This article gives an overview of Bluetooth and Bluetooth Low Energy. Furthermore, it presents BlueTrk+, a lightweight application for tracking presence and position securely and flexibly for military-related or Disconnected, Intermittent and Limited (DIL) environments. For tracking presence, four schemes with varying security levels are presented for broadcasting identities. For tracking position, a polar coordinate-based approach is used. It involves using a radar-inspired method for estimating direction/angle and a machine learning method for estimating distance. Experimental results are presented to evaluate the positioning methods.
In recent years, there has been considerable interest in indoor positioning with the advent of smartphones. Conventional indoor positioning methods are mostly infrastructure-based and non-collaborative. With the recent development of Ultra-WideBand (UWB) technologies, highly accurate distance and orientation detection have become available for supporting collaborative positioning, a new positioning paradigm. Hence there is a strong need to study collaborative positioning, which is referred to in this paper as mobile ad-hoc positioning (MAP). To contribute to the development of MAP, we present novel positioning vectors with the potential to tackle many related collaborative positioning problems and open an interesting area of research. Our contributions are outlined as follows. First, we present the concept of positioning vectors with the foundational features. Second, we present both experimental and simulation results, illustrating the use of positioning vectors. In particular, we discuss a COVID-19 related case study on social distancing. Last but not least, we discuss the future research directions of positioning vectors. In summary, this paper provides valuable insights into the development of MAP in general and positioning vectors in particular.
Recent years have seen considerable interest in mobile cloud computing and edge cloud computing. This paper presents a mobile Intercloud system for supporting mobile cloud computing in general and edge cloud computing in particular. In essence, a mobile user with a mobile terminal can set up a virtual mobile terminal with applications and data in a central/home cloud. The virtual mobile terminal can facilitate task and computation offloading and other functions. Moreover, when a mobile terminal joins an edge cloud, the virtual mobile terminal (including required applications and data) can be migrated to enhance system efficiency and the user experience (e.g., shorter access delays). An experimental prototype has been developed for evaluating certain basic object transfer functions. To support the application transfer function, we formulate both finite- and infinite-horizon Markov decision models to determine decision policies (i.e., should an application be transferred to an edge cloud). The transfer decision depends on various factors, including transfer cost, duration associated with the edge cloud, usage probability, and usage cost in the central cloud and edge cloud. Based on the models, we obtain closed-form solutions for the decision policies, which can be expressed in meaningful formulas to provide useful insights for edge cloud computing in general. To evaluate the mobile Intercloud system for edge cloud computing, we conducted extensive evaluations, including experimental evaluation for testing the basic functions and protocols, analytical evaluation for studying the analytical models, and simulation evaluation for analyzing performance in a multiuser and multicloud environment in particular. The experimental, simulation, and analytical results provide useful insights into the design and development of the mobile Intercloud system for edge cloud computing as well as decision policies for application transfer.
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