Multi-sensor wireless sensor network nodes for alpine environment monitoring

The Pizol Glacier is the first glacier in Switzerland to be declared dead in 2019 and it will not be the last if global warming continues to this extent. Because glaciers and permafrost are melting, our mountains are becoming more and more unstable. In the coming years it is expected that dangerous rockfalls will increase in size and quantity and that they will also occur in previously safe areas. At the same time, leisure activities such as hiking and mountain biking are becoming popular and more and more people are living in endangered places. In order to better anticipate the effects of these changes and to be able to warn people, it has become very important to understand the movements and activities of our mountains. Despite recent efforts in deploying low-cost geophone sensors to accurately track these changes the sensor capabilities are still quite limited. To resolve these limitations, we have introduced more geophones and sensors in the latest version. These new sensors allow us to capture more and new data and enable new capabilities such as monitoring of slow changes or determining the exact position. However, the platform is in the middle of development as it still lacks essential features such as reliable error handling and robust scheduling. To achieve this, we perform a thorough analysis on the entire code base and extend the new scheduler, debugging and logging features. To place the platform even in hard-to-reach locations we have to make sure the communication works in both directions so that we can remotely change the configurations and the sensor data are stored in the backend. Through detailed power measurements and intensive testing of the complete system and all subsystems we verify the correctness. This way we make the system more robust and fail-safe. We demonstrate that if the task scheduler is improved as well as extended and the new sensor data is handled correctly, the new platform will be deployment- ready and ready for real-world testing in the coming months

Event-triggered multi-hop communication for wireless sensor networks

Wireless Sensor Networks (WSNs) play an important role in today’s society in Internet of Things, automation, environmental monitoring etc. However, as these networks should be able to operate autonomously and for a long period of time without recharging, careful energy management is required. A central aspect of such networks is the energy budget for communication which has received much attention in recent years. To ensure network-wide coordination in WSNs and accurate synchronization to avoid costly communication collisions, today’s solutions are based on a common global leader. This leader orchestrates mandatory network-wide periodic communication rounds to distribute information with short latency. However, if the nodes have nothing to send or are irrelevant for successful communication, they must be active in every communication round. To avoid a periodic overhead and its incurring inefficiency, we propose a new event-triggered approach. We only synchronize locally with nodes that have detected an event, locally aggregate data and efficiently forward the combined data to the data sink. In this thesis we present the design for an event-triggered WSN, that uses the available energy more efficiently in situations with few events per hour than common WSN solutions while latencies are on average 1.41 lower. which makes more efficient use of the available energy in situations with a few events per hour than state-of-the-art solutions while achieving latencies that are lower by 1.41 on average. This design paves the way for further developments and deployments of new applications of event-triggered WSN

STeC: Exploiting Spatial and Temporal Correlation for Event-based Communication in WSNs

Low-power wireless sensor networks have demonstrated their potential for the detection of rare events such as rockfalls and wildfires, where rapid reporting as well as long-term energy-efficient operation is vital. However, current systems require periodic synchronization to maintain network coordination, heavily rely on node placement or use costly long-range links to infrastructure. We present STeC, a novel wireless communication design that directly exploits the spatial and temporal correlation of signals from the sensed phenomenon to orchestrate event-based communication. We leverage the locality of a co-detection, where a physical event triggers multiple sensors quasi-simultaneously, to efficiently collect, characterize and report sensor data. This eliminates the overhead of periodic network activity and centralized control, resulting in more energy-efficient communication with a lower, more consistent detection latency. In doing so, we propose a fundamentally new approach to avoid the elementary conflict between duty cycle and latency requirements immanent to synchronous protocols by exploiting correlated sensor signals for networking. Experiments using real-world traces of a natural hazard detection application show that STeC reduces the detection latency by up to 87 % compared to standard single-hop communication and outperforms traditional schedule-based methods by up to 58.4 x in energy efficiency

Indigenizing the internet

To write of digital indigeneity or digital Natives is to confront the fact that, as Anishinaabe/Métis games designer Elizabeth LaPensée described in a cryptic but resonant tweet: “The Internet has been colonized” (2017 n.pag.). Popularized in the title of Marc Prensky's influential 2001 paper on educational reform, the term “digital Native” is defined by the OED as “A person born or brought up during the age of digital technology and so familiar with computers and the Internet from an early age.” Similarly, artifacts that are created with digital tools and so originate in a digital environment, having no analog equivalent, are called “born-digital” objects. The discursive colonialist violence of cyberspace as a territory inhabited by “indigenous” artifacts and “digital Natives” preempts efforts to discuss the digital creativity of actual Indigenous artists and communities. The digital then is a discursive realm where the profound conflicts generated by settler-colonialism continue to be played out. Indigenous digital interventions pose counter-discourses that oppose the violence of colonialist stereotypes, claiming digital storying as an extension of a form of expression and communication that Indigenous peoples have been using long before the advent of contemporary electronic technology. Indigenizing the digital medium constitutes a powerful message that Natives are not primitive, pre-technological, and “vanishing.” Living Indigenous cultures endure, witnessed by digital creations that work to preserve and disseminate tribal languages in genres of digital storying that perform traditional customs, beliefs, traditions, and values. Indigenous digital storying is a claim to rhetorical sovereignty that articulates Native self-determination through specific ways of knowing and being. Tribal epistemologies express a unique relationship with the world, a relation of interconnection that is performatively enacted in digital genres. This chapter offers close analyses of two dominant “digital Native” forms of storying that use the capabilities of virtual media in conjunction with traditional literary genres to instantiate Indigenous cosmologies: digital film-poems, videopoems, or “poemeos” exemplified by Heid Erdrich's Anishinaabe storying; and Elizabeth LaPensée's Anishinaabe/Métis storying through Indigenously-determined digital narrative or videogames