上海移动针对位置更新成功率偏低问题的处理案例

位置更新过程由移动终端发起,一般位置更新的失败率在10%以内,造成位置更新失败的原因多为无线链路故障、HLR无用户数据、网络传输故障等,单个LAC区位置更新成功率下降30%基本可以认定为异常。本文通过中创信令监测系统数据,针对上海移动网络发生的位置更新指标恶化进行深入分析,定位了产生位置更新失败的终端型号。     

基于多跳蜂窝网的组位置管理策略

提出了一种成组进行位置管理的策略,分析了彼此临近的移动台组成一个自组织网的基本网络模型,提出了向中继点注册,由中继点进行信令压缩,组成组控制信令,成批向网络报告位置的位置更新的策略;采用M/M/n/n模型具体比较了批处理方案与传统方案的性能,说明作者的方案不仅减少了移动台的发射功率,还大量节省了频率资源,增加了系统的吞吐能力。     

LEO卫星系统星上VLR数据库管理方案

在低轨(LEO)卫星通信系统中,航行在国外的特殊终端位置更新时需查询国内地面站访问位置寄存器(VLR),导致了长距离的信令开销.为此,提出一种星上VLR数据库管理方案,使移动终端能通过查询星上VLR进行位置更新操作.将该方案运用于具体低轨卫星系统进行仿真.结果表明,该方案能优化系统的位置管理性能.     

LTE位置管理中信令开销的分析

为了克服2G和3G移动通信网络位置管理方案的缺陷,4G长期演进(Long Term Evolution,LTE)采用了基于跟踪区列表(Tracking Area List,TAL)的位置管理方案。基于TAL的位置管理方案的性能取决于TAL分配方案。考虑到本地移动设备(User Equipment,UE)的活动区域相对固定,该文提出一种嵌入式马尔科夫链模型,用于分析本地UE的基于TAL的位置管理方案的信令开销。推导得到位置更新开销和寻呼开销的数学公式。利用这些公式,可搜索得到能使信令开销最低化的最佳TAL分配方案。     

一种基于位置更新机制的WCDMA用户屏蔽选通系统实现方案

提出了一种基于位置更新机制的WCDMA用户屏蔽选通系统实现方案。该方案利用WCDMA小区重选、身份识别和位置更新的机制,通过建立虚拟小区,诱使用户发起小区重选。通过控制信令流程,在用户位置更新过程中发起身份识别过程,获得用户的身份信息,并通过伪造位置更新回复信令,实现对覆盖范围内用户的通信屏蔽与选通。WCDMA用户屏蔽选通系统在不影响用户正常通信情况下,屏蔽非法用户的通信,可以有效应对WCDMA移动网络违规使用所带来的安全隐患。     

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。     

移动通信网中的一种边界关联位置更新策略

本文针对移动通信蜂窝网固定位置区位置管理中存在的两个主要问题:边界乒乓效应和边界信令集中,提出了一种边界关联位置更新策略,能够在很大程度上抑制乒乓效应,同时,部分平滑了位置区边界的信令负荷.采用随机游走模型和状态转移矩阵理论推导的方法,对本文提出的更新策略与传统位置更新策略进行了分析比较,并通过仿真进一步验证了结果.分析和仿真表明,本文策略不仅相对易于实现,而且极大优化了性能.     

优化提升信令监测系统IMSI回填率的应用分析

介绍了使用中创信测信令监测系统分析高铁专网位置更新IMSI回填率低问题的案例,提出了改进IMSI回填率的优化方案。通过对比优化前后效果,说明方案的实施对于信令监测Mc口数据可用性的提升有明显的效果。这种关于IMSI关联回填的优化思路,对于信令监测系统的优化和维护工作极具推广和借鉴意义。     

