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位置管理是移动通信领域的一个具有挑战性的问题,涉及到位置更新和位置查找操作.在现行蜂窝系统的位置管理策略(简称"基本策略")中,一旦移动台越区,就需要进行位置更新.由于移动台的越区具有局部性,基本策略会造成系统资源的极大浪费.因此,降低位置管理的费用成为移动通信领域的一个研究热点.该文给出不需要进行位置更新的环状搜索位置管理策略(简称"环状策略"),并推导出搜索位置区平均层数的一个公式,然后利用这一公式对基本策略、指针推进策略与环状策略的费用进行了对比研究,得出:在一定条件下,环状策略的费用要比基本策略及基本指针推进策略小. 相似文献
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位置管理是移动通信领域的一个具有挑战性的问题,涉及到位置更新和位置查找操作.我国及其他国家目前正在使用的个人通信网络中,基本的位置管理策略(简称"基本策略")的位置查找操作采用的是,在整个位置区中同步寻呼移动台.由于所要寻找的移动台只在由众多小区所组成的位置区内的一个小区中,因此,"基本策略"会造成系统资源的极大浪费.本文给出一种对位置区内的小区进行分层,按移动台在各层小区的概率从大到小的次序,逐层进行寻呼的位置管理策略(简称"分层策略").在假定移动台在各个小区的逗留时间是符合一般概率分布的随机变量的条件下,推导出移动台处于各层小区的概率及"分层策略"所需搜索的小区平均个数公式.证明了"分层策略"的位置管理费用不大于"基本策略". 相似文献
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基于3G网络中由HLR(home location register)、GLR(gateway location register)、VLR(visitor location register)构成的3层数据库结构,提出了基于移动的增强动态位置管理策略,重点分析了该策略下位置更新和寻呼的代价模型。并使用该代价模型对3G网络中基于移动的增强动态位置管理策略、基于移动的基本动态位置管理策略和静态位置管理策略进行了评价,计算结果显示增强动态位置管理策略要优于基于移动的基本位置管理策略和静态位置管理策略。 相似文献
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通过对移动用户和网络特性的分析,结合核心网和无线侧,研究了CDMA网络的寻呼类型,给出语音和短信寻呼的基本方法,LAC(location area code,位置区码)位置区设置和周期性位置更新的重要策略,并对网络寻呼与某些业务的触发先后次序、关键定时器之间的冲突以及寻呼与移动终端的配合等问题进行了研究,提出了能够提高系统接通率和改善用户感知的寻呼策略方法:增加二次或三次寻呼、LAC边界避开话务密集地区、同一LAC下的周期性位置更新参数设为一致、周期性位置更新定时器无线侧设为小于网络侧等。 相似文献
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GSM网络位置区的合理规划对移动网络的寻呼成功率、切换成功率和位置更新成功率起关键的作用。文章分析了GSM移动通信网位置区的规划原则、及2G和3G共存时的位置区规划,并给出GSM网络中BTS的寻呼容量和位置区的大小的计算方法。 相似文献
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发展一般的移动性管理模型是一体化移动网络的重要需求.通过分析移动性的影响以及不同体系下的移动性支撑机制,本文提出了移动管理层作为移动性及其管理的概念解释.提出了一个描述移动性管理机制的索引结构模型.该模型构造了管理机制的基本单元(点和边),定义了基本操作(更新操作和查询操作).分析指出所提模型在单元和参数方面具有很大的灵活性,可以适用于很多场景.本文使用索引结构模型描述并分析了一体化网络的移动性管理方案,分析结果说明了在一体化网络中映射服务器的配置方案和其查询机制的设计将成为实现高效的移动性管理机制的关键. 相似文献
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GPRS移动台的数据业务质量受到小区更新,位置更新等移动性管理状态影响,同时数据业务能否正常进行也与其会话管理状态有关。本文通过深入研究GPRS移动台的状态转移过程,提出改善用户终端QoS的方法。 相似文献
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3G移动网络中逆向GLR故障恢复算法及分析 总被引:1,自引:0,他引:1
在3G网络中,当漫游用户在网关位置寄存器(GLR)中的位置信息不正确时,其位置查询将失败,此时将严重恶化系统性能,而传统的位置恢复算法需占用大量长途电路资源。为减少GLR位置恢复过程中对长途电路资源的占有及缩短GLR故障恢复时延,本文提出了一种新的算法逆向GLR故障恢复算法。该算法充分利用用户在访问位置寄存器(VLR)中的用户信息,从而避免在恢复过程中GLR和归属位置寄存器(HLR)的长途信令开销。通过对算法的性能作分析,证明所提出的算法是可行的。 相似文献
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Many protocols have been proposed for solving the user authentication in portable communication system. One of the schemes is based on the delegation concept. Home Location Register (HLR) delegates Mobile Station (MS) to be authenticated by Visitor Location Register (VLR). The main drawback of the scheme is that the HLR is required during the online authentication phase between VLR and MS. In this paper, a double delegation-based authentication and key agreement protocol is proposed. The main advantage of our protocol is that this scheme requires only MS and VLR online. This protocol will thoroughly utilize the proxy signature features to facilitate the operation of this protocol while only requires two members (MS, VLR) to be online at the same time. 相似文献
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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. 相似文献
