Atis Elsts

Atis Elsts
Elektronikas un datorzinātņu institūts

Dr., Computer Science

About

67
Publications
32,506
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Introduction
Senior Researcher at Institute of Electronics and Computer Science, Riga, Latvia http://atiselsts.info

Publications

Publications (67)
Article
Full-text available
Healthcare professionals currently lack the means to gather unbiased and quantitative multi-modal data about the long-term behaviors of patients in their home environments. SPHERE is a multi-modal platform of non-medical sensors for behavior monitoring in residential environments that aims to overcome this major limitation of healthcare provision t...
Article
The last decade has seen exponential growth in the field of deep learning with deep learning on microcontrollers a new frontier for this research area. This paper presents a case study about machine learning on microcontrollers, with a focus on human activity recognition using accelerometer data. We build machine learning classifiers suitable for e...
Article
Contiki-NG (Next Generation) is an open source, cross-platform operating system for severely constrained wireless embedded devices. It focuses on dependable (reliable and secure) low-power communications and standardised protocols, such as 6LoWPAN, IPv6, 6TiSCH, RPL, and CoAP. Its primary aims are to (i) facilitate rapid prototyping and evaluation...
Preprint
Full-text available
Low-power wireless IoT networks have traditionally operated over a single physical layer (PHY)-many based on the IEEE 802.15.4 standard. However, recent low-power wireless chipsets offer both the IEEE 802.15.4 and all four PHYs of the Bluetooth 5 (BT 5) standard. This introduces the intriguing possibility that IoT solutions might not necessarily be...
Conference Paper
Body Coupled Communication (BCC) is a growing research area that promises to deliver more secure and more energy-efficient body-area wireless sensor networks. Existing research articles on BCC show high variance in their experimen- tal results, indicating potential methodological problems in the published work. We perform analysis of several potent...
Article
Full-text available
Background: Thousands of people die every day around the world from infections acquired in a hospital. Hands are the main pathways of germ transmission during healthcare. Hand hygiene monitoring can be performed using various methods. One of the latest techniques that can combine all is a neural network-based hand hygiene monitoring system. Methods...
Article
Full-text available
Time Slotted Channel Hopping (TSCH) is a medium access protocol defined in the IEEE 802.15.4 standard. It has proven to be one of the most reliable options when it comes to industrial applications. TSCH offers a degree of high flexibility and can be tailored to the requirements of specific applications. Several performance aspects of TSCH have been...
Preprint
Full-text available
Uniswap is the largest decentralized exchange (DEX) and one of cornerstones of Decentralized Finance (DeFi). Uniswap uses liquidity pools to provide Automated Market Making (AMM) functionality. Uniswap v3 is the most recent version of the protocol that introduces a number of new features, notably the concentrated liquidity feature, which allows the...
Preprint
Full-text available
Time Slotted Channel Hopping (TSCH) is a medium access protocol defined in the IEEE 802.15.4 standard. It has been demonstrated to be one of the most reliable options when it comes to industrial applications. TSCH offers a degree of large flexibility and can be tailored to the requirements of specific applications. Several performance aspects of TS...
Article
Full-text available
A large number of different low-power wireless network technologies exist, including IEEE 802.15.4, Bluetooth Low Energy, multiple protocol standards of WiFi (IEEE 802.11), Near Field Communication (NFC), and LoRa. Given this number of competing technologies, the selection of the best one for a new project is not trivial. This paper aims to help In...
Article
Full-text available
Washing hands is one of the most important ways to prevent infectious diseases, including COVID-19. The World Health Organization (WHO) has published hand-washing guidelines. This paper presents a large real-world dataset with videos recording medical staff washing their hands as part of their normal job duties in the Pauls Stradins Clinical Univer...
Article
Full-text available
The TSCH (Time Slotted Channel Hopping) protocol from the IEEE 802.15.4-2015 standard is known to be suitable for highly reliable applications in low-power networks of severely constrained wireless embedded devices. Most of the research on TSCH has focused on the 2.4 GHz frequency band. The present work extends the TSCH protocol to low data rate ap...
