TD-LTE系统F频段的干扰及解决方案

介绍现网各系统干扰的基本情况,描述TD-LTE系统干扰产生的原因、分类及危害。以TD-LTE系统的F频段(1.9 GHz)为例,介绍GSM900和DCS1800两个系统与F频段的TD-LTE系统共存时产生的系统间干扰,说明这些干扰对TD-LTE系统的影响,对所产生的危害进行分析,提出干扰解决方案,以降低系统间干扰对网络的影响。     

TD-LTE与卫星广播系统干扰共存仿真研究

由于频谱资源的限制和不断增长的业务需求,未来在1.4GHz上很有可能出现TD-LTE室内覆盖系统与卫星广播业务(BSS)共存的情况,两系统在同一地理区域共存时产生的干扰会引起系统吞吐量的损失。针对这一问题,对TD-LTE室内覆盖系统与卫星广播系统在1.4GHz频段上的共存拓扑结构进行了重点分析,并通过确定性分析和系统级仿真两种方法评估了TD-LTE室内覆盖系统与BSS在同频和邻频两种情况下共存时的干扰状况,得到了两系统在不同地球站仰角下所需要的最小保护距离。通过仿真给出的相应结果和结论,对未来在1.4GHz频段上TDLTE室内覆盖系统与BSS系统的实际部署提出了合理建议。     

TD-LTE与卫星广播系统干扰共存仿真研究

由于频谱资源的限制和不断增长的业务需求,未来在1.4GHz上很有可能出现TD-LTE室内覆盖系统与卫星广播业务（BSS）共存的情况,两系统在同一地理区域共存时产生的干扰会引起系统吞吐量的损失。针对这一问题,对TD-LTE室内覆盖系统与卫星广播系统在1.4GHz频段上的共存拓扑结构进行了重点分析,并通过确定性分析和系统级仿真两种方法评估了TD-LTE室内覆盖系统与BSS在同频和邻频两种情况下共存时的干扰状况,得到了两系统在不同地球站仰角下所需要的最小保护距离。通过仿真给出的相应结果和结论,对未来在1.4GHz频段上TDLTE室内覆盖系统与BSS系统的实际部署提出了合理建议。     

TD-LTE与LTE FDD系统间干扰分析及射频技术指标

对邻频部署1.9 GHz频段TD-LTE与1.8 GHz/2.1 GHz频段LTE FDD系统间干扰情况进行研究,分析了干扰产生的机理和干扰场景,并将重点聚焦于基站与基站之间的干扰。结合确定性分析和仿真研究两种方法的干扰计算结果,给出了TD-LTE与LTE FDD系统间共存时基站设备和终端的射频技术指标与组网要求,并通过实验室测试和外场试验,对上述指标和组网要求进行验证,同时对现网新的干扰情况展开进一步分析,为4G系统国内使用和台站协同提供依据。     

TD-LTE系统间干扰问题的分析与研究

本文主要对TD-LTE多频段组网中的干扰问题进行分析.论文首先对TD-LTE可能的共址共存异系统工作频段进行了分析,指出了可能产生干扰的异系统和频段.并对不同干扰产生的原因分别进行了研究.在此基础上,论文提出了TD-LTE干扰隔离分析方法以及TD-LTE宏基站与其他系统共址时干扰隔离距离要求.通过对干扰隔离的计算,本文最终给出了TD-LTE室外宏站(F频段)、室外宏站(D频段)以及室分系统与其他系统共站时的干扰隔离结论.     

TD-LTE系统与雷达的干扰仿真分析

TD-LTE系统是我国自主知识产权的第三代移动通信技术TD-SCDMA的演进系统。根据国家相关政策,2300-2400MHz频段可能成为TD-LTE系统首选工作频段,但是,我国在2300-2400MHz频段已经部署了一定规模的军用脉冲式雷达。本文针对在2300MHz-2400MHz频段上,TD-LTE系统和雷达可能发生的相互干扰问题,进行了干扰分析的确定性计算,并且仿真TD-LTE系统和雷达的相互干扰结果,分析了两个系统在互不干扰条件下部署的物理间隔,最后分析了TD-LTE系统和雷达干扰可能的主要原因。     

TD-LTE系统间干扰研究与优化

在我国TD-LTE部署的频段主要为:1880~1920MHz、2300~2400MHz和2500~2635MHz三个波段.由于历史原因,大量其他业务已被部署在这些频段及相邻频段,因此TD-LTE将不可避免会存在系统间干扰问题.本文从实际应用出发,深入研究TD-LTE系统间产生、分析方法以及干扰规避措施,希望对TD-LTE后续网络优化工作中在降低干扰方面有一定的指导作用和借鉴意义.     

