Marco Cimdins, M.Sc., BSEE
|Address||Technische Hochschule Lübeck - University of Applied Sciences, Electrical Engineering and Computer Sciences
Mönkhofer Weg 239
D-23562 Lübeck, Deutschland
|Phone||+49 (0)451 300-5631|
Since February 1st, 2017 I am research associate of faculty electrical engineering and computer science at the University of Applied Sciences Lübeck. My research focus is about indoor positioning, simulation of the radio frequency propagation and simulation of wireless sensor networks.
- Dual course of studies in Electrical Engineering
- Undergraduate Student in Electrical Engineering with Bachelor of Science from the Luebeck University of Applied Sciences and Bachelor of Science in Electrical Engineering from the Milwaukee School of Engineering
- Graduate Student in Applied Information Technology with Master of Science from the Luebeck University of Applied Sciences
- Research associate at CoSA
- Exercise: Bachelor ISE - Principles of Communications I (WS 17/18 & WS 18/19)
- Exercise: Bachelor ISE - Principles of Communications II (SS 18 & SS/19)
- Project: Master AIT - Scientific Projects (WS 18/19)
|||IoTiSS: Internet of Things in Smart Streetlighting , In ITG-Fachbericht-Mobilkommunikation VDE VERLAG GmbH, 2019. [bib] [abstract]|
In the Internet of Things (IoT), sensors measure data and transfer their measurements to servers on the Internet. Street lamps cover a large area, are in the proximity of buildings and sensors and thereby provide an ideal gateway for the IoT. In this paper, we introduce a system consisting of a transport network of street lamps operating in the 868MHz ISM-band and a sensor network operating at 2.4GHz ISM-band. Therefore, each street lamp contains at least two radio frequency equipped modules that communicate with each other via a local short-range wired bus system. We set up the nodes with the Contiki-NG operating system and an open protocol stack with state-of-the-art protocols for our applications. This solution serves as an open architecture for the IoT which is portable and flexible. The first results of our testbed and simulation show the functionality of the system. In the future, optimization and further test are required to ensure the scalability of the system..
|||UWB-based Single Reference Point Positioning System , In ITG-Fachbericht-Mobilkommunikation VDE VERLAG GmbH, 2017. [bib] [abstract]|
Indoor positioning enables new applications, for instance monitoring of goods in smart factories. For such applications, indoor positioning requires cost-effective solutions with high accuracy. State-of-the-art positioning systems are expensive due to high infrastructure and maintenance costs. In this paper we suggest an accurate UWB-based single reference point positioning system using multiple antennas. We compare lateration and hyperbolic lateration as positioning methods and present efficient algorithms for UWB-based single reference point positioning systems. We present theoretical limits based on the Cramer-Rao lower bound and derive an error estimation as well as evaluation results. Our measurements indicate that decimeter accuracy is possible.
|||On the Effective Length of Channel Impulse Responses in UWB Single Anchor Localization , In International Conference on Localization and GNSS, 2019. [bib] [abstract]|
Recently, single anchor localization evolves as a new research topic that exploits multipath propagation for calculation of tag positions. With a combination of movement information and particle filters, they provide a precision that is similar to multi-anchor systems. However, a systematic approach to the design and implementation of such systems is not yet available. The combination of theory and mathematical modeling for channel impulse responses is still an open research question that we address in this paper. Therefore, we propose a new representation of a channel impulse response targeted for single anchor localization systems. Based on this representation, we model the relationship between tag positions and channel impulse responses and evaluate the statistic properties of channel impulse responses in this application. In this paper, we introduce a new metric for the assessment of anchor positions, the effective length of CIRs. By the shortest effective length of a set of CIRs, we identify the best anchor position, since it indicates the position where requirements for the measurement of the channel impulse response are lowest.
