TY - CHAP A1 - Chatharajupalli, Navya Sneha A1 - Rotta, Randolf A1 - Nolte, Jörg T1 - P2 - VibroMote: Energy efficient Vibration Monitoring for Railway tracks and Bridges T2 - iCCC2024 - iCampµs Cottbus Conference 2024-05-14 - 2024-05-16 N2 - Filtering, storing, and transmitting measurements of high-resolution sensors within a limited energy budget is challenging. For instance, a 3-axis MEMS acceleration sensor for structural condition monitoring and predictive maintenance generates up to 160 kB/s at a sampling rate of 26.6 kHz. This paper discusses the design space with focus on solar harvesting solutions. VibroMote is an energy efficient sensor node that combines a multi-radio micro-controller, an ultra-low power co-processor with persistent memory, a solar harvester, and multiple energy storage options. This enables prototyping of solar-powered long-term data acquisition, in-node processing, and wireless networking for high-resolution sensors. KW - structural condition monitoring KW - predictive maintenance KW - energy efficiency KW - solar harvesting Y1 - 2024 SN - 978-3-910600-00-3 U6 - https://doi.org/10.5162/iCCC2024/P2 SP - 123 EP - 126 PB - AMA Service GmbH, Von-Münchhausen-Str. 49, 31515 Wunstorf, Germany ER - TY - GEN A1 - Rabenstein, Jonas A1 - Nguyen, Dustin A1 - Giersch, Oliver A1 - Eichler, Christian A1 - Hönig, Timo A1 - Nolte, Jörg A1 - Schröder-Preikschat, Wolfgang ED - Goumas, Georgios ED - Tomforde, Sven ED - Brehm, Jürgen ED - Wildermann, Stefan ED - Pionteck, Thilo T1 - Back to the core-memory age: running operating systems in NVRAM only T2 - Proceedings: architecture of computing systems: 36th International Conference, ARCS 2023, June 13 - 15, 2023 N2 - The classic core memory was completely non-volatile and thus kept at least part of the operating system persistently in main memory, even over power cycles. Nowadays we can repeat this approach with NVRAM, but with terabytes of main memory on a completely different scale and with parts of the operating-system state stored in volatile CPU caches. In this paper, we discuss our experiences of running large modern operating systems including their applications entirely in NVRAM. We adapted stock Linux and FreeBSD kernels to work exclusively with NVRAM by hiding all DRAM from the kernels at boot time to establish a realistic performance baseline without changing anything else. Following this entirely NVRAM-agnostic approach, we could observe an effective performance penalty of a factor of about four, but only negligible increases in whole-system power draw. For our system with two CPU sockets and 56 cores total, we also observed a reduction in power draw in several scenarios. Due to prolonged execution times, the energy consumption increased as well for these measured workloads. While this might be discouraging at first sight, this result was achieved without any performance tuning as to the specific characteristics of today’s NVRAM technology. Therefore, we are also discussing means to mitigate the observed shortcomings by integrating NVRAM appropriately into the memory hierarchy of future robust persistent systems. KW - NVRAM KW - Operating Systems KW - Energy Y1 - 2023 SN - 978-3-031-42784-8 U6 - https://doi.org/10.1007/978-3-031-42785-5_11 SP - 153 EP - 167 PB - Springer-Verlag ER - TY - GEN A1 - Giersch, Oliver A1 - Nguyen, Dustin A1 - Nolte, Jörg A1 - Schröder-Preikschat, Wolfgang T1 - Virtual memory revisited for tiered memory T2 - Proceedings of the 15th ACM SIGOPS Asia-Pacific Workshop on Systems N2 - The landscape of memory technologies has grown substantially more diverse and heterogeneous, with a number of special-purpose memory technologies reaching market maturity in recent years, such as NVRAM (Non-Volatile Memory), HBM (High-Bandwidth Memory) or the upcoming CXL.mem. Future computing systems will have to contend with byte-addressable and cache-coherent main memory that is highly diverse, either in terms of the fundamental performance characteristics of its underlying memory technology, or due to the fact that CXL.mem will allow accessing homogenous but remote memory. The VM (Virtual Memory) subsystems of today have been empirically optimized over decades, but were designed for a single tier of main memory only. While recent approaches that integrated tiered memory have focused on better memory access metrics to improve page placement strategies, we seek to leverage the proven heuristics that are already in place. In times of high load we assign pages from slower memory, demote inactive pages according to standard page replacement strategies and use lazy page promotions when sufficient resources are available again to retain the inherently high reactivity of demand paging with regard to working set changes. We integrate these mechanisms into the VM subsystem of a full-featured mainstream operating system (FreeBSD) with