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.

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.

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.

信息敏感行业3G移动办公安全解决方案

随着运营商对3G投资的不断增加,3G行业快速发展,基于3G网络的移动办公得到了广泛的应用,然而,随之而来的安全问题也日益突出。本文分析了3G移动办公面临的安全问题,构建了5大安全体系,从专用APN、身份认证、网络隔离等方面提出了基于3G移动办公的安全解决方案。

一种GPRS接入系统及安全解决方案

随着无线通信技术的发展,基于GPRS(General Packet Radio Service)的移动应用系统如雨后春笋般快速发展了起来,但另一方面,GPRS平台本身的安全漏洞也给各种应用带来了不少的麻烦,移动通信环境下的信息安全问题日益突出。提出了一种GPRS接入方案,并且针对信息安全问题,综合运用VPN、动态密码技术、访问认证和开发应用安全等技术手段,提出了相应的解决方案,实践表明,系统达到了预期的目标。

从《国际编目原则声明》看团体名称检索点

《国际编目原则声明》中有关检索点与规范标目的论述是我们选取和确立团体名称检索点的基本依据。文章从《国际编目原则声明》的角度,对《普通图书著录规则》标目法、《中国文献编目规则》及其第二版中有关选取团体名称检索点以及确立规范标目的规则进行了对比、分析,对中文团体名称检索点的规范提出了自己的看法。

APN技术在地震前兆观测系统中的应用

数据通讯传输是地震前兆观测系统中重要的组成部分,也是研究人员一直致力解决的问题。随着通讯技术的发展,基于GPRS的APN无线网络通讯技术成为一种新型高效通讯模式,并将其应用于地震前兆观测系统。实际运行结果表明,应用该技术可提高数据传输的稳定性、可靠性、安全性和实时性,是地震前兆观测数据传输的有效通讯手段。

第三代移动通信GSN性能管理分析

为了设计高性能GSN系统、做好系统容量规划、提升系统服务性能,以分析3G系统中GSN子系统关键性能测量、数据处理能力、未来容量预期及挖掘性能管理数据为系统业务规划提供依据是文中的主要目的。运用了信令面模型和数据面模型统计方法分析系统的容量和性能,接入模式不同的归一化处理容限边界条件方法来分析数据处理能力以及多元线性回归法预测网络流量。仿真分析和实践应用结果表明GSN系统在多种混合复杂接入模式下,能有效分析网络业务负荷状况、预测流量趋势、帮助问题定位以及优化网络性能。

Position Vectors Based Efcient Indoor Positioning System

With the advent and advancements in the wireless technologies,Wi-Fi ngerprinting-based Indoor Positioning System(IPS)has become one of the most promising solutions for localization in indoor environments.Unlike the outdoor environment,the lack of line-of-sight propagation in an indoor environment keeps the interest of the researchers to develop efcient and precise positioning systems that can later be incorporated in numerous applications involving Internet of Things(IoTs)and green computing.In this paper,we have proposed a technique that combines the capabilities of multiple algorithms to overcome the complexities experienced indoors.Initially,in the database development phase,Motley Kennan propagation model is used with Hough transformation to classify,detect,and assign different attenuation factors related to the types of walls.Furthermore,important parameters for system accuracy,such as,placement and geometry of Access Points(APs)in the coverage area are also considered.New algorithm for deployment of an additional AP to an already existing infrastructure is proposed by using Genetic Algorithm(GA)coupled with Enhanced Dilution of Precision(EDOP).Moreover,classication algorithm based on k-Nearest Neighbors(k-NN)is used to nd the position of a stationary or mobile user inside the given coverage area.For k-NN to provide low localization error and reduced space dimensionality,three APs are required to be selected optimally.In this paper,we have suggested an idea to select APs based on Position Vectors(PV)as an input to the localization algorithm.Deducing from our comprehensive investigations,it is revealed that the accuracy of indoor positioning system using the proposed technique unblemished the existing solutions with signicant improvements.

