Andreas Lewandowski

AirShield: A system-of-systems MUAV remote sensing architecture for disaster response

For clarification, containment and combat of large danger areas, fast and flexible survey of potentially contaminated areas is an emerging challenge. In this paper we present a project that focuses on incidents, that are caused by uncontrolled emissions of liquid or gaseous contaminants (e.g. explosive or toxic gases or liquids, biological, chemical or nuclear weapons). Instead of sending specially equipped forces with expensive transport and measurement devices into the contaminated area, our proposed system makes use of an autonomous, wireless connected swarm of Micro Unmanned Aerial Vehicles (MUAV), often simply known as drones, that are featured with lightweight mobile sensor systems. In this paper we will be particularly focusing on the complex communication system, which on the one hand has to organize the on-board-communication between the control systems of the MUAV and the sensors and on the other hand has to establish wireless connections to the mission control center on the ground as well as to neighboring MUAVs in the air via a mesh network.

A comprehensive approach for optimizing ToA-localization in harsh industrial environments

Real-life industrial environments pose a challenge for todays radio-based localization systems, as the radio channel is highly affected by the multiple interference present in the environment. Therefore, this paper presents a solution for generating Weighted Multilateration Position Estimation based on the RSSI (Received Signal Strength Indicator) for ToA (Time of Arrival) ranging measurements to enhance the fault tolerance, reduce the self-interference of the ranging system and finally enhance the accuracy of the position estimation. A coordinate descent algorithm for optimal anchor placement is demonstrated in this paper, which is based on results of 3D ray tracing. The applied 3D environment model is highly sophisticated, as it was generated by 3D laser scanning for gauging. In a final optimization step, power level adjustment is shown to further enhance the accuracy of the localization system. Concluding, a performance evaluation based on simulations, numerical optimization and experimental measurements in the industrial target environment will demonstrate the improvements of our comprehensive approach in terms of accuracy and robustness.

A segmentation-based Radio Tomographic Imaging approach for interference reduction in hostile industrial environments

This paper presents and evaluates a passive device-free tracking system for localization of objects or persons. The system works with a continuous evaluation of the received signal strengths of connection links between fixed installed anchor nodes. Out of the evaluated measurements, an image of the scene can be generated based on Radio Tomographic Imaging (RTI). The major contribution of this paper is an application of segmentation algorithms for sharpening the image by reducing noise and interference. The applied combination of image segmentation with a connected component labeling algorithm enables an evaluation of certain areas in the image to estimate the position and the number of objects in the room. Finally, the application of particle filtering smoothes the estimated position and leads to a reliable and accurate position estimation, which is comparable with active solutions. As interference and noise in the link measurements caused by multipath propagation effects can harm the achievable accuracy, the foreseen application area - an industrial environment- poses a huge challenge, as the radio channel is highly affected by the metallic infrastructures.

A new dynamic co-channel interference model for simulation of heterogeneous wireless networks

This paper presents an interference model of overlapping radio channels which allocate the same frequency band. The model is based on the INET Framework [12] of OMNeT++ [11] simulation engine and the raytracing tool Radiowave Propagation Simulator (RPS) [14]. By using our prediction model, we present a proposal for an easier integration of adaptive bit rate adjustment for wireless networks in OMNeT++. Since a few years, an increasing amount of technologies that use the public domain 2.4 GHz band like Wi-Fi, Bluetooth and ZigBee were launched into market which complicates a sophisticated coexistence. Therefore, we want to analyze a channel model that regards not only various Physical Layer specific circumstances but also the alignment of the different networks operating in their particular scenarios. Apart from other approaches, our simulation model uses a dynamic, coupled raytracing tool to compute Carrier-to-Interference (C/I) ratios directly out of the given ambient and alignment parameter set. Finally, the validity of the simulation implementation will be proven by applying a safety critical scenario in the area of rescue operations including monitoring of vital and ambient parameters.

Design and performance analysis of an IEEE 802.15.4 V2P pedestrian protection system

Vulnerable Road User protection systems leveraging V2P (Vehice-to-pedestrian) communications require low-power, low-cost, small size radio communication hardware in order to be suitable for a future mass-market introduction. This paper therefore proposes a Low Power Pedestrian Protection System (LP3S) based on IEEE802.15.4. It is composed of a retrofit warning unit installed in the vehicle and a miniaturized active Tag-solution with very long battery lifetime to be worn by children, bicycle riders or other endangered persons. A lean protocol design allows for a reliable detection of pedestrians within a critical distance. A comprehensive performance evaluation based on detailed, stochastic system simulation demonstrates the high potential as well as the drawbacks of this solution. The performance indicators focus on the reasonability of alarming messages, with the aim to reduce false alarms to a minimum. Therefore, several solutions for optimizing the warning trigger algorithm are proposed including protocol optimization and incorporation of radio-based distance measurements. The most promising system options are validated in a large-scale simulation containing several hundred vehicles and pedestrians in a realistically modeled environment. The results show a high reasonability for alarming messages inside the vehicle and demonstrate the feasibility and reliability of the proposed pedestrian detection system.

