Coverage Probability Analysis for Full-Duplex Relay Aided Device-to-Device Communications Networks

The coverage probability of both the cellular users and the Device-to-Device(D2D) users are analyzed. We assume that the cellular users are able to communication with the Base Station(BS) either by relying on the assistance of Full-Duplex(FD) mode relays or via direct user-to-BS links with high-enough Signal-to-Interference-plus-Noise-Ratio(SINR). Note that the FD-mode devices are capable of simultaneously operating in two modes,i.e. the D2D mode and the cooperative relay mode,with the sum power consumption at these devices kept constant. The closedform expressions for coverage probability of both tier users are derived. After that,numerical analyses are provided,showing that the coverage probability of the both the cellular and the D2D users can be substantially influenced by a variety of parameters,including the power allocation factor of the relays,the density of users,and the self-interference imposed on the FD mode relays,etc. Furthermore,in the D2D enabled networks,it is shown that the FD relay aided transmission is beneficial to enhancing the coverage probability of the cellular users if the target SINR is lower than 5 d B.

Probabilistic Models for the Probability of Wave Breaking and Whitecap Coverage Based on Kinematic Breaking Criterion

More and more researches show that neither the critical downward acceleration nor the critical slope of water waves is a universal constant. On the contrary, they vary with particular wave conditions. This fact renders the models either for the probability of wave breaking B or for the whitecap coverage W based on these criteria difficult to apply. In this paper and the one which follows we seek to develop models for the prediction of both B and W based on the kinematical criterion. First, several joint probabilistic distribution functions (PDFs) of wave characteristics are derived, based on which the breaking properties B and W are estimated. The estimation is made on the assumption that a wave breaks if the horizontal velocity of water particles at its crest exceeds the local wave celerity, and whitecapping occurs in regions of fluid where water particles travel faster than the waves. The consequent B and W depend on wave spectral moments of orders 0 to 4. Then the JONSWAP spectrum is used to represent the fetch limited sea waves in deep water, so as to relate the probability of wave breaking and the whitecap coverage with wind parameters. To this end, the time averaging technique proposed by Glazman (1986) is applied to the estimation of the spectral moments involved, and furthermore, the theoretical models are compared with available observations collected from published literature. From the comparison, the averaging time scale is determined. The final models show that the probability of wave breaking as well as the whitecap coverage depends on the dimensionless fetch. The agreement between these models and the database is reasonable.

Parameterization of Wave Breaking Probability and Whitecap Coverage

The model for whitecap coverage and wave breaking probability are parameterized by the dimensionless wind fetch X^-. This paper aims at replacing X^- with other parameters such as the average wave period T^-, wind speed U10 or wave age ξ in order to improve the suitability and convenience of the model for application. First, W and B are expressed in terms of T^- and U10, which are relatively easy to measure in the field. Further, U10 is replaced with the friction velocity U. by use of the empirical relationship. As wave age has been widely used to parameterize spectral models of ocean waves and air-sea fluxes, W and B are then expressed as a simple function of wave age, respectively. The new forms of the model obtained are W= 1 - Ф（3.02ξ0＂76） and B = exp（ - 4.54ξ^1.52） . The two forms are mere applicable in pracrice, since ξ is relatively easy to measure or determine from wave and wind records. Comparisons between these expressions and data collected from published literature are made and agreement is fairly good.

Coverage probability of cellular networks using interference alignment under imperfect CSI

Interference alignment （IA） is well understood to approach the capacity of interference channels, and believed to be crucial in cellular networks in which the ability to control and exploit interference is key. However, the achievable performance of IA in cellular networks depends on the quality of channel state information （CSI） and how effective IA is in practical settings is not known. This paper studies the use of IA to mitigate inter-cell interference of cellular networks under imperfect CSI conditions. Our analysis is based on stochastic geometry where the structure of the base station （BS） locations is considered by a Poisson point process （PPP）. Our main contribution is the coverage probability of the network and simulation results confirm the accuracy.

