Mobile multi-user ATM platforms: architectures, design issues, andchallenges

Rapid growth in use of the Internet at and away from the workplace has spurred tremendous interest in the provision of anytime-anywhere network connectivity to mobile users. Commonly studied mobility scenarios involve users equipped with portable data terminals roaming around at slow to moderate speeds within a coverage area. Mobile IP and wireless ATM are examples of protocols designed for providing network connectivity to such mobiles in IP and ATM networks. A different application involving mobile multi-user platforms (MMUP) equipped with onboard private ATM networks is discussed in this article. Examples of such mobile platforms include airplanes, trains, and ships. The presence of an onboard network, multiple users, and potentially high speed of travel presents unique challenges in provision of internetwork connectivity to these MMUPs. Specific characteristics of MMUPs, architectural issues in design of the underlying cellular network, subnetwork mobility within ATM internetworks, location management of MMUPs, and multi-user connection handoffs on MMUP moves are the main issues addressed in the article. Network architectures and protocols developed for terminal mobility scenarios are evaluated for applicability in the present context, and new solutions are presented for problems unique to the MMUP application scenario     

A Transparent Failover Mechanism for a Mobile Network with Multiple Mobile Routers

In a mobile network that is multihomed by multiple mobile routers, a mobile router that loses link connectivity can be replaced by the other mobile routers. We propose a transparent failover mechanism (TFM) to provide seamless Internet services to nodes in the mobile network, which is validated by implementing a real test-bed. Compared to the network mobility basic support protocol, TFM does not require the nodes attached to the failed mobile router to change their addresses, and hence has two advantages: (a) IP connectivity is maintained transparently, and (b) failover is quickly accomplished by avoiding the address re-configuration process in each node.     

Building Secure Tunnel from PPP Wireless Network

The rapid development of mobile businesses raises the need for exchanging information between mobile computing devices via Internet. If a secure connection is necessary then a virtual private network (VPN) is essential. Currently, VPN protocols set up secure connections between two nodes with fixed IP addresses. However, if several people work in a moving vehicle with their mobiles or computers, the secure connection will be lost due to the IP change and a new connection has to be built from scratch. The current solution to this problem is to run tunnels over Mobile IP (MIP). However, that is inefficient due to double tunneling. In this paper, the authors add a novel form of mobility support to secure L2TP/IPsec tunnels which will be shared by everyone in the vehicle using a Point-to-Point Protocol (PPP) wireless network. The mobility support properly handles the IP change (users may even change to a different kind of network such as from Universal Mobile Telecommunications System (UMTS) to Worldwide Interoperability for Microwave Access (WiMAX) without using an MIP, and without incurring tunnel-re-establishment at handoff. The novel solution achieves better security than current mobility solutions for VPN, and supports fast handoff in IPv4 networks.     

Extending Global IP Connectivity for Ad Hoc Networks

Ad hoc networks have thus far been regarded as stand-alone networks without assumed connectivity to wired IP networks and the Internet. With wireless broadband communications and portable devices with appropriate CPU, memory and battery performance, ad hoc connectivity will become more feasible and demand for global connectivity through ad hoc networking is likely to rapidly grow. In this paper we propose an algorithm and describe a developed prototype for connectivity between an ad hoc network running the ad hoc on-demand distance-vector protocol and a wired IP network where mobile IP is used for mobility management. Implementation issues and performance metrics are also discussed.     

Network mobility protocol for vehicular ad hoc networks

The goal of the network mobility management is to effectively reduce the complexity of handoff procedure and keep mobile devices connecting to the Internet. When users are going to leave an old subnet and enter a new subnet, the handoff procedure is executed on the mobile device, and it may break off the real‐time service, such as VoIP or mobile TV, because of the mobility of mobile devices. Because a vehicle is moving so fast, it may cause the handoff and packet loss problems. Both of the problems will lower down the throughput of the network. To overcome these problems, we propose a novel network mobility protocol for vehicular ad hoc networks. In a highway, because every car is moving in a fixed direction at a high speed, a car adopting our protocol can acquire an IP address from the vehicular ad hoc network through the vehicle‐to‐vehicle communications. The vehicle can rely on the assistance of a front vehicle to execute the prehandoff procedure, or it may acquire a new IP address through multihop relays from the car on the lanes of the same or opposite direction and thus may reduce the handoff delay and maintain the connectivity to the Internet. Simulation results have shown that the proposed scheme is able to reduce both the handoff delay and packet loss rate. Copyright © 2013 John Wiley & Sons, Ltd.     

