Service Composition for Mobile Environments

Service Composition, that is, the development of customized services by discovering, integrating and executing existing services has received a lot of attention in the last couple of years with respect to wired-infrastructure or Internet web services. With the advancement in the wireless technology and rapid deployment of mobile devices, we envision that in the near future wirelessly connected mobile devices in a given vicinity will also provide services that can be leveraged in the composition process. This is particularly true of what have been described as “pervasive computing” environments. However, wired-infrastructure based service composition architectures are not designed to consider the various factors like mobility, device heterogeneity, resource variability and reliability in a mobile environment. In this paper, we describe the issues related to service composition in mobile environments and evaluate criteria for judging protocols that enable such composition. We present a distributed architecture and associated protocols for service composition in mobile environments that take into consideration mobility, dynamic changing service topology and device resources. The composition protocols are based on distributed brokerage mechanisms and utilize a distributed service discovery process over ad-hoc network connectivity. We present simulation results of our protocols, and compare them with a centralized service composition protocol traditionally used for wired-infrastructure environments. The results show that our approach clearly outperforms the existing centralized approaches, and that our protocols are able to adapt and better utilize the changing service topology and resources in a mobile environment.This work is supported in part by NSF awards 9875433 and 0070802, DARPA DAML program and IBM. Dipanjan Chakraborty is a Ph.D candidate and a research member of ebiquity research group at University of Maryland, Baltimore County (UMBC). His reserach is in the areas of mobile and pervasive computing environments, mobile and e-commerce, peer-to-peer systems with special interests in the fields of service discovery, information aggregation and composition, ad-hoc network application-centric routing, agent-based systems. He specializes in the development and modeling of distributed architectures to enable mobile and pervasive commerce in ubiquitous environments. His thesis is in the area of service discovery and composition for pervasive environments. He has been a fellow of IBM during the 3 years of his Ph.D candidacy. Anupam Joshi is an Associate Professor of Computer Science and Electrical Engineering at UMBC. Earlier, he was an Assistant Professor in the CECS department at the University of Missouri, Columbia. He obtained a B. Tech degree in Electrical Engineering from IIT Delhi in 1989, and a Masters and Ph.D. in Computer Science from Purdue University in 1991 and 1993 respectively. His research interests are in the broad area of networked computing and intelligent systems. His primary focus has been on data management for mobile computing systems in general, and most recently on data management and security in pervasive computing and sensor environments. He has created agent based middleware to support discovery, composition, and secure access of services/data over both infrastructure based (e.g. 802.11, cellular) and ad-hoc wireless networks (e.g. Bluetooth). He is also interested in Semantic Web and Data/Web Mining, where he has worked on personalizing the web space using a combination of agents and soft computing. His other interests include networked HPCC. He has published over 50 technical papers, and has obtained research support from NSF, NASA, DARPA, DoD, IBM, AetherSystens, HP, AT&T and Intel. He has presented tutorials in conferences, served as guest editor for special issues for IEEE Personal Comm., Comm. ACM etc., and served as an Associate Editor of IEEE Transactions of Fuzzy Systems from 99-03. At UMBC, Joshi teaches courses in Operating Systems, Mobile Computing, Networking, and Web Mining. He is a member of IEEE, IEEE-CS, and ACM. Tim Finin is a Professor in the Department of Computer Science and Electrical Engineering at the University of Maryland Baltimore County (UMBC). He has over 30 years of experience in the applications of Artificial Intelligence to problems in information systems, intelligent interfaces and robotics and is currently working on the theory and applications of intelligent software agents, the semantic web, and mobile computing. He holds degrees from MIT and the University of Illinois. Prior to joining the UMBC, he held positions at Unisys, the University of Pennsylvania, and the MIT AI Laboratory. Finin is the author of over 180 refereed publications and has received research grants and contracts from a variety of sources. He has been the past program chair or general chair of several major conferences. He is a former AAAI councilor and is a member of the the board of directors of the Computing Research Association. Yelena Yesha received the B.Sc. degree in Computer Science from York University, Toronto, Canada in 1984, and the M.Sc. and Ph.D degrees in Computer and Information Science from The Ohio State University in 1986 and 1989, respectively. Since 1989 she has been with the Department of Computer Science and Electrical Engineering at the University of Maryland Baltimore County, where she is presently a Verizon Professor. In addition, from December, 1994 through August, 1999 Dr. Yesha served as the Director of the Center of Excellence in Space Data and Information Sciences at NASA. Her research interests are in the areas of distributed databases, distributed systems, mobile computing, digital libraries, electronic commerce, and trusted information systems. She published 8 books and over 100 refereed articles in these areas. Dr. Yesha was a program chair and general co-chair of the ACM International Conference on Information and Knowledge Management and a member of the program committees of many prestigious conferences. She is a member of the editorial board of the Very Large Databases Journal, and the IEEE Transaction on Knowledge and Data Engineering, and is editor-in-chief of the International Journal of Digital Libraries. During 1994, Dr. Yesha was the Director of the Center for Applied Information Technology at the National Institute of Standards and Technology. Dr. Yesha is a senior member of IEEE, and a member of the ACM.This revised version was published online in August 2005 with a corrected cover date.     