The analysis of coverage probability,ASE and EE in heterogeneous ultra-dense networks with power control

The ultra-dense network is a promising technology to increase the network capacity in the forthcoming fifthgeneration(5G)mobile communication networks by deploying lots of low power Small Base Stations(SBSs)which overlap with Macro Base Stations(MBSs).The interference and energy consumption increase rapidly with the number of SBSs although each SBS transmits with small power.In this paper,we model a downlink heterogeneous ultra-dense network where a lot of SBSs are randomly deployed with MBSs based on the Poisson point process.We derive the coverage probability and its variance,and analyze the area spectral efficiency and energy efficiency of the network considering three Fractional Power Control(FPC)strategies.The numerical results and Monte Carlo simulation results show that power control can mitigate the interference and balance the performances of inner-user and edge-user equipments.Especially,a great improvement of energy efficiency is archived with a little loss of area spectral efficiency when FPC is adopted.Finally,we analyze the effect of base stations’(BSs’)sleeping on the performance of the network when it is partially loaded.

Analysis of Coverage and Area Spectrum Efficiency of UDN with Inter-Tier Dependence

Stochastic geometry is widely employed to model cellular network. But in most existing works, base stations(BSs) are modelled following a homogeneous Poisson point process(PPP) for one-tier network, or several independent homogeneous PPP for multi-tier network, which ignore the dependence among BSs. In this paper, a three-tier UDN(Ultra dense network) with Macrocell BSs(MBS) for basic coverage, Picocell BSs(PBSs) deployed outside the coverage area of MBSs for compensating coverage holes, and Femtocell BSs(FBSs) surrounding MBSs for capacity improvement modelled by point process with inter-tier dependence is proposed. The tier association probability, the coverage probability and area spectrum efficiency(ASE) are derived. Simulation results validate our derivation, and results show that the proposed network model has 25%-45% performance gain in ASE.

A Statistical Index for Evaluating the CTV Coverage Loss of Brain Stereotactic Radiosurgery When the PTV Margin Is Zero

Purpose: To develop a new statistical index “percent CTV (clinical target vo-lume) coverage probability” (%CCP), defined as the probability that a specific percent (e.g., 95%) of the CTV can be reliably covered by the prescription dose, for evaluating the coverage loss of brain (fractionated) stereotactic radiosurgery (SRS/fSRS) when the PTV (planning target volume) margin is zero. Methods: The random variable Q for CTV percent coverage was derived using a previously developed model for CTV random motion that follows a three-dimensional (3D) independent normal distribution with a zero mean and a standard deviation of 𝜎𝑆(for translation) or 𝜎𝛿(for rotation). Assuming both CTV and PTV are spherical with the same diameter dCTV, the cumulative distribution function of Q could be obtained analytically using the relation of sphere-sphere intersection. The %CCP was then derived as the reliability function of Q and was used to quantify the coverage loss for selected dCTV. Results: The 95%-95% clinical goal (95% of the times, at least 95% of the CTV is covered) is not achievable with dCTV mm. For common CTVs (dCTV mm) encountered in SRS/fSRS, only 60%-90% of the CTV could be reliably covered by the prescription dose 95% of the time. For 𝜎𝑆=0.5mm and 𝜎𝛿 =0.4˚, the 95% CCP was the highest when the distance between the CTV and the isocenter 𝑑𝐼⇔𝑇=0 and gradually decreased with the increasing 𝑑𝐼⇔𝑇. Conclusions: The %CCP was successfully derived for evaluating the CTV coverage loss for brain SRS/fSRS. When the PTV margin is zero, the 95%-95% clinical goal cannot be achieved for most targets (dCTV mm).

基于随机几何的星地融合无线网络上行覆盖性能分析

星地融合无线网络(STIN)是实现全球无缝立体覆盖的重要途径。为指导星地融合无线网络实际部署,对上行覆盖性能成因规律进行分析。利用随机几何对星地异频部署场景进行了建模,其中,卫星在轨道上服从一维泊松点过程(PPP)分布,地面基站和用户服从二维PPP分布。基于此,推导了星地融合无线网络上行覆盖概率关于基站密度、轨道倾角等参数的表达式。实验仿真验证了理论推导结果的正确性,并分析了网络设计参数对上行覆盖概率的影响。

