Traffic prediction enabled dynamic access points switching for energy saving in dense networks

To meet the ever-increasing traffic demand and enhance the coverage of cellular networks,network densification is one of the crucial paradigms of 5G and beyond mobile networks,which can improve system capacity by deploying a large number of Access Points(APs)in the service area.However,since the energy consumption of APs generally accounts for a substantial part of the communication system,how to deal with the consequent energy issue is a challenging task for a mobile network with densely deployed APs.In this paper,we propose an intelligent AP switching on/off scheme to reduce the system energy consumption with the prerequisite of guaranteeing the quality of service,where the signaling overhead is also taken into consideration to ensure the stability of the network.First,based on historical traffic data,a long short-term memory method is introduced to predict the future traffic distribution,by which we can roughly determine when the AP switching operation should be triggered;second,we present an efficient three-step AP selection strategy to determine which of the APs would be switched on or off;third,an AP switching scheme with a threshold is proposed to adjust the switching frequency so as to improve the stability of the system.Experiment results indicate that our proposed traffic forecasting method performs well in practical scenarios,where the normalized root mean square error is within 10%.Furthermore,the achieved energy-saving is more than 28% on average with a reasonable outage probability and switching frequency for an area served by 40 APs in a commercial mobile network.

Localization Algorithm of Indoor Wi-Fi Access Points Based on Signal Strength Relative Relationship and Region Division

Precise localization techniques for indoor Wi-Fi access points(APs)have important application in the security inspection.However,due to the interference of environment factors such as multipath propagation and NLOS(Non-Line-of-Sight),the existing methods for localization indoor Wi-Fi access points based on RSS ranging tend to have lower accuracy as the RSS(Received Signal Strength)is difficult to accurately measure.Therefore,the localization algorithm of indoor Wi-Fi access points based on the signal strength relative relationship and region division is proposed in this paper.The algorithm hierarchically divide the room where the target Wi-Fi AP is located,on the region division line,a modified signal collection device is used to measure RSS in two directions of each reference point.All RSS values are compared and the region where the RSS value has the relative largest signal strength is located as next candidate region.The location coordinate of the target Wi-Fi AP is obtained when the localization region of the target Wi-Fi AP is successively approximated until the candidate region is smaller than the accuracy threshold.There are 360 experiments carried out in this paper with 8 types of Wi-Fi APs including fixed APs and portable APs.The experimental results show that the average localization error of the proposed localization algorithm is 0.30 meters,and the minimum localization error is 0.16 meters,which is significantly higher than the localization accuracy of the existing typical indoor Wi-Fi access point localization methods.

PLC-Oriented Access Point Location Planning Algorithm in Smart-Grid Communication Networks

In this study, we investigate the optimal location of access points （APs） to connect end nodes with a service provider through power-line communication in smartgrid communication networks. APs are the gateways of power-distribution communication networks, connecting users to control centers. Hence, they are vital for the reliable, safe, and economical operation of a power system. This paper proposes a planning method for AP allocation that takes into consideration economics, reliability, network delay, and （n-l） resilience. First, an optimization model for the AP location is established, which minimizes the cost of installing APs, while satisfying the reliability, network delay, and （n-1） resilience constraints. Then, an improved genetic algorithm is proposed to solve the optimization problem. The simulation results indicate that the proposed planning method can deal with diverse network conditions satisfactorily. Furthermore, it can be applied effectively with high flexibility and scalability.

A Robust Wi-Fi Fingerprinting Indoor Localization Coping with Access Point Movement

A Wi-Fi fingerprinting localization approach has attracted increasing attention in recent years due to the ubiquity of Access Point( AP). However,typical fingerprinting localization methods fail to resist accidental environmental changes,such as AP movement. In order to address this problem,a robust fingerprinting indoor localization method is initiated. In the offline phase,three attributes of Received Signal Strength Indication( RSSI) —average,standard deviation and AP's response rate—are computed to prepare for the subsequent computation. In this way,the underlying location-relevant information can be captured comprehensively. Then in the online phase, a three-step voting scheme-based decision mechanism is demonstrated, detecting and eliminating the part of AP where the signals measured are severely distorted by AP 's movement. In the following localization step,in order to achieve accuracy and efficiency simultaneously,a novel fingerprinting localization algorithm is applied. Bhattacharyya distance is utilized to measure the RSSI distribution distance,thus realizing the optimization of MAximum Overlapping algorithm( MAO). Finally,experimental results are displayed,which demonstrate the effectiveness of our proposed methods in eliminating outliers and attaining relatively higher localization accuracy.

