@misc{ChatharajupalliRottaKarnapkeetal., author = {Chatharajupalli, Navya Sneha and Rotta, Randolf and Karnapke, Reinhardt and Nolte, J{\"o}rg}, title = {Assessing the Feasibility of Combined BLE and Wi-Fi Communication for High Data Sensing Applications}, series = {EWSN '23: Proceedings of the 2023 International Conference on Embedded Wireless Systems and Networks}, journal = {EWSN '23: Proceedings of the 2023 International Conference on Embedded Wireless Systems and Networks}, publisher = {Association for Computing Machinery}, address = {New York}, doi = {10.5555/3639940.3639948}, pages = {56 -- 59}, abstract = {Advanced sensors generate more data than can be transmitted using classic battery-powered wireless sensor networks. While using Wi-Fi would provide plenty of throughput, the receivers are energy hungry and, thus, the radio time needs to be reduced. Previous research suggests to combine Wi-Fi with low-power technologies such as BLE for an energy efficient coordination of the Wi-Fi radios. Existing approaches focus on individual point-to-point routes whereas certain applications require concurrent transmissions. We evaluated the combination of BLE and Wi-Fi on the ESP32-S3 multi-radio microcontroller through detailed energy and throughput measurements. The results show that established BLE connections allow to activateWi-Fi quickly on-demand; the energy efficiency of the data transmission is significantly improved over previous works but the BLE connection setup is prohibitively slow. While the combination of BLE and Wi-Fi provides high throughput with good energy efficiency, careful design of the BLE-based signalling protocol is necessary to also achieve low latency.}, language = {en} } @misc{NattkeRottaNatarovetal., author = {Nattke, Matthias and Rotta, Randolf and Natarov, Roman and Archila, Oscar and Mykytyn, Pavlo}, title = {Precise sensors for localization in the drone swarm}, series = {Proceedings iCCC2024 - iCampµs Cottbus Conference, 2024-05-14 - 2024-05-16, Cottbus}, volume = {2024}, journal = {Proceedings iCCC2024 - iCampµs Cottbus Conference, 2024-05-14 - 2024-05-16, Cottbus}, publisher = {AMA}, isbn = {978-3-910600-00-3}, doi = {10.5162/iCCC2024/P16}, pages = {166 -- 169}, abstract = {Drones can be connected as a swarm to precisely monitor large agricultural areas and manage them more sustainable. They test sensor technology in real environments and solve complex tasks faster. Key aspects include accurate localization, reliable communication, and dynamic flight control. The localization accuracy of RTK-GNSS-enabled system, which includes GPS, GLONASS, GALILEO positioning systems is compared with Ultra-Wideband (UWB) one. The UPWARDS communication hub is presented as a processing and connection point across swarm agents. This controller also incorporates collision avoidance features and testing of evasion strategies.}, language = {en} } @inproceedings{ChatharajupalliRottaNolte, author = {Chatharajupalli, Navya Sneha and Rotta, Randolf and Nolte, J{\"o}rg}, title = {P2 - VibroMote: Energy efficient Vibration Monitoring for Railway tracks and Bridges}, series = {iCCC2024 - iCampµs Cottbus Conference 2024-05-14 - 2024-05-16}, booktitle = {iCCC2024 - iCampµs Cottbus Conference 2024-05-14 - 2024-05-16}, publisher = {AMA Service GmbH, Von-M{\"u}nchhausen-Str. 49, 31515 Wunstorf, Germany}, isbn = {978-3-910600-00-3}, doi = {10.5162/iCCC2024/P2}, pages = {123 -- 126}, abstract = {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.