Preprint
Washing hands is one of the most important ways to prevent infectious diseases, including COVID-19. Unfortunately, medical staff does not always follow the World Health Organization (WHO) hand washing guidelines in their everyday work. To this end, we present neural networks for automatically recognizing the different washing movements defined by t...
Article
Full-text available
TSCH (Time-Slotted Channel Hopping) and 6TiSCH (IPv6 over the TSCH mode of IEEE 802.15.4e) low-power wireless networks are becoming prominent in the industrial Internet of Things (IoT) and other areas where high reliability is needed in conjunction with energy efficiency. Due to the complexity of IoT deployments, network simulations are typically u...
Article
Full-text available
Acceleration data for activity recognition typically are collected on battery-powered devices, leading to a trade-off between high-accuracy recognition and energy-efficient operation. We investigate this trade-off from a feature selection perspective, and propose an energy-efficient activity recognition framework with two key components: a detailed...
Conference Paper
Full-text available
The Internet of Things promises to enable numerous future applications spanning many domains, including health care. Currently, most health care devices communicate either by using wires or by using a Radio Frequency technology such as Bluetooth or WiFi. In this paper, we describe an alternative communication method: Body Coupled Communication, whe...
Article
Full-text available
The emerging Internet of Things (IoT) has the potential to solve major societal challenges associated with healthcare provision. Low-power wireless protocols for residential Health IoT applications are characterized by high reliability requirements, the need for energy-efficient operation, and the need to operate robustly in diverse environments in...
Article
Full-text available
Wearable systems constitute a promising solution to the emerging challenges of healthcare provision, feeding machine learning frameworks with necessary data. In practice, however, raw data collection is expensive in terms of energy, and therefore imposes a significant maintenance burden to the user, which in turn results in poor user experience, as...
Article
Full-text available
Time Slotted Channel Hopping (TSCH) is a link layer protocol defined in the IEEE 802.15.4 standard. Although it is designed to provide highly reliable and efficient service targeting industrial automation systems, scheduling TSCH transmissions in the time and frequency dimensions is left to the implementers. We evaluate the performance of existing...
Chapter
Several Internet of Things (IoT) applications have strict performance requirements, in terms of reliability and power consumption. IEEE 802.15.4 Time Slotted Channel Hopping (TSCH) is a recently standardised Medium Access Control (MAC) protocol that supports these requirements by keeping the nodes time-synchronised. In order to ensure successful co...
Preprint
Full-text available
Recent advances in both machine learning and Internet-of-Things have attracted attention to automatic Activity Recognition, where users wear a device with sensors and their outputs are mapped to a predefined set of activities. However, few studies have considered the balance between wearable power consumption and activity recognition accuracy. This...
Conference Paper
Several Internet of Things (IoT) applications have strict performance requirements, in terms of reliability and power consumption. IEEE 802.15.4 Time Slotted Channel Hopping (TSCH) is a recently standardised Medium Access Control (MAC) protocol that supports these requirements by keeping the nodes time-synchronised. In order to ensure successful co...
Conference Paper
Full-text available
Low-power wearable devices are becoming increasingly important for fitness and healthcare applications. However, existing protocols based on the IEEE 802.15.4 low-power wireless standard are not optimized for data collection from mobile devices. This paper presents Instant: a schedule for the IEEE 802.15.4 TSCH protocol tailored for this applicatio...
Conference Paper
One of the challenges of deploying IoT battery-powered sensing systems is managing the maintenance of batteries. To that end, practitioners often employ prediction techniques to approximate the battery lifetime of the deployed devices. Following a series of longterm residential deployments in the wild, this paper contrasts real-world battery lifeti...
Conference Paper
Full-text available
Distributed Ledger Technologies have promising applications in the Internet of Things. However, scalability and support for micropayments remain problems for blockchain-based applications, therefore other alternatives such as IOTA should be considered. This work reports on an experimental evaluation of IOTA on several different IoT platforms. We sh...