Creation of Virtual Wi-Fi Access Point and Secured Wi-Fi Pairing, through NFC

The growing ubiquity of Wi-Fi networks combined with the integration of low-cost Wi-Fi chipsets in all devices makes Wi-Fi as the wireless technology the most used for accessing to internet [1]. This means that the development of a Wi-Fi strategy has become an imperative for almost all operators worldwide. In this context, APs (Access Points) have to become as secure as cellular networks. Furthermore, authentication process between a mobile device and an access point has to be automated, without user constraining configuration. For reaching this purpose, client must have different credentials depending on authentication method. Our goal is to create an architecture that is both ergonomic and flexible in order to meet the need for connection and client mobility. We use NFC technology as a radio channel for starting communication with the network. The communication initiation will instantiate a virtual Wi-Fi AP and distribute all policies and access certificates for an authentication based on EAP-TLS (it could be extended to any EAP method for 802.1X standard). The end result of our new topology is to allow access to services through a virtual Wi-Fi AP with an enterprise-grade in a public hotspot.

Control Access Point of Devices for Delay Reduction in WBAN Systems with CSMA/CA

Due to the gathering of sickrooms and consultation rooms in almost all hospitals, the performance of wireless devices system is deteriorated by the increase of collision probability and waiting time. In order to improve the performance of wireless devices system, relay is added to control the access point and then the access of devices is distributed. The concentration of access point is avoided and then the performance of system is expected to be improved. The discrete time Markov chain (DTMC) is proposed to calculate the access probability of devices in a duration time slot. The collision probability, throughput, delay, bandwidth and so on are theoretically calculated based on the standard IEEE802.15.6 and the performance of the system with and without relay is compared. The numerical result indicates that the performance of the system with control access point is higher than that of the system without control access point when the number of devices and/or packet arrive rate are high. However, the system with control access point is more complicated. It is the trade-off between the performance and the complication.

Manageable Fast Handover at Access Point in WLAN

The handover speed is always vital for the further development of Wireless Local Area Network (WLAN), which is enjoying a fast growth. Based on the handover technology specified in IEEE 802.11 WLAN, Manageable Fast Handover (MFHO) mechanism is proposed to speed up handover at the Access Point (AP), meet handover demands of services with different Quality of Service (QoS), and ensure service continuity. Adopting a handover policy named 'Make-before-break', this mechanism enables wireless APs to control and manage handover between two stations based on improving Inter-Access Point Protocol (IAPP). Tests have been carried out to compare functions and performance of MFHO and IAPP-based handover technology. The test results prove that MFHO provides a higher successful handover ratio and better handover performance than IAPP-based handover technology.

Assessing Water Resources Access of Nouhao Sub-Basin, Burkina Faso

Water resource access in the Nouhao sub-basin, assessed based on the availability of drinking water mobilization facilities, the availability of water for uses and the quality of drinking water, revealed that in 2017 the basin was covered by 1249 modern water point, main drinking water sources. On average, the sub-basin shows a ratio of 271 users per drinking water point. Communal level shows some disparity with Bittou recording the highest number of people per drinking water point, i.e., around 537. Water that can be captured in the entire sub-basin meets only 42% of the total water needs from the three mains uses: irrigation, domestic consumption and livestock. The highest demander among these uses is Irrigation with 75% of the need, i.e., approximately 12,859,995 m3. Water in 33% drinking sources of this sub basin is of poor quality. Arsenic, one of the quality parameters studied, is found in some communes of the sub-basin. 11% of the water points in Bissiga are arsenic polluted making this commune the most arsenic contaminated location. The vulnerability maps deducted from lack of water for uses;lack of drinking water works and poor water quality shows so, the exposure level of the sub-basin’ communes to some potential risks related to low water resources access.

