仿真移动台越区漫游的Visual C++程序设计

在移动计算环境中,为了使移动台之间能够通信,系统需要确定移动台的当前位置,因而,当移动台越区———从一个位置区RA(RegistrationArea)漫游到另一个RA时,系统必须跟踪该移动台,对该移动台的位置进行管理。因此,对移动台的越区漫游规律,尤其是对移动台在K次越区漫游过程中所经过的不同的RA个数进行研究,对各种位置管理策略的性能与代价的评价来说,是一项具有现实意义的课题。该文给出八个方向越区漫游仿真算法及VisualC++(6.0)程序。     

蜂窝网络中依概率环状搜索移动性管理策略

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。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(越过位置区边界)，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，给出了不需要进行位置更新的、根据移动台访问位置区的概率进行环状搜索的位置管理策略(简称依概率环状策略)，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与依概率环状策略的费用进行了对比研究，得出在一定条件下，依概率环状策略的费用比基本策略小这一结论。     

蜂窝网络中移动台越区漫游仿真的Visual C+ +程序设计

对移动台的越区漫游规律，尤其是对移动台在越区漫游过程中所经过的不同的位置区个数进行研究，对各种位置管理策略的性能与代价的评价来说，具有现实意义。给出蜂窝网络中移动台六个方向越区漫游的仿真算法及Visual C (6．0)程序。     

个人通信业务网的越区切换管理

在无线个人通信系统中,当便携台在通话期间从一个基站BS覆盖区移动到另一个BS覆盖区时,需要进行越区切换,以保证通话的连续性。文中主要讨论越区切换管理、越区切换检测、信道分配和无线链路转接等问题。     

蜂窝网中基于位置预测的切换算法

为了满足未来移动网络蜂窝小、切换频繁、支持规模用户和多媒体应用的需求,对位置预测与越区切换进行深入分析,提出了基于位置预测的越区切换方案HDLP(Handover Decision based on Location Prediction),其基本思想是:(1)从移动用户的大量历史移动轨迹数据中挖掘频繁轨迹;(2)根据挖掘出的频繁轨迹集合生成运动规则;(3)将运动规则运用于判决蜂窝移动通信的越区切换中。对所提算法进行仿真的结果表明,与传统的切换方案相比较,本算法减少了不必要的越区切换次数,降低了错误切换率,提高了切换的准确率,进而在一定程度上降低了通信代价,提高了通信系统的容量以及QoS。     

移动通信网络中自适应的寻呼策略研究

移动通信网络中,位置管理用于跟踪移动台,有位置更新和寻呼两个基本操作。现行位置管理策略在查找移动台时对整个位置区进行同步寻呼,由于位置区由众多小区组成,而移动台只在其中一个小区,所以现行策略造成了网络资源的大量浪费。该文基于增强学习理论与方法,提出了自适应的多阶段智能寻呼策略,通过学习寻呼过程所获得的移动台位置信息,动态调整各阶段所寻呼组的小区,以降低寻呼费用。仿真实验结果表明,所提出的寻呼策略能较大地降低寻呼代价。     

基于改进遗传算法的蜂窝网络区域配置方法

提出一种新的基于遗传算法的蜂窝网络区域配置方法LAL_Coded,在目前GSM网络中使用的本地区域(LA)模式的基础上,用图的邻接表表示染色体,便于计算更新负荷以及将相邻的小区合并到同一LA中,采用只变异不交叉的方式避免了离散LA的产生,实验结果表明,用改进的遗传算法能快速得到最优区域配置,减少位置管理代价。     

基于移动的位置管理策略中最优寻呼研究

位置管理是个人通信网络的一个挑战性问题,用于跟踪移动台,有位置更新与寻呼两个基本操作.在一些知名的位置管理策略中,基于移动的位置管理策略(movement-based location management scheme)具有简单易行的特点:各移动台只需记住所越过的小区边界次数,一旦这个数超过事先定义的一个整数--移动门槛,就进行位置更新操作.在移动台的呼入符合泊松分布,移动台在各个小区的逗留时间符合指数分布的条件下,推导了基于移动的位置管理策略中移动台移动距离的概率分布及平均距离公式,并基于这些概率分布给出了最优顺序寻呼算法.最后,给出数值分析结果,以说明所给出的寻呼策略比其他已有策略更优.     

