We investigate the performance of multicast transmissions in a simple stationary wireless multihop ad hoc network test-bed. We compare several methods for MANET multicast using implementations for the protocols MOLSR, SMOLSR and SMF with an approach that uses explicit multicast and link-layer retries for reliable multicast. Results from the test-bed are compared with simulation results. We find that implementing a combination of explicit multicast with a retry mechanism gives the most promising results in test-bed and simulation compared with other approaches.

In recent years multiple simultaneous localization and mapping (SLAM) algorithms have been proposed, which address the challenges of 3D environments in combination with six degress of freedom in the robot position. Commonly, solutions based on scan-matching algorithms are applied. In contrast to these approaches, we propose to use a particle filter transferring the concept of the 2D Rao-Blackwellized particle filter SLAM to 3D. As filter input, 3D laser range data and odometry readings are obtained while the robot is in motion. The ground plane is estimated based on previously built map parts, thereby approaching the problem that not all degrees of freedom are covered by the odometry. To gain control of the high memory requirements for the particles' 3D map representations, we introduce a memory efficient search structure and adapt a technique to efficiently organize and share maps between particles. We evaluate our approach based on experimental results obtained by

Die Vernetzte Operationsführung dient der Führung und dem Einsatz von Streitkräften auf der Basis eines streitkräftegemeinsamen, führungsübergreifenden und interoperablen Kommunikations- und Informationsverbundes. Wesentliche Bestandteile der Vernetzten Operationsführung sind Kommunikations- und Sensornetze. Für den Einsatz von Mehrrobotersystemen ist die Integration in die vernetzte Operationsführung von entscheidender Bedeutung. Als Grundlage für die Integration ist jedoch ein geeignetes Kommunikationsnetz notwendig. Es werden daher zunächst basierend auf dem NATO-Workshop „1st NATO Workshop on short-term realizable (multi-)robot systems in military domains“ die Kommunikationsanforderungen an ein Mehrrobotersystem identifiziert und Schwierigkeiten bei der Umsetzung in einem Kommunikationssystem diskutiert. Anschließend wird mit dem Protokoll WNet ein flexibler Rahmen vorgestellt, um Lösungen für Kommunikationssysteme zu untersuchen, die möglichst viele dieser Anforderungen berücksichtigen. Die zusätzliche oder detailliertere Berücksichtigung von Anforderungen kann dabei durch Erweiterungen des Rahmens vorgenommen werden. WNet ist somit ein experimenteller Protokollrahmen, um unterschiedliche Verfahren zur Kommunikation in Mehrrobotersystemen zu vergleichen. Das Ergebnis dieser Vergleiche soll dann die Grundlage für ein oder mehrere geeignete Kommunikationssysteme für Mehrrobotersysteme bilden, die eine einfache Integration in die vernetzte Operationsführung erlauben.

Multi-robot systems obtain their performance advantages from close collaboration of the participating robot systems. As the demand for such cooperation increases, the aspect of wireless communication is getting more and more important. To cope with the challenges of the wireless communication we propose an easy to use communication framework for a multi-robot system. This framework is designed for wireless networks, therefore it expects unreliable communication and can even cope with complete network separations. Using multicast as the default communication scheme, the framework can directly benefit from the broadcast nature of the wireless medium if such an optimisation is supported by the lower network protocols. We therefore introduce our multicast capable wireless routing protocol, which supports this optimisation. The software is implemented and frequently used in our experimental multi-robot system.

Mobile ad hoc networks or MANETs are supposed to play an important role in future military communication. MANETs offer quickly deployable network functionality even when the existing infrastructure is damaged or unusable. But while offering many advantages, the MANET technologies today are facing new security threats. These threats arise from the simplicity to eavesdrop on the wireless medium and launch direct attacks against the routing protocol. A MANET protocol concept that deals with these challenges is presented in this paper.

Multi robot systems (MRS) have been an active research area for many years. With the robot systems leaving the laboratory environment, the aspect of wireless communication is getting more important. Especially in multi robot systems wireless communication is crucial, but existing middleware for robot systems does not regard the challenges of wireless communication. Among other aspects the fluctuation of link delay, bandwidth and availability is characteristic for wireless communication. A communication system in a multi robot system must be capable to manage these challenges. Another issue is efficient point to multipoint (multicast) communication. This allows the availability of the same data to multiple recipients without an unnecessary high increase of network load compared to unicast communication schemes. We therefore propose a multicast communication framework for a multi robot system based on wireless communication. The framework is organised in two parts. The first part is a general framework for a wireless multicast communication protocol, which is optimized to offer efficient multicast communication capabilities on wireless networks and takes the available link qualities into account. The second part is a framework for a robot middleware, which benefits from the multicast communication optimizations of the first part. The framework assumes unreliable communication, thus taking fluctuating link qualities into account. Both parts are already implemented on a real system and are used in an experimental multi robot system.

Several proposals have been made to achieve efficient routing of unicast and multicast data in wireless mobile ad hoc networks. This paper evaluates a new approach to use link layer parameters to determine a link quality value for route calculation, especially for multicast data dissemination. Simulation results suggest that a shortest path metric is rarely the best choice. Instead, a signal strength based metric yields better results than other common protocols.

Several proposals have been made to achieve efficient routing of unicast and multicast data in wireless mobile ad hoc networks. This paper evaluates a new approach to use link layer parameters to determine a link quality value for route calculation, especially for multicast data dissemination. Simulation results suggest that a shortest path metric is rarely the best choice. Instead, a signal strength based metric yields better results compared with other common protocols.

In this paper an experimental framework called V;Net for forwarding data frames in a wireless mobile ad hoc network is presented. The approach is based on the principles of the OLSR protocol but is implemented as a forwarding protocol on the MAC layer. One focus of the framework is the support of efficient multicast communication. The design allows extensions concerning quality and priority based forwarding, quality of service, congestion management, power awareness and security.Since the framework is positioned on the MAC layer, it has direct access to device parameters and can therefore determine link and node attributes. These are used to calculate link qualities that influence the forwarding decision, leading to a quality-based routing mechanism.