15～23 GHz微波链路雨衰的敏感参量分析

为了提高微波链路雨衰特征的描述精度,拓展微波链路信号的可用参数,该文利用部署于江苏江阴地区的15 GHz,18 GHz和23 GHz微波链路和雨量计开展同步对比观测,拟合得到3种频段的微波链路雨衰关系.提取并分析了接收信号电平的平均值、中位数、25％分位数、75％分位数、标准差、极大值和极小值等13个特征量与晴雨时刻、降雨强度之间的关系,得出结论:微波链路的信号变化和降雨强度的变化存在明显的负相关关系.实际拟合的雨衰关系与ITU-R的经验雨衰关系具有较好的一致性,但是在不同频段上均有差异;所有13个参量在有雨时刻和无雨时刻均存在一定概率的重叠,这是造成晴雨区分困难的主要原因;频率越高,信号变化受降雨的影响越显著,越有利于微波链路反演降雨.所得出的结论为提高微波链路测雨方法中的晴雨区分、参考值确定以及雨强反演的精度提供重要依据.     

15～23 GHz微波链路雨衰的敏感参量分析

为了提高微波链路雨衰特征的描述精度,拓展微波链路信号的可用参数,该文利用部署于江苏江阴地区的15 GHz, 18 GHz和23 GHz微波链路和雨量计开展同步对比观测,拟合得到3种频段的微波链路雨衰关系。提取并分析了接收信号电平的平均值、中位数、25%分位数、75%分位数、标准差、极大值和极小值等13个特征量与晴雨时刻、降雨强度之间的关系,得出结论:微波链路的信号变化和降雨强度的变化存在明显的负相关关系。实际拟合的雨衰关系与ITU-R的经验雨衰关系具有较好的一致性,但是在不同频段上均有差异;所有13个参量在有雨时刻和无雨时刻均存在一定概率的重叠,这是造成晴雨区分困难的主要原因;频率越高,信号变化受降雨的影响越显著,越有利于微波链路反演降雨。所得出的结论为提高微波链路测雨方法中的晴雨区分、参考值确定以及雨强反演的精度提供重要依据。     

哥德堡地区基于无线通讯网络的水汽密度监测分析

利用无线通讯网络中的微波链路来监测降雨和水汽等是大气环境监测的新技术之一。这个技术可以测量近地面的降雨强度和水汽密度等气象参数,具有时空分辨率高、成本低等优势。利用瑞典爱立信公司(Ericsson)提供的位于哥德堡地区E频段的微波通讯链路资料、位于链路一端的气象站1资料和由瑞典气象水文研究所(SMHI)气象网站提供的气象站2资料,对2017年06月13日至2017年07月13日近1个月的水汽密度进行反演计算和分析。结果表明:同一区域的不同地点处的气象要素有一定的差异性,同一区域的温度会有一定的浮动(0~4℃),两者之间的相关性为0. 87;微波通讯链路反演的水汽密度结果与研究区域的地面气象站1和气象站2测量结果有很好的一致性,两者之间的相关性分别为0. 89和0. 97,均方根误分别差为0. 75 g m3和0. 79 g m3;利用微波链路,与现有的湿度监测方法相比,可以为现有的天气监测网络提供额外的丰富的数据源。     

降水对Ku/Ka频段星地链路衰减特性的影响研究

近年来,Ku和Ka卫星在广播、通信和军事等领域应用数量越来越多,传统的Ku和Ka波段星地链路降水衰减预报模型基于经验关系和理想假设,考虑降水微物理特性不足,针对此问题,在实测降水粒子微物理特征的基础上定量分析了降水垂直分布、粒子形状、粒子取向、粒子相态等对Ku和Ka频段信号衰减的影响特性.结果表明,与考虑降水非均匀垂直分布的计算结果相比,ITU和SAM模型是基于降水分布均匀的假设,无法代表降水垂直分布不均匀时的衰减情况;降水粒子形状和取向对衰减的影响较小,在13GHz和32GHz频段,球形和非球形粒子衰减值的平均绝对偏差均在0.01dB以下,不同粒子取向时衰减系数的平均绝对偏差最大值为0.00098dB/km和0.0207dB/km;不同相态的降水引起的衰减差异较大,衰减值从大到小依次是湿雪、水和冰.研究结果可以为Ku和Ka波段星地链路传播特性评估及降雨反演新方法提供基本的理论支撑和数据参考.     