}, language = {en} } @misc{KarnapkeRichterWerner, author = {Karnapke, Reinhardt and Richter, Martin and Werner, Matthias}, title = {Virtualization in robot swarms: past, present, and future}, series = {2024 IEEE 21st Consumer Communications \& Networking Conference (CCNC)}, journal = {2024 IEEE 21st Consumer Communications \& Networking Conference (CCNC)}, publisher = {IEEE}, isbn = {979-8-3503-0457-2}, doi = {10.1109/CCNC51664.2024.10454838}, pages = {1 -- 6}, abstract = {Robot swarms have come a long way since the first mobile sensor/actuator networks. Since then, we have seen the rise of operating systems for robots and swarm operating systems that ease the use of robots, and especially of large swarms of them, a lot. Still, the description of a task is often not easy and best done by experts. In this paper we envision future swarm operating systems, where task descriptions take a form which can be realized by non-experts. We describe our idea of hugely increased virtualization in the swarm and how this can be used to realize the aforementioned vision.}, language = {en} } @misc{RabensteinNguyenGierschetal., author = {Rabenstein, Jonas and Nguyen, Dustin and Giersch, Oliver and Eichler, Christian and H{\"o}nig, Timo and Nolte, J{\"o}rg and Schr{\"o}der-Preikschat, Wolfgang}, title = {Back to the core-memory age: running operating systems in NVRAM only}, series = {Proceedings: architecture of computing systems: 36th International Conference, ARCS 2023, June 13 - 15, 2023}, journal = {Proceedings: architecture of computing systems: 36th International Conference, ARCS 2023, June 13 - 15, 2023}, editor = {Goumas, Georgios and Tomforde, Sven and Brehm, J{\"u}rgen and Wildermann, Stefan and Pionteck, Thilo}, publisher = {Springer-Verlag}, isbn = {978-3-031-42784-8}, doi = {10.1007/978-3-031-42785-5_11}, pages = {153 -- 167}, abstract = {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.}, language = {en} } @misc{GierschNguyenNolteetal., author = {Giersch, Oliver and Nguyen, Dustin and Nolte, J{\"o}rg and Schr{\"o}der-Preikschat, Wolfgang}, title = {Virtual memory revisited for tiered memory}, series = {Proceedings of the 15th ACM SIGOPS Asia-Pacific Workshop on Systems}, journal = {Proceedings of the 15th ACM SIGOPS Asia-Pacific Workshop on Systems}, publisher = {ACM}, address = {New York, NY, USA}, isbn = {979-8-4007-1105-3}, doi = {10.1145/3678015.3680475}, pages = {1 -- 7}, abstract = {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.}, language = {en} } @misc{RottaChatharajupalliNaumannetal., author = {Rotta, Randolf and Chatharajupalli, Navya Sneha and Naumann, Billy and Schulz, Julius and Karnapke, Reinhardt and Werner, Matthias and Nolte, J{\"o}rg}, title = {Demo: B.A.T.M.A.N. mesh routing on ultra low-power IEEE 802.11 modules}, series = {2024 IEEE 49th Conference on Local Computer Networks (LCN)}, journal = {2024 IEEE 49th Conference on Local Computer Networks (LCN)}, publisher = {IEEE}, isbn = {979-8-3503-8800-8}, issn = {2832-1421}, doi = {10.1109/LCN60385.2024.10639789}, pages = {4}, abstract = {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.}, language = {en} } @misc{RottaSchulzNaumannetal., author = {Rotta, Randolf and Schulz, Julius and Naumann, Billy and Chatharajupalli, Navya Sneha and Nolte, J{\"o}rg and Werner, Matthias}, title = {B.A.T.M.A.N. Mesh Networking on ESP32's 802.11}, series = {2024 IEEE 49th Conference on Local Computer Networks (LCN)}, journal = {2024 IEEE 49th Conference on Local Computer Networks (LCN)}, publisher = {IEEE}, isbn = {979-8-3503-8800-8}, issn = {2832-1421}, doi = {10.1109/LCN60385.2024.10639698}, pages = {1 -- 7}, abstract = {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.}, language = {en} } @misc{ShahinRottaArchilaetal., author = {Shahin, Keyvan and Rotta, Randolf and Archila, Oscar and Mykytyn, Pavlo and Nattke, Matthias and Reichenbach, Marc and Nolte, J{\"o}rg and Natarov, Roman}, title = {A Modular Communication Architecture for Adaptive UAV Swarms}, series = {2023 IEEE International Conference on Omni-layer Intelligent Systems (COINS)}, journal = {2023 IEEE International Conference on Omni-layer Intelligent Systems (COINS)}, publisher = {IEEE}, address = {Berlin}, isbn = {979-8-3503-4647-3}, doi = {10.1109/COINS57856.2023.10189245}, pages = {6}, abstract = {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.