不依赖位置坐标的室内Wi-Fi网络覆盖度量方法

3GPP在版本16(R16,Release 16)中升级了最小化路测(MDT,minimization of drive test)技术,提出移动终端可利用4G/5G网络自主上报Wi-Fi信号的接收信号强度指示(RSSI,received signal strength indicator),为运营商度量Wi-Fi网络的覆盖率带来了可能性。然而,现有基于MDT技术的网络覆盖度量方法严重依赖GPS提供的位置坐标,但全球定位系统(GPS,global positioning system)不能提供室内精准定位,无法用于室内Wi-Fi网络的覆盖度量。为此,提出了一种不依赖位置坐标的RSSI聚类方法,充分利用室内相近位置RSSI的统计相似性,区分不同位置的RSSI测量差异,在无位置坐标条件下准确估计出室内Wi-Fi网络的覆盖率。实验结果表明,所提方法估计的覆盖率与基于真实位置坐标测量的覆盖率相近,度量准确度明显优于现有的其他方法。

长基线中微子振荡几率和CP破坏效应

研究三味中微子在物质中的振荡,从理论上严格解出了绝热近似下在物质中三味中微子的质量平方矩阵本征值和物质中的中微子有效混合矩阵,并计算出三味中微子在长基线实验中的振荡几率和CP破坏效应。

在中微子振荡中的CP破坏

讨论了中微子味混合与中微子振荡的理论 ,定量地研究了在中微子振荡中的CP破坏效应。在一类超对称模型中 。

基于异常根源分析的工业CPS攻击故障辨识方法

针对工业信息物理系统(Cyber-Physical System,CPS)面对的网络攻击在现场系统中引起的故障与物理系统偶发故障现象上难以区分的问题。基于贝叶斯概率图,结合路径推理算法,文中提出一种攻击故障辨识方法,以炼化分馏系统作为实验对象,验证了在不同攻击故障场景下的有效辨识能力,与当前数据驱动方法相比不依赖已有数据集,可识别未知攻击故障。

A NEW PROBABILISTIC APPROACH FOR ESTIMATING FAULT DETECTION PROBABILITY

A new approach to calculate fault detection probabilities is presented. Fault-free simulation is used in the approach. The quantities of controllability and observability are defined as probabilities of controlling and observing the nodes in the circuit. The probability distribution of random signals on the circuit nodes is analyzed, and it is proved that controllability is in normal distribution. Thus the unbiasing estimation of the fault detection probability can be obtained. According to the concept of observability, we deal with the fan-out nodes. The fault coverages for actual circuits obtained from this approach agree favorably with the fault simulation results.

星地融合网络的上行链路覆盖性能分析模型

星地融合网络可以提供天、空、地、海立体全场景信息覆盖,满足用户多样的业务需求。针对星地融合网络,提出了基于覆盖概率的星座数和基站数的分析模型(AMCP)。该模型为星地融合网络的上行链路覆盖概率提供了分析方法。表述卫星星座数和基站数对用户信号的干扰,构建满足用户覆盖概率条件下的卫星星座数和基站密度的表达式。通过仿真分析了卫星星座数和基站密度对覆盖概率的影响,仿真结果为设计星地融合网络提供分析基础。

基于关键边概率与路径层接近度的多路径覆盖测试

遗传算法解决多路径覆盖中难覆盖边的问题,是当前软件测试数据自动生成领域的一个研究热点.现有方法解决多路径覆盖问题的效果不够理想,本文提出一种将关键边概率与路径层接近度相结合的多路径覆盖测试方法 .首先,本文计算节点被穿越概率找到难覆盖节点,通过难覆盖节点找到难覆盖边(即,关键边),生成目标路径.然后,本文根据关键边概率计算个体贡献度,并通过程序的路径层图计算路径层接近度,再由个体贡献度及路径层接近度设计适应度函数.最后,本文利用多种群遗传算法进化生成测试数据以覆盖目标路径,在进化过程中子种群覆盖当前目标路径后,继续尝试覆盖与其相似的其它路径.实验结果表明,该方法与同类经典方法相比,在保证平均进化时间和平均进化代数占优的同时,稳定性也有所提高,生成时间增幅标准偏差较最优的降低10.19%,离散系数降低10.79%.进化代数增幅标准偏差较最优的降低19.98%,离散系数降低28.02%.

