对3.5GHz无线接入系统 干扰C波段接收小站问题的探讨

介绍了新出现的3.5GHz无线接入信号干扰C波段卫星通信的现象、原因及处理方式等。     

银行ATM对3G通信基站千扰案例分析

2013年9月，河北省保定无线电管理局接到保定移动工作人员申诉，称建设银行自动柜员机（ATM）对TD—SCDMA基站造成干扰，受干扰频率为1880MHz～1900MHz频段。     

中国成功发射“中星”通信卫星

2003年11月15日零时01分,我国自行研制的“中星”20号通信卫星在西昌卫星发射中心由“长征”3A运载火箭发射升空,卫星准确进入预定轨道,并于北京时间11月20日14时28分成功定点于东经103度赤道上空。“中星”20号是实用型地球同步通信卫星,卫星质量为2.3吨,可以实现不同频段、不同区域之间的互联互通,为用户提供多种通信服务。这颗卫星由中国空间技术研究院研制,中国卫星通信集团所属的中国通信广播卫星公司负责经营。“中星”20号通信卫星属三轴稳定型卫星,对此类卫星实施精确控制的技术,目前世界上只有少数几个国家掌握。用于发射的“长征…     

热泵直供采暖两相流毛细管网性能研究

通过在用户自定义程序增加两相流动中质量源项和能量源项的方法,建立了毛细管网内气-液转化的CFD计算模型,对小管径光滑铜管内R22的冷凝性能进行研究。根据CFD模型,计算了不同气相进口流速下R22蒸汽的冷凝过程。得到了压力损失、冷凝系数和流速的关联曲线。对小管径毛细管网辐射末端的设计提供了理论依据,对制冷剂流速选择有一定指导意义。     

一种基于FCME的跳频通信干扰检测门限设计方法

针对跳频卫星通信在应用中面临恶意干扰威胁的问题,需要对接收信号进行干扰检测。首先使用宽带能量检测模型对接收信号进行建模,分析了检测统计量的概率分布形式,其次在FCME算法以及恒虚警门限设置方法的基础上,利用概率统计知识分析高斯分布下部分样本与总体的关系,加入迭代修正过程对噪底进行估计以设置满足恒虚警概率要求的门限,最后利用Matlab搭建仿真平台进行仿真分析。理论和仿真分析表明,基于FCME的迭代修正门限设计方法相比于已有方法在SNR为0 dB、无干扰条件下能获得满足虚警概率要求的门限,当存在部分频带干扰时算法性能下降,但所获得的门限仍能满足虚警概率要求。设计方法在干扰较弱或不存在时能满足虚警概率要求,改善了FCME算法虚警概率偏高的情况,应用于跳频通信系统干扰检测的门限设计是可行的,在工程实际应用中有一定的参考价值。     

浅谈油田注水泵变频谐波现状

油田注水泵机组变频控制产生背景谐波电压,对泵机组、周边电子设备产生谐波干扰。通过测试现场在用变频设备谐波,分析负载改变时电压总谐波畸变率的变化、各分量谐波电压含有率分布情况,了解不同频段谐波干扰类型,为治理变频谐波积累经验。     

当前抽水蓄能电站电价疏导问题分析

提出目前抽水蓄能电站电价疏导政策存在的问题,分析选择租赁方式的单一容量电价的合理性,研究电价疏导在省问和省内的特点和方式,提出现阶段合理电价疏导方式,建议新建电站宜继续采用租赁的单一容量电价,应尽早建立网间电力交易机制和深入研究省网内电厂、电网和用户之间的电价疏导比例。     

开发和利用C频段资源的新途径

本文简要介绍可在赤道平面以外的空间充分利用C频段频谱资源的两种技术手段－－倾斜轨道同步卫星和高空通信平台，并就相关系统的潜在通信容量以及新系统与现存系统的干扰协调等问题作了初步探讨。     

LTE来袭

海量的数据流量正驱动运营商对现有网络进行升级,运营商和TDD频段拥有者纷纷将目光瞄准4G制式LTE。从2G时代到3G时代,用户的行为发生了飞速变化,除了智能终端上数据超越语音成为主要应用外,用户接入无线互联网的行为呈现出接入时段碎片化、接入时长瞬态化、访问内容情感化特点,而访问内容涵盖了视频、社交、游戏、搜索、支付等。     

无奈缘自无为——证券交易所通信体系架构远落后于时代

2002年7月5日上午9:03,深圳证券卫星通信公司所租用的卫星转发器受到不明信号干扰,导致通信系统无法正常工作,使全国近千家证券营业部通信中断。深交所立即于9:25宣布紧急停市。直到下午1点,深圳股市才重新开市。据媒体披露,当日深市全天成交金     

