3G中增强的3层动态位置管理建模与分析

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。     

移动通信中的位置管理

蜂窝移动通信系统的位置管理策略的合理选择，可以明显减少系统中无线信道资源的消耗。本文介绍了位置管理的基本操作，回顾了现有2G系统使用的位置管理方案和2．5G系统中对位置管理策略的改进，重点对要求最高2Mbps数据传输率的3G系统所要采用的位置管理方式进行了综合分析，并提出一种位置管理策略的改进。     

个人通信网中的位置管理策略

介绍了当前位置管理的常规策略 ,以及位置管理策略的新技术和发展方向。     

位置敏感光电探测器

位置敏感光电探测器具有广泛的用途，介绍了器件的工作原理，输出信号的位置表达式及各种不同几何图形，等效电路，位置线性度和清晰度等参数性能，存在的缺点，以及不同几何结构的器件性能比较。     

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。     

IMS域的位置管理策略研究

UMTS(Universal Mobile Telecommunications System)R6中IMS(IP Multimedia Subsystem)域的用户的位置都要注册到归属地网络,而且终端的所有SIP信令都要经过注册服务器,导致用户在漫游状态下控制信令的迂回路径变长并限制了用户对网络中应用的使用.该文对UMTS R6的IMS位置管理方案进行了改进,提出了IMS用户位置信息的分布式管理和联系人位置信息自适应缓存机制,使得其漫游状态下的位置注册和呼叫建立过程更加迅速.分析及仿真显示:新的位置管理策略从网络信令花费上优于原位置管理策略.     

分布式数据查询策略的性能估计算法

分布式数据查询策略及其结构(DDB结构),与传统的HLR-VLR结构有很大的不同.本文提出了一种对DDB结构的性能估计方法,其基础是用户的移动性和呼叫特性的概率分布.本文对DDB结构的代价和呼叫传递时延等性能参数进行了研究,证明了DDB结构的性能优越性.     

按概率分批寻呼的位置管理策略

位置管理是移动通信领域的一个具有挑战性的课题,涉及到位置更新和位置查找操作。在假定移动台的呼入是一个泊松过程,移动台在各个蜂窝的逗留时间是符合一般概率分布的随机变量的条件下,求出了移动台在两次呼入之间从一个蜂窝移动到另一个蜂窝的概率,提出了根据移动台进入到各个蜂窝的概率分批进行寻呼的位置管理策略,证明了这种策略的位置管理费用比一些国家现行移动通信系统的位置管理策略的费用小。     

LEO卫星网位置管理策略研究

本文总结了传统的 LEO卫星网的位置管理策略 ,并提出了 LEO网基于卫星自主定位的距离门限位置管理方案。该方案定位直接通过本网络卫星实现 ,减小了移动终端的代价和复杂度。另外 ,该方案虽然增加了定位开销 ,但是大大减小了位置更新和寻呼开销     

移动通信中一种新的位置查询方案及其性能仿真

移动用户的剧增和移动通信业务的发展,对位置管理提出了更高的要求,因此,在移动通信的结构中,设计一个有效的位置管理方案是十分必要的。回顾了针对PCS网络的4种已经存在的位置查询方案,并提出了一种新的查询方案。仿真结果表明,这种新的位置查询方案在性能上要优于4种旧方案。     

A methodology for the performance evaluation of data querystrategies in universal mobile telecommunication systems (UMTS)

The anticipated emergence of third-generation mobile systems, referred to as universal mobile telecommunication systems (UMTS), raises the problem of reconsidering the design of the databases destined to contain the user information. In particular, it is expected that the key concepts of the new database architectures will be high distribution and fast updating of information. So far, the problem of determining the most appropriate distributed database (DDB) architectures for third-generation mobile systems has not been widely dealt with in literature. This paper presents a methodology for evaluating hierarchical DDB architectures by means of an analytical model of the data querying operation. This methodology allows for structural alternatives, differing on account of the number of levels and branches in the hierarchy, to be evaluated in terms of query loads and mean response times, according to a given user mobility characterization and a given search protocol operation. By way of illustration, the paper discusses a case study, concerning a query operation arising from a location updating procedure and applied to a hierarchical tree-like DDB in which some structural alternatives are considered     

Performance Evaluation of Distributed Database Architectures for UMTS Service Deployed in an Urban Area

The design of distributed databases (DDBs) destined to store user information is a key issue in third-generation mobile communication systems such as UMTS. In particular, the problem of determining the most appropriate DDB architectures for UMTS is critical due to the anticipated requirements of high distribution and adaptability of information. This paper presents a model which allows different DDB architectures to be evaluated, in terms of query loads and average search times. The model proposed puts no constraints on either the DDB structure arrangement or the user position characterization. The paper also discusses a real, significant case study, concerning a query operation arising from an access procedure performed on the DDB of a communication network covering an urban area.     