}, language = {en} } @misc{RichterKarnapkeWerner, author = {Richter, Martin and Karnapke, Reinhardt and Werner, Matthias}, title = {Utilizing sensor and actuator virtualization to achieve a systemic view of mobile heterogeneous cyber-physical systems}, series = {Proceedings of the 14th International Conference on Simulation and Modeling Methodologies, Technologies and Applications}, journal = {Proceedings of the 14th International Conference on Simulation and Modeling Methodologies, Technologies and Applications}, publisher = {SCITEPRESS - Science and Technology Publications}, isbn = {978-989-758-708-5}, doi = {10.5220/0012715800003758}, pages = {207 -- 214}, abstract = {When programming cyber-physical systems, application developers currently utilize physical sensors and actuators individually to achieve the desired observations and impacts within the physical world. This is an error-prone and complex task given the size, heterogeneity, and mobility of prevailing cyber-physical systems. We introduce an application model that allows the application developers to take a physical perspective. By means of this model, the programmers describe desired observations and influences with respect to the physical world without directly referencing physical devices. We present an additional model for a runtime environment that transparently utilizes the available physical devices to reach the application developers' targets. We show that an implementation of our models is functional via simulation.}, language = {en} } @misc{KarnapkeSeidelHeuerHoeckneretal., author = {Karnapke, Reinhardt and Seidel Heuer, Dilmari and Hoeckner, Soeren and Walther, Karsten}, title = {Secure connections in local networks despite multiple stakeholders}, series = {Proceedings of Ninth International Congress on Information and Communication Technology : ICICT 2024, London, Volume 4}, journal = {Proceedings of Ninth International Congress on Information and Communication Technology : ICICT 2024, London, Volume 4}, editor = {Yang, Xin-She and Sherratt, Simon and Dey, Nilanjan and Joshi, Amit}, publisher = {Springer-Verlag}, isbn = {978-9819735617}, pages = {141 -- 153}, abstract = {Computer usage authentication mostly comes in two flavors: Either as a key-value pair (name and password) or as certificates from a thrusted authority. Both approaches have their advantages and drawbacks when used for authentication of users on their computer and their computers on the Internet. However, in Industrial Internet of Things environments, when authenticating machines against machines that do not have a permanent Internet connection, this becomes an even bigger issue. In this paper we describe the insufficiencies of these classic approaches when dealing with attacks that originate inside a local network and present our methods of mutual authentication for devices in environments where multiple stakeholders are involved and a permanent Internet connection is not a given.}, language = {en} } @misc{ChatharajupalliRottaKarnapkeetal., author = {Chatharajupalli, Navya Sneha and Rotta, Randolf and Karnapke, Reinhardt and Nolte, J{\"o}rg}, title = {Probing considered harmful : leveraging RSSI for link quality prediction}, series = {Proceedings of the IEEE 50th Conference on Local Computer Networks : LCN 2025 : October 14-16, 2025, Sydney, Australia}, journal = {Proceedings of the IEEE 50th Conference on Local Computer Networks : LCN 2025 : October 14-16, 2025, Sydney, Australia}, publisher = {IEEE}, address = {New York, NY}, isbn = {979-8-3315-3704-3}, issn = {2831-7742}, doi = {10.1109/LCN65610.2025.11146347}, pages = {1 -- 9}, abstract = {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.}, language = {en} }