Dynamic adaptation of network connections in mobile environments

Most network applications assume continuous connectivity-an assumption that does not “migrate” to wireless environments. The authors present the design of a communication layer for mobile computing that dynamically adapts to changes in network connections. Our work was part of AMIGOS (Advanced Mobile Integration in General Operating Systems), a collaboration between researchers at the University of Copenhagen in Denmark and the University of Minho in Portugal. The AMIGOS project provides transparent support for semi connected operations on mobile computers running a standard operating system; the project home page is at http://www.econ.cbs.dk/people/birger/AMIGOS/. Briefly, our design lets a mobile user connect a mobile host to a LAN, then disconnect the host from it. The user then can reconnect, for example, via a Global System for Mobile Communications (GSM) cellular modem without losing TCP/IP connections. We want to allow existing TCP/IP based applications to be used in a mobile environment, without application modifications     

Energy-efficient multisite offloading policy using Markov decision process for mobile cloud computing

Mobile systems, such as smartphones, are becoming the primary platform of choice for a user’s computational needs. However, mobile devices still suffer from limited resources such as battery life and processor performance. To address these limitations, a popular approach used in mobile cloud computing is computation offloading, where resource-intensive mobile components are offloaded to more resourceful cloud servers. Prior studies in this area have focused on a form of offloading where only a single server is considered as the offloading site. Because there is now an environment where mobile devices can access multiple cloud providers, it is possible for mobiles to save more energy by offloading energy-intensive components to multiple cloud servers. The method proposed in this paper differentiates the data- and computation-intensive components of an application and performs a multisite offloading in a data and process-centric manner. In this paper, we present a novel model to describe the energy consumption of a multisite application execution and use a discrete time Markov chain (DTMC) to model fading wireless mobile channels. We adopt a Markov decision process (MDP) framework to formulate the multisite partitioning problem as a delay-constrained, least-cost shortest path problem on a state transition graph. Our proposed Energy-efficient Multisite Offloading Policy (EMOP) algorithm, built on a value iteration algorithm (VIA), finds the efficient solution to the multisite partitioning problem. Numerical simulations show that our algorithm considers the different capabilities of sites to distribute appropriate components such that there is a lower energy cost for data transfer from the mobile to the cloud. A multisite offloading execution using our proposed EMOP algorithm achieved a greater reduction on the energy consumption of mobiles when compared to a single site offloading execution.     

移动Agent框架的设计及其关键技术

移动Agent技术具有良好的应用前景,应如何设计和实现一个移动Agent系统?该文设计了一个移动Agent框架,并详细给出实现:(1)异步迁移与移动用户支持;(2)迁移策略与并行处理;(3)通信管理与同步机制三个关键技术的解决方法。     

Optimizing communication in mobile ad hoc network clustering

Mobile ad hoc networks (MANETs) are gaining popularity in recent years due to their flexibility, the proliferation of smart computing devices, and developments in wireless communications. Clustering is an important research problem for MANETs because it enables efficient utilization of resources, and must strike a delicate balance between battery energy, mobility, node degree, etc. In this paper, we consider the typical communication workload of every mobile node as well as the additional communication workload of clusterheads in MANET clustering. We propose an algorithm that optimizes communication workload, power consumption, clusterhead lifetime, and node degree. Experiment results show that our clustering approach produces effectively balanced clusters over a diverse set of random scenarios.     

Data management issues in mobile and peer-to-peer environments

Mobile computing is a revolutionary technology, born as a result of remarkable advance in the development of computer hardware and wireless communication. It enables us to access information anytime and anywhere even in the absence of physical network connection. More recently, there has been increasing interest in introducing ad hoc network into mobile computing, resulting in a new distributed computing style known as peer-to-peer (P2P) computing. In this paper, we discuss the data management issues in mobile and P2P environments. The use of wireless communication makes the data availability the most important problem here, so we focus on the problem of data availability and provide detailed discussion about replicating mobile databases. Not only that, we extend our discussion to mobile–P2P environment. At the end, we discuss the general data management issues in P2P environment.     