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Salah M Ramadan Ahmed El Sherbini Mahmoud Marie Mohamed Zaki 《Wireless Personal Communications》2007,41(1):57-75
One of the challenging tasks in Personal Communication Services (PCS) is to efficiently maintain the location of PCS subscribers
who move from one region to another (hereafter called mobile users). When a mobile user receives a call, the network has to
quickly determine its current location. The existing location management scheme suffers from high signaling traffic in locating
the mobile users. Two-level forwarding pointer scheme has been proposed from per-user forwarding pointer scheme to reduce
the cost of signaling traffic. In this paper, we enhance the two-level forwarding pointer scheme. When a mobile user moves
from its current Registered Area (RA), which is served by Mobile Switching Center (MSC), to another RA the local switch that
acts as a parent of those two MSCs maintains this movement in its memory (hereafter called cache entry). A cache entry is
used to locate rapidly the mobile user instead of querying the Home Location Register (HLR) and waiting for its reply. HLR
is centralized in the network and far away from the mobile users so that the signaling traffic crossing it is expensive. Sometimes
the cache entry may be failed to reach the mobile user then a two-level forwarding pointers will be created from the corresponding
Visitor Location Register (VLR), attached to its MSC, through a correct path to locate the mobile user. Thus, there is a saving
in cost of querying the underlying HLR. The analytical results indicate that such proposal efficiently reduces the signaling
traffic cost for all values of Call to Mobility Ratio (CMR), this is especially considerable when CMR ≥1, without any increase
in the call setup delay.
Salah M. Ramadan (samohra@yahoo.com) received the BS and MS degrees from Computers Engineering Department, Al-Azhar University, Cairo, Egypt,
in 1995 and 2002, respectively. From 2002, he was a Ph.D. student in Computers Engineering Department at Al-Azhar University
and is currently pursuing the Ph.D. degree, where he is a research assistant in the Wireless Networks Branch. His research
interests include traffic management in ATM networks, routing protocols, mobility management in PCS networks, and mobile computing.
He is currently an instructor in Cisco Academy, Egypt.
Ahmed M. El-Sherbini (Sherbini@mcit.gov.eg) received the Ph.D. in Electrical and Communication Engineering, Case Western University, U.S.A. March
1983 and M.Sc. in Communication Engineering, Cairo University, Giza, Egypt, June 1980. (M. Sc. Research Studies at the Ecole
Nationale Superieure des Telecommunications (ENST), Paris, France). He is the Director, National Telecommunication Institute
– Ministry of Communications and Information Technology, Egypt and Professor of Electrical and Communication Engineering Dept.
Faculty of Engineering, Cairo University, Egypt.
M. I. Marie received his B.Sc., M.Sc. and Ph.D. in electronic and communication engineering from Cairo University on 1972, 1981, 1985,
respectively. Now he is a professor of communications at Computer and System Engineering department Al-Azhar University, Cairo,
Egypt. His fields of interest includes digital communication, computer networks and protocols development.