数字移动通信系统中越区切换的计算机模拟

切换技术是数字式蜂窝移动通信系统保证移动中用户通信质量的一个重要手段,本文在论述公用陆地移动网的越区切换功能基础上,提出了一种实现越区切换功能的计算机模拟方法。     

基于不规则蜂窝网络拓扑模型的位置管理研究

针对当前大多数位置管理策略的研究都是假设在同大小、同形状、同分布的蜂窝网络下实现的,提出了基于不规则分布的蜂窝网络结构(包括宏蜂窝、微蜂窝、微微蜂窝)的位置管理策略,通过将邻近的蜂窝重组并根据基站广播的蜂窝坐标CC(cell coordinates)计算当前所在蜂窝到当前位置区最后报告所在蜂窝的实际距离,并提出了基于实际距离和方向角的动态位置更新算法.最后,通过半马尔可夫决策过程推导两次寻呼到达间的位置管理总代价计算公式.数值分析结果表明,当移动用户运动特性很强时,选择个性化的扇形位置管理策略在位置更新与寻呼总代价上优于无个性的圆形位置区.     

带门槛的指针推进移动性管理策略研究

在移动通信系统中，移动性管理是一个具有挑战性的研究内容。目前各国正在使用的移动通信系统大多配置了数据库HLR（home location register)和VLR（visitor location register)。由于现行的位置管理策略需要频繁地更新HLR，系统的效率受到很大的限制。提出了“带门槛的指针推进”移动性管理策略，并与现行策略及普通的“指针推进策略”的代价进行对比，得出：只要选择适当的门槛，所提出策略的代价优于现行策略及普通的“指针推进策略”。     

Distributed cell-centric neighborhood-related location area planning for PCS networks

An intelligent location area planning (LAP) scheme should consider the frequent replannings of location areas (LAs) due to changes in user distribution and mobility patterns along with optimization of location management costs, including location updating and paging costs. Most schemes proposed in the literature are designed through centralized techniques, thus requiring more computing time to plan the LAs. Frequent replannings to accommodate environmental changes make the situation worse. As to the optimization of location management costs, most proposed schemes consider the inter-cell crossing rate as one of the key factors in determining the optimal partitions. In some cases, the inter-cell crossing rate may lead to an unsatisfactory outcome. Another problem is the ping-pong effect which is caused by the fixed borders between any two of LAs. In this paper, we propose a distributed cell-centric neighborhood-related LAP scheme in which each cell acts as the center of an LA and in which highly correlative neighboring cells are bundled into the LA if mobile terminals (MTs) remain within the LA long enough to reduce costs. Moreover, the ping-pong effect will be alleviated because MTs always locate at the center cell of an LA whenever a new location update is performed. Finally, the scheme can be implemented in a distributed manner so the computing time incurred by frequent replannings can be reduced. Simulation results show that our scheme indeed exhibits excellent results.     

一种基于移动的Ad Hoc网络分层位置管理方案

位置管理是AdHoc网络研究中新的热点问题。论文提出一种新颖的AdHoc网络位置管理策略,结合了SLALoM和HGRID两种位置管理策略的优点,根据节点的移动特性,引入更新阈值M来控制节点的位置更新,可以在一定程度上避免乒乓效应,大大减轻了系统控制信息的开销,在大型的AdHoc网络中有较好的应用和良好的可扩展性。     

The strategy of reducing the location update traffic using forwarding pointers in virtual layer architecture

The strategy of location updating is a critical issue for tracking the current locations of users in wireless networks. Especially when the mobile user is located near the boundaries of networks, the signaling traffic of the location updating will be excessively excited. In this paper, we shall propose a newly developed scheme for reducing both the location updating rate and location updating cost. The new scheme employs forwarding pointers in the virtual layer architecture. The forwarding pointer is a useful tool to get rid of the registrations at the HLR, and thus the location updating cost can be reduced. The virtual layer architecture is efficient in lowering the high updating rate of the current location when a user moves around the boundaries of the Location Area (LA). Our scheme can significantly reduce the location updating traffic.     