基于Java-RMI技术的移动代理系统设计

移动代理是一种新型的分布式计算技术,有着许多传统分布式计算模型无法比拟的优势,是目前研究和应用热点。RMI（远程方法调用）是Java平台解决远程调用的方案,基于RMI技术设计了移动代理系统,对移动代理系统的关键问题进行了分析,通过RMI技术和动态类加载技术实现了移动代理系统,并设计实验验证了移动代理的移动性和自主性。     

基于移动计算的移动代理平台的实际应用

移动计算被认为是对未来最有影响的四大技术方向之一。它的作用在于将有用、准确、及时的信息与中央信息系统相互作用,分担中央信息系统的计算压力,使这些信息能提供给在任何时间、任何地点需要它的任何用户。为了更好的支持便携式设备上Microsoft的WinCE平台的移动计算,本文通过对基于Java的移动代理系统Aglet的比较,介绍了基于Windows平台的移动代理系统——WinMAS的优越性,同时详细地给出了相关的应用示例。     

GPS机动车辆管理系统实现方案分析

GPS机动车管理系统是利用GPS接收机、无线通信、地理信息技术等，对移动用户进行监控、调度、指挥的新型机动车管理系统。本文作为具体GPS车辆管理系统实现的参考和指导，首先从整体上介绍了基于GPS的机动车管理系统的实现方案，之后详细分析了系统各重要组成部分的设计思路和实现方式，并着重对系统中的无线通信网络的实现技术进行了分析对比。     

Mobile Server： An Efficient Mobile Computing Platform Based on Mobile Agent

A mobile agent computing platform is based on J2ME technology and Jini system architecture and Mobile Server is presented. The platform is established on extended Jini system architecture, and is embedded in software kernel to support computing style of mobile agent. In order to overcome the shortage of traditional database access technology in mobile computing enviornment, a centralized database and a distributed heterogeneous database access technology based on mobile agent is proposed. Amied at the usable resource restraints in mobile computing environment, an enviornment apperceiving middleware is designed to allocate and manage the resources. The application results show that the effect in saving computing time by using this platform is notable.     

Moset: An anonymous remote mobile cluster computing paradigm

The advance of technology in terms of cellular communications and the increasing computing power of the mobile systems have made it convenient for people to use more of mobile systems rather than static systems. This has seen more of mobile devices in personal and distributed computing, thus making the computing power ubiquitous. The combination of wireless communication and cluster computing in many applications has led to the integration of these two technologies to emerge as Mobile Cluster Computing (MCC) paradigm. This has made parallel computing feasible on mobile clusters, by making use of the idle processing power of the static and mobile nodes that form the cluster. To realize such a system for parallel computing, various issues such as connectivity, architecture and operating system heterogeneities, timeliness issues, load fluctuations on machines, machine availability variations and failures in workstations and network connectivities need to be handled. Moset, an Anonymous Remote Mobile Cluster Computing (ARMCC) paradigm is being proposed to handle these issues. Moset provides transparency to mobility of nodes, distribution of computing resources and heterogeneity of wired and wireless networks. The model has been verified and validated by implementing a distributed image-rendering algorithm over a simulated mobile cluster model.     

