Moving toward seamless mobility: state of the art and emerging aspects in standardization bodies

The challenge to provide seamless mobility in the near future emerges as a key topic in various standardization bodies. This includes first of all the support of seamless handover between homogeneous networks. Distinct technologies—such as IEEE 802.11WLANs (Wi-Fi) and IEEE 802.16 MANs WiMAX—have recently augmented such support to existing standards to enable seamless homogeneous handover. Cellular networks, in contrast, already included this inherently from the start. Currently considerable effort goes into coupling of different radio access technologies. Therefore, the second key topic in standardization is seamless heterogeneous handovers. IEEE, IETF, as well as 3GPP consider different approaches toward architectures and protocols enabling seamless mobility management. In this work, we discuss recent and on-going standardization activities within IEEE, IETF, and 3GPP toward seamless homogeneous as well as heterogeneous mobility support.     

BSS transition optimizations and analysis for VoIP over WLAN

Voice over IP (VoIP) is emerging as a critical application for IEEE 802.11 Wireless Local Area Networks (WLANs). However, the limited range of the IEEE 802.11 radio forces frequent transitions from one access point to another. Moreover, the introduction of IEEE 802.11i security and IEEE 802.11e Quality of Service (QoS) has increased the average transition time from ms to seconds, leaving mobile users with the unenviable dilemma of choosing good security and QoS while sacrificing real-time performance, or gaining acceptable real-time performance at the expense of security and QoS. Thus, optimizations to device transitioning that will provide an acceptable balance of latency, security, and QoS are needed to enable VoIP. This paper analyzes WLANs MAC layer transition procedure and optimizations being considered by IEEE 802.11 Working Group to improve transition times while retaining good security and QoS. The transition time improvements proposed in this paper are achieved through discovery phase optimizations and transition phase optimizations. The selective scanning and smart AP selection algorithms are designed to optimize the discovery phase to enable the mobile device to better exploit its ambient radio resource environment. The transition phase optimization seeks to accelerate device transition without compromising security. The paper then identifies security flaws in the current design and proposes simple corrections. Finally, experiment results for transition optimization are explained that demonstrate a significant increase in transition efficiency.     

LTE自组织网络MRO功能浅析

随着LTE网络规模的不断扩大,网络中存在的异常切换次数也逐渐增多。本文主要针对SON中的MRO功能及其实现方法进行了详尽的论述,并通过现网验证,优化后网络KPI指标有所提升,异常切换比例下降。     

QoS guaranteed integration methodology for a WLAN-WiMAX heterogeneous network

Wireless technologies which serve multimedia applications have to guarantee the Quality of Service (QoS) demands along with seamless connectivity. The complexity in attaining such demands increases if the network is heterogeneous in nature. This paper proposes a QoS guaranteed integration methodology for a heterogeneous wireless local area network (WLAN) - worldwide interoperability for microwave access (WiMAX) network. An integrated protocol stack for the mobile terminal which could work in a WLAN-WiMAX heterogeneous network is proposed. The proposed integrated protocol stack, a blend of two modules namely generic virtual link layer (GVLL) and media independent handover (MIH) is placed above the media access control (MAC) layer which includes both WLAN and WiMAX MAC. The impact of GVLL in guaranteeing the QoS on QoS deterioration and the impact of MIH in attaining seamless handover are analyzed and the results are presented.     

Performance Evaluation of Fast Handover in Mobile IPv6 Based on Link-Layer Information

Handover latency is the primary cause of packet loss resulting in performance degradation of standard Mobile IPv6. Mobile IPv6 with fast Handover enables a Mobile Node (MN) to quickly detect at the IP layer that it has moved to a new subnet by receiving link-related information from the link-layer; furthermore it gathers anticipative information about the new Access Point (AP) and the associated subnet prefix when the MN is still connected to the previous Corresponding Node (CN).This paper proposes an enhancement to Fast Mobile IPv6 handover (FMIPv6), based on link layer information, we also present performance evaluations in terms of the packet loss and handover latency using evaluation models.     

LTE/LTE-A网络中基于盲签名的具有条件隐私保护的切换认证协议

LTE/LTE-A网络的设计为移动应用提供了较低的切换时延,但LTE标准中的切换过程仍存在一定的复杂性和安全缺陷。为了解决LTE标准和传统切换认证协议的缺陷,设计了一个基于盲签名的切换认证协议。在注册接入阶段通过盲签名建立用于切换过程的认证密钥,在切换过程中通过假名的可变换性和在特定条件下变为真名的可逆性来实现 匿名性、不可跟踪性和条件隐私保护。理论分析和仿真结果表明,相较于LTE标准和其他切换认证协议,提出的协议在满足更多安全属性的同时,有更好的性能。     

基于PMIPv6的移动网络快速切换方案

针对移动网络应用在代理移动IPv6域中存在切换时延大并且缺乏对域间切换有效支持的问题,提出一种基于PMIPv6的移动网络快速切换方案。该方案通过结合二层机制在移动节点完成注册之前进行预切换,提前获取节点信息,建立缓存数据转发隧道,利用扩展的信令消息进行不同域间实体的交互,实现对域间切换的有效支持,并引入双重缓存机制,避免了切换过程中的分组丢失。分析和仿真结果表明,本方案相对传统机制,降低了系统切换时延。     

无线ATM/IPOA的移动性支持

无线 ATM (WATM)能够对终端和无线接入连接提供移动性支持。文中论述了无线 ATM的网络结构 ,无线ATM的位置管理、越区切换 ,并提出 IPOA (IP Over ATM)支持移动性的两种方法。     

QoS handover management for multimedia LEO satellite networks

Low earth orbit (LEO) satellite systems gained considerable interest towards the end of the previous decade by virtue of some of the appealing features that are endowed with, such as low propagation delay and the ability to communicate with handheld terminals. However, after the limited commercial success of the first networks of this kind, future satellite networks are now conceived as complementary rather than competitive to terrestrial networks. In this paper, we focus on one of the most influential factors in system performance, that is, the handover of a call. First, we provide a succinct review of the handover strategies that have been proposed in the literature. Then we propose two different satellite handover techniques for broadband LEO satellite systems that capitalize upon the satellite diversity that a system may provide. The proposed schemes cater for multimedia traffic and are based on the queuing of handover requests. Moreover, a deallocation scheme is also proposed according to which capacity reservation requests are countermanded when the capacity that they strive to reserve is unlikely to be used. Simulation studies further document and confirm the positive characteristics of the proposed handover schemes.     

一种移动IPv6的切换优化方案

移动节点在两个不同子网之间移动时产生切换。移动节点的切换技术是保证实时业务服务质量的关键问题之一。目前比较经典的三种切换机制是快速移动IPv6、层次型移动IPv6和快速层次移动IPv6。在简单介绍了三种机制原理并分析了它们的不足后,提出了一种自适应移动IPv6切换时延优化方案。