共查询到19条相似文献,搜索用时 171 毫秒
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为得到测速雷达系统与卫星固定业务地球站在Ku频段共存的条件,以监测中发现的测速雷达实例为依据开展兼容性分析与研究。通过构建干扰模型,讨论了系统间潜在的干扰链路,确定了干扰门限,从多个角度仿真了测速雷达对卫星固定业务地球站的干扰,得到测速雷达等效全向辐射功率为18 dBm时与卫星固定业务地球站之间共存的最大保护距离为1 450 m,最小保护距离为200 m,同时得到了不同发射功率和不同受扰频率下的保护距离。研究成果可为Ku频段静止轨道卫星监测站选址提供必要的技术支撑,还可以为卫星固定业务用户设置地球站提供理论依据。 相似文献
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针对我国Ka频段使用卫星固定业务的非对地静止卫星轨道(Non-Geostationary Satellite Orbit,NGSO)星座系统对对地静止卫星轨道(Geostationary Satellite Orbit,GSO)系统的干扰问题开展研究.在梳理国际电联技术建议书和《无线电规则》的基础上,通过理论分析和仿真计算等手段,对不同链路场景下NGSO星座系统对GSO系统在Ka频段的干扰问题进行分析计算.研究结果表明,在NGSO星座系统与GSO系统上下行通信有重叠部分的频段,其对GSO系统都会产生严重干扰.最后给出降低干扰的措施与建议.为我国未来拟使用Ka频段的NGSO星座系统对GSO系统的干扰分析提供参考. 相似文献
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国际电信联盟(ITU)现行《无线电规则》中使用同步轨道(也即静止卫星轨道)的常规卫星通信业务包含两个规划,即卫星广播业务(BSS)规划和卫星固定业务(FSS)规划。其中BSS规划频段为按照下行链路和上行馈线链路的不同分别定义在《无线电规则》附录30和附录30A中,计划今年年底发射的我国东四大平台的首发星“鑫诺二号”,也是我国第一颗专用广播卫星使用的就是BSS规划频段,另外, 相似文献
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为分析在1668~1675 MHz频段引入卫星移动系统的可行性,对该频段卫星移动系统与无线电探空系统间的兼容共存问题进行了深入分析。介绍了两个无线系统的基本特征和主要参数,讨论了两系统间潜在的干扰链路。针对卫星移动业务终端对二次测风雷达的干扰以及二次测风雷达对卫星空间电台的干扰两条主要干扰链路,采用计算机静态建模和蒙特卡洛仿真方法,对干扰情况进行了计算仿真。仿真结果表明,在卫星终端密度在50个/km2时,二次测风雷达所需的保护距离为60~80 km,而单个二次测风雷达主瓣方向发射二次测风雷达的功率高于空间卫星国际保护标准达60 d B。该研究结果可为我国无线电管理部门对该频段的重新规划提供支撑。 相似文献
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卫星气象业务是一种用于气象目的的卫星地球探测业务,在人民的生产、生活中起到极为重要的作用。1670-1710MHz频段是国际电联《无线电规则》划分给卫星气象业务用于数据传输使用的重要频段之一,该频段还同时划分给气象辅助业务、固定业务、移动业务、卫星移动业务等共同使用。本文详细介绍了目前国际上卫星气象业务在这一频段的使用情况、干扰评估准则,并结合我国卫星气象业务的频率使用情况,介绍并研究该频段内卫星气象业务与卫星移动业务、气象辅助业务之间的共用现状与技术,以期给上述业务在该频段未来的发展和使用提供借鉴。 相似文献
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新兴的非静止轨道(non geo-stationary orbit,NGSO)卫星星座系统可支持分布在地球任何位置的海量地面终端,NGSO星座系统大多使用与GSO卫星星座系统同频的频段,再加上NGSO星座系统在空、时、频、码等域的高动态特性,必然会对GSO星座系统带来时变的频率干扰问题.为解决NGSO星座系统上行链路对... 相似文献
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针对移动卫星L频段上行信号侦收覆盖范围小导致难以监测广大区域用户上行通信行为的问题,提出了一种基于协同侦收的卫星上/下行信号关联方法.通过构建协同侦收方案,实现卫星通信过程中返向链路的L频段上行信号、C频段下行信号与前向链路的L频段下行信号的协同接收,之后综合利用卫星随机接入信道(Satellite Random Access Channel,S-RACH)和卫星访问授权信道(Satellite Access Grant Channel,S-AGCH)的信号外部特征和信息内涵进行L频段上行信号和C频段下行信号之间关联分析,最终得到一种可用于关口站信号侦收的卫星上/下行信号关联方法.实验验证结果表明,所提方法具备可行性,可为后续开展基于大站的卫星信号通联分析提供技术支撑. 相似文献
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Multiple-access capacity in mobile user satellite systems 总被引:1,自引:0,他引:1
The channel capacity of a satellite direct sequence CDMA system is analyzed including the effects of faded user interference, overlapping antenna beams, imperfect equalization of the antenna pattern across an antenna cell, and diversity reception. Simplified models are used to describe the impact of these effects on the channel capacity of single and multiple cofrequency CDMA systems. In a comparison of the uplink and downlink paths, the uplink of the CDMA system is shown to limit the channel capacity because the downlink can utilize code-orthogonality and coherent demodulation. In a multiple system comparison between band-shared CDMA and band-segmented FDMA/TDMA technologies, FDMA/TDMA is shown to provide about the same capacity for uniformly distributed traffic conditions over many cells and dramatically better capacity when traffic is concentrated in one cell. Due to the peak nature of telephony, this result supports the use of band-segmented systems in mobile user satellite systems 相似文献