Chapter
Internet of Things (IoT) technology has the potential to revolutionise several domains of everyday life, including the healthcare sector. In order to reach its full potential, IoT technology needs to be evaluated in the real world, beyond controlled environments, such as laboratories and test-beds. SPHERE is an experimental sensing platform for hea...
Preprint
Full-text available
The SPHERE project has developed a multi-modal sensor platform for health and behavior monitoring in residential environments. So far, the SPHERE platform has been deployed for data collection in approximately 50 homes for duration up to one year. This document describes the format of the SPHERE dataset, as well as the known and potential data qual...
Article
Full-text available
This paper serves as a survey and empirical evaluation of the state-of-the-art in activity recognition methods using accelerometers. The paper is particularly focused on long-term activity recognition in real-world settings. In these environments, data collection is not a trivial matter; thus, there are performance trade-offs between prediction acc...
Preprint
Full-text available
This paper serves a survey and empirical evaluation of the state-of-the-art in activity recognition methods using accelerometers. We examine research that has focused on the selection of activities, the features that are extracted from the accelerometer data, the segmentation of the time-series data, the locations of accelerometers, the selection a...
Article
This article shares experiences and lessons learned from designing and developing the bespoke IoT (Internet of Things) sensing platforms of SPHERE (a Sensor Platform for Healthcare in a Residential Environment). These IoT platforms, which include a wrist-worn wearable sensor, a room-level environmental sensor, and a dual-radio gateway, constitute i...
Article
Networks deployed in real-world conditions have to cope with dynamic, unpredictable environmental temperature changes. These changes affect the clock rate on network nodes, and can cause faster clock de-synchronization compared to situations where devices are operating under stable temperature conditions. Wireless network protocols such as Time-Slo...
Article
Full-text available
Wearable technologies are valuable tools that can encourage people to monitor their own well-being and facilitate timely health interventions. In this paper, we present SPW-2; a low-profile versatile wearable sensor that employs two ultra low power accelerometers and an optional gyroscope. Designed for minimum maintenance and a long-term operation...
Article
The application of biologically and biochemically relevant constraints during the optimization of kinetic models reduces the impact of suggested changes in processes not included in the scope of the model. This increases the probability that the design suggested by model optimization can be carried out by an organism after implementation of design...
Article
Full-text available
Motivation: Due to their universal applicability, global stochastic optimization methods are popular for designing improvements of biochemical networks. The drawbacks of global stochastic optimization methods are: (i) no guarantee of finding global optima, (ii) no clear optimization run termination criteria and (iii) no criteria to detect stagnatio...
Conference Paper
Full-text available
Time-Slotted Channel Hopping (TSCH) from the IEEE 802.15.4-2015 standard uses channel hopping to combat interference and frequency-selective fading. Due to the pseudo-random nature of TSCH standard channel hopping process, the energy usage and end-to-end delay achieved in statically configured TSCH networks are suboptimal when compared to using a d...
Conference Paper
Full-text available
Building large-scale low-power Internet of Things (IoT) systems remains a challenge, as these systems have to meet the requirements of reliability, robustness, and energy- efficiency while running on resource-restricted microcontrollers without memory protection. In this paper we present the case study of IoT in SPHERE (Sensor Platform for HEalthca...
Conference Paper
Full-text available
The upcoming Internet of Things (IoT) applications include real-time human activity monitoring with wearable sensors. Compared to the traditional environmental sensing with low-power wireless nodes, these new applications generate a constant stream of a much higher rate. Nevertheless, the wearable devices remain battery powered and therefore restri...
Conference Paper
Full-text available
Synchronized communication has recently emerged as a prime option for low-power critical applications. Solutions such as Glossy or Time Slotted Channel Hopping (TSCH) have demonstrated end-to-end reliability upwards of 99.99%. In this context, the IETF Working Group 6TiSCH is currently standardizing the mechanisms to use TSCH in low-power IPv6 scen...
