance and designing samples. The EEG data which contain?mixed brain states (preparing, motor imagery and rest) were used to design spatial filters. Meanwhile, the single class data was also used to calculate spatial filters to assess whether the MRICs extracted on different class motor imagery spatial filters are similar. Furthermore, the spatial filters constructed on one subject’s EEG data were applied to extract the others’ MRICs. Finally, the different spatial filters were then applied to single-trial EEG to extract MRICs, and Support Vector Machine (SVM) classifiers were used to discriminate left hand、right-hand and foot imagery movements of BCI Competition IV Dataset 2a, which recorded four motor imagery data of nine subjects. The results suggested that any segment of finite motor imagery EEG samples could be used to design ICA spatial filters, and the extracted MRICs are consistent if the position of electrodes are the same, which confirmed the robustness and practicality of ICA used in the motor imagery Brain Computer Interfaces (MI-BCI) systems.
IEEE 802.11 is a protocol standard widely used in wireless local area network (WLAN). For the distributed coordination function (DCF) of IEEE 802.11 MAC layer, the binary exponential backoff (BEB) algorithm has the de...
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IEEE 802.11 is a protocol standard widely used in wireless local area network (WLAN). For the distributed coordination function (DCF) of IEEE 802.11 MAC layer, the binary exponential backoff (BEB) algorithm has the defect of poor access fairness. To address this issue, the design criteria of backoff algorithm is generalized from the analysis of the key performance parameters of DCF, and then a logarithmic backoff (LB) algorithm based on dynamic contention window (CW) adjustment is proposed. The algorithm dynamically adjusts the initial value of CW and the backoff size of the CW by using the logarithmic function that takes the number of network competing nodes as the variable. Simulation results show that compared with the BEB algorithm, the LB algorithm can effectively improve the fairness performance and the throughput performance, and also reduce network delay.
The method of SP-FDTD (Splitting Plane wave Finite Difference Time Domain)is applied to 3D FDTD (Finite Difference Time Domain)method for plane wave incidence. Based on the split-field formulation, the method has the ...
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The method of SP-FDTD (Splitting Plane wave Finite Difference Time Domain)is applied to 3D FDTD (Finite Difference Time Domain)method for plane wave incidence. Based on the split-field formulation, the method has the new iterative equations and can eliminate the error of interpolation and discretized phase velocity mismatch between 1D FDTD and 3D FDTD grid. Numerical results show that the present method is valid for different type of wave sources, and accuracy for oblique incident plane wave, with the leakage error on the order of -300 dB.
This paper presents an automated remote sensing image registration algorithm by using adjacent spectrum. Firstly, the feature points are extracted by Harris detection algorithm;secondly, the adjacent spectral method i...
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Randomized cyclic delay diversity (RCDD) is an effective means to capture both the space diversity and the frequency diversity with low complexity detection over frequency-selective fading channels. Since many existin...
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A full-rate distributed transmission scheme for two-way multi-antenna wireless cooperative relay networks is proposed in this paper, which is suitable for the universal bidirectional relay communication model that two...
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A full-rate distributed transmission scheme for two-way multi-antenna wireless cooperative relay networks is proposed in this paper, which is suitable for the universal bidirectional relay communication model that two source terminals and all relays are equipped with multiple antennas. Orthogonal frequency division multiplexing (OFDM) ways are adopted to complete all information transmissions among different nodes. One whole bidirectional data exchange and transmission process between both source terminals mainly includes two stages. In the first stage, the symbols to be transmitted are jointly coded appropriately at two source terminals during several time slots on each sub-carrier, and then broadcasted to all relay nodes respectively. In the second stage, each OFDM modulation symbol is cyclically delayed with proper cyclic delay value at each relay in time domain. In the amplification and forwarding (AF) process, the operated signals at all relays are transmitted to both source terminals successively in time division (TD) ways, only those antennas performing cooperative relay transmissions at each relay node work together during several proper AF time slots. According to the coding and forwarding rules, one source terminal can obtain the original data from the other terminal after eliminating self-interferences. Finally, the proposed scheme can realize full-rate transmissions with low coding and detection complexity, which is applicable to the general bidirectional relay communication case, the coding process is simple and can be extended to design similar relay schemes easily. Simulation results verify the superiority and effectiveness of the proposed scheme.
We proposed two whispered speech enhancement methods based on asymmetric cost functions in this paper to deal with the amplification and attenuation distortions of whispered speech *** modified Itakura-Saito（MIS）dis...
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We proposed two whispered speech enhancement methods based on asymmetric cost functions in this paper to deal with the amplification and attenuation distortions of whispered speech *** modified Itakura-Saito（MIS）distance function provides more penalties to speech amplification distortion,whereas the Kullback-Leibler（KL）divergence function gives more penalties to speech attenuation *** experimental results show that the MIS function based method achieves significant improvement of intelligibility in contrast to the conventional speech enhancement algorithms when the signal-to-noise ratio（SNR）falls below-6 dB,whereas the KL function based one achieves the similar result as the minimum mean square error（MMSE）speech enhancement *** results show that the effects of the amplification and attenuation distortions on the intelligibility of the enhanced whisper are different,where larger attenuation distortion may result in better intelligibility of speech with low ***,the attenuation distortion has small effects on intelligibility of speech with high SNR.
CoMP has been adopted in 3GPP LTE-Advanced to improve the coverage of high data *** the downlink transmission mode,JP or CB,should be selected for base station cooperation when the backhaul capacity is *** this paper,...
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CoMP has been adopted in 3GPP LTE-Advanced to improve the coverage of high data *** the downlink transmission mode,JP or CB,should be selected for base station cooperation when the backhaul capacity is *** this paper,considering different numbers of users,we propose an adaptive transmission mode *** mitigate the performance degradation caused by mismatching between numbers of transmitting antennas and MSs,we develop a strategy with proportional fairness that takes into account backhaul constraints and users *** simulation results show that the proposed algorithm provide considerable performance gains in the sum rates per cell and the cell-edge user throughput under constrainedcapacity backhaul links.
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