非合作信号射频域干扰抵消性能分析

针对航空测控系统面临宽带干扰时,缺乏有效的抗干扰手段的问题,研制了定向天线和全向天线的接收结构,可在射频域抵消外来的非合作信号,以保证合作信号的准确接收。并讨论了单抽头和多抽头两种结构模型。利用干扰抵消算法,以剩余非合作信号功率最小为准则,进行了理论推导。并提出在多抽头结构的工程实现中采用矢量调制器来进行幅度和相位的调整。仿真结果表明:对于单抽头结构,在2.6GHz频段,对于带宽100 MHz的信号,当延迟线长度调整误差为2%时,最优的干扰抑制能力达到了45dB,当考虑幅度调整误差为10%时,干扰抑制能力会降低约10dB;对于多抽头结构,使用与单抽头相同的信号。以双抽头为例,当传输时延差固定时,最优干扰抑制能力可达81dB,仿真结果从理论上验证了接收结构的可行性。     

Transmitters and receivers' investment to avoid interference: Is there an optimal regime?

The management of interference has been, and still is, the main concern in spectrum policy. Historically, interference has been dealt with by heavy regulation under an administrative control regime. Over the last decades, a new approach has been put forward based on users' property rights, better able to cope with a rapidly changing technological environment. The issue of dealing with interference across bands, however, remains crucial: What obligations should be put on users so as to keep interference at a socially acceptable level? Also, given that some unwanted emissions are bound to occur, how can private parties be provided with the right incentives to invest in high-quality reception technology? This paper assesses how well different regulatory regimes can lead to efficient outcomes. It develops an economic model of spectrum interference and identifies the efficient solution. A regime where spectrum users have the power to enjoin intruding emissions beyond a predefined level (property rights protection) is compared with a regime where users are forced to bear with intruding emissions, but are entitled to economic compensation for the harm suffered (liability rules protection). The analysis suggests that different regimes may perform differently under different circumstances depending on the cause of interference and, critically, on whether the services are organised as an open- or a close-architecture system. This suggests that regulators should pay more attention to the specific features of the different bands, and that the appropriate spectrum management regime should be designed to recognise these differences.     

An optimal way to licence the radio spectrum

Radio spectrum licences are generally specified in terms of the power a holder is allowed to transmit. However, if licences become flexible, allowing change of use and technology, then this licensing approach could result in significant interference between users. A new approach is proposed termed “spectrum usage rights” (SURs) which restricts the interference a licence holder is allowed to cause rather than the power they are allowed to transmit. This approach is shown to protect users against interference while providing the maximum flexibility possible and its implementation is discussed.     

Spectrum sharing in the gray space

There has been considerable effort to let more wireless devices operate in white space spectrum, that is within frequency bands and geographic areas where no wireless devices are active. Making white space available is certainly useful, but there are other sharing opportunities as well, some of which have been obscured by dangerous misconceptions about the concept of unused spectrum. This paper discusses allowing more devices to operate safely in gray space spectrum, that is spectrum that is actively being used in that transmissions are underway—something many economic models assume is impossible. The paper focuses on primary–secondary sharing, so devices gaining access to spectrum operate on a secondary basis in a way that never causes harmful interference to primary systems. Examples of primary–secondary gray space sharing mechanisms are described in which devices are allowed to share spectrum with broadcasting, radar, and cellular systems. Quantitative analysis shows that it is technically possible to support significant communications among secondary devices in spectrum that is already heavily used by cellular or radar. However, gray space sharing generally causes primary and secondary systems to be more technically interdependent than white space sharing, so different policy and governance structures are needed. Secondary market rules can support gray space sharing in cases where there is a single primary spectrum user, such as a cellular carrier. In cases where technology is static, the regulator may be able to control access for secondary devices. However, in cases with multiple primary users and multiple secondary users of spectrum, as might be seen in bands with radar for example, a new kind of governance body will be needed to facilitate spectrum sharing.     

MIMO通信系统下行链路预编码仿真研究

MIMO无线蜂窝通信系统是一种在同一时域和频域中向多个用户提供传输的系统。多用户MIMO技术利用无线通信系统中用户的独立性来增加整个系统的通信性能,从而实现多用户分集和复用。针对单天线用户的线性预编码和针对多天线用户的线性预编码,对联合迫零、迫零和最小均方误差预编码算法进行了仿真和性能对比。对实际通信系统设计具有指导意义。     

Group polarization on corporate boards: Theory and evidence on board decisions about acquisition premiums

This study investigates how a fundamental group decision‐making bias referred to as group polarization can influence boards' acquisition premium decisions. The theory suggests that when prior premium experience would lead directors on average to support a relatively high premium prior to board discussions, they will support a focal premium that is even higher after discussions; but when directors' prior premium experience would lead them on average to support a relatively low premium prior to board discussions, they will support a focal premium that is even lower after discussions. Results provided strong support for the theory. Moreover, group polarization was reduced by demographic homogeneity among directors and by minority expertise but increased by board influence. This study introduces a fundamental group decision‐making bias into governance research and explains how group processes can influence network diffusions. Copyright © 2012 John Wiley & Sons, Ltd.     

