移动IP网络中移动性管理的指针优化

移动性管理是移动通信技术中的一个关键问题,对于移动通信网络的性能具有决定性的作用。该文提出了一种在移动IP环境下的基于分布式注册服务器的指针优化策略,通过在路由器间建立并调整指针,跟踪移动节点的位置变化,使位置更新过程局部化,仅当连接请求到达时,才进行可能的对移动数据库的更新,从而减少网络中移动性管理的开销。该文中同时给出了指针优化策略的两种实现方案。     

PMIPv6域中基于扩展信令的网络移动性优化方法

针对PMIPv6域中支持网络移动性存在的总开销过大问题,提出一种基于扩展信令的网络移动性优化方法。利用扩展的信令消息,整合位置更新和转发数据过程,均衡降低了系统的位置开销和隧道开销。性能分析表明,相比传统机制,本方案有效降低了系统总开销。     

医疗云中高效安全的数据共享方案研究

随着云计算的快速发展,个人电子病历记录（Personal Health Record,PHR）作为一种新兴的健康信息交换模式,已经成为研究与应用领域的热点话题。为了实现医疗云中安全高效的数据共享,提出了可撤销的基于CP-ABE的数据共享方案。在该方案中,医疗用户被划分为个人区域（PSD）和公共区域（PUD）。在PSD中,采用改进的聚合加密（IKAE）和改进的属性签名方案分别来实现读和写访问权限。对于PUD的医疗用户来说,使用可撤销的外包加解密方案,在很大程度上减少了PHR用户的开销。该方案还可以实现及时的用户和属性撤销,并且引入多授权机构来降低密钥管理的复杂度。最后通过性能分析证明了该方案的高效性和安全性。     

面向边缘计算的属性加密方案

传统云环境下的属性加密方案在判定用户访问权限时通常仅依据年龄和职业等用户常规属性,而忽视了访问时间和位置的约束问题。为较好满足边缘计算的实时性和移动性需求,提出一种支持时间与位置约束的多授权外包属性加密方案。通过将时间域与位置域信息同时引入属性加密过程,实现更细粒度的访问控制。采用多授权机构共同管理属性信息,解决单授权机构的性能瓶颈问题,满足用户跨域访问需求。针对边缘计算中移动终端资源受限问题,将大部分解密计算外包至边缘节点,减轻移动终端设备负担。分析结果表明,在边缘计算环境下,该方案以较低的计算和存储开销实现了具有时间和位置约束的访问控制,并且可有效保障用户数据安全。     

基于边缘计算的新型任务卸载与资源分配策略

针对移动边缘计算（MEC）中密集型任务卸载时，系统开销较大和延时抖动明显的问题，提出一种新型资源分配策略。首先在系统时延约束下，分析了系统任务执行开销与终端设备的资源分配机制；其次建立了基于计算卸载和任务分配的联合凸优化目标；最后采用拉格朗日乘子法进行迭代更新得到最优解。仿真结果表明，所提任务卸载与资源分配方案在保证用户服务质量的同时降低了任务执行开销，并有效提升了MEC系统性能。     

基于动态信用等级的密文访问控制方案

针对属性基加密机制（ABE）在移动互联网环境中计算开销较大且不够灵活的问题,提出了一种基于动态信用等级的密文策略属性基加密（CP-ABE）方案。首先,该方案引入"信用等级"属性用来标识用户的"信用"并以此划分用户等级,高"信用等级"用户仅需常数级的计算开销即可解密;同时,中央授权中心（CA）在设定的时间阈值评估用户的访问行为并动态更新用户的"信用等级",更新算法避免私钥的完全重新生成。理论分析和实验结果表明,随着高"信用等级"用户占比升高,所提方案系统总时间开销不断减少,最终达到稳定并优于传统方案。该方案在保证安全性的前提下,总体上提高了移动互联网环境中访问控制的效率。     

一个新型嵌入式移动性支持方案

IETF的移动IP协议存在代理的部署少、三角路由增加网络开销以及操作系统的支持有限等问题，未得到广泛应用。该文针对移动IP协议的不足，提出了一个新型的嵌入式移动性支持方案。该方案引入嵌入式移动代理和地址索引服务器来实现移动管理，最大限度地减小了移动管理对网络基础设施的依赖，为单个或成组移动设备提供了透明的移动服务。仿真实验表明，该移动性方案开销小、效率高，易于实现。     