Concept and Performance Evaluation of a Galileo-Based Emergency Short Message Service

The European satellite navigation system Galileo is ready for service in the year 2013. New services are needed to be investigated to enlarge the capabilities of the system. In this paper we propose a Galileo Search and Rescue Short Message Service (Galileo SAR-SMS) to enable sparse text communication between endangered persons and rescue forces to optimize the process of retrieval. Galileo SAR is an addition to the well established humanitarian satellite-based SAR System Cospas-Sarsat (CS) and will be fully compliant. In succession we developed a concept for a Short Message Service which is adaptable to the existing system by exploiting the improved channel characteristics of the Galileo system. Primary, the integrated feedback channel of Galileo enables a two way communication. This paper presents a description of the service flow, message design and channel properties of Galileo SAR-SMS. The performance of the developed protocol architecture is shown to demonstrate the feasibility of the new service.

A comprehensive mobility management solution for handling peak load in cellular network scenarios

First responders are suffering from insufficient information about the incident during alerting and operations at the scene itself. Particularly at major incident operations detailed and up-to-date multimedia information are indispensable and have to be provided as fast and reliable as possible to the rescue forces. Thus, challenging requirements on the mobile communication system like traffic prioritization, seamless handover and everywhere connectivity arise from this use case. In this paper we present a holistic approach for a suitable heterogeneous communication architecture considering the complete mobility management process that consists of mobility modeling, handover trigger algorithms and IP-based handover protocols applied on a big public event at a stadium.

A multiscale real-time navigation and communication satellite simulation model for OMNeT++

This paper presents the first steps of developing the Galileo Satellite Communication Simulator (GSCS) based on the INET Framework [2] of OMNeT++ simulation engine [1]. We present our mobility model for the accurate prediction and modeling of satellite motion using NORADs (North American Aerospace Defense Command) propagation algorithm SGP (Simplified General Perturbations) for real-time satellite position modelling. Galileo specific satellite orbit data is generated in order to establish the mobility of the prospective space segment. The validity of the simulation implementation is then proved by comparing the results of our simulation with two reputable satellite tracking applications and to a real GPS receiver, from which further extensions of the simulation system are derived. In further steps the integration in a Multiscale Network Simulation Environment is described. The dynamic interaction between Environment, Radio Channel and User Mobility can then be modelled in an adequate way.

Passive Detection of Wrong Way Drivers on Motorways Based on Low Power Wireless Communications

This paper describes a solution for the problem of wrong way driving on motorways by proposing a new Passive Vehicle Detection (PVD) technology, which is able to detect the driving direction based on roadside radio sensors. The new sensor technology is combined with local and wide-area warning functionality and generates real-time telematics information to increase the safety of all road users. The major benefit of the proposed system is that the vehicle itself must not be equipped with additional hardware. Based on simulation results, we developed a prototype of the Wireless Detection and Warning System (WDWS) to perform experiments for validation. Afterwards, the system was deployed in an extensive field trial at a German motorway in Bochum. The paper describes the architecture, the algorithm design and the results of the performance evaluation. Another benefit is the enormous time gain by a factor of 33 in the generation and transmission of an automated warning to endangered road users.

Coexistence of 802.11b and 802.15.4a-CSS: Measurements, Analytical Model and Simulation

IEEE 802.15.4a Wireless Sensor Networks (WSN) and IEEE 802.11b Wi-Fi networks are operating in the 2.4GHz band. In order to examine co-channel interference scenarios and the impact on key performance indicators, this paper combines an analytical model, measurements and simulations. It is a pilot study which reflects the interference caused by the new IEEE 802.15.4a-CSS (Chirp Spread Spectrum). An analytical model for adaptive bitrate adjustment and throughput optimization reflects the performance impact and the system behaviour of IEEE 802.11b. Measurements are used for model validation before simulation results show the system behaviour for changing node constellations, radio conditions and system setups. The validated simulation model is then applied to a use case scenario for indoor localization, which shows the impact on the performance of a realistic co-existence scenario.