Mobile agent middleware for mobile computing

Mobile computing requires an advanced infrastructure that integrates suitable support protocols, mechanisms, and tools. This mobility middleware should dynamically reallocate and trace mobile users and terminals and permit communication and coordination of mobile entities. In addition, open and untrusted environments must overcome system heterogeneity and grant the appropriate security level. Solutions to these issues require compliance with standards to interoperate with different systems and legacy components and a reliable security infrastructure based on standard cryptographic mechanisms and tools. Many proposals suggest using mobile agent technology middleware to address these issues. A mobile agent moves entities in execution together with code and achieved state, making it possible to upgrade distributed computing environments without suspending service. We propose three mobile computing services: user virtual environment (UVE), mobile virtual terminal (MVT), and virtual resource management (VRM). UVE provides users with a uniform view of their working environments independent of current locations and specific terminals. MVT extends traditional terminal mobility by preserving the terminal execution state for restoration at new locations, including active processes and subscribed services. VRM permits mobile users and terminals to maintain access to resources and services by automatically requalifying the bindings and moving specific resources or services to permit load balancing and replication     

移动Agent系统构建研究

Mobile agent technology has strong adaptability to the status of network and executing environment, and provides a flexible and uniform framework for Web and distributed applications.Mobile agent system, as the foundation of agent computing, should provide the basic supports like executing support, agent migration, andcommunication, as well the extensive supports like naming service, security, fault tolerance, interoperation,application development and management tools. Based on the analysis of current mobile agent system, this article discusses these supports deeply, and also points out the main challenges to the development of mobile agent system.     

Delay analysis of downlink IP traffic on UMTS mobile networks

Since wireless networks which can carry high bit rates have become ubiquitous, mobile computing is no longer just spoken about. Mobile computing always implies access through a wireless network to an IP network such as the Internet. In order to understand the performance of such links, we propose an analytic model for the down link delay of IP traffic between the Mobile Gateway Server and the End User in a UMTS mobile network. Traffic arriving at the Gateway Server is considered to be bursty in nature and we use a Batch Markovian Arrival Process (BMAP) to model this arrival process. We model the wireless link itself as a modified multi-state Gilbert–Elliot Markov model which takes into account the number of interfering users and whether the channel experiences Ricean fading or not for what we consider a typical indoor, IP-centric environment. We also account in both the analytical model and the simulation for the Forward Error Correction provided by Turbo coding in UMTS to establish realistic packet retransmission rates. Finally we calibrate and verify the correctness of the model with a discrete event simulator.     

Efficient handover authentication with user anonymity and untraceability for Mobile Cloud Computing

Various wireless communication technologies have been generated and deployed on account of mass requirements. These enable cloud computing with integration with mobility and Mobile Cloud Computing (MCC) becomes the trend of future generation computing paradigm. In this paper, we address a challenging issue of MCC technology—security and privacy of the handover process. We propose a new design of handoff authentication for heterogeneous mobile cloud networks, which provides user anonymity and untraceability. Compared with previous protocols, our proposed mechanism achieves comprehensive features of universality, robust security and efficiency.     

用于移动汇聚节点的自适应数据采集策略

移动汇聚节点用于无线传感网络信息采集,可以提高网络能效性,延长网络生命期。研究了四轴飞行器携带 移动汇聚节点,该节点可采集地面无线传感网数据。通过分析汇聚节点空中移动特性,探讨了低功耗无线数据采集 时,移动轨迹、速率和高度与移动汇聚节点能够发送的数据量的之间的理论约束条件。在满足约束条件前提下,提出 基于数据量局部最优化策略,用以控制移动汇聚节点移动路径。在仿真环境中,详尽分析了这种数据采集策略下逗留 时间与移动轨迹、速度和高度等之间的关系,为这类应用莫定了理论基础。     

Investigation on runtime partitioning of elastic mobile applications for mobile cloud computing