Extensions for Internet QoS paradigms to mobile IP: a survey

Mobile IP has been chosen as the core mobility management mechanism for wireless LANs, 3G cellular networks, and, most recently, aeronautical networks. It is viewed as a key element in providing a universal roaming solution across different wireless access technologies. However, mobile IP in its basic form inherits the IP incapability to provide QoS guarantees. This results in mobile IP's lack of support for seamless intradomain mobility. This article surveys extensions that have been proposed to enhance the QoS functionality of mobile IP. It gives a brief overview of mobile IP and Internet QoS paradigms, and describes their general shortcomings with regard to QoS and mobility, respectively. It then discusses the extensions that have been proposed in the literature and provides a qualitative comparison.     

Seamless Support for Mobile Internet Protocol Based Cellular Environments

Cellular is the inevitable architecture for the Personal Communication Service system (PCS) in the coming future. Access to the Internet via cellular networks is expected to become an essential portion of future wireless service offerings. Providing seamless support for IP based packet switched services has become an important issue.The Internet Engineering Task Force's (IETF's) mobile IP protocol offers a standard solution for wide-area mobility at the IP layer. However, Mobile IP does not solve all of the problems involved in providing mobile Internet access to cellular users, especially during handoff period. Thus, IPv6 might be a good candidate to solve this problem.IPv6 is a new version of the Internet Protocol that was standardized by the IETF. It supports mobility and is presently being standardized by the IETF Mobile IP Working Group. At the same time, cellular is an inevitable architecture for the Personal Communication Service system (PCS).This paper introduces the current cellular support based on the Mobile Internet Protocol version 6. We will point out the short-falls using Mobile IP and try to emphasize protocols especially for mobile management schemes that can optimize a high speed mobile station moving among small wireless cells. A comparison between those schemes and future work will be presented.     

Stochastic modeling and performance analysis in balancing load and traffic for vehicular ad hoc networks: A review

The rapid growth of vehicular applications has resulted in high demand for Internet technology, which demands an unprecedented network capacity and a high quality of service (QoS). In vehicular ad hoc networks (VANETs), since nodes (vehicles) are highly mobile. The dynamic nature of the network topology in the VANET system changes due to frequent changes in link connectivity. The vehicles-to-vehicles (V2V), vehicles-to-infrastructure (V2I), and QoS, as well as the heterogeneity of applications within the VANET. VANETs have been introduced to make driving comfortable by providing safety and support to drivers. Due to the flexibility and offloading schemes available in-vehicle applications, there are some limitations. However, there are many issues in providing optimum service provisioning and scheduling in the vehicular environment. In VANETs, BSs and roadside units (RSUs) improve QoS. However, Internet services transmit packets to vehicles using stochastic models, and it predicts the traffic on a VANET. We provide open challenges to drive stochastic models in this direction.     

AMOEBA: Robust Location Privacy Scheme for VANET

Communication messages in vehicular ad hoc networks (VANET) can be used to locate and track vehicles. While tracking can be beneficial for vehicle navigation, it can also lead to threats on location privacy of vehicle user. In this paper, we address the problem of mitigating unauthorized tracking of vehicles based on their broadcast communications, to enhance the user location privacy in VANET. Compared to other mobile networks, VANET exhibits unique characteristics in terms of vehicular mobility constraints, application requirements such as a safety message broadcast period, and vehicular network connectivity. Based on the observed characteristics, we propose a scheme called AMOEBA, that provides location privacy by utilizing the group navigation of vehicles. By simulating vehicular mobility in freeways and streets, the performance of the proposed scheme is evaluated under VANET application constraints and two passive adversary models. We make use of vehicular groups for anonymous access to location based service applications in VANET, for user privacy protection. The robustness of the user privacy provided is considered under various attacks.     

