Performance Enhancement of Fast Handover for MIPv6 by Reducing Out-of-Sequence Packets

FMIPv6 can reduce packet loss using a tunnel-based handover mechanism which relies on L2 triggers, such as transmitting a packet from a previous access router (PAR) to a new access router (NAR). However, this mechanism may result in decreasing the performance of TCP due to out-of-sequence packets arriving between the tunneled packets from the Home Agent and PAR, and the directly transmitted packets from the correspondent node (CN). In this paper, we propose a new scheme called EF-MIPv6 that uses a modified snoop protocol to prevent the packet reordering problem. This new scheme can prevent sequence reordering of data packets and improve the performance of TCP using enhanced fast binding update (EF-BU). This approach requires modification of the TCP header to execute the last packet expression from the PAR, include a new polling data packet, and use the modified access point system. Simulation results demonstrate that managing the packet sequence in our proposed scheme greatly increases the overall TCP performance in a Mobile IPv6 and FMIPv6 networks.

A Low Latency Handoff Algorithm for Voice over IP Traffics in the Next Generation Packet-Based Cellular Networks: Cellular Mobile IPv6

In the mobile communication environments, Mobile IP is defined to provide users roaming everywhere and transmit information freely. It integrates communication and network systems into Internet. The Mobile IPv6 concepts are similar to Mobile IP, and some new functions of IPv6 bring new features and schemes for mobility support. Two major problems in mobile environments are packet loss and handoff. To solve those problems, a mobile management scheme – the cellular mobile IPv6 (CMIv6) is proposed. Our approach isbased on the Internet Protocol version 6 and is compatible with the Mobile IPv6 standard. Besides, it also combines with the cellular technologies which is an inevitable architecture for the future Personal Communication Service system (PCS). In this paper, {Cellular Mobile IPv6 (CMIv6)}, a new solutionmigrated from Mobile IPv6, is proposed for mobile nodes moving among small wireless cells at high speed. This is important for future mobile communication trends. CMIv6 can solve the problems of communication break off within smaller cellular coverage during high-speed movement when packet-switched data or the real-time voice messages are transmitted. Voice over IP (VoIP) packets were chosen to verify this system. The G.723.1 Codec scheme was selected because it has better jitter resistance than GSM and G729 in a packet-based cellular network. Simulation results using OPNET show smooth and non-breaking handoffs during high-speed movement.     

Fast Handover Mechanism for Seamless Multicasting Services in Mobile IPv6 Wireless Networks

This paper proposes a fast handover mechanism to provide a seamless multicast service for Mobile IPv6 hosts. With the proposed Fast handover based on a Mobile IP-Multi casting (FMIP-M) protocol, the selection of a new multicast service method, service preparation, and initialization procedures are all performed during the fast handover period, thereby enabling a reliable and efficient multicast service. When mobile hosts move to other networks, they can encounter data loss, out-of-synch problems for multicast data, and multicast service exchange latency. Therefore, the proposed FMIP-M allows the new access router to select a suitable multicast service method according to the multicast service-related network conditions and supports a reliable multicast transmission by compensating for data losses from the previous access router. An analysis is conducted of the overheads associated with a fast multicast handover, including the signaling cost and multicast packet-forwarding cost, where the costs are formulated based on timing diagrams, and compared with a fast handover using Mobile IPv6. The performance analysis and numerical results confirm that the proposed FMIP-M provides a fast multicast handover and reliable service with a relatively small signaling cost and packet-delivery cost.     

IPv6快速路由查找算法分析与研究

分析了IPv6路由结构的特点,介绍了IPv6中的各种路由查找技术,提出了基于聚集位向量的快速路由查找算法,并对该算法和常用二分查找算法的性能进行了分析比较,实验结果表明该算法较好地提高了查找速度,减少了对内存的消耗.     

NGI之路:IPv6-CJ试验网组播桥实验与分析

描述了IPv6-CJ试验网存在的IPv6组播互操作问题,详细描述了在IPv6-CJ试验网上进行的IPv6组播互操作实验,以及如何建立IPv4/IPv6组播桥和配置IPv6路由器,以解决不同厂商路由器之间的IPv6组播通信问题,并对实验中遇到的问题和解决方法进行了分析.通过一台FreeBSD主机建立的组播桥解决了不同品牌IPv6路由器之间的组播互操作问题,使得位于北京的日立路由器、位于上海的富士通路由器和位于广州的NEC路由器之间可以通畅地进行IPv6组播通信.鉴于NGI网络很可能由多个品牌的IPv6路由器共同组成,因此本实验所获得的经验对NGI环境下的IPv6组播通信有着重要的参考意义.同时展示了三种IPv6路由器的不同命令风格和配置界面.     

Network Layer Access Control for Context-Aware IPv6 Applications

As part of the Lancaster GUIDE II project, we have developed a novel wireless access point protocol designed to support the development of next generation mobile context-aware applications in our local environs. Once deployed, this architecture will allow ordinary citizens secure, accountable and convenient access to a set of tailored applications including location, multimedia and context based services, and the public Internet. Our architecture utilises packet marking and network level packet filtering techniques within a modified Mobile IPv6 protocol stack to perform access control over a range of wireless network technologies. In this paper, we describe the rationale for, and components of, our architecture and contrast our approach with other state-of-the-art systems. The paper also contains details of our current implementation work, including preliminary performance measurements.     