无蜂窝大规模MIMO系统接入点动态选择算法

在无蜂窝大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)系统中,所有接入点(Access Point,AP)为用户提供服务的方式会造成较大的功率消耗和增加前传链路压力。以“用户为中心”的AP选择方案为每个用户选择最佳的AP集合,使系统频谱效率和能量效率得以提升。为了给每个用户选择最佳的AP集合,提出了一种基于反向传播(Back Propagation,BP)神经网络的接入点动态选择算法。将AP与用户之间的大尺度衰落向量作为输入,AP与用户之间的连接关系作为BP神经网络输出的预测向量,同时,针对BP神经网络初始化权值,提出了一种改进的自适应遗传算法以提高算法的收敛速度和收敛性能。仿真结果表明,改进后的BP神经网络预测结果更接近于实际值,并且比全连接和启发式的AP选择方案具有更高的系统和速率。

一种多用户频谱分配优化模型建立与求解

为解决多区域多用户在通信过程中的频谱最优分配与激励问题,本文首先在考虑多个通信运营商及多个小区用户的情况下,通过区块链理论对不同小区不同用户的频谱分配问题进行分析建模,并建立频谱最优分配优化模型;其次,针对优化模型的约束条件,通过引入拉格朗日及二分法理论对其进行求解,进而得出不同小区用户人数与频谱分配之间的数学关系;最后,通过仿真证明了容纳小区人数与频谱持有量近似地呈线性关系,且基站功率越大,近似直线的斜率越大。当基站的持有频谱量较少时,提高功率对可容纳人数的增加影响较小,随着频谱量的增加,提高基站功率,可容纳人数随之近似线性增加。

考虑综合经济性的风光配电网储能优化配置

在配电网中配置储能系统可以有效缓解风光接入对配电网产生的影响,提升对风光的消纳能力、减少电压偏差等,而储能接入的位置和容量不同会对配电网产生不同的影响。首先分析储能建设过程中的主要费用,考虑基于分时电价下的网损成本和峰谷差收益,以年综合成本、配电网的日节点电压偏差和最小为目标,建立配电网储能选址定容模型,采用改进多目标遗传二代算法(improved multi-objective nondominated sorting genetic Ⅱ algorithm, INSGA-Ⅱ)对模型进行求解,利用改进理想点决策法(improved ideal point based decision, IIPBD)来选取最优配置方案,最后在IEEE-33节点模型中对方案进行验证。仿真结果表明:使用INSGA-Ⅱ算法进行求解时最终决策出的储能配置方案实现了成本最小,并且显著提升了电压的稳定性,验证了改进后算法的优良性和所提出的储能优化配置方案的有效性。

知信行护理模式对老年糖尿病合并高血压患者负面情绪及自我管理行为的长期影响

目的探讨知信行(Krone Access Point,KAP)护理模式对老年糖尿病合并高血压患者负面情绪及自我管理行为的长期影响。方法选取深圳市中医院于2022年3月—2023年3月收治的110例老年糖尿病合并高血压患者为研究对象,按照分层随机法分为常规组(行常规护理)与KAP组(行KAP护理),各55例。比较两组负面情绪与自我管理行为评分。结果干预前,两组焦虑、抑郁评分比较,差异无统计学意义(P均>0.05);干预3、6个月后,KAP组焦虑、抑郁评分均低于常规组,差异有统计学意义(P均<0.05)。干预前,两组在病情监测、饮食、情绪、运动、用药等方面的管理行为评分比较,差异无统计学意义(P均>0.05);干预6个月后,KAP组各方面的管理行为评分均高于常规组,差异有统计学意义(P均<0.05)。结论将KAP护理模式应用于老年糖尿病合并高血压患者,有助于缓解其负面情绪,规范其自我管理行为。