Analytical model for connectivity of vehicular ad hoc networks in the presence of channel randomness

A vehicular ad hoc network (VANET) is a highly mobile wireless ad hoc network formed by vehicles equipped with communication facilities. Developing multihop communication in VANETs is a challenging problem because of rapidly changing network topology and frequent network disconnections. This paper investigates the network connectivity probability of one‐dimensional VANET in the presence of channel randomness. Network connectivity is one of the most important issues in VANETs, because the dissemination of time‐critical information requires, as a preliminary condition, the network to be fully connected. We present an analytical procedure for the computation of network connectivity probability, taking into account the underlying wireless channel. Three different fading models are considered for the connectivity analysis: Rayleigh, Rician, and Weibull. A distance‐dependent power law model is employed for the pathloss in a vehicle‐to‐vehicle channel. Furthermore, the speed of each vehicle on the highway is assumed to be a Gaussian distributed random variable. The analysis provides a general framework for investigating the dependence of various parameters such as vehicle arrival rate, vehicle density, vehicle speed, highway length, and various physical layer parameters such as transmit power, receive signal‐to‐noise ratio threshold, path loss exponent, and fading factors (Rician and Weibull) on VANET connectivity. Copyright © 2011 John Wiley & Sons, Ltd.     

Mobility management alternatives for migration to mobile Internet session-based services

Session-based Internet protocol (IP) applications, such as Internet telephony, are an important component of the emerging mobile Internet. The ubiquitous availability of these services is critical to the success of the mobile Internet. Because all-IP networks will be deployed in phases and current mobile telecommunication systems will be in operation for decades to come, the interworking and migration between current network services and all-IP services is a key problem. In this paper, we address seamless roaming for session initiation protocol-based services across current cellular telecommunication networks and emerging all-IP wireless networks, such as those using third-generation and WiFi networks. We present an abstract mobility model, and map this model to three basic approaches for supporting seamless mobility: a master-slave approach, a federated system, and a unified approach. We discuss the challenges and implementation of an instance of the unified mobility management approach, called the Unified Mobility Manager, and then compare the tradeoffs of the three systems using a comparative performance analysis. We conclude that unified mobility management is most efficient if a great deal of interworking is required, and as more users invoke IP-based services; the federated approach is efficient when a single network technology is dominant and data access is limited, but requires sharing of data across networks; the master-slave approach is the least efficient, but is easy to introduce if the number of network types is small.     

Performance Analysis with Traffic Accident for Cooperative Active Safety Driving in VANET/ITS

Recently, by using vehicle-to-vehicle and vehicle-to-infrastructure communications for VANET/ITS, the cooperative active safety driving (ASD) providing vehicular traffic information sharing among vehicles significantly prevents accidents. Clearly, the performance analysis of ASD becomes difficult because of high vehicle mobility, diverse road topologies, and high wireless interference. An inaccurate analysis of packet connectivity probability significantly affects and degrades the VANET/ITS performance. Especially, most of related studies seldom concern the impact factors of vehicular accidents for the performance analyses of VANET/ITS. Thus, this paper proposes a two-phase approach to model a distributed VANET/ITS network with considering accidents happening on roads and to analyze the connectivity probability. Phase 1 proposes a reliable packet routing and then analyzes an analytical model of packet connectivity. Moreover, the analysis is extended to the cases with and without exhibiting transportation accidents. In phase 2, by applying the analysis results of phase 1 to phase 2, an adaptive vehicle routing, namely adaptive vehicle routing (AVR), is proposed for accomplishing dynamic vehicular navigation, in which the cost of a road link is defined in terms of several critical factors: traffic density, vehicle velocity, road class, etc. Finally, the path with the least path cost is selected as the optimal vehicle routing path. Numerical results demonstrate that the analytical packet connectivity probability and packet delay are close to that of simulations. The yielded supreme features justify the analytical model. In evaluations, the proposed approach outperforms the compared approaches in packet connectivity probability, average travel time, average exhausted gasoline. However, the proposed approach may lead to a longer travel distance because it enables the navigated vehicle to avoid traversing via the roads with a higher traffic density.     

