A nonparametric Bayesian method is presented to classify the MPSK （M-ary phase shift keying） signals. The MPSK signals with unknown signal noise ratios （SNRs） are modeled as a Gaussian mixture model with unknown m...A nonparametric Bayesian method is presented to classify the MPSK （M-ary phase shift keying） signals. The MPSK signals with unknown signal noise ratios （SNRs） are modeled as a Gaussian mixture model with unknown means and covariances in the constellation plane, and a clustering method is proposed to estimate the probability density of the MPSK signals. The method is based on the nonparametric Bayesian inference, which introduces the Dirichlet process as the prior probability of the mixture coefficient, and applies a normal inverse Wishart （NIW） distribution as the prior probability of the unknown mean and covariance. Then, according to the received signals, the parameters are adjusted by the Monte Carlo Markov chain （MCMC） random sampling algorithm. By iterations, the density estimation of the MPSK signals can be estimated. Simulation results show that the correct recognition ratio of 2/4/8PSK is greater than 95% under the condition that SNR 〉5 dB and 1 600 symbols are used in this method.展开更多
This paper argues that models developed in 20th century management literature can offer a valuable perspective on the organization of the ancient Roman wine trade. Similar to modem business, Roman entrepreneurs tried ...This paper argues that models developed in 20th century management literature can offer a valuable perspective on the organization of the ancient Roman wine trade. Similar to modem business, Roman entrepreneurs tried to enhance efficiency by implementing a wide range of techniques according to goals and available resources. The famous Ansoff matrix is used to analyse these techniques in function of the markets supplied by Roman merchants and the product diversification they applied. This approach explains how Roman entrepreneurs tried to cope with the limitations of a volatile pre-industrial business world： only the combination of a large family of semi-dependent agents and elite capital allowed successful large-scale engagement in the wine trade.展开更多
In this paper, we give design methods for three-transmit-antenna space-time codes which have reasonable parameters. A few examples are given to show that some unitary space-time codes constructed with our methods are ...In this paper, we give design methods for three-transmit-antenna space-time codes which have reasonable parameters. A few examples are given to show that some unitary space-time codes constructed with our methods are better than the previously best-known ones.展开更多
基金Cultivation Fund of the Key Scientific and Technical Innovation Project of Ministry of Education of China(No.3104001014)
文摘A nonparametric Bayesian method is presented to classify the MPSK （M-ary phase shift keying） signals. The MPSK signals with unknown signal noise ratios （SNRs） are modeled as a Gaussian mixture model with unknown means and covariances in the constellation plane, and a clustering method is proposed to estimate the probability density of the MPSK signals. The method is based on the nonparametric Bayesian inference, which introduces the Dirichlet process as the prior probability of the mixture coefficient, and applies a normal inverse Wishart （NIW） distribution as the prior probability of the unknown mean and covariance. Then, according to the received signals, the parameters are adjusted by the Monte Carlo Markov chain （MCMC） random sampling algorithm. By iterations, the density estimation of the MPSK signals can be estimated. Simulation results show that the correct recognition ratio of 2/4/8PSK is greater than 95% under the condition that SNR 〉5 dB and 1 600 symbols are used in this method.
文摘This paper argues that models developed in 20th century management literature can offer a valuable perspective on the organization of the ancient Roman wine trade. Similar to modem business, Roman entrepreneurs tried to enhance efficiency by implementing a wide range of techniques according to goals and available resources. The famous Ansoff matrix is used to analyse these techniques in function of the markets supplied by Roman merchants and the product diversification they applied. This approach explains how Roman entrepreneurs tried to cope with the limitations of a volatile pre-industrial business world： only the combination of a large family of semi-dependent agents and elite capital allowed successful large-scale engagement in the wine trade.
基金The research is supported by the National Natural Science Foundation of China under Grant No.60673074.
文摘In this paper, we give design methods for three-transmit-antenna space-time codes which have reasonable parameters. A few examples are given to show that some unitary space-time codes constructed with our methods are better than the previously best-known ones.