The latest developments in mobile computing technology have increased the computing capabilities of smartphones in terms of storage capacity, features support such as multimodal connectivity, and support for customized user applications. Mobile devices are, however, still intrinsically limited by low bandwidth, computing power, and battery lifetime. Therefore, the computing power of computational clouds is tapped on demand basis for mitigating resources limitations in mobile devices. Mobile cloud computing (MCC) is believed to be able to leverage cloud application processing services for alleviating the computing limitations of smartphones. In MCC, application offloading is implemented as a significant software level solution for sharing the application processing load of smartphones. The challenging aspect of application offloading frameworks is the resources intensive mechanism of runtime profiling and partitioning of elastic mobile applications, which involves additional computing resources utilization on Smart Mobile Devices (SMDs). This paper investigates the overhead of runtime application partitioning on SMD by analyzing additional resources utilization on SMD in the mechanism of runtime application profiling and partitioning. We evaluate the mechanism of runtime application partitioning on SMDs in the SmartSim simulation environment and validate the overhead of runtime application profiling by running prototype application in the real mobile computing environment. Empirical results indicate that additional computing resources are utilized in runtime application profiling and partitioning. Hence, lightweight alternatives with optimal distributed deployment and management mechanism are mandatory for accessing application processing services of computational clouds.     

An energy-efficient task scheduling for mobile devices based on cloud assistant

Mobile cloud computing is an emerging service model to extend the capability and the battery life of mobile devices. Mostly one network application can be decomposed into fine-grained tasks which consist of sequential tasks and parallel tasks. With the assistance of mobile cloud computing, some tasks could be offloaded to the cloud for speeding up executions and saving energy. However, the task offloading results in some additional cost during the communication between cloud and mobile devices. Therefore, this paper proposes an energy-efficient scheduling of tasks, in which the mobile device offloads appropriate tasks to the cloud via a Wi-Fi access point. The scheduling aims to minimize the energy consumption of mobile device for one application under the constraint of total completion time. This task scheduling problem is reconstructed into a constrained shortest path problem and the LARAC method is applied to get the approximate optimal solution. The proposed energy-efficient strategy decreases 81.93% of energy consumption and 25.70% of time at most, compared with the local strategy. Moreover, the applicability and performance of the proposed strategy are verified in different patterns of applications, where the time constraint, the workload ratio between communication and computation are various.     

Wireless network extension using mobile IP

Over the last two decades, we have seen a dramatic shift in computing systems, away from the monolithic mainframe and toward increasingly distributed, client-server systems. One of the key elements enabling the success of the distributed computing environment was the interconnecting network technology. High-speed, reliable network hardware and protocols evolved to support client-server applications. Network technology has now progressed to the point that applications are being written to specifically exploit the capabilities of the network. The explosion of World Wide Web applications is the latest example of the fact that the network is now the focus of the distributed computing environment. In a concurrent development, personal computing platforms placed increasingly powerful systems in ever smaller form factors. Users have embraced these advances: Mobile computers, in the form of laptops, palmtops, and personal digital assistants (PDAs), are a significant element of the current computing environment. However, to be fully productive, the mobile computer user requires access to the network. Further, access to a network is not sufficient. Mobile users need access to the same network-the same resources and services and communications capabilities-that they would if they were at their desktops. We refer to this concept of providing home network access to the mobile user as network extension. Addressing many requirements for practical wireless access, this Internet technology aids the development of advanced data services for wireless networks, including the integrated dispatch enhanced network     

A framework for context-aware self-adaptive mobile applications SPL

Mobile Applications are rapidly emerging as a convenient medium for using a variety of services. Over time and with the high penetration of smartphones in society, self-adaptation has become an essential capability required by mobile application users. In an ideal scenario, an application is required to adjust its behavior according to the current context of its use. This raises the challenge in mobile computing towards the design and development of applications that sense and react to contextual changes to provide a value-added user experience. In its general sense, context information can relate to the environment, the user, or the device status. In this paper, we propose a novel framework for building context aware and adaptive mobile applications. Based on feature modeling and Software Product Lines (SPL) concepts, this framework guides the modeling of adaptability at design time and supports context awareness and adaptability at runtime. In the core of the approach, is a feature meta-model that incorporates, in addition to SPL concepts, application feature priorities to drive the adaptability. A tool, based on that feature model, is presented to model the mobile application features and to derive the SPL members. A mobile framework, built on top of OSGI framework to dynamically adapt the application at runtime is also described.