Position-Based Adaptive Clustering Model (PACM) for Efficient Data Caching in Vehicular Named Data Networks (VNDN)

The seamless data delivery is essential in VANET for application such as autonomous vehicle, intelligent traffic management and for the road safety and emergency applications. The incorporation of named data networking (NDN) with VANET, intended to frame intelligent traffic flow and seamless data delivery. Such integration of vehicular ad hoc networks (VANET) with NDN is termed as vehicular named data networks (VNDN). Because of the continuous node/vehicle mobility, it is a tedious process to build constant and consistent communication between vehicles. With that concern, for enhancing the performance of VNDN and solving the issues such as frequent cluster formation on heavy loaded data transmissions, position-based adaptive clustering model (PACM) is developed. The major intention of PACM is to form clusters based on trajectory. Besides, PACM performs efficient data caching by collecting significant data from vehicles to establish consistent data communication with all nodes in the network. Efficient data caching is done with the elected cluster heads among the framed clusters based on its positions and mobility models. For handling the vehicles at higher mobility speed, mutual data caching process is also designed that makes vehicles to perform on-demand data gathering from cluster heads. Further, the model is simulated and the obtained results are compared with the existing models based on the metrics such as packet delivery ratio, mean delay, cache hit rate and mean hop distance. The comparative analysis shows that the proposed model outperforms the available techniques.

     

Mobility support in wireless Internet

The tremendous advancement and popularity of wireless access technologies necessitates the convergence of multimedia (audio, video, and text) services on a unified global (seamless) network infrastructure. Circuit-switched proprietary telecommunication networks are evolving toward more cost-effective and uniform packet-switched networks such as those based on IP. However, one of the key challenges for the deployment of such wireless Internet infrastructure is to efficiently manage user mobility. To provide seamless services to mobile users, several protocols have been proposed over the years targeting different layers in the network protocol stack. In this article we present a cross-layer perspective on the mobility protocols by identifying the key features of their design principles and performance issues. An analysis of the signaling overhead and handoff delay for some representative protocols in each layer is also presented. Our conclusion is that although the application layer protocol is worse than the protocols operating in the lower layers, in terms of handoff delay and signaling overhead, it is better suited as a potential mobility solution for the next-generation heterogeneous networks, if we consider such factors as protocol stack modification, infrastructure change, and inherent operational complexity.     

Mobility management in wireless ATM networks

Mobile ATM offers a common wired network infrastructure to support mobility of wireless terminals, independent of the wireless access protocol. In addition, it allows seamless migration to future wireless broadband services, such as wireless ATM, by enabling mobility of end-to-end ATM connections. In spite of the diversity in mobile networking technologies (e.g., cellular telephony, mobile-IP, packet data services, PCS), all of them require two fundamental mechanisms: location management and handoff. This article describes different schemes for augmenting a wired ATM network to support location management of mobile terminals and handoff protocols for rerouting a connection data path when the endpoint moves. A prototype implementation of mobile ATM integrating mobility support with ATM signaling and connection setup, is presented. It shows how mobile ATM may be used to provide mobility support to an IP terminal using non-ATM wireless access     

Mobile and Multicast IP Services in PACS: System Architecture, Prototype, and Performance

Traditionally, wireless cellular communication systems have been engineered for voice. With the explosive growth of Internet applications and users, there is an increasing demand on providing Internet services to mobile users based on the voice-oriented cellular networks. However, Internet services add a set of radically different requirements on to the cellular wireless networks, because the nature of communication is very different from voice. It is a challenge to develop an adequate network architecture and necessary systems components to meet those requirements.This paper describes our experience on developing Internet services, in particular, mobile and multicast IP services, in PACS (Personal Access Communication Systems). Our major contributions are five-fold: (i) PACS system architecture that provides wireless Internet and Intranet access by augmenting the voice network with IP routers and backbone links to connect to the Internet; (ii) simplified design of RPCU (Radio Port Controller Unit) for easy service maintenance and migration to future IP standards such as IPv6; (iii) native PACS multicast to efficiently support dynamic IP multicast and MBone connectivity; (iv) optimization and incorporation of Mobile IP into PACS handoff mechanism to efficiently support roaming within a PACS network as well as global mobility between PACS networks and the Internet; (v) successful prototype design of the new architecture and services verified by extensive performance measurements of IP applications. Our design experience and measurement results demonstrate that it is highly feasible to seamlessly integrate the PACS networks into the Internet with global IP mobility and IP multicast services.     