Piecewise Network Awareness Service for Wireless/Mobile Pervasive Computing

This paper presents a piecewise framework for network awareness service (NAS) for wireless/mobile pervasive computing. We investigate how piecewise consideration of wired and wireless elements of the framework architecture benefits service advertisement and discovery and network-awareness techniques. We also discuss scalability of the NAS framework with respect to platform computing capabilities. The framework is suitable for a wide range of computing devices, from powerful ones with multi-tasking operating systems (OS) to small ones with lightweight OS. Case studies applying the NAS framework to sensor monitoring in home networks and data streaming in pervasive multimedia computing are presented. The analytical results on the performance of the NAS framework in these case studies show that it has significant advantages over traditional network-awareness frameworks in terms of reducing wireless bandwidth consumption and saving battery energy of mobile devices.     

Service Discovery in Agent-Based Pervasive Computing Environments

Directory based service discovery mechanisms are unsuitable for ad-hoc m-commerce environments. Working towards finding an alternate mechanism, we developed Allia: a peer-to-peer caching based and policy-driven agent-service discovery framework that facilitates cross-platform service discovery in ad-hoc environments. Our approach achieves a high degree of flexibility in adapting itself to changes in ad-hoc environments and is devoid of common problems associated with structured compound formation in mobile commerce environments. Device capabilities and limitations, user preferences regarding device usage, application specifics with respect to mobile commerce are factors that our framework adapts to. We have described our initial implementation of Allia over ThinkPads and iPAQs by extending the LEAP Agent Platform and using Bluetooth as the underlying network protocol. In addition, we evaluated Allia's performance by running simulations of our protocol in Glomosim simulator. We also compared our framework against a structured compound-based architecture.     

QoS-Aware Semantic Web Service Composition with Uncertainties

Choosing the optimal execution plan is an important process of semantic web service composition. However, Quality of service （QoS） based plan selection is still challenging because the uncertain QoS values and uncertain user preference make data aggregation and decision making hard. This paper presents a novel Uncertain multiattribute decision making-based semantic web service composition algorithm （UMC） to solve the above difficulties for the first time. UMC takes all possible QoS expression types （real number, interval and linguistic） into consideration and includes three main steps： defuzzifying linguistic data, normalizing the decision matrix and evaluating alternatives synthetically. Further, the strategies of uncertain preference conversion are also discussed in UMC. Other contributions of the paper include an extensible QoS ontology to express the relative concepts, a QoS aggregation algorithm and a set of experiments that demonstrate the effectiveness and benefits of our approach.     

Wireless Body Area Networks for Pervasive Healthcare and Smart Environments

Wireless body area networks(WBANs)use RF communication for interconnection of tiny sensor nodes located in,on,or in close proximity to the human body.A WBAN enables physiological signals,physical activity,and body position to be continuously monitored.Designing a WBAN is challenging because of the limited energy that a WBAN can consume and the limited processing capabilities of sensor nodes.Also,the radio communication environment is highly variable and prone to interference.Recent ad-     

A User-Centric Approach for Personalized Service Provisioning in Pervasive Environments

The vision of pervasive environments is being realized more than ever with the proliferation of services and computing resources located in our surrounding environments. Identifying those services that deserve the attention of the user is becoming an increasingly-challenging task. In this paper, we present an adaptive multi-criteria decision making mechanism for recommending relevant services to the mobile user. In this context, “Relevance” is determined based on a user-centric approach that combines both the reputation of the service, the user’s current context, the user’s profile, as well as a record of the history of recommendations. Our decision making mechanism is adaptive in the sense that it is able to cope with users’ contexts that are changing and drifts in the users’ interests, while it simultaneously can track the reputations of services, and suppress repetitive notifications based on the history of the recommendations. The paper also includes some brief but comprehensive results concerning the task of tracking service reputations by analyzing and comprehending Word-of-Mouth communications, as well as by suppressing repetitive notifications. We believe that our architecture presents a significant contribution towards realizing intelligent and personalized service provisioning in pervasive environments.     