A new distributed location management algorithm for broadbandpersonal communication networks

We propose an efficient location management algorithm for broadband personal communication networks (PCNs) which reduces the complexity of network signaling and delay due to database access when locating a portable station (PS). Previous works on updating and search algorithms for personal communications have concentrated on the access delay due to signaling network traffic only. But, with the advances in fiber optic technology, it will be possible to provide the capacity of signaling network on the order of several Mbps in broadband PCNs. Thus it may be more important to simplify the signaling procedure and reduce the number of database accesses for mobility management at the cost of some increase of signaling traffic. In the proposed algorithm, we first remove all visitor location registers (VLRs) in order to achieve the simplicity of signaling procedure. Thus, only home databases for mobility management are distributed in a global network, and each database keeps only the current locations of PSs initially registered in its management area. It can solve the problem of requiring an impractically large database in a centralized database structure by distributing home location registers (HLRs) while maintaining the simplicity of mobility management and reducing database loads. This algorithm has a simple signaling procedure, and reduces database operations when compared to hierarchical algorithms as network switching hierarchy increases or relocation and calling rate increase     

Dynamic hierarchical database architecture for location managementin PCS networks

This paper introduces a dynamic hierarchical database architecture for location management in personal communications service (PCS) networks. The proposed scheme allows the dynamic adjustments of user location information distribution based on the mobility and calling patterns of the mobile terminals (MTs). A unique distribution strategy is determined for each MT, and location pointers are set up at selected remote locations which indicate the current location of the MTs. This method effectively reduces the signaling and database access overhead for location registration and call delivery. Besides, the required processing is handled by a distributed network of directory registers and centralized coordination is not necessary. The functions of the other network elements, such as the home location register (HLR) and the visitor location registers (VLRs), remain primarily unchanged. This greatly facilitates the deployment of this scheme in current PCS networks     

More efficient location tracking in PCS systems using a noveldistributed database system

In personal communication services (PCS), the complete location information and subscribers' profiles are kept in a database called the home location register (HLR). Another database, the visitor location register (VLR), is used to store partial location information. When a mobile user is called, the system queries the HLR to determine the location of the called party. Distributed databases have been introduced to improve the efficiency of querying the HLR. This paper presents an alternative means of constructing a distributed database. The proposed database design employs fixed pointers to link distributed data. Each database contains a portion of the system's information as well as several pointers. The pointers identify the location of real data, enabling the system to obtain the required information efficiently. The database of the proposed design is markedly smaller than the fully distributed databases since each database of the proposed design stores only partial information. Subscriber information is stored only in one database, thus allowing a single database, rather than multiple databases, to be updated. The single update presented herein notably reduces the signal traffic load. If the caller is in the registration area of some HLR, which holds the called party's information, the response time is significantly decreased since the transactions are served only by the local database. This phenomenon is referred to as the calling locality. The proposed method effectively shares the database and the network loading that originates from several databases' tracking mobile users in a PCS system. According to the results presented, this method is highly effective for systems with a heavy load and high calling locality. The single update feature of the proposed design reduces the traffic in the signaling link and the processing load of a database. However, the proposed method includes no fault tolerance and therein differs from the fully distributed design     

A cost effective distributed location management strategy for wireless networks

The mobility feature of mobile stations (MSs) imposes a large burden on network traffic control as a result of location management. Design issues of location management include MS registration (updating) and call setup (paging). Previous approaches introduced several network topologies for updating and paging procedures, but most of them focused on a single problem: either updating optimization or paging optimization. In this paper, we design and integrate two mechanisms, distributed temporary location caches (TLCs) and distributed home location registers (HLRs), to reduce database access delay and to decrease network signaling traffic in both updating and paging for low power, low tier micro cellular systems. By using TLCs, our approach can improve the performance of updating and paging in comparison with previous approaches. Experimental results based on our analytic model show that our location management procedures have lower HLR access rate, lower registration cost, and lower call setup cost than other approaches.     

A distributed location management strategy for next- generation IP-based wireless networks

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…     

Some experiences with a distributed database testbed system

DDTS (Distributed Database Testbed System) was developed for the purpose of evaluating alternative approaches and algorithms for managing data stored in several databases on different machines. An overview of the system and information architectures of DDTS, as well as an example of the execution of a distributed request, are presented. The results of experiments with three query optimization algorithms are summerized. Our approach for dealing with semantic integrity constraints in a distributed system is reviewed. By sacrificing the enforcement of semantic integrity constraints that span sites, DDTS can be used as a federated distributed database management system.     

On location management for personal communications networks

Personal communications services (PCS) support mobile terminals (MTs) which are free to travel within the service coverage area. In order to effectively locate an MT when a called is initiated, location management schemes are used to keep track of the locations of the MTs. The current approach to location management requires each MT to report its location to the network periodically. The location information is then stored in databases. When a call is initiated. The network determines the current location of the called MT through a database lookup and paging procedure. A currently available standard for location management is described. Research results on location management are surveyed in detail