|||RF-Based Safety-Critical Hybrid Localization , In The Ninth International Conference on Indoor Positioning and Indoor Navigation (IPIN), 2018. [bib] [abstract]|
In safety-critical environments, e.g. paint or machine shops, precise knowledge of positions of persons is important. If an emergency is detected, e.g. a fire or an intruder in the safety-critical area of heavy machinery, emergency shutdown procedures are activated. This requires fine-grained localization with a tag-based localization system, where the person carries a tag. Without a person carrying a tag, precise localization and detection is difficult. In this paper, we propose a RF-based hybrid localization system for safety-critical localization that consists of two major components: a tag-based and device-free subsystem. The device-free subsystem provides coarse-grained localization and monitors a gate area, serving as an entrance towards the safety-critical area where fine-grained localization is required. We propose an architecture of the system, discuss our setup and evaluate typical use cases. Our preliminary evaluation demonstrates that our system detects the correct state of the hybrid localization system with an accuracy of 90%.
|||Sundew: Design and Evaluation of a Model-based Device-free Localization System , In The Ninth International Conference on Indoor Positioning and Indoor Navigation (IPIN), 2018. [bib] [abstract]|
The state-of-the-art in device-free localization systems based on RF-measurements is fingerprinting. Fingerprinting requires reference measurements called fingerprints that are recorded during a training phase. Especially in device-free localization systems, recording of reference measurements for fingerprinting is a tedious, costly, and error-prone task. In this paper, we propose Sundew, a model-based device-free localization system that does not need fingerprinting in the sense of reference measurements but is able to calculate signal strength values at any position and compare it to actual measurements after a simple calibration phase. Sundew — as any device-free localization system — requires a metric for comparison of feature vectors. In this paper, we investigate the influence of nine different distance metrics on the positioning accuracy. Simulations and measurements show that our suggested model-based device-free localization system works best with the L 1 distance metric. Sundew estimates 90% of positions in a 2.5m x 2.5m grid correctly, independent of the orientation of the person in the target area.
|||Investigation of Anomaly-based Passive Localization with Received Signal Strength for IEEE 802.15.4 , In The Seventh International Conference on Indoor Positioning and Indoor Navigation, 2016. [bib] [abstract]|
Localization has important applications, for instance intrusion detection and elderly care. Such applications benefit from Device-free passive (DfP) localization systems, which employ received signal strength measurements (RSSM) to detect and track entities that neither participate actively in the localization process nor emit signals actively. RSSMs include received signal strength indicator (RSSI), energy detection (ED) and link quality indicator (LQI) measurements. This paper compares different packet-based RSSMs for DfP localization and presents detection results of a DfP anomaly-based detection system employed by IEEE 802.15.4 compliant devices. Furthermore, we investigate techniques for anomaly detection with continuous RSSI measurements.
|||Modeling the Magnitude and Phase of Multipath UWB Signals for the Use in Passive Localization , In 16th Workshop on Positioning, Navigation and Communication, 2019. [bib] [abstract]|
Radio-frequency (RF)-based device-free localization (DFL) systems measure RF parameters such as the received signal strength or channel state information to detect and track objects within a certain area. However, the change of the RF signal caused by the object is superimposed with various changes of the RF signal due to multipath propagation, especially in indoor environments. In this paper, we develop a model for ultra-wideband (UWB) channel impulse response (CIR) measurements for application in DFL systems. The model predicts received signal parameters in a setup with a transmitter and a receiver node, a person and multipath propagation. Different from other approaches, the RF hardware, and the model provides both magnitude and phase information for individual multipath components. We evaluate the new model with real measurements that have been conducted with a Decawave DW1000 radio chip. For the magnitudes, we achieved a correlation factor from 0.78 to 0.87 and maximum mean and standard deviation errors of 1.7 dB and 2.2 dB respectively. For the phase, we achieved correlation factor from 0.6 to 0.81 and maximum mean and standard deviation errors of 0.32 dB and 0.47 dB respectively, showing that the prediction of our proposed model for the magnitude and phase fits well to our measurements.