基于时序约束分解的QoS感知的Web服务组合

基于时序约束的QoS感知的Web服务组合(TC-QSC)问题是在考虑时序约束的基础上寻找满足QoS约束或效用最大化的Web服务组合问题,受到了越来越多的关注.本文提出了一种时序约束分解方法,把施加于整个或部分工作流的时序约束分解为施加于每个活动的局部时序约束,从而将TC-QSC问题转换为一般的QoS感知的Web服务组合(QSC)问题,并通过过滤不满足局部时序约束的候选服务,一定程度上减小原问题的规模.这种时序约束分解过程主要依赖于工作流及其涉及的活动,而与各活动的候选服务关联不大,复杂度较低.实验测试了该方法的效果与时间开销,验证了其对于局部优选算法的必要性.     

Wireless Location Tracking Algorithms for Environments with Insufficient Signal Sources

Location estimation and tracking for the mobile devices have attracted a significant amount of attention in recent years. The network-based location estimation schemes have been widely adopted based on the radio signals between the mobile device and the base stations. The location estimators associated with the Kalman filtering techniques are exploited to both acquire location estimation and trajectory tracking for the mobile devices. However, most of the existing schemes become inapplicable for location tracking due to the deficiency of signal sources. In this paper, two predictive location tracking algorithms are proposed to alleviate this problem. The Predictive Location Tracking (PLT) scheme utilizes the predictive information obtained from the Kalman filter in order to provide the additional signal inputs for the location estimator. Furthermore, the Geometric-assisted PLT (GPLT) scheme incorporates the Geometric Dilution of Precision (GDOP) information into the algorithm design. Persistent accuracy for location tracking can be achieved by adopting the proposed GPLT scheme, especially with inadequate signal sources. Numerical results demonstrate that the GPLT algorithm can achieve better precision in comparison with other network-based location tracking schemes.     

基于ASM的普适环境下的服务动态组合

在综合研究已有的服务组合的各种方案的基础上,采用层次结构的服务组合框架,同时利用回溯树进行服务的动态组合,最后用ASM建立一个普适环境下服务动态组合的基础模型并对其进行精化,同时通过CoreASM对该模型进行模拟执行验证.     

QSynth-TopK:一个支持Top K查询的质量敏感的自动服务组合系统

质量敏感的自动服务组合旨在根据用户的输入输出请求和服务质量约束,从海量的Web服务中快速搜索满足要求的最优组合方案,能够有效应用于服务组合辅助建模、正确性校验等领域.为了向用户提供更多的组合方案,以满足多样化的应用需求,并消除由于集中选择最优方案所带来的性能瓶颈隐患,我们在QSynth系统的基础上开发了一个支持top k查询的系统——QSynth-TopK.该系统通过对最优组合方案中的服务进行迭代地替换,实现全局服务质量的有序递减,以得到组合质量排名前k个的服务组合方案.理论证明该算法具有可靠的精确性,实验证明系统在大规模服务集上有着良好的、稳定的运行效率.     

Mobile IP-Based Protocol for Wireless Personal Area Networks in Critical Environments

Low-power Wireless Personal Area Networks (LoWPANs) are still in their early stage of development, but the range of conceivable usage scenarios and applications is tremendous. That range is extended by its inclusion in Internet with IPv6 Low-Power Personal Area Networks (6LoWPANs). This makes it obvious that multi-technology topologies, security and mobility support will be prevalent in 6LoWPAN. Mobility based communication increases the connectivity, and allows extending and adapting LoWPANs to changes in their location and environment infrastructure. However, the required mobility is heavily dependent on the individual service scenario and the LoWPAN architecture. In this context, an optimized solution is proposed for critical applications, such as military, fire rescue or healthcare, where people need to frequently change their position. Our scenario is health monitoring in an oil refinery where many obstacles have been found to the effective use of LoWPANs in these scenarios, mainly due to transmission medium features i.e. high losses, high latency and low reliability. Therefore, it is very difficult to provide continuous health monitoring with such stringent requirements on mobility. In this paper, a paradigm is proposed for mobility over 6LoWPAN for critical environments. On the one hand the intra-mobility is supported by GinMAC, which is an extension of IEEE 802.15.4 to support a topology control algorithm, which offers intra-mobility transparently, and Movement Direction Determination (MDD) of the Mobile Node (MN). On the other hand, the inter-mobility is based on pre-set-up of the network parameters in the visited networks, such as Care of Address and channel, to reach a fast and smooth handoff. Pre-set-up is reached since MDD allows discovering the next 6LoWPAN network towards which MN is moving. The proposed approach has been simulated, prototyped, evaluated, and is being studied in a scenario of wearable physiological monitoring in hazardous industrial areas, specifically oil refineries, in the scope of the GinSeng European project.     

