Hanping Lufei

e-QoS: energy-aware QoS for application sessions across multiple protocol domains in mobile computing

In this paper we propose a novel energy-aware QoS model, e-QoS, for application sessions that might across multiple protocol domains. The model provides the QoS guarantee by dynamically selecting and adapting application protocols. To the best of our knowledge, our model is the first attempt to address QoS adaptation at the application session level by proposing a new QoS metric called session lifetime. To show the effectiveness of the proposed scheme, we have implemented a case study: instant messenger applications between two PocketPCs. Experiment shows that the session lifetime has been successfully extended to the value negotiated by two PocketPCs with very diverse battery capacities.

Fractal: a mobile code based framework for dynamic application protocol adaptation in pervasive computing

The rapid growth of heterogeneous devices and diverse networks in our daily life, makes it is very difficult, if not impossible, to build a one-size-fits-all application or protocol, which can run well in such a dynamic environment. Adaptation has been considered as a general approach to address the mismatch problem between clients and servers; however, we envision that the missing part, which is also a big challenge, is how to inject and deploy adaptation functionality into the environment. In this paper we propose a novel application level protocol adaptation framework, Fractal, which uses the mobile code technology for protocol adaptation and leverages existing content distribution networks (CDN) for protocol adaptors (mobile codes) deployment. To the best of our knowledge, Fractal is the first application level protocol adaptation framework that considers the real deployment problem using mobile code and content distribution networks. To evaluate the proposed framework, we implement an adaptive communication optimization protocol by dynamically selecting four communication protocols, including Direct sending, Gzip, Bitmap, and Vary-sized blocking. In the comparison with the static and centralized protocol adaptation approaches, evaluation shows good results on both the client side and server side. For some clients, the total communication overhead reduces 41% compared with no protocol adaptation mechanism, and 14% compared with the static protocol adaptation approach.

On the effects of bandwidth reduction techniques in distributed applications

Communication optimization plays an important role in building networked distributed applications. In this paper, we systematically evaluate four bandwidth reduction algorithms, namely direct sending, delta-encoding, fix-sized blocking, and vary-sized blocking, using five types of documents including source code, images, Web contents, Microsoft Word documents, and Latex files. The experiments were performed under four representative network connection technologies. Performance evaluation results show that different approaches have different performance in terms of different metrics. Completely different results can be achieved by the same algorithm with respect to different types of documents. Network condition can affect some algorithms substantially. Furthermore, the effect of block size to the system performance (for block-based algorithms) was also studied.

Towards Ubiquitous Access of Computer-Assisted Surgery Systems

Traditional stand-alone computer-assisted surgery (CAS) systems impede the ubiquitous and simultaneous access by multiple users. With advances in computing and networking technologies, ubiquitous access to CAS systems becomes possi ble and promising. Based on our preliminary work, CASMIL, a stand-alone CAS server developed at Wayne State University, we propose a novel mobile CAS system, UbiCAS, which allows surgeons to retrieve, review and interpret multimodal medical images, and to perform some critical neurosurgical procedures on heterogeneous devices from anywhere at anytime. Fur thermore, various optimization techniques, including caching, prefetching, pseudo-streaming-model, and compression, are used to guarantee the QoS of the UbiCAS system. UbiCAS enables doctors at remote locations to actively participate remote surgeries, share patient information in real time before, during, and after the surgery

Fractal: a mobile code-based framework for dynamic application protocol adaptation

The rapid growth of heterogeneous devices and diverse networks in our daily life, makes it is very difficult, if not impossible, to build a one-size-fits-all application or protocol, which can run well in such a dynamic environment. Adaptation has been considered as a general approach to address the mismatch problem between clients and servers; however, we envision that the missing part, which is also a big challenge, is how to inject and deploy adaptation functionality into the environment. In this paper we propose a novel application level protocol adaptation framework, Fractal, which uses the mobile code technology for protocol adaptation and leverages existing content distribution networks (CDN) for protocol adaptors (mobile codes) deployment. To the best of our knowledge, Fractal is the first application level protocol adaptation framework that considers the real deployment problem using mobile code and CDN. To evaluate the proposed framework, we have implemented two case studies: an adaptive message encryption protocol and an adaptive communication optimization protocol. In the adaptive message encryption protocol, Fractal always chooses a proper encryption algorithm according to different application requirements and device characteristics. And the adaptive communication optimization protocol is capable of dynamically selecting the best one from four communication protocols, including Direct sending, Gzip, Bitmap, and Vary-sized blocking, for different hardware and network configurations. In comparison with other adaptation approaches, evaluation results show the proposed adaptive approach performs very well on both the client side and server side. For some clients, the total communication overhead reduces 41% compared with no protocol adaptation mechanism, and 14% compared with the static protocol adaptation approach.