Location management in mobile network: A survey

Location management is an important area of mobile computing. Location management in mobile network deals with location registration and tracking of mobile terminals. The location registration process is called location update and the searching process is called paging. Various types of location management methods exist such as mobility based location management, data replication based location management, signal attenuation based location tracking, time, zone and distance based location update etc. In this paper, existing location management schemes are discussed and compared with respect to their cost consumption in terms of bytes. Finally the key issues are addressed in the context of location management for future generation mobile network.     

Efficient location area planning for cellular networks with hierarchical location databases

Location area planning (LAP) is an important issue in the design of high-performance PCS networks. It could have a serious impact on the total mobility management cost of mobile terminals. Most of the previous works either explored the LAP problem as a 0–1 linear programming problem or used adopted techniques, such as simulated annealing, taboo search, and genetic algorithms [IEEE Trans. Vehicular Technol. 49 (2000) 1678; Proceedings of 1999 Vehicular Technology Conference, vol. 4, 1999, pp. 2119–2123; IEEE Vehicular Technol. Conf. 3 (1996) 1835; Proceedings of IEEE INFOCOM'01, Anchorage, Alaska, April 2001; IEEE Trans. Vehicular Technol. 47 (1998) 987], to derive a solution to minimize the location update cost. In this paper, we model and resolve the LAP problem as a set-covering problem. The main advantage of this approach is that it can adapt to the changing mobility patterns of the mobile terminals. We propose the set-covering-based location area planning (SCBLP) algorithm to minimize the total number of location updates, in which the cost-benefit functions are defined based on the coupling and cohesive functions among neighboring cells. We then apply SCBLP to the location database system with a hierarchical structure to further improve the overall system performance in searching and updating the location databases. Extensive simulation experiments have been conducted, and the experimental results show that our proposed algorithms can significantly reduce the location management costs, compared to the greedy algorithm and the random algorithm.     

Cell-related location area planning for 4G PCS networks with variable-order Markov model

Location management is a critical issue in personal communication service (PCS) networks, tracking the location of user equipment (UE) with the goal of minimizing total signaling cost. Previous work can be classified into two categories: static and dynamic. Static schemes partition networks into fixed size LAs. However, these schemes are inefficient because they do not take UEs’ mobility and the call arrival rate into account. On the other hand, focusing on individual UEs, dynamic schemes have minimized the location management cost. However, they are difficult to implement because recording the individual information of numerous UEs and planning each of their LAs consume uncontrollable cost. Because of these reasons, we propose a cell-based scheme between static and dynamic schemes. Considering people usually stay in specific zones for long periods and the movement of UEs usually presents a strong moving direction in areas, this study presents a distributed algorithm by employing variable-order Markov models to find the mobility characteristic shared by UEs to plan better LAs with lower location management cost. When the order of Markov model is set to 1, our method is equal to a pure cell-centric LAP scheme; while the order of Markov model is high, it is more like a profile-based dynamic scheme. So, the setting of the order actually is a trade-off problem between the overall location management cost and the computing complexity. We present to retrieve a balance by using the expected location management cost and the number of total states of Markov models. In simulations, the origin–destination matrix (O–D matrix) from the Taipei Rapid Transit Corporation is used for representing the association between two cells. Simulation results demonstrate that the proposed scheme achieves good performance.     

基于位置服务器树的移动汇聚点的位置管理与路由协议

对于无线传感器网( WSN),提出了基于位置服务器树的移动汇聚点(Sink)的位置管理与路由协议LSTLMRP( Location Server Tree based Location Management and Routing Protocol).当汇聚点移动时,它只需对它的局部位置服务器树或整个位置服务器树,而不...