分析了Ka频段卫星通信的信道特性与模型,对基于小波包分复用(wavelet packet division multiplex,WPDM)的Ka频段卫星传输系统进行了研究;并采用支撑长度低的小波函数来降低系统的高峰均功率比(peak to average vatio,PAPR)。仿真结果能...分析了Ka频段卫星通信的信道特性与模型,对基于小波包分复用(wavelet packet division multiplex,WPDM)的Ka频段卫星传输系统进行了研究;并采用支撑长度低的小波函数来降低系统的高峰均功率比(peak to average vatio,PAPR)。仿真结果能和该系统的误码率分析结果很好地吻合,并通过与OFDM(orthogonal frequency division multiplex)系统仿真对比得到在误码率为10-3时可节约3 dB;且显示出支撑长度低的小波函数能有效降低系统峰均功率比,从而提高系统性能。展开更多
This paper is concerned with the development of product data management （PDM） systems--WPDM systems based on web technologies. As a tool to integrate information, traditional PDM system has many benefits for the com...This paper is concerned with the development of product data management （PDM） systems--WPDM systems based on web technologies. As a tool to integrate information, traditional PDM system has many benefits for the companies in such aspects as improving design productivity, better control over projects and so on. With the maturing of web technologies, the advantages of WPDM system are obvious. We will show these advantages in detail in Part 3. WPDM system is built on three-tier application model to provide security and flexibility, they are back-end, middle layer and front-end. The basic designs in each layer will be briefly introduced in Part 4. In the future, WPDM will be extended to integrate with other applications to provide a complete web-based engineering environment.展开更多
文摘分析了Ka频段卫星通信的信道特性与模型,对基于小波包分复用(wavelet packet division multiplex,WPDM)的Ka频段卫星传输系统进行了研究;并采用支撑长度低的小波函数来降低系统的高峰均功率比(peak to average vatio,PAPR)。仿真结果能和该系统的误码率分析结果很好地吻合,并通过与OFDM(orthogonal frequency division multiplex)系统仿真对比得到在误码率为10-3时可节约3 dB;且显示出支撑长度低的小波函数能有效降低系统峰均功率比,从而提高系统性能。
文摘This paper is concerned with the development of product data management （PDM） systems--WPDM systems based on web technologies. As a tool to integrate information, traditional PDM system has many benefits for the companies in such aspects as improving design productivity, better control over projects and so on. With the maturing of web technologies, the advantages of WPDM system are obvious. We will show these advantages in detail in Part 3. WPDM system is built on three-tier application model to provide security and flexibility, they are back-end, middle layer and front-end. The basic designs in each layer will be briefly introduced in Part 4. In the future, WPDM will be extended to integrate with other applications to provide a complete web-based engineering environment.
