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In this paper, we explicitly consider the scenario of supporting applications with high-bandwidth and low-latency requirements in mobile social networks (MSNs), by leveraging the existing social network sites. Our solution does not assume any centralized server who coordinates the data storage, access, and group management. We address the fundamental challenge supporting such applications, namely: the limited bandwidth availability and intense bandwidth requirement that may hinder the deployment of these applications. We propose a link-based congestion management (LCM) mechanism to adjust the source rate of each stream, and a prioritized flow management mechanism composed of a novel concept of “stress weight” and its associated utility function. Extensive simulation results show that our proposal achieves 50% less rate reduction under the severe congestions, and the achievable source rate of the proposed LCM scheme is over one order of magnitude higher than the alternative approach.

In this paper, we present “HealthKiosk”, a family-based healthcare system, to provide rich contextual information and alerting mechanisms for continuous monitoring of health conditions. HealthKiosk significantly improves the reach and quality of regional and community healthcare services, and could potentially minimize the efforts of care professionals for the chronical illness, not only applicable for the elderly but also children and young fitness trainers. The proposed architecture leverages the RESTful design style, nevertheless introducing a novel development of the “sensor proxy”, both in a stationary PC style and as a mobile widget. The sensor proxy behaves not only as a bridge between the raw sensor readings and the kiosk controller, but also as a data processing logic to integrate, correlate, and transform a variety of data from multiple data sources to an integrated XML format. We demonstrate the system performance by showing two complete case studies for both stationary and mobile sensor proxies used in the developed HealthKiosk system. Finally, the proposed solution has been piloted and deployed at the Peking University People's Hospital (PKUPH) for diabetes patients, via building an evidence-based clinical care solution focusing on chronic disease management in China.

In this paper, we propose an efficient energy-management framework in wireless sensor networks (WSNs) to address the fundamental research challenge imposed by both the maintenance of the energy supply and the support of the quality-of-information (QoI) requirements. By quantifying the QoI benefit the tasks receive in relation to the level of QoI they request as the QoI satisfaction index), we propose a QoI-aware energy-management scheme to distributedly decide the participating state of each sensor. Specifically, by using the mathematical framework of the Gur Game, we propose a novel pay-off structure taking into account the QoI and the energy consumption. We finally evaluate the proposed scheme under an event occurrence detection scenario, where the proposed scheme successfully guarantees less than 7% QoI outage, saves 80% of the energy reserve if compared with the lower bound solution, and achieves the suboptimum with only 4% gap if compared with optimal solution.

This paper considers the novel area of quality-of-information (QoI)-aware network management of multitasking wireless sensor networks (WSNs). Specifically, it provides an investigation of new task admission and resource utilization mechanisms for controlling the individual QoI provided to new and existing tasks using real-time feedback-based monitoring mechanisms. The paper describes three key design elements in support of the above: (a) the QoI satisfaction index of a task, which quantifies the degree to which the required QoI is satisfied by the WSN; (b) the QoI network capacity, which expresses the ability of the WSN to host a new task with specific QoI requirements without sacrificing the attained QoI levels of other existing tasks, and (c) an adaptive, negotiation-based admission control mechanism that reconfigures and optimizes the usage of network resources in order to optimally accommodate the QoI requirements of all tasks. Finally, extensive results are presented for assessing the performance of the proposed solution for the case of an intruder detection application scenario.

Controlled mobile helper nodes called data ferries have recently been proposed to bridge communications between disconnected nodes in a delay-tolerant manner. While existing work has explored various trajectory designs for the data ferry by assuming either static nodes or full observations at the data ferry, the problem remains open when the nodes are mobile and the ferry only has partial observations. In this paper, we investigate the problem of dynamic ferry mobility control under limited-range sensing. Assuming the data ferries are capable of sensing node presence within certain range and adjust their movements dynamically, we aim to design control policies that maximize the number of effective contacts. We provide a comprehensive model of the control framework using Partially Observable Markov Decision Process (POMDP), based on which we study the structure of the optimal policy and propose an efficient heuristic policy which shows significant improvement over the predetermined benchmark. To the best of our knowledge, this is the first data ferry control mechanism that can handle both stochastic node mobility and incomplete ferry observations.

In this paper, a novel mission-oriented sensor network architecture for military applications is proposed involving multiple sensing missions with varying quality of information (QoI) requirements. A new concept of mission QoI satisfaction index indicating the degree of satisfaction for any mission in the network is introduced. Furthermore, the 5WH (why, when, where, what, who, how) principle on the operational context of information is extended to capture the changes of QoI satisfaction indexes for mission admission and completion. These allow modeling the whole network as a "black box". With system inputs including the QoI requirements of the existing and newly arriving missions and output the QoI satisfaction index, the new concept of sensor network capacity is introduced and mathematically described. The QoI-centric sensor network capacity is a key element of the proposed architecture and aids controlling of admission of newly arriving missions in accordance with the QoI needs of all (existing and newly admitted missions). Finally, the proposed architecture and its key design parameters are illustrated through an example of a sensor network deployed for detecting the presence of a hazardous, chemical material.

Wireless mesh networks (WMNs) are emerging as a promising technology for backhauling data traffic from wireless access networks to the wired Internet. Such networks are expected to support various types of applications with different quality of service (QoS) requirements. In this paper, we provide a complete cross-layer solution for WMNs together with its OPNET simulation architecture that comprises client, server and mesh router models spanning all layers from physical to application. Different TCP algorithm and techniques are implemented on top of a novel joint multi-constrained QoS routing and opportunistic scheduling scheme and their interaction and performance is evaluated through extensive simulations.

