移动集群计算关键技术研究

随着集群和移动计算技术的快速发展及广泛应用,一种结合了这两种技术的新的计算方式——移动集群计算应运而生。分析讨论了移动集群计算的体系结构和实现移动集群计算的一些关键问题及解决方案。     

Distributed Game-Theoretical D2D-Enabled Task Offloading in Mobile Edge Computing

Journal of Computer Science and Technology - Mobile edge computing (MEC) has been envisioned as a promising distributed computing paradigm where mobile users offload their tasks to edge nodes to...     

Integrating mobile agents into the mobile middleware

Mobile agents are a new paradigm for distributed computing that is especially well suited for mobile computing over global wireless networks. This paper describes the approach taken in the ACTS On TheMove project to integrate a mobile agent system into the Mobile Application Support Environment (MASE), a middleware for mobile computing. In this project, an existing mobile agent system was adapted for the requirements of mobile computing. We present the changes that had to be made to the agent system to adapt it to the wireless communication. We also present some of the application areas where a mobile agent system is suitable for mobile communication. We describe an agent based pre-fetcher application where an agent operaes disconnected from the user on the fixed network and prepares web pages for the anticipated next connection of the user using the Quality-of-Service trading functions available in MASE.     

一种基于地理位置信息的高能效无线传感器网络

分簇协议的目的是要利用节点有限的资源, 完成高效的数据采集任务, 延长网络使用寿命. 在基于簇的网络结构基础上, 提出并行分布式自组织成簇协议 (Parallel distributed self-organization clustering protocol, PDSOCP), 按地理位置将目标区域划分为若干均匀分布的逻辑区域, 每个区域根据节点剩余能量多少以及到区域内其余节点平均距离远近选择一个簇头, 以代理和簇头共同管理簇事务, 并建立了自适应路由. 实验表明, 该算法能够减少网络能耗, 有效延长网络寿命, 获得更好的性能.     

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.     

Distributed wireless power transfer in sensor networks with multiple Mobile Chargers

We investigate the problem of efficient wireless power transfer in wireless sensor networks. In our approach, special mobile entities (called the Mobile Chargers) traverse the network and wirelessly replenish the energy of sensor nodes. In contrast to most current approaches, we envision methods that are distributed and use limited network information. We propose four new protocols for efficient charging, addressing key issues which we identify, most notably (i) what are good coordination procedures for the Mobile Chargers and (ii) what are good trajectories for the Mobile Chargers. Two of our protocols (DC, DCLK) perform distributed, limited network knowledge coordination and charging, while two others (CC, CCGK) perform centralized, global network knowledge coordination and charging. As detailed simulations demonstrate, one of our distributed protocols outperforms a known state of the art method, while its performance gets quite close to the performance of the powerful centralized global knowledge method.     

On performance evaluation and design of atomic commit protocols for mobile transactions

The challenges of wireless and mobile computing environments have attracted the attention of researchers to revisit the conventional transaction paradigm. Indeed, this paradigm is an indispensable asset in modern information systems. The atomicity property of a distributed transaction is ensured with the use of an atomic commit protocol (ACP). Due to their great importance for transaction systems, the recent advances in mobile computing development have renewed the interest in the design of ACPs for mobile systems. The work presented in this paper studies the impact of the various and fluctuant parameters of wireless and mobile systems on a set of ACPs for mobile environment. It highlights performance indices which give orientations to the design of an adaptable approach that supports different atomicity notions satisfying a wide range of applications and environment requirements.     

基于移动代理的负载平衡策略

在异构计算环境中负载平衡是一个重要问题。移动代理是一种新的分布计算模式,具有许多优势,比如移动代理能够从一台机器移动到另一台机器执行任务。该文提出了一个基于移动代理的并行计算框架,利用一个二段负载平衡策略使程序能够适应不断变化的异构计算环境。实验结果显示移动代理不仅能够用于并行计算,而且能够有效地改善负载平衡。     

An improved ant colony optimization-based approach with mobile sink for wireless sensor networks