Conference Paper
Full-text available
SPES-2 is a sensing board for room-level monitoring in a home environment. It constitutes a vital modality of the SPHERE architecture: a multi-modal sensing platform for healthcare in a residential environment. SPES-2 uses an op-timised implementation of the IEEE 802.15.4-2015 TSCH (Time-Slotted Channel Hopping) standard to operate efficiently and...
Chapter
Full-text available
It can be tempting to think about smart homes like one thinks about smart cities. On the surface, smart homes and smart cities comprise coherent systems enabled by similar sensing and interactive technologies. It can also be argued that both are broadly underpinned by shared goals of sustainable development, inclusive user engagement and improved s...
Conference Paper
Full-text available
Time-Slotted Channel Hopping from the IEEE 802.15.4-2015 standard requires that network nodes are tightly time-synchronized. Existing implementations of TSCH on embedded hardware are characterized by tens-of-microseconds large synchronization errors; higher synchronization accuracy would enable reduction of idle listening time on receivers, in this...
Conference Paper
Full-text available
We experimentally investigate the performance of IEEE 802.15.4 radio links and their failure modes in an office building, and, based on this study, propose an adaptation mechanism to conciliate application-level reliability requirements with the underlying network-level properties. The mechanism has two aspects: the spatially-adaptive aspect, imple...
Conference Paper
Full-text available
Low-power wireless link quality is known to be frequency-dependent because of multipath fading and other factors. We present a performance study of IEEE 802.15.4 radio links that quantifies and analyzes this frequency-specific performance in a clear-field outdoor environment. Using data from 16 channels on 240 links, we show that effect from channe...
Conference Paper
Full-text available
Sensor network macroprogramming methodologies such as the Abstract Task Graph hold the promise of enabling high-level sensor network application development. However, progress in this area is hampered by the scarcity of tools, and also because of insufficient focus on developing tool support for programming applications aware of performance require...
Article
Full-text available
Vehicle activity monitoring is an important problem in the transport domain: the activities have impact on the fuel consumption of the vehicle, and therefore its economical feasibility. Activity detection usually is performed using relatively expensive and complicated GNSS receivers. We propose a Bayesian network based algorithm for vehicle mode de...
Thesis
Full-text available
Wireless sensor networks is a technology that was originally envisioned as a tool for broad range of purposes and target audiences. However, wireless sensor network software development is complicated, because it brings together the complexity of resource-constrained embedded system software and the complexity of distributed system software. This i...
Conference Paper
Full-text available
A lot of the prospective wireless sensor network users are novice programmers. Their experience in general-purpose programming languages is either limited or completely nonexistent. There are both financial and scientific incentives to empower these users and allow them to write sensor network applications on their own, rather than having to rely o...
Conference Paper
Full-text available
Wireless sensor network research community has constructed a number of operating systems that enable development of sensor network applications using novel and appropriate software abstractions. Unfortunately, the abstractions are not always easily usable by inexperienced users, because the learning curves of these existing operating systems are qu...
Article
Full-text available
Wireless sensor networks (WSNs) have been a widely researched field since the beginning of the 21st century. The field is already maturing, and TinyOS has established itself as the de facto standard WSN Operating System (OS). However, the WSN researcher community is still active in building more flexible, efficient and user-friendly WSN operating s...
Conference Paper
Full-text available
In this demonstration we present SEAL-Blockly, a visual pro-gramming tool which allows users to develop a wireless sensor network (WSN) applications like assembling a picture puzzle, using graphical blocks. While domain-specific languages for WSN is a well explored area, visual programming is less so. Compared to textual programming, it pro-vides a...
Article
Full-text available
Wireless sensor networks (WSN) consist of a number of low-power spatially distributed autonomous nodes equipped with means of communication. Developing software for WSN is challenging; operating system (OS) support is required. In this paper we present MansOS, a portable and easy-to-use WSN operating system that has a smooth learn-ing curve for use...
Conference Paper
Full-text available
The advantages of vehicular sensor networks over common wireless sensor networks include the possibility to cover wide measurement area using relatively small number of sensor nodes as well as less strict limits on device dimensions, weight and power consumption. These useful features are reason for expansion of vehicular sensor networks for variou...