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An overview of the application of smart antennas in DS-CDMA systems, including IS-95 and IS-2000, is presented. Since CDMA systems are interference-limited, adaptive antenna arrays have great potential for improving the performance of such systems in terms of capacity, coverage, and quality of service, In this paper, we study the multiple-access interference that affects a CDMA system, and we describe how smart antennas can be implemented in an IS-2000-based mobile communications system. When smart antennas are used at the base station to transmit in narrow beams, the interference on the downlink is reduced, and C/I is improved. This, in turn, increases the system capacity on the downlink or, alternatively, the quality of service is improved. Such gains will prove very beneficial for asymmetric high-speed data applications, requiring much higher bit rates on the downlink than on the uplink. By reducing the base-station receiver's sensitivity, smart antennas can boost the capacity of the reverse link. Results are presented that outline how this reduction can be employed by the system designer on the uplink to increase capacity, reduce the mobile transmit power, or effect a tradeoff between capacity improvement and coverage or range extension under different system-loading scenarios 相似文献
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论文基于即时消息业务中上下行消息流之间的相关特性,提出了一种根据先前所处理消息的方向为移动终端状态定时器分配不同阈值的机制,并研究了其对下行包队列长度、下行消息时延和功耗节省等性能的影响。仿真结果表明,与传统单值状态定时器方案相比,该机制在保证相似服务质量的基础上显著降低了移动终端的功耗。 相似文献
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The design of 60 Mbit/s/180 Mbit/s time-division multiple-access (TDMA) channels for the European Communication Satellite (ECS) system is analyzed and a possible configuration is suggested [1]. The effects of adjacent-channel interference, nonlinear power amplifiers both on the ground and in space, uplink and downlink noise are investigated and results are shown. Methods for carrier recovery are investigated and comparisons made. The complete channel design includes pulse-shaping filters, satellite filters, limiters before each TWT, and a filter after the earth-station TWT to limit the radiated spectrum. 相似文献
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John Pahl John Parker Kumar Singarajah 《International Journal of Satellite Communications and Networking》1994,12(1):107-123
An option being considered by current and prospective mobile satellite service (MSS) operators is the use of constellations of non-geostationary orbit (NGSO) satellites to provide global personal communications. The scarcity of free spectrum, together with the bandwidth typically required, means that any new MSS system must consider sharing spectrum with other systems and services. Spectrum sharing must be based on defined interference criteria being satisfied. When multiple NGSO satellites are considered there is no accepted method for assessing interference. This paper describes a model used as the basis for a computer simulation of interference scenarios involving MSS, fixed service (FS) and fixed satellite service (FSS) systems. The simulation includes NGSO dynamics, constellations of MSS satellites with multi-spot antennas, multiple geostationary FSS satellites and multiple hop FS links. Interference events are based on C/I calculations, and statistics, such as the percentage of time that the C/I falls below a required protection ratio, are calculated. More generally C/I cumulative distribution functions are produced. 相似文献
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Holma H. Heikkinen S. Lehtinen O.-A. Toskala A. 《Selected Areas in Communications, IEEE Journal on》2000,18(8):1386-1393
The air interface of the UMTS Terrestrial Radio Access (UTRA) covers both a frequency division duplex (FDD) part for the paired bands and a time division duplex (TDD) part for the unpaired bands of the UMTS spectrum. The Universal Mobile Telecommunication System (UMTS) is the 3rd-generation mobile communication system. This paper presents an interference evaluation of the UTRA TDD. Since both uplink and downlink share the same frequency in TDD, the signals of the two transmission directions can interfere with each other. This interference can occur between two mobile stations or between two base stations within one carrier or between two operators. The interference between uplink and downlink is evaluated by system simulations. Synchronization and coordination requirements of UTRA TDD are evaluated based on the results 相似文献