Traditional wireless sensor networks (WSNs) with one static sink node suffer from the well-known hot spot problem, that of sensor nodes near the static sink bear more traffic load than outlying nodes. Thus, the overall network lifetime is reduced due to the fact some nodes deplete their energy reserves much faster compared to the rest. Recently, adopting sink mobility has been considered as a good strategy to overcome the hot spot problem. Mobile sink(s) physically move within the network and communicate with selected nodes, such as cluster heads (CHs), to perform direct data collection through short-range communications that requires no routing. Finding an optimal mobility trajectory for the mobile sink is critical in order to achieve energy efficiency. Taking hints from nature, the ant colony optimization (ACO) algorithm has been seen as a good solution to finding an optimal traversal path. Whereas the traditional ACO algorithm will guide ants to take a small step to the next node using current information, over time they will deviate from the target. Likewise, a mobile sink may communicate with selected node for a relatively long time making the traditional ACO algorithm delays not suitable for high real-time WSNs applications. In this paper, we propose an improved ACO algorithm approach for WSNs that use mobile sinks by considering CH distances. In this research, the network is divided into several clusters and each cluster has one CH. While the distance between CHs is considered under the traditional ACO algorithm, the mobile sink node finds an optimal mobility trajectory to communicate with CHs under our improved ACO algorithm. Simulation results show that the proposed algorithm can significantly improve wireless sensor network performance compared to other routing algorithms.     

移动代理系统综述

移动代理技术是新型的分布计算技术,具有很好的应用前景、移动代理系统是实现移动代理应用的基础框架。简述了移动代理（mobile agent)的定义和特点、移动代理系统（mobile agent system)的定义和基本内容,移动代理技术的优点和应用范围。着重讨论了8个有代表性的移动代理系统,就各自的体系结构和特色作出说明,并且综合分析了实现移动代理系统所需的技术和当前研究中存在的问题及可能的发展趋势。     

基于PC集群的MPI并行环境的搭建

集群是充分利用计算资源的一个重要概念,PC集群是最易构建的分布式并行计算环境。MPI是应用最广的并行程序设计平台。本文通过实例阐述PC集群及PC集群上的MPI并行计算环境的搭建。     

Supporting mobility with wireless ATM

An implicit assumption underlying most networking research has been that two Internet users would be connected only by fixed links (wire lines). Increased use of portable computers, wireless networks and satellites has generated interest in supporting “computing on the move”, or mobile computing. Instead of maintaining a fixed position in a network, users in this environment are free to roam. Mobile computing raises interesting issues, such as how to route packets as the mobile user (host) moves about and how to guarantee the quality of service (QOS) that an application running on such a mobile host may need. Other issues include the choice of a transport protocol to use on top of a mobile host and how to deal with poor performance in wireless links. There are two possible approaches to supporting mobile computing over the Internet. The first uses a mobile IP (Internet Protocol), whereby packets (datagrams) are forwarded by a designated stationary host to the mobile host. The second approach involves wireless ATM (asynchronous transfer mode), with host mobility supported by rerouting/rearranging the end-to-end ATM connection between mobile and stationary hosts     

TEA-CBRP: Distributed cluster head election in MANET by using AHP

Mobile Ad hoc Network consists of a set of mobile nodes that are communicating in a wireless channel. In this network, the number of nodes and their mobility have an impact on the routing performance. In order to improve the routing performance of large scale Mobile Ad Hoc Networks, clustering is one of the solution. When clustering is implemented, an unconditional cooperation among the intra cluster and inter cluster nodes is necessary. In the event where a malicious or selfish node is elected as a cluster head, the routing performance gets significantly affected. In this paper, the key decision factors such as the trust value, remaining energy, and the time of availability of the mobile node is explored to elect a cluster head. Further, these three decision factors are incorporated into the Analytical Hierarchy Process technique in order to elect the most cooperative node as the cluster head. An enhancement to the existing Cluster based Routing Protocol, is proposed in this paper and then enhanced work, is termed as Trust Energy Availability based Cluster Based Routing Protocol. A network based on the proposed protocol is simulated. The important routing performance parameters such as packet delivery ratio, end to end latency, routing packet overhead, and the number of times cluster head changes are discussed for the simulated network and the results are compared with AODV and CBRP routing protocols. The simulation results have shown that the proposed cluster based routing protocol improves the network performance by eliminating malicious and selfish nodes from being elected as cluster head.     

Video streaming application over WEAC protocol in MANET

Performance of wireless networks under video traffic is subjected to two main issues: power minimization and other QoS requirements such as delay jitter. Mobile Ad Hoc Networks (MANETs) are more sensitive to these issues where each mobile device acts like a router. Thus, routing delay adds significantly to overall end-to-end delay. This paper analyzes the performance of the Warning Energy Aware Clusterhead/Virtual Base Station-On demand (WEAC/VBS-O) protocol in terms of average delay, multi-hop communication and power minimization aspects that are subject to video traffic. H.263 and H.264 standards are utilized to model the simulated network. HCB model is also utilized to minimize the power consumption. The simulation results are demonstrated on a single hop and multi-hop settings. This includes the power consumption and the effect of sudden demise of cluster heads in the Warning Energy Aware Cluster head (WEAC) protocol.     

