平流层通信,HAPbasedWirelessNetwork教程.ppt

Introduction(3) Optical free-space point-to-point communication links Certain application involving HAPs HAPs Location in a cloud free atmospheric altitude Enabling reliable line-of-sight links between different HAPs Meshed interconnected HAP network Optical down link to the terrestrial network would be feasible using site-deversity Test Scenario(1) Tethered Balloon Trial Autumn 2004, 400m altitude was tested Data rate was 270MBPS Transmission wave band was 808nm with 500mW mean source power Angle : 16 degree Test Scenario(2) Stratospheric Trials FELT (Free-Space Experimental Leaser Terminal) Ascending 2 hours to an altitude of 22Km, staying there 8 hours while it drift of horizontally to max 60Km imposing a link distance of up to 64Km. Description of FELT(1) FELT consists of motorised periscope for beam setting * * * * * * * * General sketch of the possible CAPANINA network * * Basic configuration of HAP based network: multiple HAP case * * Basic configuration of HAP based network: singular HAP case * * CAPANINA project scenario * * * * * * 流星余迹通信的主要优点是 (1)通信距离远。实验表明，利用功率为500瓦至几千瓦的发射机及普通的八木天线，通信距离就可达1500千米，最大通信距离约2300千米。(2)必威体育官网网址性强。由于电磁波反射具有非常明显的方向性，不易被窃听，而且容易防止干扰台的影响。(3)通信的稳定性好，不易受电离层骚扰和极光的影响。其不足之处是:由于发送状态是断续的，信息有延迟，有时可达几分钟，因而不适应传送实时信息，终端设备较复杂。 流星流星余迹散射 流星余迹特点 － 高度80 ~ 120 km，长度15 ~ 40 km 存留时间：小于1秒至几分钟 频率 － 30 ~ 100 MHz 距离 － 1000 km以上 特点 － 低速存储、高速突发、断续传输 * 流星余迹散射通信 流星余迹 谢谢！ * * * * Antennas(1) Requirements High frequency for High bandwidth High gain, directional antenna Multibeam antenna with 100+ beams Fig. 34 for footprint Beam controllability Low payload and low power Reliability Antennas(2) Array of the antenna at 2.2Ghz, 21Km height Wider array with high altitude, narrower array with high frequency Multibeam Horn(MBH) Digital Beamforming(DBF) Table XⅡ Applications and Related Projects(1) - Applications - HAPs is able to RAPID DEPLOY Olympic Game, Pop concert, Rescue management Wideband Internet access, entertainment video, audio