GPRS/CDMA业务在青海用电信息采集系统中的应用

用电信息采集系统中,远程通信是保障采集系统稳定运行的重要环节,GPRS/CDMA为用电信息采集系统提供了一种高可靠、易扩展和便于维护的远程通信方式。文章通过对GPRS/CDMA业务在青海用电信息采集系统的应用,介绍了GPRS/CDMA的组网方案、特点及其相关技术。

Enabling Efficient Caching in High Mobility UAV Communications Network under Limited Backhaul

Due to flexible deployment,unmanned aerial vehicle(UAV)mounted aerial access points are capable of expanding the coverage capabilities of existing terrestrial base stations(TBSs).Different from TBSs,however,UAV access points(UAPs)are of high mobility in horizontal and vertical dimensions,which may deteriorate the coverage performance.Worsestill,the mobility of UAPs would as well increase the pressure of wireless backhaul.In this light,we investigate the performance of the cache-enabled UAV communications network(CUCN)in terms of network spatial throughput(ST)by analyzing the line of sight(LoS)connections and non-line of sight(NLoS)connections.It is found that the network ST is exponentially decreased with the square of UAP altitude.Furthermore,contrary to intuition,a large cache size may deteriorate the network ST when UAPs are over-deployed.The reason is that a large cache size increases the hit probability,which may increase the activation of UAPs and consequently result in complicated interference.Aiming to maximize the network ST,we optimize the cache strategy under limited backhaul.Remarkably,the results show that network ST could be substantially improved by the optimized cache strategy and the performance degeneration brought by UAP high mobility could be even eliminated especially when the UAP altitude is high.

Adaptive access points deployment for indoor bluetooth positioning accuracy enhancement

The indoor positioning system based on fingerprint receives more and more attention due to its high positioning accuracy and time efficiency.In the existing positioning approaches,much consideration is given to the positioning accuracy improvement by using the angle of signal,but the optimization of access points(APs)deployment is ignored.In this circumstance,an adaptive APs deployment approach is proposed.First of all,the criterion of reference points(RPs)effective coverage is proposed,and the number of deployed APs in target environment is obtained by using the region partition algorithm and full coverage algorithm.Secondly,the wireless signal propagation model is established for target environment,and meanwhile based on the initial APs deployment,the simulation fingerprint database is constructed for the sake of establishing the discrimination function with respect to fingerprint database.Thirdly,the greedy algorithm is applied to optimize APs deployment.Finally,the extensive experiments show that the proposed approach is capable of achieving adaptive APs deployment as well as improving positioning accuracy.

Neighboring AP discovery and information exchange methods in Plug-and-Play WLAN system

To overcome the problem of existing neighboring access point （AP） discovery methods in WLAN, for example they （PnP） of mul proposed. Us can not provide the accurate neighboring APs information needed for the Plug-and-Play ti-mode APs, three kinds of neighboring AP discovery and information exchange methods are ing these three neighboring AP discovery methods, passive discovery method, active discovery method and station assistant discovery method, the multi-mode AP can discover all neighboring APs and obtain needed information. We further propose two whole process flows, which combine three discovery methods in different manner, to achieve different goals. One process flow is to discover the neighboring AP as fast as possible, called fast discovery process flow. The other is to discover the neighboring AP with minimal interference to neighboring and accuracy of the method is confirmed APs, called the minimal interference process flow. The validity by the simulation.

Scheme of Rogue AP detection in managed WLAN based on AP's location

A scheme of rogue access point(Rogue AP)detection based on AP's localization is proposed.Global position system(GPS)information and received signal strength(RSS)information are used to get the location of AP in a smartphone,which is compared with the database located in a remote server.The proposed scheme can detect not only fake access point(Fake AP)but also Evil Twin AP.It can be a user-oriented solution to detecting Rogue AP threats,and users can use it flexibly.

