Kai Daniel

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.

Role-Based Connectivity Management with Realistic Air-to-Ground Channels for Cooperative UAVs

Ad-hoc aerial sensor networks leveraging MUAVs (Micro Unmanned Aerial Vehicles) are ideally suited to cost-efficiently explore unknown or hostile environments for example in case of incidents producing harmful gases or radiation. In this manuscript we present results on the investigations of communication-aware steering algorithms for cooperative MUAV swarms. The mission objective is to achieve a maximum spatial exploration efficiency with the simultaneous ability to self-optimize the communication links by exploiting controlled mobility. While our previous work has mainly considered the performance of the Air-to-Air mesh network, in this paper we focus on the Air-to-Ground-link connectivity control. To achieve appropriate communication links to a central sensor data sink even while exploring larger search areas, an agent-based role management strategy is used to provide suitable multi-hop connectivity. The novel algorithms are investigated for static as well as dynamically changing environments. Key results include a detailed realistic aerial channel characterization and network dimensioning analysis considering numbers of MUAVs and density of ground stations vs. exploration speed and sensor data latency.

Cognitive Agent Mobility for Aerial Sensor Networks

For efficient sensor coverage of large industrial and incident areas, fast and flexible strategies for collecting sensor data through an autonomous, wirelessly connected swarm of (Micro) Unmanned Aerial Vehicles (MUAVs) are still an emerging challenge. Deploying multiple MUAVs which stably carry sensing equipment in hostile environments yields cost efficiency and reducing the risk to human life. The use of an aerial ad hoc sensor network based on MUAV agents promises more timely and accurate information by fusing measurements from different types of sensors. In this paper, we examine agent-based mobility algorithms that target high spatial coverage distribution, high total coverage, and high-quality communication links. For these key figures, the performance of the different novel mobility algorithms is evaluated. We particularly focus on channel aware mobility and on self-organizing mesh topologies of MUAV-based sensor swarms with respect to communication constraints.

Performance Evaluation of IEEE 802.16 WiMAX Link With Respect to Higher Layer Protocols

The WiMAX technology based on the IEEE802.16-d standard is a broadband wireless access (BWA) technology and considered to be an important ingredient of the composition of the next generation networks (NGN). Till date, due to lack of deployment, not enough data is available in terms of its operational capabilities and efficiencies. The main objective of this paper is to evaluate, analyze and compare the performance of a WiMAX link under different load and traffic conditions. For this purpose an experimental WiMAX test-bed has been deployed at the Communication Network Institute (CNI), University Dortmund and several experiments and stress tests are carried out over this CNI WiMAX test-bed in the uplink and downlink directions for various service and traffic types and at various distances from the base station. The results of these experiments are presented in this paper.

Coverage evaluation of wireless networks for Unmanned Aerial Systems

Unmanned Aerial Vehicles (UAVs) gained a lot popularity during the last years and are used in many applications ranging from reconnaissance over disaster recovery to remote sensing [1][2]. In most applications some sort of communication link is needed to transmit telemetry and payload data. Especially for homeland security and civil operations the realization is sometimes very demanding due to missing radio frequencies. In order to overcome this constraint we investigate the usability of existing cellular networks. Considering these UAVs to communicate by means of cellular networks for establishing reliable air-to-ground links, claims an analysis and evaluation of the cellular channel characteristics in the low altitude operational area. In this paper we present a coverage analysis for cellular networks for altitudes up to 500m based on aerial RSSI measurements.

Link quality dependent mobility strategies for distributed aerial sensor networks

The in-depth reconnaissance and surveillance of incidents that are caused by uncontrolled emissions of liquid or gaseous contaminants, e.g. in cases of volcanic eruptions, large fires, industrial incidents or terrorist attacks, is still an emerging challenge. Mounting sensors on unmanned aerial vehicles (UAV) is a feasible approach since recent advances in the area of propulsion, carbon reinforced materials and batteries enable for miniaturization and cost-efficient deployment. Our proposed system makes use of an autonomous, wireless connected swarm of Micro UAVs, that is featured with a lightweight mobile sensor system. For this purpose a mobile ad hoc remote sensing network is set up in the air, that allows for calculation of potential fields like a aerosol propagation maps or 3D geomorphologies. Next to this system-of-systems approach, we uniquely show how to optimize the spatial sensor coverage while maintaining the communication quality. In this paper we analyze the equilibrium between coverage and link quality for a cluster based mobility scheme which is combined with randomized cognitive repelling walks.