minimal adaptations. The resulting multi-tier VM system runs in a stable and efficient manner under high stress even with highly unfavorable work loads. KW - Operating Systems KW - Resource Disaggregation Y1 - 2024 SN - 979-8-4007-1105-3 U6 - https://doi.org/10.1145/3678015.3680475 SP - 1 EP - 7 PB - ACM CY - New York, NY, USA ER - TY - GEN A1 - Rotta, Randolf A1 - Chatharajupalli, Navya Sneha A1 - Naumann, Billy A1 - Schulz, Julius A1 - Karnapke, Reinhardt A1 - Werner, Matthias A1 - Nolte, Jörg T1 - Demo: B.A.T.M.A.N. mesh routing on ultra low-power IEEE 802.11 modules T2 - 2024 IEEE 49th Conference on Local Computer Networks (LCN) N2 - When implementing multi-hop mesh network protocols, efficient direct communication, route discovery, and route repair are crucial to achieve high network throughput. To our knowledge, there is no open mesh routing protocol available for ultra low power IEEE 802.11 modules. Previous work relied on single board computers like Raspberry Pi. We implemented the B.A.T.M.A.N. mesh protocol on the popular Espressif ESP32 along with a novel hybrid rate adaptation for the selection of efficient routes. In this demo we showcase challenges and solutions related to the implementation on ESP32 and how the hybrid rate adaptation improves end-to-end throughput. KW - ad-hoc networks KW - mesh networks KW - low power electronics KW - throughput Y1 - 2024 SN - 979-8-3503-8800-8 U6 - https://doi.org/10.1109/LCN60385.2024.10639789 SN - 2832-1421 PB - IEEE ER - TY - GEN A1 - Rotta, Randolf A1 - Schulz, Julius A1 - Naumann, Billy A1 - Chatharajupalli, Navya Sneha A1 - Nolte, Jörg A1 - Werner, Matthias T1 - B.A.T.M.A.N. Mesh Networking on ESP32’s 802.11 T2 - 2024 IEEE 49th Conference on Local Computer Networks (LCN) N2 - Mesh routing protocols are widely used in IoT and sensor networks. In recent years, the ESP32 Wi-Fi/BLE SoC became popular for prototyping IoT applications. However, the existing mesh networks for this platform lack efficient node to node communication, fast route discovery and repair, and energy efficiency. This paper addresses the formation of IEEE 802.11 based ad-hoc mesh networks without the delays inflicted by the Station to Access Point association protocol. We implemented the B.A.T.M.A.N. protocol on top of the ESP32 Wi-Fi MAC interface and integrated it into the LwIP network stack. The performance evaluation with respect to UDP/IP and TCP/IP end-to-end throughput shows the general usefulness but also identifies bottlenecks caused by limitations of the existing MAC interface. Overall, this opens an interesting opportunity for research on mesh protocols by providing a simpler platform than full featured Wi-Fi routers; and for wireless IoT applications by providing higher throughput than subGHz and BLE technologies. KW - wireless communication KW - mesh networks KW - wireless sensor networks KW - routing protocols Y1 - 2024 SN - 979-8-3503-8800-8 U6 - https://doi.org/10.1109/LCN60385.2024.10639698 SN - 2832-1421 SN - 2831-7742 SP - 1 EP - 7 PB - IEEE ER - TY - GEN A1 - Shahin, Keyvan A1 - Rotta, Randolf A1 - Archila, Oscar A1 - Mykytyn, Pavlo A1 - Nattke, Matthias A1 - Reichenbach, Marc A1 - Nolte, Jörg A1 - Natarov, Roman T1 - A Modular Communication Architecture for Adaptive UAV Swarms T2 - 2023 IEEE International Conference on Omni-layer Intelligent Systems (COINS) N2 - Small Unmanned Aerial Vehicles (UAVs) have vast application potential from industrial logistics and disaster monitoring to smart farming, for example, to create maps with Normalized Difference Vegetation Index (NDVI) cameras and AI-based image classification or the precision spot application of fertilizers. Operating multiple UAVs in parallel, including those with different specializations, enables efficient coverage of large areas. While existing research focused mainly on predefined flight formations for swarms or autonomous missions for single UAVs, the focus of this work is on multiple UAVs with individually adaptable missions. We derive communication system requirements from swarm coordination algorithms and present a respective design. The resulting modular architecture enables future research on autonomous adaptive UAV swarms and their use as flying sensor platforms. Y1 - 2023 SN - 979-8-3503-4647-3 SN - 979-8-3503-4648-0 U6 - https://doi.org/10.1109/COINS57856.2023.10189245 PB - IEEE CY - Berlin ER - TY - GEN A1 - Chatharajupalli, Navya Sneha A1 - Rotta, Randolf A1 - Karnapke, Reinhardt A1 - Nolte, Jörg T1 - Probing considered harmful : leveraging RSSI for link quality prediction T2 - Proceedings of the IEEE 50th Conference on Local Computer Networks : LCN 2025 : October 14-16, 2025, Sydney, Australia N2 - Wireless mesh protocols that use a routing metric based on throughput or airtime require predictions about future throughput for all mesh neighbors. Typically, the Wi-Fi rate controller