Wi-Fi as a Commercial Service: New Technology and Policy Implications

While Wi-Fi has enjoyed explosive growth and deployment for use in residential homes, the rollout of commercial Wi-Fi service has been more limited. Part of the holdback on large-scale commercial deployment has been the strategic concern that the commons model to spectrum management lacks the incentives for service providers to invest due to the limited ability to manage interference in the unlicensed band. Today, however, this situation appears to have changed. To explain the new confidence by service providers in commercial Wi-Fi, the activities of the Wi-Fi Alliance and IEEE 802.11 standards body are analyzed to show how these groups essentially replicate many, but not all, of the functions traditionally employed by an effective band manager that is optimizing efficiency on a licensed spectrum block more typically associated with the deployment of commercial services. Consequently, with the Wi-Fi ecosystem functioning as an effective spectrum manager, it is concluded that the service provider investment in Public Wi-Fi networks is rational and the risk posed by saturation or overuse has been reduced to an acceptable level. The strategic implications of this finding on the Wi-Fi platform are the examined. How the requirements from service providers are already significantly influencing the evolution of the Wi-Fi standard is discussed, and an attempt is made to address the risks and liabilities associated with the unlicensed spectrum management model. Thus, service providers increasingly need functionality in Wi-Fi technology to manage interference, and monitor and improve network performance. The current ideas under discussion are elaborated for the next version of Wi-Fi to support both commercial Wi-Fi requirements, which address the interference concerns, but only up to a point, as the unlicensed model intrinsically leaves some risk to participants of spectrum saturation through overuse.     

跳频通信中一种结合干扰预处理的平方定时同步算法

为了提高跳频通信中定时同步算法的准确性,设计了一种结合干扰预处理的跳频信号定时同步算法。首先对解跳后信号在时域完成基于能量的自适应门限的干扰检测,并根据检测结果将受干扰信号进行置零预处理;其次对预处理后的信号采用平方法进行定时误差估计;最后根据估计结果内插完成定时恢复。结果表明,提出的改进算法选取长度为200跳的符号,在干扰相对带宽为30%、干信比为10 dB、信噪比为5 dB、时钟稳定度为1×10^-6的条件下,进行干扰预处理后定时,归一化定时误差的方差为0.000 75,满足跳频系统解调性能损失小于0.5 dB的要求。设计方法提高了干扰条件下平方法定时的准确性,在跳频通信抗干扰应用中有一定的参考价值。     

Beachfront commons

Technology competition between wireless communication technologies can lead to new, more or less disruptive services. A potentially disruptive technology would be to have unlicensed transmission in the lower UHF bands at power levels up to, e.g. 2 W EIRP. This would give citizens a share of the best spectrum for free use. Tools against congestion could be based on mandatory stochastic channel back-off or, if multiple users are present, on adaptive power and bandwidth control. Compared to the FCC TV white space regulation, no back link would be needed as the spectrum would be used exclusively by wireless devices. In an environment of shrinking interest in terrestrial TV broadcasting, such a regulation is expected to create a new market for high-range consumer devices, competing with licensed communication, while also being suitable for offloading traffic from licensed operations. Furthermore, the approach will allow for efficient digitization of equipment for Programme Making and Special Events (PMSE), but could also be made compatible with novel disaster relief services. To enable accurate interference prediction, it is proposed that, instead of only providing transmitter regulation, receivers should also be regulated, such as be required to adhere to a certain minimum selectivity. The proposal should be taken up in the WRC process.     

抓好过程控制确保专网通信服务质量

为满足用户需求，向用户提供优质服务，通信服务质量管理首先要重视并运用以人为本的管理理念和方法，以不断建立健全服务工作的规章制度为基础。加强服务的硬件设施维护，保证服务设备运行正常。同时，要做好各服务部门间、服务岗位间服务串连，不能因内部原因而影响服务。要运用激励机制，提高服务人员的积极性，促进服务水平的提高。积极做好与用户的沟通和交流，增加与用户的相互理解，对用户提出的意见和建议要认真加以分析研究，并及时反馈整改信息。