Hierarchical mobile network binding scheme for route optimization in NEMO

Recently, there has been a great deal of research on network mobility management that can support the movement of a mobile network consisting of several mobile nodes. The IETF NEMO working group proposed a basic support protocol, which defines methodology for supporting network mobility by using bi-directional tunneling between the home agent and the mobile router. This protocol, however, suffers from the ‘pinball routing problem,’ and most of the research attempts to solve this problem still have limitations in the efficiency of intra-domain communication. Moreover, these methods require additional binding procedures in case of the root mobile router handover. In this paper, we propose new route optimization methodology that can remedy these limitations by using asymmetric tunneling and a hierarchical local binding mechanism, which can provide faster signaling and data transmission. It can also be easily extended to support micro-mobility without the need for additional extensions. The performance is evaluated by simulation which can show the efficiency of the approach, compared with several previous route optimization methods.     

Performance Analysis of a Header Compression Protocol: The ROHC Unidirectional Mode

The performance of IPv6 in the radio link can be improved using header compression algorithms. The 3GPP (3rd Generation Partnership Project) consortium in its technical specification has adopted the ROHC (RObust Header Compression) protocol of the IETF (Internet Engineering Task Force) standard track for real-time applications using RTP/UDP/IPv6 and UDP/IPv6. This paper presents the analysis of the proposed standard ROHC deployed in an UMTS radio link and discusses different schemes to increase compression performance. The results are based on our IPv6 implementation of the ROHC header compression algorithm and on a simple and accurate analytical model used to evaluate the packet loss probability.     

A fast seamless handover scheme and its CDT optimization for ping-pong type of movement

In mobile IPv6 networks, the ping-pong type of movement brings about frequent handovers and thus increases signaling burden. This letter proposes a fast seamless handover scheme where the access router keeps the mobile node＇s old reservation till the offline Count Down Timer （CDT） expires in order to reduce handover signaling and delay while the mobile node returns in a very short period of time. Based upon a poisson mobility model, an simple expression for CDT optimization is given out for the scheme to achieve the best cost performance of resource reservation.     

基于IPv6、NAT-PT与L2TP隧道的公司网络拓展

IPv6与IPv4共存有多种机制,但很多公司企业由于历史、经济原因以及目前的实际运营情况,不能对原有网络系统进行升级和改造。针对这种现况,利用原有网络,增加基于IPv6新子网,并基于L2TP隧道传输IPv6数据包以实现IPv6子网之间的通信。在不升级IPv4网条件下,利用NAT-PT机制完成原IPv4子网与新IPv6子网之间的互通。     

无线传感器网络与IPv6网络的互联方式研究

如何实现无线传感器网络(WSN)与TCP/IP(v6)网络的互联是当前的热点研究方向之一,全IP互联方式是当前讨论最为激烈的焦点问题.在WSN内部是否需要采用IPv6,是WSN协议设计需要回答的一个基本问题,其结论将在很大程度上影响今后WSN协议发展的基本走向.本文首先介绍了WSN与IPv6网络互联的各种方式,然后重点对采用全IP互联方式的必要性以及需要解决的关键技术问题进行了分析探讨,分析结果表明:全IP方式是实现WSN与IPv6网络互联的一种非常重要的思路,值得进行深入研究.     

TSB:一种多阶段IPv6路由表查找算法

充分分析IPv6地址结构、IPv6地址分配策略和IPv6骨干网路由表的特点后,将二叉树、段表和路由桶技术相结合,提出一种多阶段IPv6路由表查找算法.和已有算法相比,提出的算法查找速度快、占用内存少、扩展性好、支持增量更新.实验结果表明算法的软件参考实现在装有P4 2.4GHz CPU,512M DDR333 内存和Linux 操作系统的普通PC 机上的查找能力可以到达16MPPS(Million Packet per Second),这可以满足10Gbps 80 字节IPv6最小包的线速转发.对于当前IPv6骨干网BGP 路由表,算法的参考实现只占用几百K 字节的内存.     

SIPv6 analyzer: an analysis tool for 3GPP IMS services

The 3rd Generation Partnership Project (3GPP) defines IP Multimedia Core Network Subsystem (IMS) to support IP‐based multimedia services. IMS utilizes protocols such as IP version 6 (IPv6), Session Initiation Protocol (SIP), and Real‐time Transport Protocol (RTP) to deliver the multimedia content. This paper proposes an analysis tool referred to as SIPv6 Analyzer to investigate the IMS‐related protocols during IMS service deployment. The SIPv6 Analyzer not only dissects the protocol headers but also provides user‐friendly functions such as message flow generation and audio/video replay for IPv6, SIP, and RTP. We describe the design of the SIPv6 Analyzer and use examples to illustrate how it works. Copyright © 2006 John Wiley & Sons, Ltd.     