An Adaptive Encryption Protocol in Mobile Computing

Use of encryption for secure communication plays an important role in building applications in mobile computing environments. With the emergence of more and more heterogeneous devices and diverse networks, it is difficult, if not impossible, to use a one-size-fits-all encryption algorithm that always has the best performance in such a dynamic environment. We envision that the only way to accelerate the deployment of encryption algorithms is providing a flexible adaptation of choosing an appropriate encryption algorithm from multiple diverse algorithms according to the characteristics of heterogeneous mobile computing environments.

Energy-aware QoS for application sessions across multiple protocol domains in mobile computing

The proliferation of heterogeneous devices and diverse networking technologies demands flexible models to guarantee the quality-of-service (QoS) at the application session level, which is a common behavior of many network-centric applications, e.g., Web browsing and Instant messaging. Several QoS models have been proposed for heterogeneous wired/wireless environments. However, we envision that the missing part, which is also a big challenge, is taking energy, a scarce resource for mobile and energy-constrained devices, into consideration. In this paper we propose a novel energy-aware QoS model, e-QoS, for application sessions that might across multiple protocol domains, which will be common in the future Internet, rather than an exception. The model provides QoS guarantee by dynamically selecting and adapting application protocols. To the best of our knowledge, our model is the first attempt to address QoS adaptation at the application session level by introducing a new QoS metric called session lifetime. To show the effectiveness of the proposed scheme, we have implemented two case studies: Web browsing from a Pocket PC to a regular Web server, and an instant messaging application between two Pocket PCs. In the former case study, our approach outperforms the conventional approach without energy-aware QoS by more than 30% in terms of the session lifetime. In the second case study, we also successfully extend the session lifetime to the value negotiated by two Pocket PCs with very diverse battery capacities.

M-CASEngine: A collaborative environment for computer-assisted surgery

Most computer-assisted surgery systems are an isolated standalone system in the operation room with obtrusive and cumbersome wired connections. Surgery data preparation, registration, segmentation, planning, etc. have to be running at one place. Dynamic data acquisition and cooperation during the surgical procedure is not currently possible. We develop the M-CASEngine system which provides a distributed collaborative environment for computer-assisted surgery. It enables the doctors to access and plan the surgery, and actively participate in remote surgeries, share patient information and exchange opinions in real time from anywhere at any time. By utilizing cutting-edge network technologies, the system greatly improves the overall performance of computer-assisted surgery.Linking top-level ontologies and surgical workflows O. Burgert Æ T. Neumuth Æ F. Lempp Æ R. Mudunuri Æ J. Meixensberger Æ G. Strauß Æ A. Dietz Æ P. Jannin Æ H.U. Lemke Innovation Center Computer Assisted Surgery (ICCAS), Leipzig, Germany University Hospital Leipzig, Department of Neurosurgery, Germany University Hospital Leipzig, ENT-Department/Plastic Surgery, Germany University of Rennes, Visages-U746 INSERM, INRIA, France Abstract Surgical Workflows describe the course of surgical interventions Since they are an abstraction from reality one needs unambiguous description of the single items and actions – concepts and relationships – involved in the surgical intervention. Furthermore, for computer aided analysis of surgical workflows, abstractions and relations are needed. These should be comparable between different workflows and surgical disciplines. An ontology can provide an abstract view of the world one wants to represent by using an explicit and formal description. This paper introduces an upper-levelontology based on GOL (General Ontological Language) for representing surgical interventions.

Secure Application-Aware Service Differentiation in Public Area Wireless Networks

We are witnessing the increasing demand for pervasive Internet access from public area wireless networks (PAWNs). As their popularity grows, the inherent untrusted nature of public places and the diverse service requirements of end users are two key issues that need to be addressed. We have proposed two approaches to address these issues. First, the Home-based Authentication Protocol (HAP) that provides a framework by which to establish trust between a nomadic client and a service provider using a trusted third party (home). Second, we argue that the best-effort-based service model provided by many access points is not enough to satisfy the end user fairness and to maximize the wireless link utilization for a diverse user population. We have proposed an application-aware service differentiation (AASD) mechanism that takes both application semantics and user requirements into consideration. Our analysis of this framework shows several fruitful results. The total authentication latency increases with the number of clients but at a rate that is much less than linear increasing latency. Also, in comparison with two other bandwidth allocation approaches, the best effort and static access control, our proposed application-aware service differentiation method, outperforms them in terms of the client fairness and wireless bandwidth utilization.

Application-aware service differentiation in PAWNs

We have witnessed the increasing demand for pervasive Internet access from public area wireless networks (PAWNs). The diverse service requirements from end users necessitate an efficient service differentiation mechanism, which should satisfy two goals: end-user fairness and maximizing the utilization of wireless link. However, we found that the existing best-effort based service model is not enough to satisfy either goal. We have proposed an application-aware service differentiation mechanism which takes both application semantics and user requirements into consideration. The results show that our proposed method outperforms two other bandwidth allocation approaches, best effort and static allocation, in terms of both client fairness and wireless link bandwidth utilization, especially in heavy load environments.