TD-LTE网络与TD-SCDMA共存时特殊子帧的配置研究

TD-LTE与TD-SCDMA系统同频段共存时,为避免交叉时隙干扰,要求TD-LTE系统与TD-SCDMA系统上下行时隙转换点对齐.按照3GPP标准现有的配置模式,将空置6～8个TD-LTE OFDM符号的资源.结合我国TD-SCDMA网络现状及TD-LTE可能的引入方式,本文对规避交叉时隙干扰的方法进一步分析研究,提...     

WLAN与TD-LTE系统在2.4GHz频段共存干扰

作为系统共存产生的带外干扰,由接收机和发射机特性的不完善造成。工作于ISM频段的WLAN设备的带外辐射值会对TD-LTE系统造成一定程度干扰,因此,需要对WLAN设备的带外辐射值进行限制。     

TD-LTE和LTE-FDD系统共存的千扰分析

文章主要研究了两个LTE系统(TD-LTE与LTE-FDD系统)在同一地理区域相邻频段下共存时由系统间干扰引起的系统性能损失,在不同的基站位置偏移、载波频率和功控参数下,给出了四种干扰场景下的仿真结果,并对其进行分析,最后给出了减小干扰的一些措施.     

Comparative Analysis of Intercell Interference Mitigation Techniques in LTE-A Network

The performance of long term evolution-advance (LTE-A) depends on different factors such as spectral efficiency, throughput and signal interference to noise ratio (SINR). Interference causes the performance of a network to be grassed to very low level, it directly affects the parameters such as noise interference, receiving diversity and system receiving gain so to mitigate the interference in LTE-A network is very important. Interference occurs in two forms, intra-cell interference and inter-cell interference. Intra-cell interference is removed by orthogonal frequency division multiple access, but the problem of inter-cell interference still exists due to reception of signals from two adjacent base stations at same frequency on user equipment, so coordination is applied between the cells to reduce the interference between the cells. This paper focuses on coordination between the base stations using dynamic cooperative Base Station selection (DCBS). In this paper, SINR, system capacity, minimum and maximum rates of the system are analyzed when coordination is applied between the cells. Three different scenarios are discussed in this paper, which includes coordinated multipoint transmission and reception (COMP), non-COMP and DCBS and then the results of these scenarios are compared.     

Effect of Propagation System Design Modeling on LOS Microcellular

Linear microcells employing low base stationantennas have been proposed for emerging PCS systems. Insuch systems, the characteristics of the propagation online-of-sight (LOS) radio links will fundamentally determine the system performance. In thiscontext, it is meaningful to discuss the effect onsystem design of the two commonly used propagationmodels, the two-slope model and the single-slope model.In this paper we present several methods tocompare the frequency reuse pattern and base stationseparation based on these two propagation models, andverify the importance of correct propagation modeling for efficient system design. We considerinterfering signals coming from two cochannel basestations in the first tier, and include slow fading losswhen comparing system performances. Based on systemdesign results and subsequent performance, thetwo-slope model is recommended for LOS PCSmicrocells.     

Interference considerations for the time division duplex mode ofthe UMTS Terrestrial Radio Access

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     

长基线高精度时间频率传递技术的综合应用

针对同步网络内长基线分布的节点,实现高精度时间与频率无线传递的方法主要包括双向卫星时间频率传递法(TWSTFT)与GPS共视法(CV)两种卫星技术手段.介绍了这两种技术的工作原理,分析了误差环节,比较了两种技术手段,在此基础上指出,这两种技术手段都属于远距离传递,都易受外界环境和传输链路影响,因此建议实际应用中这两种方式应该是独立运行、交叉互验的必要技术手段,需要综合利用,而并非一般认为的二选一竞争关系.     