浅谈家庭Wi-Fi的组网方式及发展前景

随着通信及互联网技术的发展和日益完善,智慧家庭的概念开始广泛进入千家万户,居民通过与手机等智能终端的互动即可方便快捷的享受到舒适、高效的家居生活,而作为承载智慧家庭的家庭宽带网络,Wi-Fi(Wireless Fidelity)已成为大多数家庭必不可少的组成部分。文章主要介绍了现如今比较流行的几种家庭Wi-Fi组网方式,并对未来家庭WiFi的发展前景做出简要分析和研究。

A Hybrid Small-Cell and Clustered Cell-Free Massive MIMO System under Mobility Scenarios

Recently,cell-free(CF)massive multipleinput multiple-output(MIMO)becomes a promising architecture for the next generation wireless communication system,where a large number of distributed access points(APs)are deployed to simultaneously serve multiple user equipments(UEs)for improved performance.Meanwhile,a clustered CF system is considered to tackle the backhaul overhead issue in the huge connection network.In this paper,taking into account the more realistic mobility scenarios,we propose a hybrid small-cell(SC)and clustered CF massive MIMO system through classifications of the UEs and APs,and constructing the corresponding pairs to run in SC or CF mode.A joint initial AP selection of this paradigm for all the UEs is firstly proposed,which is based on the statistics of estimated channel.Then,closed-form expressions of the downlink achievable rates for both the static and moving UEs are provided under Ricean fading channel and Doppler shift effect.We also develop a semi-heuristic search algorithm to deal with the AP selection for the moving UEs by maximizing the weight average achievable rate.Numerical results demonstrate the performance gains and effective rates balancing of the proposed system.

Secure resource allocation against colluding eavesdropping in a user-centric cell-free massive multiple-input multiple-output system

We investigate the resource allocation problem of a cell-free massive multiple-input multiple-output system under the condition of colluding eavesdropping by multiple passive eavesdroppers.To address the problem of limited pilot resources,a scheme is proposed to allocate the pilot with the minimum pollution to users based on access point selection and optimize the pilot transmission power to improve the accuracy of channel estimation.Aiming at the secure transmission problem under a colluding eavesdropping environment by multiple passive eavesdroppers,based on the local partial zero-forcing precoding scheme,a transmission power optimization scheme is formulated to maximize the system’s minimum security spectral efficiency.Simulation results show that the proposed scheme can effectively reduce channel estimation error and improve system security.

Survey of outdoor and indoor architecture design in TVWS networks

To understand the utilizability of TV white spaces （TVWS）, a comprehensive overview of the outdoor and indoor network design over TVWS is given. The related challenges are analyzed. The potential approaches to overcoming these challenges are discussed. The open research issues are investigated. The result shows that： in the indoor scenario, the white space ratio is on average 18.4% higher than that in the outdoor scenario, which corresponds to 7.7 vacant TV channels. Both network design includes 7 key components： TV spectrum identification, access point （AP） discovery, AP association, spectrum allocation, band width adaptation, interface control and disruption handling. Due to building penetration loss, the indoor TVWS identification and AP placement should be carefully considered in the indoor scenario.

A New Enhanced Fast Handover Algorithm in Hierarchical Mobile IPv6 Network

Hierarchical Mobile IPv6 (HMIPv6) can reduce the delay and the amount of signaling during handover compared with the basic mobile IPv6. However, the protocol still cannot meet the requirement for traffic that is delay sensitive, such as voice, especially in macro mobility handover. Duplicate address detection and the transmission time for the handover operation could cause high handover delay. This paper proposes a new mechanism to improve the fast handover algorithm's efficiency in HMIPv6 network. And we present and analyze the performance testing for our proposal by comparing it with the traditional HMIPv6 fast handover algorithm. The results of simulation show that our scheme can reduce the handover delay much more than the traditional fast handover method for HMIPv6 network.