|||Evaluation of time-based ranging methods: Does the choice matter? , In 14th Workshop on Positioning, Navigation and Communication, 2017. [bib] [abstract]|
Positioning is useful in a number of applications, for instance smart home, smart factory and health care applications. Time-based ranging methods for positioning are the state-of-the-art but require precise timestamping. Sophisticated ranging methods compensate sources of errors, for instance clock drift caused by a crystal or an asymmetrical measuring principle, to provide precise timestamping. So far, no comprehensive study of different time-based ranging methods using the same hardware and the same evaluation setup was carried out. Consequently, we discuss, implement and evaluate five time-based ranging methods, including Two-Way Ranging, Double Two-Way Ranging, Asymmetrical Double-Sided Two-Way Ranging, Symmetrical Double-Sided Two-Way Ranging and Burst Mode Symmetric Double-Sided Two-Way Ranging. We evaluate accuracy, precision, robustness and run time for the ranging methods and answer the question if the choice of the time-based ranging method matters.
|||Anomaly-based Device-free Localization with Particle Filtering , In Workshop on Dependable Wireless Communications and Localization for the IoT, 2017. [bib] [abstract]|
In the Internet of Things (IoT), devices, e.g. sensors or actuators, transmit packets to transfer data. For the IoT localization information is crucial, as it provides additional context for the data. We envision that devices in the IoT know their position and on receipt of a packet, the received signal strength is measured. This measurement is used to build a device-free localization (DFL) system to improve the dependability of the IoT system. DFL systems are able to detect and track persons within a target area that neither wear a device nor participate actively in the process of localization. This work presents an anomaly-based DFL system that measures if a person affects the radio frequency (RF) propagation and determines the position with a particle filter. In our 65m 2 indoor testbed, we employ eight IEEE 802.15.4 compliant wireless transceivers and estimate the position of a person with a median localization error of 1.4m.
|||Modeling Received Signal Strength and Multipath Propagation Effects of Moving Persons , In 14th Workshop on Positioning, Navigation and Communication, 2017. [bib] [abstract]|
Device-free localization (DFL) systems detect and track persons without devices that participate in the localization process. A person moving within a target area affects the electromagnetic field that is measured by received signal strength (RSS) values. Consequently for DFL systems modeling of RSS is important and still an open issue. In this paper, we develop a simple model for prediction of RSS values in a setup with transmitter and receiver devices, a person and multipath propagation. We design and implement the model as a superposition of both, knife-edge diffraction to account for the change made by the person, and, propagation effects such as multipath propagation that result in reflection and path loss including the antenna characteristics. We evaluate our model in comparison with real measurements in various setups with and without multipath propagation. We achieve an accuracy that is close to our hardware limitations, which is the resolution of the measured RSS values of the receiver.
|||A Practical Toolbox for Getting Started with mmWave FMCW Radar Sensors , Technical report, Technische Universität Braunschweig, 2019. [bib] [pdf] [abstract]|
In this paper, we sum up our experience gathered working with mmWave FMCW radar sensors for localization problems. We give a glimpse of the foundations of radar that is necessary to understand the benefit and advantages of this technology. Moreover, we introduce our open-source software toolbox pymmw based on Python for Texas Instruments IWR1443 ES2.0 EVM sensors to provide students and researchers easy access to those radar sensors. In doing so, one can jump right into sensing with mmWave FMCW radar from a practical point of view and start doing experiments and developing own applications. Finally, pymmw is used for data acquisition of a scene illuminated by three virtual radars in three different states of occupancy showing the potential of mmWave FMCW radar for indoor and distance-based localization applications.
|||Phase Error Correction for IEEE 802.11 Channel State Information , (T. M. Buzug et. al., ed.), 2019. [bib] [abstract]|
Channel State Information (CSI) capture is a new technology, which measures the phase and magnitude of WLAN signals. In this paper, we investigate the accuracy and predictability of CSI phase measurements for potential use in geometric localization. We determine known sources of linear and non-linear error. The known sources of error are then correct for by utilizing a curve fitting method. An ideal mathematical model is created and compared to the corrected phase results. The conclusion is that the phase correction method was effective in some cases, however, the results were inconsistent with additional unaccounted sources of error.