分层移动IP网络的自适应移动性管理

移动IP(mobile IP,MIP)使主机在移动过程中不需改变IP地址便可连续访问Internet,其主要缺点是主机在移动过程中需要频繁地进行绑定更新,产生的信令开销较大。为降低移动IPv6的信令开销,IETF(Internet engineering task force)提出了分层移动IPv6(hierarchical mobile IPv6,HMIPv6)协议。基于HMIPv6,提出了一种自适应的分层移动性管理方案。这种方案采用模糊逻辑,根据移动主机的移动次数及移动性管理代价,动态选取MAP(mobility anchor point)并调整MAP区域所管辖的接入路由器个数。仿真分析表明,所提出的方案的代价优于固定MAP区域的移动性管理方案。     

移动高速数据传输与HSDPA最新进展

文中基于由IS-95和GSM向第三代移动通信（IMT-2000）的两种过渡方案，讨论了用于实现移动高速数据传输的各种增强技术，对其应用背景和性能进行了分析比较。结合最新3GPP提案，还对实现高速下行分组接入（HSDPA）的各项关键技术进行了分析，探讨了未来移动通信高速数据传输的技术重点和研究方向。     

一种结合移动IP和SIP实现IP网络移动性管理的优化方案

本文提出了一种网络层和应用层相结合实现IP网络移动性管理的新方案。移动终端的固定IP地址作为数据传输的地址；当终端和所在子网使用的是不同的IP子网前缀时，使用转交地址形成隧道对数据进行收发；SIP地址作为用户帐号，是在应用层使用服务的地址，通过把它动态地和移动终端绑定来使用终端。方案中还提出了以SIP地址域的分级方式进行组织管理的用户数据库系统，定义了为子网中移动终端服务的区域代理。新方案能够对现役设备和协议改动较小的程度下，为下一代网络提供移动性管理。     

Performance analysis of a fixed local anchor scheme for supporting UPT services

Intelligent Networks (INs) are well suited for implementing Universal Personal Telecommunication (UPT) services. For efficient planning of IN accommodating UPT services, it is essential to analyze the effect of UPT user personal mobility. In this paper, an IN architecture with a fixed local anchor (FLA) is proposed for supporting UPT services. The performance of the proposed IN architecture is compared with an IN architecture based on IS-41 with consideration of UPT user personal mobility in terms of call delivery cost and location update cost. The performance of the proposed IN depends on the characteristics of UPT user mobility and incall deregistration. The proposed IN yields better performance than an IN based on IS-41 as UPT user mobility decreases and the probability of explicit incall deregistration increases.     

Evaluating location management schemes for third generation mobile networks

Several strategies have been proposed recently to improve the performance of the IS-41 location management scheme. A forwarding pointers' strategy and a built-in memory strategy are proposed to reduce the signaling cost for location update and improve the IS-41 location update procedure. In this paper, we present a performance analysis of each strategy in an arbitrary time interval. In this analysis, users are classified by their call to mobility ratio which is defined as the call arrival rate divided by the mobility rate. We evaluate each of these strategies using this call to mobility ratio in order to come up with a set of recommendations that determine when each strategy is beneficial and for which class of users. We provide also a simplified analysis of the database loads generated by each strategy.     

On signaling performance bounds of location management in Next Generation Wireless Networks

Next Generation Wireless Networks (NGWN) are proposed to achieve the goal of ubiquitous broadband networking by utilizing multiple wireless access subnetworks serving overlapping areas. Location management schemes play a very important role in NGWN since mobile users roam in coverage areas of these subnetworks simultaneously. The performance of location management schemes directly affect the overall performance of NGWN at large. In this paper, signaling performance bounds achievable by a location management scheme in the wireless portion of NGWN are presented. Assuming complete knowledge about user mobility, call arrival patterns, detailed maps of subnetworks coverage areas, and other NGWN parameters, equations for signaling performance achievable by an idealized location management scheme over the wireless interface has been derived. The performance bounds presented in this paper serve as an upper bound for the performance of any other location management scheme designed for NGWN. These bounds are intended to serve as a benchmark to determine how well a proposed location management scheme operates in NGWN and will help to determine how much room for improvement exists.     

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.     

A location management scheme to support non-geographic phone numbers in personal communications services

Subscribers in future personal communications system (PCS) networks will be assigned portable personal numbers, or non-geographic phone numbers (NGPNs), which will not indicate the service provider and home location register (HLR) database which serves the subscribers. A location management scheme for future PCSs based on a three-level hierarchical database architecture, which consists of a directory register (DR), regional location registers (RLRs), and visitor location registers (VLRs), is proposed under the assumption of local property in both called party distribution and user mobility. In addition to inherently providing non-geographic phone numbers, the proposed scheme reduces the number of database access attempts and the signaling cost for location management.     