Wireless mesh networks (WMNs) are emerging as a promising technology for backhauling data tra‐c from wireless access networks to the wired Internet that expected to support various types of applications with difierent quality of service (QoS) requirements. While wireless mesh networking has attracted great industrial and academic interest, many research challenges remain in all protocol layers. Moreover, traditional layered approaches, initially designed for wired networks, have been proven insu‐cient for WMNs due to the wireless channel variability, co-channel interference and new data tra‐c peculiarities. In this work we provide a complete cross-layer solution for WMNs. Our protocol architecture framework comprises a novel joint QoS routing and opportunistic scheduling scheme that exploits the multi-user diversity gain while guarantees end-to-end packet delivery that satisfles the multiple QoS requirements of the underlying applications. On top of this, the interaction of these algorithms with the transport layer is investigated where the suitability of several techniques, such as Explicit Congestion Notiflcation, Explicit Loss Notiflcation and Explicit Rate Notiflcation is considered. In order to assess the performance of the proposed protocols, a realistic and comprehensive simulation platform for WMNs that spans all layers from physical to application has been implemented using OPNET modeler. This paper provides a detailed description of the proposed protocols and the simulation platform together with some performance evaluation results.

Multihop wireless mesh networks (WMNs) are considered a promising technology to backhaul heterogeneous data traffic from wireless access networks to the wired Internet. WMNs are expected to support various types of applications with diverse quality of service (QoS) requirements, such as end-to-end packet delay, throughput, and packet-error-rate (PER). Recent works in this area are mainly concentrated on network layer routing algorithms with QoS provisioning that unfortunately cannot cooperate efficiently with existing medium access control (MAC) solutions to strictly guarantee multiple QoS constraints. This drawback may significantly deteriorate the and-to-end network performance and end-user experience especially for delay/throughput-sensitive applications such as voice-over IP (voIP) and interactive video. In this paper, we propose a fully distributed multi-constrained QoS scheduling algorithm to overcome this disadvantage. We show by simulation that the proposed scheduling scheme can efficiently organize the resources in physical (PHY) and MAC layers to successfully increase the network goodput, decrease the end-to-end (ETE) packet delay, and achieve less QoS outage probability if compared with other protocols.

Wireless mesh networks (WMNs) is a promising key technology for next generation wireless backhauling that have recently attracted both the academic and industrial interest. Such networks are expected to have high throughput demands and support various types of applications with different quality-of-service (QoS) constraints. Opportunistic scheduling has been proven highly beneficial in such networks since it takes advantage of the dynamic nature of the channel between different wireless mesh routers. Recently a promising cross-layered framework has been proposed (IQoSR) that combines a distributed opportunistic scheduler with a multi-constrained QoS routing scheme and has been proven to outperform conventional layer 2 and 3 approaches. However, opportunistic scheduling cannot provide hard resource reservation; therefore, the admission of new flows in a route may jeopardize the QoS of the ongoing flows. In order to overcome this problem, in this work we introduce a connection admission control (CAC) scheme for different levels of QoS to efficiently manage the resources among existing and new flows. In this way, we improve the overall network performance and minimize the outage probability of the ongoing flows while we guarantee the required grade-of-service (GoS) to the underlying applications. Simulation analysis shows that the proposed scheme achieves lower blocking probability while it reduces the outage probability of the existing flows.

Cross-layer routing and scheduling algorithms design for wireless backhaul mesh network has attracted much research interest recently. The network is expected to support various types of applications with different quality of service (QoS) requirements from both routing and scheduling perspectives. Existing works do not efficiently integrate these QoS constraints in route discovery and maintenance phases and overlook the interaction between medium access control (MAC) and routing algorithms. In this work, we propose a novel cross- layer framework of QoS routing and distributed opportunistic scheduling for wireless mesh network, which provides resource reservation for QoS flows. Studies with different scheduling algorithms and routing protocols have shown that our algorithm successfully guarantees various QoS requirements and achieves higher network throughput when compared with other standard techniques.

Multiple-input-multiple-output (MIMO) transceivers can take advantage of random channel fading and multi-path delay spread for multiplying transfer rates (multiplexing gain), improve transmission quality/reliability (diversity gain) at no cost of extra spectrum, or allow the spatial separation of the signals of different transceivers in a multi-user scenario, thus providing a multiple-access gain.

An interleaved resonant converter for high voltage application is presented in this paper. There are two half-bridge legs connected in series and two split capacitors in the adopted circuit to limit the voltage stress of each active switch at one-half of input voltage. Thus MOSFETs with 600V voltage rating can be adopted for 1200V input voltage application. For each half-bridge leg, two series resonant circuits are operated with interleaved one-half of switching period. The secondary windings of two transformers are connected in series in order to balance the transformer primary currents and to share the input current. Thus the sizes of the transformer core and bobbin are reduced. The centre-tapped rectifier is used on the output side to reduce the conduction loss with one diode voltage drop. Based on the resonant behaviour, MOSFETs are turned on at ZVS, and rectifier diodes can be turned off at ZCS if the switching frequency is less than the series resonant frequency. Two half-bridge legs are operated with one-fourth of switching period such that the ripple currents at input and output sides arc reduced. Finally, experiments with a 960W prototype, verifying the effectiveness of the proposed converter, are described.