3G 蜂窝网络中GLR 故障恢复分析

在3G蜂窝网络中,归属位置寄存器(HLR)、网关位置寄存器(GLR)、访问位置寄存器(VLR)组成三级数据库结构。当漫游移动用户在GLR中的位置信息错误或过时时,对该用户的入呼将失败。由于三层结构设计中,GLR与HLR的通信一般涉及国际长途信令,使得GLR的故障恢复设计非常重要。为尽可能减少对长途资源的占有,对GLR故障恢复提出了一种新的算法并对其性能作了相应的分析。     

华为HLR N＋1容灾中心解决方案

HLR(Home Location Register，家区位置寄存器)作为移动网络中最重要的数据中心，保存着用户的签约数据和位置信息，网络地位非常重要。一旦HLR发生故障，将导致严重后果：对于用户而言，将造成所有用户不能作被叫、不能进行位置更新、不能取到鉴权信息、不能接收短消息、不能修改用户自定义的补充业务；对于运营商而言，网络无法运营、营业厅及客     

基于Openflow网络的高可靠性虚拟网络映射算法

该文基于Openflow网络提出了具有容错能力的虚拟网络映射模型,并且采用蚁群算法对其进行求解。针对虚拟网络的故障恢复机制,提出了区分用户优先级的故障恢复算法(Priority_Diff),该算法为用户提供不同的网络可靠性级别,对高级用户采用提前映射的备份路径替代故障链路,对低级用户重新映射故障链路;设计了故障备份链路重映射(BLRM)算法,将故障链路中的备份资源迁移到相邻链路,增强了备份链路的可用性。最后,通过仿真实验,从虚拟网络故障修复率、虚拟网络成功运行率和工作链路资源利用率3个方面验证了所提算法的优越性。     

移动网络中一种分布式GLR设计方案

UMTS核心网在访问网络处引入可选网元GLR来减少用户远离HLR漫游时的位置管理信令开销。传统GLR方案中,GLR一般在访问网络处集中设置,随着访问网络处漫游用户数的增多,GLR有可能成为系统瓶颈,且GLR的故障对系统是致命的。针对集中式GLR存在的问题,该文提出一种分布式GLR设置方案,使用户在访问网络处的首个访问VLR成为其GLR,从而提高系统对GLR故障的抗毁性,有效降低GLR潜在的瓶颈问题。分析结果表明,该文提出的分布式GLR方案在抗毁性,缓解瓶颈问题,降低入呼数据库查询开销及延迟等指标方面都优于传统GLR方案,同时,所提出的分布式GLR方案易于实现,只需相关网元软件升级即可。     

移动网络中一种分布式GLR设计方案

UMTS核心网在访问网络处引入可选网元GLR来减少用户远离HLR漫游时的位置管理信令开销。传统GLR方案中，GLR一般在访问网络处集中设置，随着访问网络处漫游用户数的增多，GLR有可能成为系统瓶颈，且GLR的故障对系统是致命的。针对集中式GLR存在的问题，该文提出一种分布式GLR设置方案，使用户在访问网络处的首个访问VLR成为其GLR，从而提高系统对GLR故障的抗毁性，有效降低GLR潜在的瓶颈问题。分析结果表明，该文提出的分布式GLR方案在抗毁性，缓解瓶颈问题，降低入呼数据库查询开销及延迟等指标方面都优于传统GLR方案，同时，所提出的分布式GLR方案易于实现，只需相关网元软件升级即可。     

卫星与地面移动通信系统综合环境下的一种位置管理策略

提出了一种在卫星与地面移动系统综合环境下的位置管理方案，即把两系统相重叠的小区设置为边界位置区(BLA)，漫游用户在BLA中进行位置更新，呼叫到达时，BLA中的位置寄存器配合系统进行寻呼。通过计算和数值分析证明该方案不仅可以使原有两系统结构不发生变化，并且能有效减小位置更新与寻呼造成的系统开销。     

2G网络复制卡双活和防范技术

现网中有时会出现具有相同IMSI(国际移动用户识别码)和MSISDN(移动台国际移动用户识别码)的SIM卡用户在不相同的MSC/VLR(移动交换中心/拜访位置寄存器)都有注册信息的情况,这种故障现象称为复制卡双活。文章讲述2G网络SIM卡复制原理,介绍导致复制卡双活的主要信令流程,并对复制卡产业链进行分析,最后对复制卡双活的防范措施做出总结。     