An efficient metric-based (EM-B) location management scheme for wireless cellular networks

In the current era, the wireless cellular network is gaining much attention in the network mobility for qualitative service. Towards enhancing the QoS and narrowing the dilemma of network management (location management) an efficient metric-based location management technique is introduced in this paper to capture the current location of mobile subscribers. The attributes of this technique are based on metrics calculation and location management message routing path determination. First, the current mobile switching center will calculate the shortest metric-based path between current and master (previous) location of mobile terminals (user), thereafter it performs the location management procedure through the optimal suggested path by the mobile switching center. This proposed technique will reduce the signaling cost, registration delay, call setup delay, network overheads and total location management cost. The proposed analytical model checks the scalability and effectiveness of proposed system over certain attributes and a comparison is made with the existing available techniques.     

基于用户移动性的认知网络频谱移动管理的数学建模

针对IEEE802.22的无线地域网（WARN）,首次,建立了考虑用户移动性的认知无线网络频谱移动管理的数学模型,更加真实地描述了认知无线网络中的用户行为,利用马尔科夫模型对提出的系统进行了仿真与分析.在此基础上,为了改善系统性能,还提出了带有切换保护信道的马尔科夫模型.     

A General Probability Formula of the Number of Location Areas Boundaries Crossed by a Mobile Between Two Successive Call Arrivals

Mobility management is a challenging topic in mobile computing environment. Studying the situation of mobiles crossing the boundaries of location areas is significant for evaluating the costs and performances of various location management strategies. Hitherto, several formulae were derived to describe the probability of the number of location areas' boundaries crossed by a mobile. Some of them were widely used in analyzing the costs and performances of mobility management strategies. Utilizing the density evolution method of vector Markov processes, we propose a general probability formula of the number of location areas' boundaries crossed by a mobile between two successive calls. Fortunately, several widely-used formulae are special cases of the proposed formula.     

Dynamic application placement in the Mobile Cloud Network

To meet the challenges of consistent performance, low communication latency, and a high degree of user mobility, cloud and Telecom infrastructure vendors and operators foresee a Mobile Cloud Network that incorporates public cloud infrastructures with cloud augmented Telecom nodes in forthcoming mobile access networks. A Mobile Cloud Network is composed of distributed cost- and capacity-heterogeneous resources that host applications that in turn are subject to a spatially and quantitatively rapidly changing demand. Such an infrastructure requires a holistic management approach that ensures that the resident applications’ performance requirements are met while sustainably supported by the underlying infrastructure. The contribution of this paper is three-fold. Firstly, this paper contributes with a model that captures the cost- and capacity-heterogeneity of a Mobile Cloud Network infrastructure. The model bridges the Mobile Edge Computing and Distributed Cloud paradigms by modelling multiple tiers of resources across the network and serves not just mobile devices but any client beyond and within the network. A set of resource management challenges is presented based on this model. Secondly, an algorithm that holistically and optimally solves these challenges is proposed. The algorithm is formulated as an application placement method that incorporates aspects of network link capacity, desired user latency and user mobility, as well as data centre resource utilisation and server provisioning costs. Thirdly, to address scalability, a tractable locally optimal algorithm is presented. The evaluation demonstrates that the placement algorithm significantly improves latency, resource utilisation skewness while minimising the operational cost of the system. Additionally, the proposed model and evaluation method demonstrate the viability of dynamic resource management of the Mobile Cloud Network and the need for accommodating rapidly mobile demand in a holistic manner.     

Performance analysis of DNS-assisted global mobility management scheme in cost-optimized proxy mobile IPv6 Networks

Proxy Mobile IPv6 (PMIPv6) is designed to provide a network-based localized mobility management protocol, but it does not handle the global mobility of hosts. In this paper, we propose a location management scheme based on Domain Name System (DNS) for PMIPv6. In this proposed scheme, DNS as a location manager provides PMIPv6 for global mobility. In addition, a paging extension scheme is introduced to PMIPv6 in order to support large numbers of mobile terminals and enhance network scalability. To evaluate the proposed location management scheme, we establish an analytical model, also formulate the location update and the paging cost, and analyse the influence of the different factors on the total signalling cost. The performance results show how the total signal cost changes under various parameters.