Mid Sweden University

Users require applications and services to be available everywhere, enabling users to focus on what is important to them. Therefore, context information from users (e.g., spatial data, preferences, available connectivity and devices, etc.) needs to be accessible to systems that deliver services via a heterogeneous infrastructure. We present a novel approach to support ubiquitous sensing and availability of context to services and applications. This approach offers a scalable, distributed storage of context derived from sensor networks wirelessly attached to mobile phones and other devices. The support handles frequent updates of sensor information and is interoperable with presence services in 3G mobile systems, thus enabling ubiquitous sensing applications. We demonstrate these concepts and the principle operation in a sample ubiquitous mobile awareness service. The importance of this contribution, in comparison to earlier work, lies in the availability of real-time ubiquitous sensing to both applications on the Internet as well as applications in mobile systems.

Context-aware applications and services require ubiquitous access to context information about the users or sensors such as preferences, spatial & environmental data, available connectivity, and device capabilities. Systems for the brokering or the provisioning of context data via wireless networks do so with centralized servers or by employing protocols that do not scale well with real-time distribution capabilities. In other cases, such as the extending of presence systems, the data models are limited in expressive capabilities and consequently incur unnecessary signaling overhead. This paper presents a distributed protocol, the Distributed Context eXchange Protocol (DCXP), and an architecture for the real-time distribution of context information to ubiquitous mobile services: We present the architecture and its principle operation in a sample ubiquitous mobile awareness service. Preliminary results indicate that our approach scales well for the ubiquitous provision of context data in real-time to clients on the Internet via 3G wireless systems. Performed measurements show that DCXP can reduce the time to process context data with a factor of 20 compared to similar approaches.

Mobile telecommunication is evolving rapidly. People no longer only communicate with each other regardless of time and place, but also share other information that is important for tasks with which they are involved. In response to this growing trend the MediaSense framework addresses the intelligent delivery of any information to any host, anywhere, based on context-aware information regarding personal preferences, presence information, and sensor values. This includes another challenge to achieve seamless delivery, especially of multimedia content, and multimodal services via heterogeneous connections.

Users require applications and services to be available everywhere,enabling them to focus on what is important to them. Therefore, contextinformation (e.g., spatial data, user preferences, available connectivity anddevices, etc.) has to be accessible to applications that run in end systems closeto users. In response to this, we present a novel architecture for ubiquitoussensing and sharing of context in mobile services and applications. Thearchitecture offers distributed storage of context derived from sensor networkswirelessly attached to mobile phones and other devices. The architecture alsohandles frequent updates of sensor information and is interoperable withpresence in 3G mobile systems, thus enabling ubiquitous sensing applications.We demonstrate these concepts and the principle operation in a sampleubiquitous Mobile Awareness service.

Wireless sensor network is remarkable for its promising use on human-unattended information collection, such as forest fire monitoring. In order to support efficient communication, many routing algorithms specially designed for such networks have been proposed. However, there is no idea about whether these proposed routing algorithms are already good enough or still have a long way to become “perfect”, since there is currently a lack of understanding about the optimal routing performance. This paper makes a progress in the understanding of the optimal routing performance. Metrics here used to measure the routing performance are the network lifetime finally acquired and the total information finally collected. The condition used to judge the network’s death is defined by the user’s requirement on the guaranteed network information collecting ability. Optimization models based on the metrics and death condition mentioned above are proposed. Experiments show some existing routing proposals already work well when the user’s requirement is strict, but few of them satisfy when the user’s requirement is loose.

Traditionally, Group of Pictures (GOP) is used to solve IPTV channel tune-in issues. However, channel changes issued by a TV viewer are quite rare which indicates it is redundant to solve channel tune-in with GOP. In this paper we extend our earlier work on Synchronization Frames for Channel Switching (SFCS) for reducing bandwidth utilization in IPTV networks to include encoding/decoding standards not supporting SI/SP-frames. We propose modifications to SFCS to work with MPEG-2. Channel tune-in quality and synchronization stream generation is also addressed. We provide bandwidth estimation expressions which are verified with an experimental simulation. Results show that SFCS adapted to MPEG-2 can reduce the bandwidth utilization with 9% compared to a traditional GOP system with equal steady state quality.

A secure multicast downstream authentication protocol in sensor network: we develop a authentication protocol for sensor networks where the transmitted data is protected by algorithms� for privacy and authentication

Wireless sensor networks have maily been designed for information-collecting purposes, such as habitat monitoring, product process tracing, battlefield surveillance, etc. In order to support efficient communications for such networks, many routing protocols have been proposed. However, protocol designs are out-pacing formal analysis. We propose an optimization model in this paper to bound the routing performance in terms of network information collection. We first argue that a network can only be given a death sentence when it fails to satisfy the application's requirement and propose a more reasonable network lifetime definition. Then, the optimization model concerning maximizing information collection routing is presented based on this new network lifetime definition. Existing typical routing algorithms: MH, MTE, FA and MREP are simulated as references to validate the model proposed. Results show our model can provide a tight upper bound and thus can be used to evaluate existing and up-coming routing algorithms.

In this paper, a novel proposal regarding the transmission of the next generation of live-TV content in an IPTV environment is presented. Today live-TV IP transmission systems utilizes a Group Of Pictures (GOP) structure in order to provide stream synchronization points for the clients. Synchronization points are used when a TV-channel switch occurs. The number of channel switches made by TV audiences have been shown to be rather rare. It is therefore redundant to send synchronization events in a GOP manner. Our proposal, Synchronization Frames for Channel Switching (SFCS), only requests synchronization points when required. Due to channel popularity distributions and the number of connected users, the total number of synchronization requests for a popular channel can increase to a level that makes SFCS less effective than GOP. Therefore, we introduce an SFCS-GOP hybrid. A complete network traffic analysis model, verified by a simple simulation environment, is also presented and the results show that the SFCS-GOP hybrid significantly increases the bandwidth utilization compared to a traditional GOP system