基于视距概率模型的6G室内无线通信系统性能分析

工业物联网、大型商超、体育场馆等室内通信场景的重要性在6G无线通信系统中日益显著。研究室内视距(LoS)信号概率模型有利于提升室内通信系统性能分析准确性。针对室内环境,考虑家具、设备等室内阻挡物的任意位置以及任意高度,构建了视距信号概率模型。该模型可以准确刻画不同阻挡物场景下的视距概率。基于视距信号概率模型,推导了信噪比分布,并研究了室内覆盖性能和能量效率。相关研究成果有助于指导室内无线通信系统部署,降低成本。

一种检验测试覆盖率的定义方法及其马尔可夫验证

基于FMEDA分析提出了一种检验测试覆盖率的定义方法,以及可以提高检验测试覆盖率的措施,基于单卡三重化系统利用马尔可夫模型建模,表征检验测试覆盖率的提高对安全仪表系统(SIS)的PFDavg的影响。应用表明,该检验测试覆盖率的定义方法提出的措施可以有效提高检验测试覆盖率,仿真结果发现:提高检验测试覆盖率,并合理增加检验测试频率可以使SIS在其使用期间内的PFDavg大幅降低。

基于CNN的轴承剩余寿命区间预测

针对轴承剩余使用寿命(RUL)预测中的不确定性量化问题,综合考虑数据不确定性与模型不确定性,提出了一种基于卷积神经网络(CNN)的RUL区间预测方法。首先,对轴承输入数据进行了预处理,并提取了轴承振动信号的时域特征,选用有强趋势性的参数作为模型输入,接着设计了一个在输出层放置正态分布的CNN模型,将其用于点预测及数据不确定性的捕捉;然后,采用集成方法对模型不确定性进行了量化,输出了区间预测结果;最后,采用PHM2012轴承退化公开数据集对基于CNN的区间预测方法的有效性进行了验证,并将结果与采用贝叶斯神经网络(BNN)所得结果进行了比较。实验结果表明:在轴承RUL预测的应用中,基于CNN的区间预测方法的区间覆盖率(PICP)最高,其值比BNN高出了63.9%,点预测结果的均方根误差(RMSE)值最小,其值为0.1997。研究结果表明:基于CNN的区间预测方法可确保点预测估计的准确性,同时,在描述预测不确定性方面具有更大的优越性和实际意义。

Coverage in Cooperative LEO Satellite Networks

Low-earth orbit(LEO)satellite networks ignite global wireless connectivity.However,signal outages and co-channel interference limit the coverage in traditional LEO satellite networks where a user is served by a single satellite.This paper explores the possibility of satellite cooperation in the downlink transmissions.Using tools from stochastic geometry,we model and analyze the downlink coverage of a typical user with satellite cooperation under Nakagami fading channels.Moreover,we derive the joint distance distribution of cooperative LEO satellites to the typical user.Our model incorporates fading channels,cooperation among several satellites,satellites'density and altitude,and co-channel interference.Extensive Monte Carlo simulations are performed to validate analytical results.Simulation and numerical results suggest that coverage with LEO satellites cooperation considerably exceeds coverage without cooperation.Moreover,there are optimal satellite density and satellite altitude that maximize the coverage probability,which gives valuable network design insights.

Acquisition probability differences in cloud coverage of the available Landsat observations over mainland Southeast Asia from 1986 to 2015

Landsat data are the longest available records that consistently document global change.However,the extent and degree of cloud coverage typically determine its usability,especially in the tropics.In this study,scene-based metadata from the U.S.Geological Survey Landsat inventories,ten-day,monthly,seasonal,and annual acquisition probabilities(AP)of targeted images at various cloud coverage thresholds(10%to 100%)were statistically analyzed using available Landsat TM,ETM+,and OLI observations over mainland Southeast Asia(MSEA)from 1986 to 2015.Four significant results were found.First,the cumulative average acquisition probability of available Landsat observations over MSEA at the 30%cloud cover(CC)threshold was approximately 41.05%.Second,monthly and ten-day level probability statistics for the 30%CC threshold coincide with the temporal distribution of the dry and rainy seasons.This demonstrates that Landsat images acquired during the dry season satisfy the requirements needed for land cover monitoring.Third,differences in acquisition probabilities at the 30%CC threshold are different between the western and eastern regions of MSEA.Finally,the ability of TM,ETM+,and OLI to acquire high-quality imagery has gradually enhanced over time,especially during the dry season,along with consequently larger probabilities at lower CC thresholds.