|||Improvements to UWB Channel Impulse Response Measurements for Indoor Localization , (T. M. Buzug et. al., ed.), 2019. [bib] [abstract]|
This paper proposes two methods to improve the accuracy of UWB channel impulse response (CIR) measurements. Improving the accuracy of UWB CIR measurements results in an improvement of the overall accuracy of an indoor localization system. Two methods are analyzed, both with the idea of combining a series of CIR measurements to yield higher accuracy than a single measurement. We evaluated both methods by gathering data at different positions within a room. These methods reduced the error by an average of 7% and 4% respectively. The results indicate that utilizing these techniques will improve the accuracy of localization.
|||Investigation of the Message Delay in Wireless Sensor Networks , (T. M. Buzug et. al., ed.), 2019. [bib] [abstract]|
Wireless sensor networks (WSN) can be implemented across entire cities to connect devices and sensors with each other. The example used in this paper to represent a WSN is that street lamps (nodes) build a transport network, which will be investigated to find the message delay. Furthermore, each street lamp is connected to a garbage can (sensor) via a second network. So that, a garbage-can sends data to a street lamp and the street lamp forwards the data through the transport network until the destination receives the message. Each hop of the message occurs a delay which sums up to a multi-hop delay. In this paper, we simulate the transport network by using Contiki-NG with Cooja and calculate the delay of a message with an algorithm. The algorithm finds the routing path of the received message and saves the calculated multihop delay. Our results demonstrate that the delay of the messages becomes smaller if the throughput to the nodes decreases. For the garbage bin example, the delay would not be a problem, however, keep in mind that a delay of 1s is too much for many applications.
|||Proceedings of the 4th KuVS/GI Expert Talk on Localization , Technical report, Technische Universität Braunschweig, 2019. [bib] [pdf]|
|||Impact of the antenna orientation for distance estimation , Technical report, Technische Universität Braunschweig, 2018. [bib] [pdf] [abstract]|
Indoor localization is important for a wide range of use cases including industrial, medical and scientific applications. The location accuracy is affected by the localization algorithm and the quality of the measurements as input for the algorithm. Many indoor localization systems employ ultra-wideband distance measurements, as they offer high accuracy and are cost effective. One of the methods for distance measurement is twoway ranging. This paper investigates the impact of the antenna orientation on the distance measurement based on symmetrical double-sided two-way ranging. We show that up to 0.25m of the measurement error is attributed to the orientation of the antennas. We provide explanations and suggest solutions to reduce the effect.
|||Comparison of Antenna Types and Frequency Bands for Radio-based Device-free Localization , Technical report, Technische Universität Braunschweig, 2018. [bib] [pdf] [abstract]|
Radio-based device-free localization systems measure effects on radio signals e.g. signal strength variations to locate objects or persons in a target area. Such systems detect and track persons that do not participate in the localization process. Models for calculating the radio signal propagation are key for the performance in device-free localization systems. Received signal strength (RSS) is simple to measure. However, it is susceptible to changes in the environment and multipath propagation. In this paper, we compare PCB antennas to a circularly polarized cloverleaf antenna and measurements in the 2.4 GHz with measurements to the 868MHz ISM band. We investigate especially if a circularly polarized cloverleaf antenna is resilient against multipath propagation. Our preliminary results demonstrate that our model is suitable to the 868MHz band and the use of the 868MHz band increases the area where a person affects the RSS. The use of a circularly polarized cloverleaf antenna does not help to avoid multipath propagation.
|||Proceedings of the 3rd KuVS/GI Expert Talk on Localization , Technical report, Technische Universität Braunschweig, 2018. [bib] [pdf]|
|||Investigation of Anomaly-based Passive Localization with IEEE 802.15.4 , Technical report, RWTH Aachen University, 2016. [bib] [pdf]|