国产SW26010-Pro处理器上3级BLAS函数众核并行优化

BLAS(basic linear algebra subprograms)是最基本、最重要的底层数学库之一.在一个标准的BLAS库中,BLAS 3级函数涵盖的矩阵-矩阵运算尤为重要,在许多大规模科学与工程计算应用中被广泛调用.另外,BLAS 3级属于计算密集型函数,对充分发挥处理器的计算性能有至关重要的作用.针对国产SW26010-Pro处理器研究BLAS 3级函数的众核并行优化技术.具体而言,根据SW26010-Pro的存储层次结构,设计多级分块算法,挖掘矩阵运算的并行性.在此基础上,基于远程内存访问(remote memory access,RMA)机制设计数据共享策略,提高从核间的数据传输效率.进一步地,采用三缓冲、参数调优等方法对算法进行全面优化,隐藏直接内存访问(direct memory access,DMA)访存开销和RMA通信开销.此外,利用SW26010-Pro的两条硬件流水线和若干向量化计算/访存指令,还对BLAS 3级函数的矩阵-矩阵乘法、矩阵方程组求解、矩阵转置操作等若干运算进行手工汇编优化,提高了函数的浮点计算效率.实验结果显示,所提出的并行优化技术在SW26010-Pro处理器上为BLAS 3级函数带来了明显的性能提升,单核组BLAS 3级函数的浮点计算性能最高可达峰值性能的92%,多核组BLAS 3级函数的浮点计算性能最高可达峰值性能的88%.

中国基础教育的交通可达性及其空间公平研究

教育公平是实现社会公平的重要基础,基础教育资源在空间上的不公平,是中国当下亟待解决的一项关键问题。然而,全国层面的基础教育交通可达性研究在路网交通时耗的精细测算上尚存在缺失。本研究基于POI、DEM、交通路网、土地利用、人口网格等数据,采用成本距离栅格分析、人口加权基尼系数、双变量莫兰指数测算等方法,分析了中国基础教育设施的交通可达性格局,并评估了基础教育设施交通可达性的多尺度公平性特征。研究发现:①小学和中学的15 min交通等时圈分别覆盖了全国79.7%和78.8%的人口,交通可达性较高的地区地形主要为平原及盆地,多分布于城市群、都市圈地区;②县域尺度上,可达性的“高水平”与“高均衡”呈相互集聚分布,小学和中学的人口覆盖率与可达性变异系数的双变量莫兰指数分别为-0.602和-0.587,即服务水平高的地区及周边往往均衡性也较好;③省域尺度上,可达性的“高水平”与“高均衡”不吻合,北京等基础教育高可达性地区基尼系数达到0.7以上,通常自然地理环境越复杂多样,县域间基础教育可达性公平性通常越低。建议严格规范乡村地区学校撤并,发挥地区间转移支付对完善基础教育设施的作用,并为中小学生提供良好的上学交通出行条件。

可扩展无蜂窝无线接入网性能分析:一种随机几何方法

无蜂窝无线接入网(Cell-Free Radio Access Network,CF-RAN)打破了传统的蜂窝组网方式,形成网络节点规模可扩展的无线接入网架构。CF-RAN在传统无蜂窝大规模MIMO(Cell-Free massive Multiple Input Multiple Output,CF-mMIMO)系统的基础上,对物理层功能进行了合理划分,包括远程射频单元(Remote Radio Unit,RRU)、边缘分布式单元(Edge Distributed Unit,EDU)和以用户为中心的分布式单元(User-Centered Distributed Unit,UCDU)以及中央处理器(Central Processing Unit,CPU),实现了CF-mMIMO系统协作传输中复杂度和性能之间的权衡。在该网络架构中,RRU负责完成射频信号的发送和接收以及数模/模数转换;EDU负责完成基带信号处理中的信道估计、多用户/多数据流检测、多用户/多数据流预编码、上下行信道互易校准等;UCDU负责将接收到的多个EDU发送的属于同一用户的上行数据进行合并,将多个下行数据流分发给对应的EDU,以及RRU之间校准所需的信道估计;CPU负责确定EDU和UCDU之间的数据流对应关系。作为一种新型无蜂窝网络架构下,有必要对其系统级性能进行理论分析,特别是同时考虑信道随机性和空间位置随机性的性能分析,这是本文的主要研究动机。首先,考虑信道估计误差和导频污染的影响,采用可扩展的全导频迫零(Full-pilot Zero-Forcing,FZF)合并预编码,本文给出了系统上下行可达信号干扰噪声比(Signal-to-Interference-Noise Ratio,SINR)的闭合表达式。在此基础上,考虑用户设备(User Equipment,UE)和RRU的空间位置随机性,本文将UE和RRU的位置建模为有限区域内的两个独立二项式点过程(Binomial Point Process,BPP),推导出了用户速率覆盖概率的理论表达式,通过仿真验证了理论结果的准确性。在仿真中,本文在EDU-RRU关联方案上分别采用了基于遗传算法(Genetic Algorithm,GA)的节点交织部署,基于k-means算法的节点聚类部署和随机节点部署。根据数值分析结果,可扩展CF-RAN架构实现了集中式处理和分布式处理之间的灵活权衡,在具备可扩展性的同时,系统性能方面优于全分布式架构,接近全集中式架构。此外,相比其他两种部署方案,基于GA的节点交织部署可以获得最好的性能,而基于k-means算法的节点聚类部署导致的性能损失最大。最后,根据随机几何分析结果,CF-RAN用户下行覆盖概率分别会随着EDU数量和UE数量的增加而降低。

