308 research outputs found

    SSR : Segment-by-Segment Routing in large-scale mobile ad hoc networks

    Get PDF
    2006-2007 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

    Connectivity, Coverage and Placement in Wireless Sensor Networks

    Get PDF
    Wireless communication between sensors allows the formation of flexible sensor networks, which can be deployed rapidly over wide or inaccessible areas. However, the need to gather data from all sensors in the network imposes constraints on the distances between sensors. This survey describes the state of the art in techniques for determining the minimum density and optimal locations of relay nodes and ordinary sensors to ensure connectivity, subject to various degrees of uncertainty in the locations of the nodes

    Minimum Throughput Maximization for Multi-UAV Enabled WPCN: A Deep Reinforcement Learning Method

    Get PDF
    This paper investigates joint unmanned aerial vehicle (UAV) trajectory planning and time resource allocation for minimum throughput maximization in a multiple UAV-enabled wireless powered communication network (WPCN). In particular, the UAVs perform as base stations (BS) to broadcast energy signals in the downlink to charge IoT devices, while the IoT devices send their independent information in the uplink by utilizing the collected energy. The formulated throughput optimization problem which involves joint optimization of 3D path design and channel resource assignment with the constraint of flight speed of UAVs and uplink transmit power of IoT devices, is not convex and thus is extremely difficult to solve directly. We take advantage of the multi-agent deep Q learning (DQL) strategy and propose a novel algorithm to tackle this problem. Simulation results indicate that the proposed DQL-based algorithm significantly improve performance gain in terms of minimum throughput maximization compared with the conventional WPCN scheme

    The Industrial Organization of Hong Kong's Progression Toward a Cashless Economy (1960s-2000s)

    Get PDF
    A dramatic change occurred in retail banking technology in Hong Kong between 1960 and 2000. Initially, the relevant technologies were installed and managed within the boundaries of large banks, such as HSBC. Over the course of this period, however, the industrial organization of the relevant technologies transformed to include provisions outsourced to nonbank institutions. This article seeks to account for this shift in the organization of computer technology. Specifically, the authors compare the adoption of computers at HSBC in the 1960s and 1970s with the Octopus micropayment system, which was developed in the 1990s by a consortium that excluded financial firms, thanks to the development (both in terms of depth and breadth) of an epistemic community of computer professionals and computer-literate managers in Hong Kong

    Energy-Efficient {WSN} Infrastructure

    No full text
    International audienceEnergy conserving communication is one of the main challenges of wireless sensor networks. A number of studies and research are focused on saving energy and on extending the lifetime of these networks. Architectural approaches, like hierarchical structures, tend to organize network nodes in order to save energy. Most of these protocols need background information on the network in order to be efficient. In this paper, we describe a new approach for organizing large sensor networks into zones, based on the number of hops. This network architecture enables a hierarchical network view, with the purpose of offering efficient routing protocols based on zone partitioning. Simulations undertaken demonstrate that our approach is energy-efficient; this is highlighted by the reduction of traffic overhead

    Information Granulation for the Design of Granular Information Retrieval Systems

    Get PDF
    With the explosive growth of the amount of information stored on computer networks such as the Internet, it is increasingly more difficult for information seekers to retrieve relevant information. Traditional document ranking functions employed by Internet search engines can be enhanced to improve the effectiveness of information retrieval (IR). This paper illustrates the design and development of a granular IR system to facilitate domain specific search. In particular, a novel computational model is designed to rank documents according the searchers’ specific granularity requirements. The initial experiments confirm that our granular IR system outperforms a classical vector-based IR system. In addition, user-based evaluations also demonstrate that our granular IR system is effective when compared with a well-known Internet search engine. Our research work opens the door to the design and development of the next generation of Internet search engines to alleviate the problem of information overload

    Overlay virtualized wireless sensor networks for application in industrial internet of things : a review

    Get PDF
    Abstract: In recent times, Wireless Sensor Networks (WSNs) are broadly applied in the Industrial Internet of Things (IIoT) in order to enhance the productivity and efficiency of existing and prospective manufacturing industries. In particular, an area of interest that concerns the use of WSNs in IIoT is the concept of sensor network virtualization and overlay networks. Both network virtualization and overlay networks are considered contemporary because they provide the capacity to create services and applications at the edge of existing virtual networks without changing the underlying infrastructure. This capability makes both network virtualization and overlay network services highly beneficial, particularly for the dynamic needs of IIoT based applications such as in smart industry applications, smart city, and smart home applications. Consequently, the study of both WSN virtualization and overlay networks has become highly patronized in the literature, leading to the growth and maturity of the research area. In line with this growth, this paper provides a review of the development made thus far concerning virtualized sensor networks, with emphasis on the application of overlay networks in IIoT. Principally, the process of virtualization in WSN is discussed along with its importance in IIoT applications. Different challenges in WSN are also presented along with possible solutions given by the use of virtualized WSNs. Further details are also presented concerning the use of overlay networks as the next step to supporting virtualization in shared sensor networks. Our discussion closes with an exposition of the existing challenges in the use of virtualized WSN for IIoT applications. In general, because overlay networks will be contributory to the future development and advancement of smart industrial and smart city applications, this review may be considered by researchers as a reference point for those particularly interested in the study of this growing field
    corecore