软交换跨MGW位置更新问题分析

介绍了采用软交换设备进行信令跟踪,对移动通信网中华为软交换同一server下跨MGW位置更新时第一次位置更新都不成功原因的分析以及对一些特殊消息进行的分析。     

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。     

Two-level pointer forwarding strategy for location management in PCS networks

For a IPCS network to effectively deliver services to its mobile users, it must have an efficient way to keep track of the mobile users. The location management fulfills this task through location registration and paging. To reduce the signaling traffic, many schemes such as a local anchor (LA) scheme, per-user caching scheme and pointer forwarding scheme have been proposed in the past. In this paper, we present a new location management scheme which intends to mitigate the signaling traffic as well as reduce the tracking delay in the PCS systems. In this strategy, we choose a set of visitor location registers (VLRs) traversed by users as the mobility agents (MA), which form another level of management in order to make some registration signaling traffic localized. The idea is as follows: instead of always updating to the home location register (HLR), which would become the bottleneck otherwise, many location updates are carried out in the mobility agents. Thus, the two-level pointer forwarding scheme is designed to reduce the signaling traffic: pointers can be set up between VLRs as the traditional pointer forwarding scheme and can also be set up between MAs. The numerical results show that this strategy can significantly reduce the network signaling traffic for users with low CMR without increasing much of the call setup delay.     

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.     

A simple analytical framework for location management in personalcommunication systems

Efficient mobility management for portable stations (PS's)-handoff, channel assignment and locating-will play an important role in future personal communication systems (PCS's). Among these tasks, location management plays a critical role for wide-area roaming. The key elements of locating are location registration/updating and paging. Due to the smaller cell size in PCS, the high boundary crossing rate of PS will result in more frequent location area (LA) updating. This, in turn, will result in more interrogations with location registers, which will generate a higher volume of access and signaling traffic (SS7 traffic). One solution to this problem is to increase the size of LA, which, unfortunately, also increases paging traffic. Efficient paging algorithms may generate relatively less paging traffic such that larger LA's may become plausible. Depending on the call-arrival rate to the cell, boundary crossing rate, optimum size of LA, and paging technique used, the overall cost could vary substantially. The paging techniques considered in this paper are simultaneous paging and sequential paging. The two schemes are studied in detail in order to understand the problems associated with location management in the PCS environment. In the authors' opinion, this paper provides, for the first time, a simple yet powerful analytical framework which can be used to analyze “intelligent” paging schemes as well as simultaneous and sequential paging     

小区分层依概率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".     

A Novel Location Tracking Scheme for Reducing Location Updating Traffic in a Personal Communication System

How to reduce location updating traffic is a critical issue for tracking the current locations of users in a personal communication system. Traditional location management approaches usually bring about network overload or bottleneck of the HLR when a mobile user moves back and forth between adjacent location areas. So far, many works have focused on this research topic to solve the location updating rate or the location updating cost. In this paper, we shall employ both concepts of time stamp and virtual overlapping to propose a newly developed scheme for reducing both the location updating rate and the location updating cost. From the simulated results, our scheme can significantly reduce the location updating traffic.     

GSM网位置更新成功率低的案例分析

首先对移动网位置更新知识进行了介绍,然后根据A接口的信令消息对失败原因进行了分析,并有针对性地对MSC参数进行了调整,解决了位置更新成功率低的问题。     

A Combination of Optimal Partitioning and Location Prediction to Assist Paging in Mobile Cellular Networks

The correlated both in space and time user mobility behavior can aid significantly in the localization of a moving terminal in the network coverage area. However, there is always some uncertainty in mobile user position and a network-wide search cannot be done. Therefore, a predictive paging scheme must always be combined with a location update strategy and a compatible algorithm to conduct the search. In this paper, we introduce a new strategy that combines an optimal partitioning of the location area (LA) with a model to predict user movements, based on the additional information of the cell where the last interaction between the network and the terminal took place. We study the performance of the strategy under delay bounds and different mobility and call arrival characteristics. It is found that the new scheme further minimizes signaling costs and enhances previous sequential paging algorithms.     

Reducing overhead in movement based dynamic location management scheme for cellular networks

One of the key issues in cellular mobile communication is to find the current location of mobile terminal (MT) to deliver the services, which is called location management (LM). Much research has been done on dynamic LM that reduced the LM cost up to a large extent. In movement based dynamic LM scheme, the location area is defined in the form of ring of cells for individual user. Whenever an MT visits a cell outside of its current location area (LA), it triggers location update (LU). For this purpose, network must inform the mobile terminal about ID of all the cells present in its current location area. In this paper, a simple way of cell-ID assignment is proposed under which, network sends only the ID of center cell of LA ring to MT and then MT can compute IDs of all other cells in its location area. This saves a significant amount of wireless bandwidth by minimizing the signaling traffic at VLR level and thus reduces the mobility management overhead.     

Local anchor scheme for reducing signaling costs in personalcommunications networks

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