摘要
利用排队论方法建立了变比特率语音业务迭加流的排队模型，导出了变比特率语音业务迭加流的分布函数．结果表明，变比特率语音业务流迭加后，其相邻两个话音突峰的间隔时间服从超负指数分布．分析研究了变比特率语音迭加流的特性．结果表明，当输入话务量较大（≥４７Ｅｒｌ）时，变比特率语音迭加流的数学期望和均方差很接近，因此，在这种情况下，变比特率语音迭加流可看成是一具有相同强度的泊松流．
The close relationship among wavelet transform and quadrature mirror filter(QMF) banks and the scattering matrix is analyzed in detail. The parametrization of orthonormal compactly supported wavelet bases that have arbitrary number of vanishing moment is obtained by building any QMF pair out of elementary factors of the scattering matrix. In addition, the parameter's optimization that is based on the regularity constrain is presented. A new improved CELP coder scheme adopting wavelet transform(WT) is also presented. Combining the compactly supported wavelet that has the most vanishing moments with CELP, it ensures high quality speech at 4.8 kbit/s by using a WT approach instead of the stochastic codebook based vector quantization. It reduces the complexity of computation and the required store of the coder. So the algorithm is simple and more suitable for real time implementation.
出处
《北京邮电大学学报》
EI
CAS
CSCD
北大核心
1997年第3期30-33,共4页
Journal of Beijing University of Posts and Telecommunications
关键词
话务理论
变比特率
迭加流
分布函数
电话
speech coding
parametrization
compactly supported orthonormal wavelet
CELP
