Carsten Koch

System architecture for data communication and localization under harsh environmental conditions in maritime automation

This paper shows an initial approach of a system architecture for a wireless sensor network (WSN), addressing the maritime domain. Novel architectures, technologies and prototypes for WSNs have been in focus of researchers and economists for several years. The proposed system architecture is focused on maritime automation - the construction and maintenance of offshore wind farms with their specific requirements. Harsh environmental conditions impede the performance of wireless technologies in onshore and offshore applications, caused for instance by many metal components, wayless terrain, often non-line-of sight (NLOS) connections between mobile motes, and dynamic ground motion for example onto a jack up ship for offshore construction work. Furthermore, many approaches for WSN are addressing either communication or localization networks. The proposed system architecture covers both at the same time, based on Ultra Wide Band radio technology (UWB). UWB allows robust distance measurements and communication, in particular in harsh environments.

A mobile open infrastructure network protocol (MOIN) for localization and data communication in UWB based wireless sensor networks

In this paper, a novel network protocol (MOIN - Mobile Open Infrastructure Network Protocol) for non synchronized UWB based wireless sensor networks is presented. Applications of classical protocols for such non synchronized networks, where anchor nodes are not synchronized for ranging and communication purposes, typically are not effective for simultaneous ranging and communication tasks. The proposed MOIN protocol overcomes these shortcomings by using an optimized scheduling scheme for rangings. The channel access is realized by a centralized hybrid MAC layer which uses TDMA and CDMA. In addition, the MOIN protocol supports multiple sensor domains to achieve a higher network range. Dynamic domain selection and adaptive slot assignment depending on the number of network participants at runtime are key features to reduce the delay between each ranging procedure which minimizes motion artefacts. A sequential pre-defined ranging order can be ensured to minimize the position error. Another advantage of the adaptive slot assignment is the minimization of time slots in each superframe. This leads to a shorter superframe duration and significantly increases network throughput and update frequency rates.

Detection of distorted IR-UWB pulses in low SNR NLOS scenarios

In dense environments, for example residential, office or industrial, the predominant type of link within a real time localization system (RTLS) is non-line-of-sight (NLOS). In some NLOS scenarios the signal-to-noise-ratio (SNR) of the first incoming Ultra Wideband (UWB) pulse content is much below 0 dB and the shape of the pulse is distorted. Accordingly the detection of the first pulse is critical. In those cases a possible solution is to detect several sample values which show a high probability to be the center of an UWB pulse. In Time-of-Flight (ToF) based ranging, this leads into a number of pulse or rather distance candidates. The aim of the paper is to present a novel scheme for an improved detection of distorted UWB pulses, especially with SNR below 0 dB. A major objective is to minimize the number of necessary pulse candidates for a defined pulse detection quality. The robustness of the approach has been analyzed by a simulation with a huge number of synthetic pulses in dependency of the SNR and a further series with the degree of distortion as parameter. For a wall of brick and a thickness up to 25 cm an average improvement of 32 % against traditional matched filter (MF) method is achieved.

A hybrid MAC layer for localization and data communication in ultra wide band based wireless sensor networks

This paper presents a hybrid MAC layer design for UWB based sensor networks to handle multiple access with the ability to combine localization and data communication. UWB networks allow high precision ranging and robust data communication in harsh environmental conditions and for this are well suited for typical automation applications. To minimize localization errors in this applications, e. g. by moving sensor nodes, rangings have strong realtime requirements and must be done in a distinct pre-defined order. This can not be guaranteed in common MAC layer implementations, which are typically based on the IEEE 802.15.3 standard with contention access (CSMA/CA) and contention free access part (TDMA). The MAC scheme proposed in this paper overcomes this limitations as the contention access part is replaced by a TDMA/CDMA scheme. Evaluation results presented in this paper show that this novel approach outperforms existing schemes and fulfils the requirement for realtime ranging and communication.

Optimization of wireless locating in complex environments by placement of anchor nodes with evolutionary algorithms

Lateration based real time locating systems (RTLS) require anchor nodes with known positions to calculate the position of a mobile target. The geometry of the anchor nodes constrains the accuracy of the locating. In complex environments such as ships or factory floors, obstacles in the line of sight between target and anchors decrease the precision significantly. This is caused by the influence of multipathing effects and shadowing on distance measurements. In this work, we propose a heuristic approach to find reasonable geometries for anchor nodes in complex environments. We achieve this by simulation of anchor geometries and the employment of evolutionary algorithms to search for optimizations.

Development of smart field devices using heterogeneous multicore processors

This work gives an overview of established communication architectures for field devices and addresses the usage of heterogeneous multicore processors for the development of a new generation of smart field devices, using service-oriented architectures (SOA) of modern cross-layer infrastructures.

Anchor node placement in complex environments with physical raytracing and genetic algorithms

In this work, a method for placing anchor nodes for lateration based wireless 3D indoor locating systems is presented. It combines genetic optimization with radio impulse propagation simulation using a physical ray-tracer. It is shown that the proposed methods results decrease the locating error for a variety of real environments with increasing complexity in comparison to an organic equidistant anchor node setup with a similar amount of nodes.

Smart least-resolution imager for industrial applications

This paper discusses realisation aspects and limitations of optical least-resolution sensors with less than 1k pixels to fill the gap between a light barrier and common smart cameras. The capability of the proposed hard- and software-architecture is demonstrated by an industrial example application in conjunction with Model-Driven Software Development which aim is to locate mechanical components for robot guidance.