arXiv subjects

Michel Rottleuthner

Publications and source records attributed to Michel Rottleuthner.

4 recordsLinked to original sources

arXiv2025

Duty-Cycling is Not Enough in Constrained IoT Networking: Revealing the Energy Savings of Dynamic Clock Scaling

Minimizing energy consumption of low-power wireless nodes is a persistent challenge from the constrained Internet of Things (IoT). In this paper, we start from the observation that constrained IoT devices have largely different hardware (im-)balances than full-scale machines. We find that the performance gap between MCU and network throughput on constrained devices enables minimal energy delay product (EDP) for IoT networking at largely reduced clock frequencies. We analyze the potentials by integrating dynamic voltage and frequency scaling (DVFS) into the RIOT IoT operating system and show that the DVFS reconfiguration overhead stays below the energy saved for a single, downscaled MAC operation. Backed by these findings, we systematically investigate how DVFS further improves energy-efficiency for common networking tasks -- in addition to duty-cycling. We measure IoT communication scenarios between real-world systems and analyze two MAC operating modes -- CSMA/CA and time slotting -- in combination with different CoAP transactions, payload sizes, as well as DTLS transport encryption. Our experiments reveal energy savings between 24% and 52% for MAC operations and up to 37% for encrypted CoAP communication. These results shall encourage research and system design work to integrate DVFS in future IoT devices for performing tasks at their optimal frequencies and thereby significantly extending battery lifetimes.

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arXiv2022

Dynamic Clock Reconfiguration for the Constrained IoT and its Application to Energy-efficient Networking

Clock configuration takes a key role in tuning constrained general-purpose microcontrollers for performance, timing accuracy, and energy efficiency. Configuring the underlying clock tree, however, involves a large parameter space with complex dependencies and dynamic constraints. We argue for clock configuration as a generic operating system module that bridges the gap between highly configurable but complex embedded hardware and easy application development. In this paper, we propose a method and a runtime subsystem for dynamic clock reconfiguration on constrained Internet of Things (IoT) devices named ScaleClock. ScaleClock derives measures to dynamically optimize clock configurations by abstracting the hardware-specific clock trees. The ScaleClock system service grants portable access to the optimization potential of dynamic clock scaling for applications. We implement the approach on the popular IoT operating system RIOT for two target platforms of different manufacturers and evaluate its performance in static and dynamic scenarios on real devices. We demonstrate the potential of ScaleClock by designing a platform-independent dynamic voltage and frequency scaling (DVFS) mechanism that enables RIOT to autonomously adapt the hardware performance to requirements of the software currently executed. In a use case study, we manage to boost energy efficiency of constrained network communication by reducing the MCU consumption by 40 % at negligible performance impact.

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arXiv2021

PHiLIP on the HiL: Automated Multi-platform OS Testing with External Reference Devices

Developing an operating system (OS) for low-end embedded devices requires continuous adaptation to new hardware architectures and components, while serviceability of features needs to be assured for each individual platform under tight resource constraints. It is challenging to design a versatile and accurate heterogeneous test environment that is agile enough to cover a continuous evolution of the code base and platforms. This mission is even morehallenging when organized in an agile open-source community process with many contributors such as for the RIOT OS. Hardware in the Loop (HiL) testing and Continuous Integration (CI) are automatable approaches to verify functionality, prevent regressions, and improve the overall quality at development speed in large community projects. In this paper, we present PHiLIP (Primitive Hardware in the Loop Integration Product), an open-source external reference device together with tools that validate the system software while it controls hardware and interprets physical signals. Instead of focusing on a specific test setting, PHiLIP takes the approach of a tool-assisted agile HiL test process, designed for continuous evolution and deployment cycles. We explain its design, describe how it supports HiL tests, evaluate performance metrics, and report on practical experiences of employing PHiLIP in an automated CI test infrastructure. Our initial deployment comprises 22 unique platforms, each of which executes 98 peripheral tests every night. PHiLIP allows for easy extension of low-cost, adaptive testing infrastructures but serves testing techniques and tools to a much wider range of applications.

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arXiv2019

Eco: A Hardware-Software Co-Design for In Situ Power Measurement on Low-end IoT Systems

Energy-constrained sensor nodes can adaptively optimize their energy consumption if a continuous measurement exists. This is of particular importance in scenarios of high dynamics such as energy harvesting or adaptive task scheduling. However, self-measuring of power consumption at reasonable cost and complexity is unavailable as a generic system service. In this paper, we present Eco, a hardware-software co-design enabling generic energy management on IoT nodes. Eco is tailored to devices with limited resources and thus targets most of the upcoming IoT scenarios. The proposed measurement module combines commodity components with a common system interfaces to achieve easy, flexible integration with various hardware platforms and the RIOT IoT operating system. We thoroughly evaluate and compare accuracy and overhead. Our findings indicate that our commodity design competes well with highly optimized solutions, while being significantly more versatile. We employ Eco for energy management on RIOT and validate its readiness for deployment in a five-week field trial integrated with energy harvesting.

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