智能网与先验位置信息在呼叫连接中的应用

在个人通信以及联网寻呼中，怎样能够以最小的网络负载和最少的费用最快地期望的用户，最值得研究的问题。本文基于智能网提出了先验位置信息的概念，并给出了这种信息在位置登记器中的应用算法。计算机性能模拟显示它使原有的位置登记器中的智能网性能得到了改善。     

个人通信位置管理的计时双位置算法

提出了一种新的位置管理算法——计时双位置算法，从理论上导出了TTLA算法的总代价函数，给出了传统IS-41和双位置算法(TLA)的统～数学框架。通过性能分析可知，TTLA算法能根据用户的呼叫移动比，在IS-41和TLA两者之间进行选择，综合性能好，且在某些情况下，性能要超过另两种算法。     

基于小世界网络的用户位置行为兴趣模型

移动智能终端的快速发展为用户的位置服务提供了新的应用,以用户位置行为分析为核心的服务技术具有重要的商业应用价值。用户位置及其活动特点和趋势与其所在位置的实际状况及本人意愿密切联系,用户所在位置的资源和状况信息直接影响了用户的位置行为。本文引入小世界网络模型分析用户的位置行为特征,发现用户基于位置的行为属性和聚类。采用推荐度计算方法描述结点之间的相似性,通过将用户位置作为一个树根,把位置资源作为用户的兴趣结点,将兴趣搜索转换为最短路径计算问题。通过改进的最短路径算法计算根结点到各个结点的推荐度,分析用户最感兴趣的位置资源结点。实验结果表明,采用该方法建立的用户位置行为兴趣模型能够很好地描述用户基于位置的兴趣和意愿,算法在结果精度和计算时间上都具有良好的性能。     

一种3G中基于三层数据库的呼叫建立机制研究

基于3G网络三层数据库结构中GLR (Gateway Location Register)服务区远大于VLR (Visitor Location Register)服务区的情况,考虑被呼业务本地化(即本地移动用户呼叫本地移动用户的比例占总呼叫数的比例大),通过在GLR中设置缓存的方法,给出了一种新的呼叫建立机制。建立分析模型得到新机制的总代价函数和总时间延迟函数,并同基本呼叫建立机制以及2G网络基于VLR缓存的呼叫建立机制进行了对比分析,验证了新呼叫建立机制的优越性。     

Enhanced privacy and authentication for the global system for mobile communications

The Global System for Mobile Communications (GSM) is widely recognized as the modern digital mobile network architecture. Increasing market demands point toward the relevancy of securityrelated issues in communications. The security requirements of mobile communications for the mobile users include: (1) the authentication of the mobile user and Visitor Location Register/Home Location Register; (2) the data confidentiality between mobile station and Visitor Location Register, and the data confidentiality between Visitor Location Register and Visitor Location Register/Home Location Register (VLR/HLR); (3) the location privacy of mobile user. However, GSM does not provide enough security functions to meet these requirements. We propose three improved methods to enhance the security, to reduce the storage space, to eliminate the sensitive information stored in VLR, and consequently to improve the performance of the system. Proposed methods include an improved authentication protocol for the mobile station, a data confidentiality protocol, and a location privacy protocol. The merit of the proposed methods is to improve but not to alter the existing architecture of the system. Furthermore, this study also performs computational and capacity analyses to evaluate the original GSM system and proposed approaches on a comparative basis.     

Trial Results of Intelligent Paging in GERAN

In cellular networks, location managements has a strong impact on signaling load. To minimise mobility-based signaling traffic. Location Areas (LAs) have to be defined correctly. Large LAs increase paging traffic, while small LAs increase location updates. Thus, operators have to trade-off these two constraints to maximize network performance. Several authors have proposed selective paging to reduce paging load. This paper describes an intelligent paging algorithm based on most-recent interaction data. Trial results in a live GSM-EDGE Radio Access Network (GERAN) show that the algorithm can reduce paging traffic significantly, while keeping paging success rates almost unaltered.     