Protocol Design and Delay Analysis for a MUAV-Based Aerial Sensor Swarm

In dynamic networks such as highly mobile swarms of micro unmanned aerial vehicles (MUAV) the round trip time (RTT) is a crucial key figure for the reliability and viability of the system. For this purpose the deployed protocols and underlying network architecture have to be designed in awareness of the available and allocatable throughput. In this paper we are investigating a network and protocol design of a novel system approach for aerial remote sensing by means of MUAV swarms. Since effectiveness and performance ability of the navigation, control and guidance algorithms depend not only on sense and avoid or collision avoidance capabilities of each MUAV, we are particularly analyzing the delays and RTT between each node in the considered agent-based avionic mesh network. As the proposed protocol design has got a significant impact on the processing delay of embedded systems, a major focus is given to the RTT analysis of a multi-hop WLAN mesh network. Next to the self-interference caused in the experimental testbed, external co-channel and common channel interference are considered to emulate a realistic environment.

Leveraging public wireless communication infrastructures for UAV-based sensor networks

Unmanned Aerial Vehicles (UAV) enable the in-depth reconnaissance and surveillance of major incidents. Uncontrolled emissions of liquid or gaseous contaminants in cases of volcanic eruptions, large fires, industrial incidents or terrorist attacks can be analyzed by utilizing UAVs (cf. Fig. 1). Hence, the use of cognitive Unmanned Aerial Systems (UAS) for distributing mobile sensors in incident areas is in general a significant value add for remote sensing, reconnaissance, surveillance and communication purposes [1][2]. Police departments, fire brigades and other homeland security organizations will have access to medium and small size UAVs in the near future and will integrate UAVs in their work flow. In this paper we are focusing on the civilian concepts of operations (CONOPS) for UAVs, in particular for small-scale UAVs. We present viable concepts on system level for leveraging public wireless communication networks for UAV-based sensor networks with respect to existing constraints and user requirements.

Three dimensional channel characterization for low altitude aerial vehicles

Based on the recent developments in the area of lithium polymer batteries and carbon fiber-reinforced plastic materials Micro Unmanned Aerial Vehicles (MUAV) have significantly gained in importance. Therefore, the use of MUAV based swarms is a feasible approach for remote sensing, surveillance and in particular for emergency and rescue missions [1][2]. Developing MUAVs which operate at low altitudes opens a new and challenging use case for both aerial mesh networks and existing cellular networks. The channel characteristics are crucial for the design of the required communication system. Since channel models for cellular networks typically assume that the users are at ground level, the use of these models for aerial deployment is a questionable attempt. For this reason, we are focusing in this paper on the channel characterization and analysis of an aerial mesh network based on a MUAV swarms. A choice of well known analytical and empirical channel models are adapted to the boundary conditions of low altitude platforms and subsequently validated by raytracing measurements in order to state their applicability.

Channel Aware mobility for self organizing wireless sensor swarms based on low altitude platforms

Based on the recent developments in the area of lithium polymer batteries and carbon fiber-reinforced plastic materials Micro Unmanned Aerial Vehicles (MUAV) significantly gain in importance. The use of cognitive MUAV swarms for distributing mobile sensors is a significant value add for chemical plume detection in rescue missions and also in particular for remote sensing and surveillance purposes [1][2]. The objective of our proposed cognitive and sensor aided mesh network is to maximize the spatial sensing coverage on the one hand and the connectivity between the cooperative MUAVs on the other. Next to these contrary optimization goals we developed bio-inspired algorithms seeking concurrently for a global target and a coherent topology of the swarm in order to avoid self-separations. In this paper we particularly focus on an agent-based methodology for communication aware mobility behavior of self-organizing MUAVs at high vehicular speeds which provoke fast topology changes and lead to a transient aerial mesh network. To determine the key figures of the system, the performance of dynamically adapted mobility algorithms is analyzed and compared under lognormal channel conditions.