An Empirical Analysis of Handoff Performance for SIP,Mobile IP,and SCTP Protocols

Over the last decade, we have witnessed a growing interest in the design and deployment of various network architectures and protocols aimed at supporting mobile users as they move across different types of networks. One of the goals of these emerging network solutions is to provide uninterrupted, seamless connectivity to mobile users giving them the ability to access information anywhere, anytime. Handoff management, an important component of mobility management, is crucial in enabling such seamless mobility across heterogeneous network infrastructures. In this work, we investigate the handoff performance of three of the most widely used mobility protocols namely, Mobile IP, Session Initiation Protocol (SIP), and Stream Control Transmission Protocol (SCTP). Our empirical handoff tests were executed on an actual heterogeneous network testbed consisting of wired, wireless local area, and cellular networks using performance metrics such as handoff delay and handoff signaling time. Our empirical results reveal that Mobile IP yields the highest handoff delay among the three mobility protocols. In addition, we also found that SIP and SCTP yield 33 and 55% lower handoff delays respectively compared to Mobile IP.     

Enabling Heterogeneous Mobility in Android Devices

The fast growing of mobile Internet users with the ability of using a wide diversity of access technologies such as Wi-Fi, WiMAX and UMTS/LTE, and the increasing proliferation of mobile devices with heterogeneous network interfaces, require versatile mobility mechanisms providing seamless roaming across those access technologies. Mobility agents such as Mobile IP and Fast MIPv6 are common, however, these solutions still have limitations when dealing with multiple link-layer technologies. In this context, the emerging standard IEEE 802.21 provides a framework which enables mobile agents and network operators to improve the handover process in heterogeneous networks. In this context, this paper presents and discusses the design and implementation of a mobility-aware solution for an Android device, using the IEEE 802.21 framework. A modified Android user terminal is proposed to improve the handover process, assuming a make-before-break approach. Resorting to an experimental testbed, the obtained results show that the proposed solution is an effective contribution to successfully accomplish seamless mobility of Android-based devices operating in 3G and Wi-Fi networks.     

子网移动性管理及其性能优化研究

子网移动性管理的最终目标是移动网络中的所有节点郝可以通过一个永久的IP地址被访问,并且当移动网络的路由器改变接入点时,内部节点仍然可以保持连续的通信。但当前的移动性管理方案由于其基本协议的切换时延较大,丢包率较高而不能适应实时业务和移动通信的要求,需要对移动性管理策略进行改善。文中介绍一种基于SIP和SCTP协议的混合方法Hybrid—NEMO,解决基于MIPv6的NEMO所存在的问题。通过建立相应模型并进行仿真对比分析,该方案能够保证网络移动切换过程中零丢包率和可控制的时延抖动,完全可以实现网络无缝移动的有关性能指标,从而较好地解决了现有移动网络模型实现无缝移动过程中的不足。     

A terminal-assisted route optimized NEMO management

The NEMO basic support protocol enhances mobile IPv6 (MIPv6) to enable mobile router (MR) to move together with mobile network node (MNN) as a unit. This protocol suffers from pinball routing effect which has triggered research works to enable direct routing between MNNs in the presence of network mobility. Instead of relying on MIPv6, this paper describes network mobility using a novel terminal-assisted IP mobility protocol on MNNs that work cooperatively with MRs and access routers to provide seamless connectivity. This protocol is superior as it neither suffers from pinball routing effect nor requires dedicated infrastructure support such as home agent. It also eliminates the need to dynamically increase the size of IP header in IP tunneling. Through quantitative comparisons with existing protocol, we show that this protocol performs better than existing protocols in terms of average packet delivery overhead and packet generation.