共查询到17条相似文献,搜索用时 718 毫秒
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讨论了流星突发通信欠密类余迹的信道特性及其模型。以TMS320VC5509 DSP为核心设计了流星信道模拟器系统,并给出模拟器在实验室流星突发通信自适应变速率系统设计中的测试应用。 相似文献
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流星余迹信道短时突发的特点使得流星突发通信呈现间歇性,在等待一颗适合的流星出现前往往需要等待很长的时间,同时由于流星突发通信的"足迹"和"热点"特性,使其通信距离受到限制。为解决上述问题,提出一种基于流星余迹通信的无线分组网,首先针对流星余迹信道特点给出了适合该网络的路由选择策略,其次介绍了工作流程,最后对分组长度进行了分析,并给出了仿真结果。 相似文献
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流星余迹通信具有间歇性、信道时变性的特点,大大限制了其网络稳定性和数据传输量,因此,如何提高流星余迹通信的稳定性和数据传输量,是流星余迹通信的关键技术之一。在多基站环状网络结构的基础上,将各基站用高速有线链路连成全连通网络以克服环状网络稳定性低的缺点,并且对基于停等协议传输的流星余迹通信网络,利用Opnet网络仿真工具搭建了网络仿真模型,对包长度和发包速率进行了分析,最后给出了仿真结果。 相似文献
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针对流星余迹通信原理及信道特点,建立了适用于流星余迹通信系统的智能天线系统模型。在热区跟踪上,使用波束切换技术;而对于可用流星余迹使用自适应数字波束形成技术。针对流星余迹持续时间短的特点,为了获得最佳接收性能,缩短等待时间,对自适应算法提出了收敛速度快、计算复杂度小的要求,这里采用变步长LMS算法与判决导向算法相结合的半盲自适应算法,并对半算法进行了仿真分析。 相似文献
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An estimate of the capacity of the meteor burst communication channel is given. The model takes into account both overdense and underdense trails as well as the effects of wind-induced trail warping. 相似文献
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Ray-tracing techniques are used to derive the impulse response at VHF of a meteor burst communications channel. An approach to analyze the effects of multipath arising from wind shear is also presented and is applied to a simplified model of trail distortion. Within the limitations of the models adopted, we have found that a single path with a spread of approximately 0.2 μs adequately describes the channel behavior within roughly half a second from trail formation, and that a multipath structure with several paths and a total multipath spread of approximately 2 μs is typically associated with the channel at later times, when the wind shear substantially affects the trail shape. These results are consistent with experimental findings according to which a meteor trail communications channel is capable of transmitting beyond-the-horizon bursts of television images of broadcast quality typically for a fraction of a second after trail formation. 相似文献
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流星余迹信道是一种典型的突发无线超视距信道,对流星突发通信系统的设计方案,使用模拟信道进行分析比较,有着简易、经济的优势。基于公认的流星突发信道的数学模型,通过合理假设,推导出适合建立计算机模型的数学表达式,由此编写Matlab程序,选取典型信道参数,实现了对流星突发信道的计算机模拟。 相似文献
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流星余迹通信具有其他通信系统无法比拟的优点,如:大跨距、抗干扰、低截获概率特性和抗毁性等特点,使得这种通信方式的应用范围越来越广泛,尤其是支援短波通信及用作卫星通信的替补手段。但是流星余迹信道又是一种典型的突发信道,通信容量小和实时性差。为了最大限度地利用短暂的流星余迹信道,人们设计了链路自适应技术。此技术能够根据信道状况自动调整发射机和接收机的参数,使得流星余迹信道资源得到最大限度的利用。 相似文献
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Meteor scatter: an overview 总被引:3,自引:0,他引:3
The phenomenon of radio propagation using meteor trails is reviewed. Underdense and overdense propagation mechanisms are described. The multipath and fading profile of the meteor channel is examined. Mechanisms other than meteor trails that are commonly observed on meteor links and can change the characteristics of the meteor communication channel are considered. These include sporadic-E propagation, auroral scatter, ionospheric scatter, diffraction, line-of-sight propagation, and tropospheric scatter 相似文献
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High-latitude propagation phenomena, such as scatter from the aurora and sporadic-E propagation, can alter the communication characteristics of the meteor communication channel. This paper describes an experiment in which the fading and multipath profiles of the high-latitude meteor communication channel were characterized. The effects of high-latitude propagation phenomena on the capacity and reliability of meteor burst communication are discussed. 相似文献