共查询到18条相似文献，搜索用时 46 毫秒
1.
Ｒ．Ｊａｉｎ在移动通信中利用前向指针技术减少对ＨＬＲ的访问和系统代价。本文建立的理论模型对这种方法的性能进行了分析图，呼叫移动比高时使用指针策略反而会增加系统开销。针对这个问题。本文提出一种自适应方法，仿真结果表明该方法随着呼叫移动比变化可自动调整到最佳的最大指针链长度，并能在呼叫移动比高时自动停止使用指针策略． 相似文献
2.
3.
鉴权管理是移动通信移动管理中非常重要的技术,其策略的选择将直接影响网络中各网元的信令负荷。本文主要讨论移动通信系统前向指针位置管理策略中的鉴权管理。当用户在远离其HLR的不同VLR对应覆盖区域移动时,系统通过向其原VLR索取剩余鉴权数据或向其HLR申请新鉴权数据来实现用户的鉴权管理。通过鉴权开销及被呼处理时延等指标的分析,本文提出的鉴权管理算法较适合于CMR较小的MS鉴权管理;当MS的CMR增大时,本文提出的鉴权管理算法与二层管理策略如GSM或IS-41移动系统的开销及时延等指标逐渐接近。 相似文献
4.
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
5.
分布式位置管理策略及其分布式数据库结构与传统位置管理策略和HLR－VLR结构有显著区别,本文基于一种对DDB结构新的性能估计方法,从用户的移动性概率分布出发,对DDB结构下的数据库负载和位置更新性能进行了研究。 相似文献
6.
7.
8.
9.
针对现有HIP机制不支持节点微移动的问题,该文提出了基于动态层次位置管理的HIP移动性支持机制。在该机制中,网络划分成多个自治域,每个自治域划分成多个注册域。当节点在同一个注册域内移动时,在管理该注册域的本地集合服务点中进行位置更新;当节点在同一个自治域内移动时,在管理该自治域的网关集合服务点中进行位置更新。节点根据自己的移动速率以及呼叫到达率选取本地集合服务点并计算注册域的最佳范围。仿真结果表明,该机制能较好地降低节点移动时的信令开销,支持节点微移动。 相似文献
10.
指针推进移动性管理策略中指针链长度的概率 总被引：7，自引：1，他引：6
为了降低移动通信网络中位置跟踪操作的代价,指针推进策略被提出.显然,指针链长度的确定对这一策略的有效应用是至为重要的.已有论文假定移动台在位置区的逗留时间服从指数分布的条件下,对指针链的长度进行研究,但指数分布的特殊性,限制了其研究结果的应用.本文推广了上述结果,研究了移动台在位置区的逗留时间服从一般概率分布的指针推进策略,通过构造向量马氏过程,利用密度演化方法,导出了指针链长度的概率公式,这个公式可用于对各种指针推进策略性能的评价. 相似文献
11.
By introducing a mobility anchor point(MAP),hierarchical mobile IPv6(HMIPv6)reduces the binding update signaling cost associated with mobile IPv6,but there still exist deficiencies.For instance,a mobile node(MN)needs to orderly accomplish two binding updates with the MAP and home agent(HA)when the MN performs inter-MAP mobility.This results in a high signaling cost,thus affecting network performance.To reduce the inter-MAP binding update cost of idle MN in HMIPv6,an optimization scheme based on pointer forwarding with a threshold is proposed.The scheme can reduces the binding update cost of idle MN by using the binding update between MAP to replace several home binding updates.The signaling cost difference is derived by analyzing the cost of the basic scheme and the optimization scheme between two successive sessions.Simulation results show that,the optimization scheme can reduce the binding update signaling cost and improve the network performance as long as a suitable threshold is chosen.The discussions on the sensitivity of tele-parameters are also given. 相似文献
12.
Location management is important to effectively keep track of mobile terminals with reduced signal flows and database queries. Even though dynamic location management strategies are known to show good performance, we in this paper consider the static location management strategy which is easy to implement. A system with single home location register and pointer forwarding is assumed. A mobile terminal is assumed to have memory to store the IDs of visitor location registers (VLRs) each of which has the forwarding pointer to identify its current location. To obtain the registration point which minimizes the database access and signaling cost from the current time to the time of power-off probabilistic dynamic programming formulation is presented. A Selective Pointer Forwarding scheme is proposed which is based on one-step dynamic programming. The proposed location update scheme determines the least cost temporary VLR which point forwards the latest location of the mobile. The computational results show that the proposed scheme outperforms IS-41, pure Pointer Forwarding, and One-step Pointer Forwarding at the expense of small storage and a few computations at the mobile terminals. 相似文献
13.
14.
为了应对实际的业务应用需求,在一定程度上提高网络带宽利用率,在一般实时数据转发系统（RTDFS）的基础上．针对该类系统,提出了优化TCP链路和转发缓冲区取值的方法。主要根据转发系统的网络链路状况,以及实时数据到达转发系统的特征,利用排队论的相关理论建立相应的数学模型,并利用影响TCP传输吞吐量的主要参数,计算出系统运行服务器中最佳的转发缓冲区大小和并行的线程数量。实际系统的实现结果表明,标称带宽为2M,实时数据记录端到实时数据转发端的往返时延约为2ms。实时数据转发端到集控中心服务器的往返时延约为154ms的情况下,转发端的缓冲区无限大、多线程个数为4时,系统运行带宽利用率能达到90％以上,并且验证了该数学模型的理论计算。 相似文献
15.
16.
SONG Mei FENG Rui-jun HUANG Jian-wen SONG Jun-dePCN CAD Center School of Electronic Engineering Beijing University of Posts Telecommunications Beijing China 《中国邮电高校学报(英文版)》2006,13(3):38-42
1 Introduction Mobility management is a key technical aspect in mobile communication systems. The main purpose of mobility management is to enable mobile terminals or users to communicate with each other continuously while moving—— while minimizing data… 相似文献
17.
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
18.
基于无线电测向的台站定位 总被引：5，自引：2，他引：5
无线电定位技术有看广泛的应用前景,基于无线电测向的台站定位,推导出了平面和球面双站定位算法,给出了多站定位算法,并对以上算法进行了实例计算,验证了算法的正确性。平面和球面台站定位算法对于台站定位有很好的实用性,尤其是球面定位算法对于提高定位精度有很大的作用。 相似文献