Abstract
Crowd-sourcing the resources of mobile devices is a hot topic of research given the game-changing applications it may enable. In this paper we study the feasibility of using edge-clouds of mobile devices to reduce the load in traditional WiFi infrastructures for video dissemination applications. For this purpose, we designed and implemented a mobile application for video dissemination in sport venues that retrieves replays from a central server, through the access points in the WiFi infrastructure, into a smartphone. The fan's smartphones organize themselves into WiFi-Direct groups and exchange video replays whenever possible, bypassing the central server and access points. We performed a real-world experiment using the live TV feed for the Champions League game Benfica-Besiktas with the help of a group of volunteers using the application at the student's union lounge. The analysis of the logs strongly suggests that edge-clouds can significantly reduce the load in the access points at such large venues and improve quality of experience. Indeed, the edge-clouds formed were able to serve up to 80% of connected users and provide 56% of all downloads requested from within.

Abstract
In the last decade, technological advances and improved manufacturing processes have significantly dropped the price tag of mobile devices such as smartphones and tablets whilst augmenting their storage and computational capabilities. Their ubiquity fostered research on mobile edge-clouds, formed by sets of such devices in close proximity, with the goal of mastering their global computational and storage resources. The development of crowdsourcing applications that take advantage of such edge-clouds is, however, hampered by the complexity of network formation and maintenance, the intrinsic instability of wireless links and the heterogeneity of the hardware and operating systems in the devices. In this paper we present a middleware to deal with this complexity, providing a building block upon which crowd-sourcing applications may be built.We motivate the development of the middleware through a discussion of real-world applications, and present the middleware's architecture along with the associated components and current development status. The middleware takes form as a Java API for Android devices that allows for the establishment of links using heterogeneous communication technologies (e.g., Wifi-Direct, Bluetooth), and the combination of these links to form a logical edge-cloud network. On top of this functionality, services for edge computation, storage, and streaming are also being developed. © 2017 Association for Computing Machinery.

Abstract

Abstract
Wireless sensor networks are notoriously difficult to program and debug. This fact not only stems from the nature of the hardware, but also from the current approaches for developing programming languages and runtime systems for these platforms. In particular, current systems do not place enough stress on providing formal descriptions of the language and its runtime system, and on proving static properties, like type-safety and soundness. In this paper, we present the design, specification, and implementation of a programming language and a runtime system for wireless sensor networks that are safe by design. We say this in the sense that we can statically detect a large set of would-be runtime errors, and that the runtime system will not incorrectly execute an application, once the latter is deployed. We have a full prototype implementation of the system that supports SunSPOT devices, the simulation tool VisualSense, and local computer networks for fast deployment and testing of applications. Development is supported by an IDE implemented on top of the Eclipse tool that embeds both the compiler and the virtual machine seamlessly, and is used to produce software releases.

Abstract

Abstract