基于微波技术的低功耗无线自主网技术

<正>针对应用传统技术组建的网络功率消耗量较大问题，为此提出基于微波技术的低功耗无限自主网技术研究。根据输电线路杆塔为线状分布的特点，构建星型+链型通信信道，开展星型+链型组网；利用微波技术实现网络无线通信；根据通信信号强度与网络设备功耗关系开发智能通信链路管理算法，依据设定的通信信道强度门限值计算通信链路状态，以此完成基于微波技术的低功耗无限自主网。     

基于微波高光谱技术的数据仿真及参数反演研究

发展高光谱微波辐射计对于提升大气参数反演精度具有重要意义。利用微波辐射传输模型mpm93以及BP 神经网络方法分别构建正演上行辐射亮温和反演大气温度廓线的模型,并研究了晴空条件下高光谱微波辐射计反演大气温度廓线的精度。54～58 GHz、64～68 GHz 在氧气吸收波段选取80 个通道作为高光谱通道,基于2015 年5～12 月昆明的探空资料进行正、反演仿真实验。选取微波成像仪/ 探测仪(SSMIS)的9 个温度探测通道进行对比实验,评估分析反演效果。实验结果表明:在大气3～10 km 高度范围内,高光谱通道的反演精度较SSMIS 提高了0.3 ～0.6 K;在0～3 km 高度范围内,反演精度提高了1 K。     

基于矢量合波原理的微波稳相光传输研究

针对微波光子链路在实际应用中信号相位受光纤温度变化产生的波动,利用检波器矢量和原理检测微波信号的相位偏差量,并设计了信息处理模块控制可调谐电移相器进行精准的相位补偿,实现微波信号的相位稳定传送。在理论模型的基础上,实验测试了温度变化对微波光链路相位的影响,并构造了微波稳相光传输系统,使用25 km的标准单模光纤传输10 GHz微波信号,对系统输出信号进行了长时间测量,相位波动稳定控制在±2°以内,实验结果验证了该方案的可行性。     

相对强度噪声对微波光子链路性能影响规律研究

激光器的相对强度噪声(RIN)在微波光子链路中转换为噪声功率,进而影响链路的动态范围.文章建立了基本结构的非相干和相干微波光子链路的动态范围(SFDR)模型,并通过仿真对比分析了激光器的RIN对这两种链路结构的影响.在光器件的性能水平较低时,非相干微波光子链路能获得更大的SFDR;随着光器件性能水平的提升,相干微波光子链路的SFDR将超过非相干微波光子链路.而在目前典型的器件参数条件下,两种链路的理论SFDR都能达到120 dB·Hz2/3左右.     

基于双向时分复用同纤同波传输的时间同步系统

设计了一种基于双向时分复用同纤同波传输的时间同步系统。为了消除钟差,实现从端与主端的时间同步,利用双向时分复用同纤同波时间比对得到从端与主端的钟差,通过校频和比例-积分-微分控制算法调整从端压控晶振的输出频率。双向时分同纤同波传输链路双向传输的时延对称性,使系统只需进行端机标定,无需对不同长度的光纤链路进行标定。在实验室盘纤和实地光纤链路上的实验结果表明,不同长度光纤链路下,本系统同步后的平均钟差均优于10 ps;在长约60 km的实地光纤链路上,本系统同步后的平均钟差小于9 ps, 3σ钟差优于285 ps,时间偏差优于16 ps/s(短稳)、7 ps/10~4 s(长稳)。     

微波辐射计探测大气剖面的相关向量机算法

提出了利用地基双通道水汽微波辐射计探测大气水汽、温度和折射率剖面的相关向量机反演算法,基于青岛地区的历史探空数据和仿真得到的双通道水汽微波辐射计亮温训练了相关向量机网络.青岛地区的实验和仿真比较表明:相关向量机反演得到的剖面与实际大气剖面有较好的一致性.     

Performance Analysis of Cooperative Wireless Backhaul Networks Operating at Extremely High Frequencies

Extremely high frequency (EHF) bands above 50 GHz have been proposed to be used as backhaul links of modern cellular mobile networks. They provide interconnectivity between the base stations and the core network. In this paper, we propose the employment of cooperative techniques in backhaul networks. More specifically, the outage performance analysis of a simple cooperative diversity system operating at EHF bands is presented. The destination node combines the direct link with the signal received through a regenerative relay using selection combining. A combined statiform and convective model of rainfall rate for the rain attenuation prediction is considered. The correlation properties and the joint statistics among the microwave paths are also calculated. Numerical results present the impact of the geometrical parameters and the climatic conditions on the outage performance.     