SmallWorld Model-Based Polylogarithmic Routing Using Mobile Nodes

The use of mobile nodes to improve network system performance has drawn considerable attention recently. The movement-assisted model considers mobility as a desirable feature,where routing is based on the store-carry-forward paradigm with random or controlled movement of resource rich mobile nodes.The application of such a model has been used in several emerging networks,including mobile ad hoc networks(MANETs),wireless sensor networks(WSNs),and delay tolerant networks(DTNs).It is well known that mobility increases the capacity of MANETs by reducing the number of relays for routing,prolonging the lifespan of WSNs by using mobile nodes in place of bottleneck static sensors,and ensuring network connectivity in DTNs using mobile nodes to connect different parts of a disconnected network.Trajectory planning and the coordination of mobile nodes are two important design issues aiming to optimize or balance several measures, including delay,average number of relays,and moving distance.In this paper,we propose a new controlled mobility model with an expected polylogarithmic number of relays to achieve a good balance among several contradictory goals,including delay,the number of relays,and moving distance.The model is based on the small-world model where each static node has"short"link connections to its nearest neighbors and"long"link connections to other nodes following a certain probability distribution.Short links are regular wireless connections whereas long links are implemented using mobile nodes.Various issues are considered,including trade-offs between delay and average number of relays,selection of the number of mobile nodes,and selection of the number of long links.The effectiveness of the proposed model is evaluated analytically as well as through simulation.     

移动Agent系统中的安全问题和技术研究综述

移动Agent是分布式计算领域中一种新的计算模式。由于其在异步性、自治性以及移动性等方面的优势,移动Agent技术应用范围日益广泛,而随之而来的系统安全性问题也日益突出。拳文对移动Agent系统中的主要安全威胁做了细致的分析;在此基础上,从主机和Agent两技术方面以及社会角度总结了目前主要存在的安全保障措施;描述并比较了几种具代表性的移动Agent系统及各自的安全实现机制。     

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     

Application Security Models for Mobile Agent Systems

Mobile agents are a distributed computing paradigm based on mobile autonomous programs. Mobile applications must balance security requirements with available security mechanisms in order to meet application level security goals. We introduce a trust framework to reason about application security requirements, trust expression, and agent protection mechanisms. We develop application security models that capture initial trust relationships and consider their use for mobile agent security.     

无线自组织网络中多层综合的节点行为异常检测方法

Ad hoe网络由于采用无线信道、有限的电源和带宽、分布式控制等,会比有线网络更易受到入侵攻击.通常的入侵检测技术具有检测能力单一、缺乏对抗新入侵方式的能力等缺陷.在分布式入侵检测系统(IDS)的基础上,提出一种针对移动节点网络行为的异常检测机制.基于多层综合的观测值序列,采用隐半马尔可夫模型(HSMM)建立描述网络中合法节点正常行为的检测模型,继而对网络中的正常与异常行为进行判断与识别.实验表明,此方法能针对现有多种入侵方式进行有效的检测.     

Distributed computing paradigms for collaborative signal and information processing in sensor networks

In this paper, we report the development of an energy-efficient, high-performance distributed computing paradigm to carry out Collaborative Signal and Information Processing (CSIP) in sensor networks using mobile agents. In this paradigm, the processing code is moved to the sensor nodes through mobile agents, in contrast to the client/server-based computing, where local data are transferred to a processing center. Although the client/server paradigm has been widely used in distributed computing, the many advantages of the mobile agent paradigm make it more suitable for sensor networks. The paper first presents simulation models for both the client/server paradigm and the mobile agent paradigm. We use the execution time, energy and energy*delay as metrics to measure the performance. Several experiments are designed to show the effect of different parameters on the performance of the paradigms. Experimental results show that the mobile agent paradigm performs much better when the number of nodes is large while the client/server paradigm is advantageous when the number of nodes is small. Based on this observation, we then propose a cluster-based hybrid computing paradigm to combine the advantages of these two paradigms. There are two schemes in this paradigm and simulation results show that there is always one scheme which performs better than either the client/server or the mobile agent paradigms. Thus, the cluster-based hybrid computing provides an energy-efficient and high-performance solution to CSIP.