提高微机变电站综合自动化系统抗干扰能力的几项措施

在微机变电站综合自动化系统中,为了保证数字信号处理子系统采集到的信号有精度的频率、相位和足够的幅度,采用实验的手法,去观察和分析传感器输出信号、前置放大电路输出信号、电压比较电路输出信号、系统电源输出电压的波形等.根据不同电路信号频率、幅度和相位的特点与实际需要,利用LC低通无源滤波器和乘法器方式的功率因数纠正电路来过滤采集信号中含的杂波.利用窗口电压比较器使采集信号幅度位于两个指定的门限(参考电平)之间.使用这些措施得到结果是微机变电站综合自动化系统处理信号能力更准确、更快、更安全、更稳定.     

Frequency response of advanced silicon bipolar transistors at lowtemperature

The high-frequency behavior of advanced bipolar silicon transistors has been measured at temperatures between 83 and 350 K. The cutoff frequency, DC gain, and associated frequency-dependent parameters are reported. Although the transistors are optimized for room-temperature operation, their performance at liquid-nitrogen temperature is not severely degraded. Though decreased, the current gain remains sufficiently high for use in some applications. The cutoff frequency is reduced by about a factor of two. It is suggested that this is primarily due to an increase of the base transit time and that increasing the base doping may improve the low-temperature response. Using the maximum frequency of oscillation to predict circuit switching speed, it appears that small, high-performance transistors suffer a speed degradation at near liquid-nitrogen temperature     

3.5 GHz频段5G系统对ATG系统干扰分析

为研究3.5 GHz频段地面5G系统对地空宽带通信(air to ground, ATG)系统同频同步干扰情况,对该频段中5G系统与飞机上ATG系统间的同频共存问题进行了系统间同频共存分析. 采用5G系统技术参数,在城区、城郊连续和郊区不同场景下,仿真5G系统基站(base station, BS)对机载ATG系统干扰情况及5G系统用户对ATG BS干扰情况,分别计算得到不同场景下5G系统BS对机载ATG系统及5G系统用户对ATG BS的平均干扰功率密度. 仿真结果表明,地面5G系统BS对机上ATG系统的同频干扰影响较小,可将该干扰视为可接受干扰. 同时,本文还给出了ATG BS的部署隔离距离参考值.     

Proposal of a Fixed Communication System Sharing the Bandwidth of an Existing Personal Communication Network

This paper deals with the proposal and performance evaluation of a fixed microwave communication (FMC) system that shares the same bandwidth with a wireless personal communication network. In particular, the focus here is on the case of an existing universal mobile telecommunication system (UMTS) network for which an FMC system is considered to provide a wireless connection between a remote base station not having the possibility of a wired connection to the core network and a base station having this possibility (a core network access point). This facility is of special interest in a dense urban environment or whenever a wired connection is prohibitive for service providers due to its implementation cost or lack of frequency spectrum. The mutual interference effects between the FMC systems and the existing UMTSs are investigated by focusing on typical application scenarios. A receiving scheme where interference signals are first detected and then canceled from the other received signals is proposed. The performance of the two interfering systems has been evaluated in terms of bit error rates (BERs) both by means of an analytical approach and computer simulations. The obtained results clearly demonstrate the effectiveness of the proposed method, in particular, by allowing efficient bandwidth sharing between the FMC system and the existing UMTS network.     

三极管特征频率下1GHz振荡器设计与仿真

三极管振荡器一般工作在截止频率附近，这时虽然能够输出较大信号，获得较好的频率稳定度，但是电路中滤波器性能的好坏直接影响输出的高次谐波干扰，而且这种设计思想大大限制了三极管往更高频率上的应用。谩计了在特征频率工作下的三极管振荡嚣，严格限制了高次谐波干扰。建立了射频三极管分布参数、封装参数模型，利用上述模型模拟了三极管特征频率下工作的振荡器振荡频率，输出电压与电源电压、振荡频率与电源电压、振荡频率与基极电感、输出电压与基极电感的关系。最后得出模拟与实验测试一致的结果。     

导频比和多普勒频移对OFDM系统影响的研究

参考无线多径信道中的COST-207信道模型,选取COST-207模型中的典型城市环境针对不同导频比与不同多普勒频移频率对基带OFDM通信系统性能的影响进行了仿真分析.从仿真结果得出使用块状导频形式的OFDM系统容易受多普勒频移与时间选择性信道变化的影响.同时当信噪比达到一定程度后,子载波间干扰是构成系统噪声的主要部分.而梳状导频虽然在性能上不如块状导频,但在对抗多普勒频移与时间选择性衰落信道方面相比块状导频具有一定的优势.