泊松点过程(Poisson Point Process,PPP)为异构蜂窝网络(Heterogeneous Cellular Networks,HetNets)的分析提供易于处理的结果,因此在无线网络建模和性能分析中得到了广泛的应用。然而,它不能准确反映实际基站的空间分布特征。考虑到宏...泊松点过程(Poisson Point Process,PPP)为异构蜂窝网络(Heterogeneous Cellular Networks,HetNets)的分析提供易于处理的结果,因此在无线网络建模和性能分析中得到了广泛的应用。然而,它不能准确反映实际基站的空间分布特征。考虑到宏基站(Macro Base Station,MBS)的分布具有排斥性,文中采用Matérn硬核点过程(Matérn Hard⁃Core Point Process,MHCPP)对MBS的部署进行建模,采用一种简单的近似方法分析了两层MHCPP⁃PPP网络的信噪比分布,推导了异构蜂窝网络的覆盖概率、平均可达速率和能量效率,提出了一种优化算法提高异构蜂窝网络的能量效率。最后,采用单输入单输出(SISO)、空分多址(SDMA)、单用户波束形成(SUBF)三种传输技术对系统的性能进行了仿真和分析。仿真结果表明,通过文中提出的算法得到最优的PBS发射功率可以有效地提高系统的能量效率。此外,两层MHCPP⁃PPP异构蜂窝网络的能量效率高于两层PPP⁃PPP网络。展开更多
We design a planar metasurface to modulate the wavefront of a water surface wave（WSW） on a deep sub-wavelength scale. The metasurface is composed of an array of coiling-up-space units with specially designed paramet...We design a planar metasurface to modulate the wavefront of a water surface wave（WSW） on a deep sub-wavelength scale. The metasurface is composed of an array of coiling-up-space units with specially designed parameters, and can take on the work of steering the wavefront when it is pierced into water. Like their acoustic counterparts, the modulation of WSW is ascribed to the gradient phase shift of the coiling-up-space units, which can be perfectly tuned by changing the coiling plate length and channel number inside the units. According to the generalized Snell＇s law, negative refraction and ＇driven＇ surface mode of WSW are also demonstrated at certain incidences. Specially, the transmitted WSW could be efficiently guided out by linking a symmetrically-corrugated channel in ＇driven＇ surface mode. This work may have potential applications in water wave energy extraction and coastal protection.展开更多
文摘泊松点过程(Poisson Point Process,PPP)为异构蜂窝网络(Heterogeneous Cellular Networks,HetNets)的分析提供易于处理的结果,因此在无线网络建模和性能分析中得到了广泛的应用。然而,它不能准确反映实际基站的空间分布特征。考虑到宏基站(Macro Base Station,MBS)的分布具有排斥性,文中采用Matérn硬核点过程(Matérn Hard⁃Core Point Process,MHCPP)对MBS的部署进行建模,采用一种简单的近似方法分析了两层MHCPP⁃PPP网络的信噪比分布,推导了异构蜂窝网络的覆盖概率、平均可达速率和能量效率,提出了一种优化算法提高异构蜂窝网络的能量效率。最后,采用单输入单输出(SISO)、空分多址(SDMA)、单用户波束形成(SUBF)三种传输技术对系统的性能进行了仿真和分析。仿真结果表明,通过文中提出的算法得到最优的PBS发射功率可以有效地提高系统的能量效率。此外,两层MHCPP⁃PPP异构蜂窝网络的能量效率高于两层PPP⁃PPP网络。
基金Project supported by the National Basic Research Program of China(Grant No.2012CB921504)the National Natural Science Foundation of China(Grant Nos.11474162,11274171,11274099,and 11204145)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant Nos.20110091120040 and 20120091110001)
文摘We design a planar metasurface to modulate the wavefront of a water surface wave（WSW） on a deep sub-wavelength scale. The metasurface is composed of an array of coiling-up-space units with specially designed parameters, and can take on the work of steering the wavefront when it is pierced into water. Like their acoustic counterparts, the modulation of WSW is ascribed to the gradient phase shift of the coiling-up-space units, which can be perfectly tuned by changing the coiling plate length and channel number inside the units. According to the generalized Snell＇s law, negative refraction and ＇driven＇ surface mode of WSW are also demonstrated at certain incidences. Specially, the transmitted WSW could be efficiently guided out by linking a symmetrically-corrugated channel in ＇driven＇ surface mode. This work may have potential applications in water wave energy extraction and coastal protection.