基于人工蜂群算法的去蜂窝大规模MIMO系统AP选择技术

为了提升去蜂窝大规模多输入多输出(multiple input multiple output,MIMO)系统中接入点(access point,AP)选择方案的性能,结合迫零(zero forcing,ZF)预编码技术和人工蜂群算法,提出了针对去蜂窝大规模MIMO系统用户端的AP选择算法。基于各个用户所需接收的信号,采用ZF预编码算法,使得所有AP都参与预编码,从而获得预编码信号;针对每个用户,利用人工蜂群算法,在优化目标为最大化用户的信道容量的前提下,求解相应的AP选择方案。仿真结果表明,相比于不进行AP选择的方案,提出的去蜂窝大规模MIMO系统的AP选择方案在信道容量性能方面表现更优。当用户数量为5、信噪比(signal to noise ratio,SNR)为40 dB、AP数量为40时,提出的AP选择算法对应的信道容量为14.8 bit/(s·Hz),与不进行AP选择的算法相比,信道容量提高5 bit/(s·Hz)。

协同双小区下行协作NOMA-SWIPT中断性能分析

本文研究了在毫微微蜂窝网络(femtocell network,FN)中,协同双小区系统的非正交多址接入(non-orthogonal multiple access,NOMA)与无线携能通信(simultaneous wireless information and power transfer,SWIPT)下行协作通信的中断性能,提出了一种边缘用户在邻基站及源基站随机中心用户共同协作的下行接入方案。所提方案共分为两个时隙:第一时隙内由两基站向所有用户广播叠加信号,提供中继服务的中心用户对其所接收的叠加信号逐级解码并收集能量。第二时隙,中心用户将其第一时隙内所收集的能量作为额外功率资源,在优先保证自身通信质量的前提下对成功解码的边缘用户信息进行再编码转发。基于空间均质泊松点过程(Poisson point process,PPP)中心用户的位置模型,推导了中心用户与边缘用户平均中断概率的表达式,进行了蒙特卡罗仿真验证,同时分析了各仿真参数(中心用户分布半径、用户阈值速率、路径损耗指数等)与中心用户、边缘用户平均中断概率的关系。结果表明:所提方案可以改善边缘用户的下行接入中断性能和系统吞吐量。

Microsoft Office Access中的像控点入库与成果管理方案

目前传统的离散化、目录式成果存储模式数据利用效率低,数据格式不统一,已不适应日益发展的信息化管理需求。本文以遥感影像生产中像控点成果为例,摒弃传统的文档、纸质式存储方案,将像控点成果以数据库的形式存储和管理,把像控点的各类要素关联起来,使离散的数据被索引化,在成果的使用和再利用方面比传统成果管理方式具有更大优势。

5G应用接入终端与物流园区设施设备的互操作性

文中介绍了5G技术的基本原理、关键特性及其在物流领域中的潜在应用。然后,探讨了5G应用接入终端的种类,包括物联网设备、传感器、机器人等,并探讨了它们如何与物流园区设施设备进行互操作。研究发现,5G技术提供了高速、低延迟的连接,使物流园区设施设备能实现实时的数据传输和远程控制,提高了物流效率和安全性。