1,446 research outputs found

    Uplink (Reverse Link) Capacity of An Air-Ground W-CDMA System

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    In this work, the uplink capacity and the interference statistics are given for an W-CDMA 3-D Airto- Ground (AG) cellular like network assuming imperfect power control and finite transmitted power. The free space model of propagation is used to calculate the intercellular interference. The uplink capacity has been studied for different frequencies and scenarios. It has been shown that, the effect of rain is to reduce the uplink capacity and the maximum allowable cell radius. Also it is shown that, the frequency of operation should be lower or equal to 2 GHz. For a frequency of operation of 2 GHz, the cell capacity can reach 70 voice users or 46 data users when the cell radius is 350km. The new contribution of the paper is the study of the effect of the imperfect power control and the finite transmitted power on the uplink capacity of the Air-Ground system for different values of outage

    成層圏飛翔体通信における無線通信路及びその性能に関する研究

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    制度:新 ; 文部省報告番号:甲2383号 ; 学位の種類:博士(国際情報通信学) ; 授与年月日:2007/3/15 ; 早大学位記番号:新447

    Wireless Phone Threat Assessment for Aircraft Communication and Navigation Radios

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    Emissions in aircraft communication and navigation bands are measured for the latest generation of wireless phones. The two wireless technologies considered, GSM/GPRS and CDMA2000, are the latest available to general consumers in the U.S. A base-station simulator is used to control the phones. The measurements are conducted using reverberation chambers, and the results are compared against FCC and aircraft installed equipment emission limits. The results are also compared against baseline emissions from laptop computers and personal digital assistant devices that are currently allowed to operate on aircraft

    Improving the system capacity of broadband services using multiple high-altitude platforms

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    A method of significantly improving the capacity of high-altitude platform (HAP) communications networks operating in the millimeter-wave bands is presented. It is shown how constellations of HAPs can share a common frequency allocation by exploiting the directionality of the user antenna. The system capacity of such constellations is critically affected by the minimum angular separation of the HAPs and the sidelobe level of the user antenna. For typical antenna beamwidths of approximately 5/spl deg/ an inter-HAP spacing of 4 km is sufficient to deliver optimum performance. The aggregate bandwidth efficiency is evaluated, both theoretically using the Shannon equation, and using practical modulation and coding schemes, for multiple HAP configurations delivering either single or multiple cells. For the user antenna beamwidths used, it is shown that capacity increases are commensurate with the increase in the number of platforms, up to 10 HAPs. For increases beyond this the choice of constellation strategy becomes increasingly important

    3D Outside Cell Interference Factor for an Air-Ground CDMA ‘Cellular’ System

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    We compute the outside-cell interference factor of a code-division multiple-access (CDMA) system for a three-dimensional (3-D) air-to-ground (AG) cellular-like network consisting of a set of uniformly distributed ground base stations and airborne mobile users. The CDMA capacity is roughly inversely proportional to the outside-cell interference factor. It is shown that for the nearly free-space propagation environment of these systems, the outside-cell interference factor can be larger than that for terrestrial propagation models (as expected) and depends approximately logarithmically upon both the cell height and cell radius
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