VDNROM: A novel four-physical-bits/cell vertical channel dual-nitride-trapping-layers ROM for high density flash memory applications

A novel vertical channel dual-nitride-trapping-layer ROM (VDNROM) flash memory with oxide–nitride–oxide–nitride–oxide (ONONO) dielectrics stack is proposed and experimentally demonstrated. Compared with the conventional planar NROM cell, since the cell area of the proposed vertical structure is independent of the gate length, the VDNROM structure can relax the limitation of the gate length scaling, and can have high capability of cell area shrinking. The fabrication process of this VDNROM device is basically compatible with planar CMOS technology. The VDNROM cell can be programmed and erased by the hot carrier injection to the localized trapping dual-nitride layers, so it can achieve a four-physical-bits storage capability each cell. The reliability behaviors including the cycling endurance and the bake retention at 150 °C have also been investigated and show the acceptable characteristics. The experiment results verify the VDNROM cell as a good candidate for high density applications.     

A solvent-free lift-off method for realizing vertical organic transistors with low leakage current and high ON/OFF ratio

A solvent-free lift-off method has been introduced to fabricate the aluminum nano-hole array with diameter down to 80 nm as the base electrode for a vertical organic transistor. The imprinted vertical organic transistor exhibited base leakage current density as low as 5 × 10⁻⁵ mA/cm² and high ON/OFF current ratio as high as 10⁵.     

Holography and plasma oxidation for uniform nanoscale two dimensional channel formation of vertical organic field-effect transistors with suppressed gate leakage current

Vertical organic field-effect transistors (VOFETs) with nanoscale channel openings have been fabricated using pentacene as an active layer material. To achieve uniform nanoscale two-dimensional channel openings, a laser holography lithography has been introduced. Uniformly distributed and well-aligned holes with 250 nm diameter were successfully obtained with the laser holography lithography. VOFET devices with these channel openings have shown high on/off ratio of about 10³ without any further treatment. Gate leakage current was also decreased with an additional insulating layer generated on the gate electrode sidewall via plasma oxidation.     

IPv6 for Future Wireless Networks

The functionalities of the next generation Internet protocol, IPv6, havebecome increasingly interesting due to the current merging of the traditionalcellular mobile communications and the traditional data-communications intothe future wireless systems, as e.g., UMTS. IPv6 provides several enhancedfunctionalities requested for the future mobile systems. In this article thelargest advantages in relation to mobile systems are presented. Variousaspects of introducing IP throughout the entire mobile network (core, accessand termainals) are also presented along with an illustration of the abilitiesof the future wireless network.     

Dynamic and hierarchical IPv6 address configuration for a mobile ad hoc network

The paper proposes a dynamic and hierarchical IPv6 address configuration scheme for a mobile ad hoc network (MANET). The scheme proposes the hierarchical architecture and combines the distributed and centralized address configuration approaches. In the architecture, a central node assigns IPv6 addresses for cluster heads that are distributed around a MANET, and distributed cluster heads assign IPv6 addresses for cluster members. The generation algorithm of a cluster is proposed, and it uses the number of potential cluster members as a measurement unit and minimizes the number of cluster heads. Therefore, the address configuration cost for cluster heads is reduced. A central node/cluster head uses the unicast communication mode to achieve the real‐time address recovery in order to ensure that it has enough address resources for assignment. The paper also proposes the low‐cost MANET merging/partitioning algorithm that guarantees that no address collision happens during the MANET merging/partitioning process. This paper analyzes the performance parameters of the proposed scheme, including the address configuration cost, the address configuration delay, and the number of MANET merging. The analytical results show that the proposed scheme effectively reduces the address configuration cost, shortens the address configuration delay, and decreases the number of MANET merging. Copyright © 2013 John Wiley & Sons, Ltd.     

Sub-100 nm ALD-assisted nanoimprint lithography for realizing vertical organic transistors with high ON/OFF ratio and high output current

We introduced a conformal atomic-layer-deposited aluminum oxide layer to cover the imprint mold to reduce the feature size and to strengthen the mold durability. A nano-hole array pattern with diameter down to 85 nm was successfully transferred to sample substrate to fabricate a vertical organic transistor. The Imprint vertical organic transistor exhibited high output current density as 4.35 cm²/V s and high ON/OFF current ratio as 11,000 at a low operation voltage as 1.5 V.     

Mobile city applications for Brussels citizens: Smart City trends,challenges and a reality check

This article combines quantitative and qualitative methods to take a first look at the app economy and mobile services landscape in the City and Region of Brussels, capital of Belgium and Europe. By scraping the iTunes App Store and Google Play market places we get a view on platform distribution, pricing, public vs. commercial, adoption, appreciation and popular categories of Brussels apps aimed at citizens, as well as a view on the app economy in the city. This data is then complemented by qualitative expert interviews with actors in the field, such as cities, interest groups and developers. In the context of the current debate surrounding what constitutes a Smart City and the importance of smartphones and mobile in this area, we perform a reality check, using Brussels as a case. We find that the laggard position Brussels is currently in could be an opportunity to leapfrog in the field of mobile services, but that a focused vision and clear mobile strategy, while thinking of the city as a local innovation platform built on open data, is quintessential to achieving this.