WiSE: Best-Path Selection in Wireless Multihoming Environments

This paper introduces WiSE, a sender-side, transport-layer protocol that modifies the standard SCTP protocol. WiSE aims at exploiting SCTP's multihoming capabilities by selecting in real time the best choice among available, alternate paths to the same destination. Through the use of bandwidth estimation techniques, WiSE tries to infer whether losses are due to congestion or to radio channel errors. At the same time, the available bandwidth of the current path used for transmission is matched to that of an alternate path, also probed for available bandwidth. If the current path is severely congested and the alternate path is lightly loaded, WiSE switches the transmission onto the alternate path using SCTP's flexible path management capabilities. Extensive simulations under different scenarios highlight the superiority of the proposed solution with respect to TCP and the standard SCTP implementation.     

移动无线传感器网络中节点自定位算法研究

移动无线传感器网络(MWSN)是一种全新的信息获取和处理技术,可以在广泛的应用领域内实现复杂的大规模监测和追踪任务,而移动节点的位置信息则是其应用的基础。针对这一特征,文章深入探讨了移动节点自定位算法的研究现状,介绍了移动无线传感器网络节点定位的基本方法,讨论了定位算法的性能评价指标,并对各种算法性能进行了比较,最后指出了算法存在的问题和解决办法。文章认为三维全节点移动的定位算法将成为以后的研究趋势。     

基于扇区化的OFDM小区选择算法

首先给出了一种基于扇区化（Sectorizing）技术的OFDM蜂窝模型。该蜂窝模型利用定向天线的方向性特点,通过在小区内合理地分配频谱资源,减轻小区间的同频干扰,提高基站和移动终端间传输信号的载干比,从而提高网络总容量。然后将两种应用于全向天线蜂窝网络中的基于下行链路的小区选择模型应用在了该模型上,并通过仿真给出了性能分析结果。     

QoS-Aware Service Discovery and Selection Management for Cloud-Edge Computing Using a Hybrid Meta-Heuristic Algorithm in IoT

Wireless Personal Communications - Cloud-edge computing is an emerging computing model based on Service Oriented Architecture that provides reliable and available cloud services as scalable...     

A Novel GPS-free Method for Mobile Unit Global Positioning in Outdoor Wireless Environments

This paper investigates a Global Positioning system (GPS)-free positioning method for mobile units (MUs) in outdoor wireless environments by using the Bayesian filtering formulation. The procedure utilizes simulated inertial measurements, cell-ID of the serving base station, and pre-determined locations grouped according to cell antennas radio coverage in the experimentation area. The developed algorithm makes no assumptions on the initial position of the MU. However, the algorithm takes some time to converge. Experiments show the range of inertial measurement errors that would maintain reliable location information with accuracy comparable to GPS positioning.

A New Equalization Algorithms for Distortion Signal Extraction in Mobile Wireless System

In the high-speed mobile wideband communication system, motions of receivers, transmitters or wireless environments generate Doppler frequency. The Doppler effect and instantaneous fading frequency induces serious waveform distortion in the received signal. To solve these problems, the paper presents an improved equalization model, the new model combines the Bayesian detector and decision feedback equalizer (DFE) to form a new effective BDFE structure, which is superior to traditional equalization structure in the mobile environment. Further, a new algorithm is given to achieve faster convergence and smaller steady-state error, the new algorithm take Marr function as a basis function, and two parameters shape the profile of function, with the simulation tool, the optimization values are obtained for the new model and algorithm. The experimental results show that the new algorithm can improve the output SNR up to 6 dB gain with the new BDFE model.     

BIONETS: Bio-Inspired Networking for Pervasive Communication Environments

This paper presents BIONETS, which is a novel bio-inspired approach to the design of localized services in pervasive communication/computing environments. Conventional networking approaches are not suitable for such scenarios, where they face three main issues, namely: 1) heterogeneity, 2) scalability, and 3) complexity. The proposed solution draws inspiration from the living world in terms of 1) evolutionary paradigms able to drive the adaptation process of autonomic services and 2) social paradigms for the provisioning of the necessary cooperation mechanisms. The net result is the introduction of autonomic self-evolving services that are able to adapt to localized needs and conditions while ensuring the maintenance of a purposeful system. Such a system requires scalable support from the communication standpoint. In networking terms, this results in the introduction of a two-tier architecture based on localized opportunistic exchanges of information. The presented approach is able to achieve better scalability properties when compared to more conventional communication approaches