基于复杂网络的Psor链路预测算法

复杂网络领域中,链路预测在网络演化规律的研究中被广泛应用,具有巨大的实际应用价值。针对现有的基于网络拓扑的链路预测方法存在预测精度偏低的问题,提出了一种基于复杂网络的Psor链路预测算法。该算法综合节点自身和邻居节点的度,定义了节点的Psor指数和Psor相似性指标进行链路预测。该算法能够全面考虑复杂网络的局部结构信息,更加准确地对复杂网络链路进行预测。仿真结果表明,Psor链路预测算法的预测精度相比8种经典的相似性算法的预测精度最高提升了37.96%。     

Accounting for Link Load Correlation in the Estimation of Blocking Probabilities in Arbitrary Network Topologies

In this paper, we discuss an efficient analytical framework that can accurately account for the link correlation in generic-topology circuit-switched networks. The model takes all active paths, as well as all free links, as independent objects on the network topology. Therefore, the actual sets of sequentially connected busy links (paths) and free links are seen as they appear in the network and the link correlation can be straightforwardly considered. Comparisons with results obtained from simulations show the excellent performance of the proposed analytical modeling for a variety of network topologies.     

Link scheduling with power control for throughput enhancement in multihop wireless networks

Joint scheduling and power control schemes have previously been proposed to reduce power dissipation in wireless ad hoc networks. However, instead of power consumption, throughput is a more important performance concern for some emerging multihop wireless networks, such as wireless mesh networks. This paper examines joint link scheduling and power control with the objective of throughput improvement. The MAximum THroughput link Scheduling with Power Control (MATH-SPC) problem is first formulated and then a mixed integer linear programming (MILP) formulation is presented to provide optimal solutions. However, simply maximizing the throughput may lead to a severe bias on bandwidth allocation among links. To achieve a good tradeoff between throughput and fairness, a new parameter called the demand satisfaction factor (DSF) to characterize the fairness of bandwidth allocation and formulate the MAximum Throughput fAir link Scheduling with Power Control (MATA-SPC) problem is defined. An MILP formulation and an effective polynomial-time heuristic algorithm, namely, the serial linear programming rounding (SLPR) heuristic, to solve the MATA-SPC problem are also presented. Numerical results show that bandwidth can be fairly allocated among all links/flows by solving the MILP formulation or by using the heuristic algorithm at the cost of a minor reduction of network throughput. In addition, extensions to end-to-end throughput and fairness and multiradio wireless multihop networks are discussed.     

A simple computer program for microwave radio link performance analysis

A simple computer program is developed for system power budget analysis of microwave radio links. As known, such an analysis is very important in radio link network planning and optimization of the existing transmission networks. The performance of the program developed in this study is tested by applying it to Adana region and by comparing with measurement results.     

The deflection self-routing Banyan network: A large-scale ATMswitch using the fully adaptive self-routing and its performanceanalyses

Because the Internet traffic, that will be the major traffic of broadband integrated services digital networks, is bursty when cells are being switched within the multistage switching network, it has a higher possibility that multiple cells arriving simultaneously at a switching element through different incoming links may have to be forwarded along the same outgoing link. We propose a high-performance large-scale ATM switch dealing with such link contention problem. It is a new unbuffered augmented Banyan network using fully adaptive self-routing control: the deflection self-routing Banyan network. To utilize all the links of the network as alternate paths, we employ the deflection-routing algorithm in each switching element, such that cells failing to get selected for the intended link are sent along different links, in the hope that they later return, or detour the contended link and continue their journey to the destination. Cells are never dropped within the switching network, whereas the switch has no multiple cell buffers. The proposed routing is as simple as that of the generic Banyan network, and all the switch elements (SEs) have a uniform structure. To design the proposed network and its self-routing, we use the topological properties that all the SEs of the Banyan network are arranged in a regular pattern topologically. We formulate and prove these properties through an algebraic formalism. We also ran a performance analysis to provide quantitative comparison against the Banyan network and the replicated Banyan networks. As a result, we show that the new network has a far better performance and scalability than the other networks     

无线Mesh网络集中式信道分配算法设计

以集中式无线Mesh网络(WMN)为基础,分析和研究了传统多信道分配算法,并在此基础上提出了以节点优先级和分组为特点的多接口多信道分配算法(Channel Assignment based on Rank of Node and Link group,CAR-NL),该算法结合节点分级和链路负载预期评估机制,通过节点链路分组按级分配信道。通过仿真实验表明,该算法能有效提高无线Mesh网络多业务流并发执行时系统整体吞吐量,并实现较低的丢包率。