M. Zaki (azhar@mailer.scu.eun.eg) is the professor of software engineering, Computer and System Engineering Department, Faculty of
Engineering, Al-Azhar University at Cairo. He received his B.Sc. and M.Sc. degrees in electrical engineering from Cairo University
in 1968 and 1973 respectively. He received his Ph.D. degrees in computer engineering from Warsaw Technical University, Poland
in 1977. His fields of interest include artificial intelligence, soft computing, and distributed system. 相似文献
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A personal communications network (PCN) location tracking scheme called local anchoring is introduced which reduces the signalling cost as compared to the location management strategy proposed in the IS-41 standard. Local anchoring reduces the number of location registration messages between the home location register (HLR) and the visitor location registers (VLRs) in a way that location change is reported to a nearby VLR called the local anchor (LA) instead of to the HLR. This method successfully reduces the cost for location tracking when the call arrival rate is low relative to the mobility rate and the cost for location registration is high. A dynamic local anchoring mechanism is then introduced which dynamically selects the LA such that the expected cost for location registration and call delivery can be further reduced. It is demonstrated that the cost of dynamic local anchoring is always lower than or equal to that of the IS-41 scheme 相似文献
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Location tracking with distributed HLR's and pointer forwarding 总被引:11,自引:0,他引:11
Location tracking operations in a personal communications service (PCS) network are expensive. A location tracking algorithm called pointer forwarding has been proposed to reduce the location update cost. The key observation behind forwarding is that if users change PCS registration areas (RAs) frequently, but receive calls relatively infrequently, it should be possible to avoid registrations at the home-location register (HLR) database by simply setting up a forwarding pointer from the previous visitor-location register (VLR). Calls to a given user will first query the user's HLR to determine the first VLR, which the user was registered at, and then follow a chain of forwarding pointers to the user's current VLR. To reduce the “find” cost in call delivery, the PCS provider may distribute HLR databases in the network. This paper integrates the concept of distributed HLRs with pointer forwarding, and the new scheme is referred to as the pointer forwarding with distributed HLR (PFDHLR). Since no registration to the HLR is performed in the pointer forwarding scheme when a user moves to the new locations, the cost of updating multiple HLRs is eliminated in PFDHLR. Our study indicates that PFDHLR may significantly reduce the mobility management cost compared with the single HLR approach 相似文献
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提出了基于阈值的两级指针推进策略(TPFT,two-level pointer forwarding with thresholds)将一部分VLR(visitor location register)中的移动用户选为移动代理(MA,mobile agent),在MA之间建立第一级指针链;在MA与VLR之间建立第二级指针链,两级指针链均设定长度阈值。将该策略与“基本位置管理策略”及“通行用户指针推进策略”和“带门槛的指针推进策略”的开销进行比较得出:选择适当的两级阈值,TPFT策略的开销优于上述策略。同时,TPFT策略是将系统中对HLR(home location register)的修改与查询的信号量分布到各个MA中,提高了系统效率。 相似文献
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An auxiliary user location strategy employing forwarding pointers to reduce network impacts of PCS 总被引:3,自引:0,他引:3
We propose an auxiliary strategy, calledper-user forwarding, for locating users who move from place to place while using Personal Communications Services (PCS). The forwarding strategy augments the basic location strategy proposed in existing standards such as GSM and IS-41, with the objective of reducing network signalling and database loads in exchange for increased CPU processing and memory costs. The key observation behind forwarding is that if users change PCS registration areas frequently but receive calls relatively infrequently, it should be possible to avoid registrations at the Home Location Register (HLR) database, by simply setting up a forwarding pointer from the previous Visitor Location Register (VLR). Calls to a given user will first query the user's HLR to determine the first VLR which the user was registered at, and then follow a chain of forwarding pointers to the user's current VLR. We use a reference PCS architecture and the notion of a user'scall-to-mobility ratio (CMR) to quantify the costs and benefits of using forwarding and classes of users for whom it would be beneficial. We show that under a variety of assumptions forwarding is likely to yield significant net benefits in terms of reduced signalling network traffic and database loads for certain classes of users. For instance, under certain cost assumptions, for users withCMR<0.5, forwarding can result in 20–60% savins over the basic strategy. This net benefit is due to the significant saving in location update compared to a penalty of moderately increased call setup times for the infrequent occasions when these users do receive calls. 相似文献