provides this information, and state-of-the-art rate control algorithms estimate it based on statistics from past unicast transmissions. This introduces an adverse cross-layer dependency because meaningful statistics are only available for the links that were used by the routing layer. Existing implementations either ignore this, or use other routing metrics, such as distance, or generate artificial periodic probe traffic to all neighbors. Unfortunately, probing reacts slowly to changing conditions, increases the medium contention, and can lead to overly optimistic predictions. To overcome this, we introduce an RSSI-based link quality prediction for the routing layer. Benchmarks in a B.A.T.M.A.N. version V mesh show a decrease of round-trip time by three orders of magnitude and an increase of the end-to-end packet delivery ratio. TCP connections became possible over long routes that were previously unusable. Although highly imprecise, the easy to acquire RSSI provided sufficiently good predictions for our mesh network. KW - Wireless Mesh Network KW - Multi-hop routing KW - Neural Networks KW - Machine Learning KW - Link quality predictors Y1 - 2025 SN - 979-8-3315-3704-3 U6 - https://doi.org/10.1109/LCN65610.2025.11146347 SN - 2831-7742 SP - 1 EP - 9 PB - IEEE CY - New York, NY ER - TY - GEN A1 - Chatharajupalli, Navya Sneha A1 - Rotta, Randolf A1 - Karnapke, Reinhardt A1 - Nolte, Jörg T1 - Animal health monitoring and tracking through solar-powered mesh network T2 - 22. GI/ITG KuVS Fachgespräch Sensornetze : 11. und 12. September 2025, Clausthal-Zellerfeld N2 - Various health and movement sensors, especially bolus sensors inside a cow’s stomach, are crucial for timely medical interventions. Commonly, wall-powered gateways are used to retrieve sensor updates and forward them quickly to an analysis service. In large outdoor farmlands, however, localisation of individual cows becomes important while the long-term operation of wall-powered gateways is costly. Previous solutions that use a LoRaWAN gateway with bigger antennas are still limited to 500m and provide only poor localization information. Existing solutions based on a mesh network of repeaters provide good localization but still depend on external wall power. Solar-powered mesh nodes would simplify the long-term operation. In order to achieve this, a significant improvement of the energy efficiency of the mesh nodes is necessary. This paper explores protocol design choices for the energy-efficient communication between mesh nodes and the bolus sensors. By introducing synchronised sleep and communication intervals, the size of the solar panels and energy storage can be reduced. KW - Wireless Networks KW - Solar-harvesting KW - Localisation Y1 - 2025 UR - https://dokumente.ub.tu-clausthal.de/receive/clausthal_mods_00002954 U6 - https://doi.org/10.21268/20250805-0 SP - 1 EP - 3 PB - TU Clausthal-Zellerfeld CY - Clausthal-Zellerfeld ER - TY - GEN A1 - Chatharajupalli, Navya Sneha A1 - Rotta, Randolf A1 - Karnapke, Reinhardt A1 - Nolte, Jörg T1 - VibroMote : Wi-Fi-based mesh communication for railway bridge inspection and monitoring T2 - 2025 International Symposium on Networks, Computers and Communications (ISNCC) N2 - Vibration sensing provides insights into the dynamic behaviour of engineering constructions such as railway bridges. Cable-based sensors are viable only for long-term condition monitoring and rare special inspections because of the labor-intensive deployment. Although wireless sensors significantly reduce this overhead, their energy constraints limited the network throughput and, hence, their resolution in space and time. Batteryor solar-powered sensor nodes with high network throughput would enable in-depth measurements during regular inspections and improve the access to high-quality monitoring data. We present “VibroMote”, which combines energy harvesting, a high-bandwidth 3-axis MEMS accelerometer, and high-throughput, self-organizing mesh communication via IEEE 802.11 Wi-Fi. The evaluation on a real bridge with 18 VibroMotes shows that the deployment time can be reduced from hours to minutes; the multi-hop mesh provides sufficient throughput reserves for the application whereas direct one-hop communication failed; the battery runtime is sufficient for temporary measurements during inspections; and the energy consumption during sleep modes would be low enough for solar-powered long-term monitoring. Hence, the combination of high-throughput Wi-Fi with mesh networking is a strong alternative to the commonly used low-power radio technologies when long range between the sensors is not needed. KW - Wireless Mesh Network KW - Condition Monitoring KW - Multi-hop routing KW - Wi-Fi Mesh Y1 - 2025 SN - 978-1-6654-5769-9 U6 - https://doi.org/10.1109/ISNCC66965.2025.11250402 SN - 2768-0940 SP - 1 EP - 6 PB - IEEE CY - Piscataway, NJ ER -