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It is well-known that placing disks in the triangular lattice pattern is optimal for achieving full coverage on a plane. With the emergence of wireless sensor networks, however, it is now no longer enough to consider coverage alone when deploying a wireless sensor network; connectivity must also be con-sidered. While moderate loss in coverage can be(More)
Falls are a major health risk that diminish the quality of life among elderly people. With the elderly population surging, especially with aging “baby boomers”, fall detection becomes increasingly important. However, existing commercial products and academic solutions struggle to achieve pervasive fall detection. In this paper, we propose(More)
Falls are a major health risk that diminishes the quality of life among the elderly people. The importance of fall detection increases as the elderly population surges, especially with aging “baby boomers”. However, existing commercial products and academic solutions all fall short of pervasive fall detection. In this paper, we propose utilizing mobile(More)
In this paper, we study the issue of mobility based sensor networks deployment. The distinguishing feature of our work is that the sensors in our model have limited mobilities. More specifically, the mobility in the sensors we consider is restricted to a flip, where the distance of the flip is bounded. Given an initial deployment of sensors in a field, our(More)
We study the issue of optimal deployment to achieve four connectivity and full coverage for wireless sensor networks (WSNs) under different ratios of sensors' communication range (denoted by r<sub>c</sub>) to their sensing range (denoted by r<sub>s</sub>). We propose a "Diamond" pattern, which can be viewed as a series of different evolving patterns. When(More)
In this paper, we propose deployment patterns to achieve full coverage and three-connectivity, and full coverage and five-connectivity under different ratios of sensor communication range (denoted by R<sub>c</sub>) over sensing range (denoted by R<sub>s</sub>) for wireless sensor networks (WSNs). We also discover that there exists a hexagon-based(More)
An important phase of sensor networks operation is deployment of sensors in the field of interest. Critical goals during sensor networks deployment include coverage, connectivity, load balancing, etc. A class of work has recently appeared, where mobility in sensors is leveraged to meet deployment objectives. In this paper, we study deployment of sensor(More)
In this paper, we study deployment patterns to achieve full coverage and <i>k</i>-connectivity (<i>k</i> &#8804; 6) under different ratios of the sensor communication range (denoted by <i>R<inf>c</inf></i>) to the sensing range (denoted by <i>R<inf>s</inf></i>) for homogeneous wireless sensor networks (WSNs). In particular, we propose new patterns for 3-(More)
In this paper, we propose E-Shadow, a distributed mobile phone-based local social networking system. E-Shadow has two main components: (1) Local profiles. They enable EShadow users to record and share their names, interests, and other information with fine-grained privacy controls. (2) Mobile phone based local social interaction tools. E-Shadow provides(More)
Security in mobile ad-hoc networks (MANETs) continues to attract attention after years of research. Recent advances in identity-based cryptography (IBC) sheds light on this problem and has become popular as a solution base. We present a comprehensive picture and capture the state of the art of IBC security applications in MANETs based on a survey of(More)