Research on HLR mobility database failure recovery and performance analysis for CDMA2000 systems

In this paper, a novel Home Location Register(HLR) mobility database recovery scheme is proposed. With database backing-up and signal sending as its key processes, the presented scheme is designed for the purpose of both decreasing system costs and reducing number of lost calls. In our scheme, an algorithm is developed for an HLR to identify such VLRs that there are new MSs roaming into them since the latest HLR database backing up. The identification of those VLRs is used by the HLR to send Unreliable Roaming Data Directive messages to each of them to get the correct location information of those new MSs.Additionally, two kinds of relationships, one between the number of lost calls and the database backing-up period and the other between the backing-up cost and the period, are well analyzed. Both analytical and numerical results indicate that there will be an optimal HLR database backing-up period if certain system parameters are given and the total cost can be consequently minimized.     

带门槛的环形搜索移动性管理策略中移动台所 越过的位置区环数

位置管理或移动性管理是移动计算研究领域的一个具有挑战性的问题.我国及其他国家目前正在使用的个人通信网络如GSM、IS-41中,用两层数据库HLR/VLR支持位置管理.在这些网络中,每当移动台从一个位置区LA(Location area)移动到另一个位置区,其基本的位置管理策略(简称"基本策略")不管是否必要均立即进行位置更新操作,因而造成系统资源的极大浪费,降低了系统的性能.本文给出一种带门槛的环形搜索策略(简称"门槛环形策略")——将位置区分成环,设定一个门槛(整数),当移动台越过的位置区的环数没有达到门槛时,系统不进行位置更新操作,以减少位置管理的费用.在假定移动台的呼入是一个泊松过程,移动台在各个位置区的逗留时间是符合一般概率分布的随机变量的条件下,推导出在两次呼入之间移动台处于各位置区环的概率及移动台所越过的位置区环数公式,给出了"门槛环形策略"的位置管理费用小于"基本策略"的条件.     

Secure probabilistic location verification in randomly deployed wireless sensor networks

Security plays an important role in the ability to deploy and retrieve trustworthy data from a wireless sensor network. Location verification is an effective defense against attacks which take advantage of a lack, or compromise, of location information. In this work, a secure probabilistic location verification method for randomly deployed dense sensor networks is proposed. The proposed Probabilistic Location Verification (PLV) algorithm leverages the probabilistic dependence of the number of hops a broadcast packet traverses to reach a destination and the Euclidean distance between the source and the destination. A small number of verifier nodes are used to determine the plausibility of the claimed location, which is represented by a real number between zero and one. Using the calculated plausibility metric, it is possible to create arbitrary number of trust levels in the location claimed. Simulation studies verify that the proposed solution provides high performance in face of various types of attacks.     

Demand re‐registration for PCS database restoration

In a Personal Communications Services (PCS) network, mobility databases such as Home Location Register (HLR) and Visitor Location Register (VLR) are utilized to support mobility management for Mobile Stations (MSs). If the location databases fail, the location information loss or corruption will seriously degrade the service offered to the subscribers. In this paper, we propose a new VLR failure recovery scheme called demand reregistration. In this scheme, the VLR broadcasts a reregistration request to all MSs after the VLR failure. When an MS receives the reregistration request, it sends a registration message to the VLR to recover the location record. Since all MSs will reregister after receiving the broadcasting request, traffic jam (and thus collisions) may occur. If a collision occurs, then the involved MSs must resend the registration messages. This paper studies the performance of demand reregistration by investigating how effectively the reregistration can recover the location record for an MS before the first MS call termination occurs. Our results indicate that demand reregistration can effectively recover VLR failure.     

Wireless Location Tracking Algorithms for Environments with Insufficient Signal Sources

Location estimation and tracking for the mobile devices have attracted a significant amount of attention in recent years. The network-based location estimation schemes have been widely adopted based on the radio signals between the mobile device and the base stations. The location estimators associated with the Kalman filtering techniques are exploited to both acquire location estimation and trajectory tracking for the mobile devices. However, most of the existing schemes become inapplicable for location tracking due to the deficiency of signal sources. In this paper, two predictive location tracking algorithms are proposed to alleviate this problem. The Predictive Location Tracking (PLT) scheme utilizes the predictive information obtained from the Kalman filter in order to provide the additional signal inputs for the location estimator. Furthermore, the Geometric-assisted PLT (GPLT) scheme incorporates the Geometric Dilution of Precision (GDOP) information into the algorithm design. Persistent accuracy for location tracking can be achieved by adopting the proposed GPLT scheme, especially with inadequate signal sources. Numerical results demonstrate that the GPLT algorithm can achieve better precision in comparison with other network-based location tracking schemes.