Silvia Krug

Movement patterns for mobile networks in disaster scenarios

Node mobility is one essential feature of mobile networks, especially for delay tolerant networks, where packet delivery is only possible through node movements. In mobile ad hoc networks, mobility adds new challenges to the protocol design. Therefore, realistic movement models are required to evaluate protocol performance. Usually, random node movement is considered for that but this kind of movement is not applicable for first responders in disaster scenarios. Their movements are driven by tactical mission requirements and highly depend on the type of disaster. In this paper, we analyze two different movement scenarios to derive common features as well as differences and present how to use these results to generate generic and at the same time realistic movements for first responders.

Impact of Traffic and Mobility Patterns on Network Performance in Disaster Scenarios

First responders show specific movement and traffic patterns that are closely related to their current task during a disaster relief mission. In order to develop efficient communication systems both aspects should be considered. This is important especially if Delay Tolerant Networks (DTN) are used, because they are exploiting the mobility of the nodes in order to deliver messages in scenarios with intermittent connectivity. In a disaster scenario, such a network is formed by the communication equipment of first responders. In this paper, we evaluate different mobility models and traffic generation options and show their impact on the performance of the epidemic routing protocol. Our results show that the correlation between traffic and mobility in disaster scenarios has a significant impact on the delivery ratio and experienced delay, respectively

A Realistic Underlay Concept for Delay Tolerant Networks in Disaster Scenarios

During disaster relief missions, it is essential to provide reliable communication between the different rescue teams and to the victims as well. Since a disaster is likely toe Mobile Ad hoc Networks (MANETs) are the best choice to reestablish communication. However, this type of networks has a major drawback, it can only cover relatively small areas. In large disaster sites, this results in creating frequent partitions of the network as rescue teams spread over the area. In order to handle these disruptions, delay tolerant networks could be used by employing mobile nodes as data ferries between different partitions. These ferries provide the same functionality as border nodes interconnecting different MANETs. In this paper, we present our concept of delay tolerant border nodes and a realistic mechanism to resolve names in such disaster scenarios. This approach enables robust communication throughout the disaster area while supporting heterogeneous technologies and different organizational policies.

An empirical study on generic multicopter energy consumption profiles

Unmanned Micro-aerial vehicles (MAVs) enjoy high popularity in various application fields. They are capable of flying autonomously, following the instructions received from a controlling ground entity. One physical limitation of all mobile robotic vehicles is the restricted energy storage capacity they are able to carry. All processes in a robotic system, prominently in-air movements, consume energy and are thereby defining the overall operation time limit. This paper presents results of an analysis of the energy consumption in various discrete movement states of a multicopter, measured for two different systems. Findings regarding a systematic relation between system and movement parameters and the energy consumption levels are discussed. Furthermore, a generic energy consumption profile model is presented and validated.

Routing-based and location-aware service discovery in Mobile Ad-hoc Networks

In disaster scenarios, a stable and reliable communication is essential for coordinating rescue operations. As the communication infrastructure could be hit, e.g. by earthquakes or hurricanes, mobile ad hoc networks (MANETs) can be used for connection establishment. As such networks should be decentralized to increase robustness, some usual services are no longer available. In our previous publications, we presented our name resolution framework based on an adaptive routing system. In this paper, we show a service discovery mechanism based on this system.We show, how this mechanism can easily be improved with the use of location information, which is an important issue for service availability.

Buffer Management for Reliable Multicast over Delay Tolerant Networks

Flooding, earthquakes, and other disasters are recent phenomenons which unfortunately occur more and more often. After such occurrences, the infrastructure is likely damaged, but rescue teams need to communicate with each other to plan the rescue missions. Mobile Ad hoc Networks (MANETs) are an efficient and cost-effective opportunity to establish communication, if no working infrastructure is available. However, they come with several challenges, e.g. Interruptions due to partitioned MANETs. Delay Tolerant Networks (DTNs) are a possible solution to overcome this problem. Furthermore, rescue missions require reliable communication between different rescue teams and among their team members. In order to efficiently reach all members of a team, multicast is promising. However, guaranteeing that all recipients receive a DTN multicast message is difficult and might consume too much buffer space in the DTN nodes. In this paper, we present our approach of a DTN-based multicast protocol that provides efficient buffer management without neglecting the required reliability. We explain our algorithm to efficiently free the node buffers. Our simulation results will show that our algorithm increases the delivery ratio for different group sizes.

Poster: Utilization of Additional Nodes in Hybrid DTN-MANET Scenarios

In case of disasters, efficient and robust communication is essential. Hybrid network architectures combining traditional mobile ad hoc networks (MANETs) and delay tolerant networks (DTNs) have been proposed to achieve both aspects. The combination is needed to handle intermittent connectivity. However, the DTN principles cause additional delay that should be minimized. Nodes that are deployed in addition to the devices carried by rescue workers are one option to enhance connectivity and thus limit the delay. These nodes could be placed at fixed positions or be mobile eventually with controllable mobility. In this paper, we first present a simulation model to enable the evaluation of such additional nodes and present their impact on the DTN routing protocol performance in a realistic disaster scenario. Our results show that additional nodes are able to provide better connectivity, but current DTN protocols are not able to utilize them efficiently.

Evaluation of BLE Mesh capabilities: A case study based on CSRMesh

This work examines the applicability of the relatively young radio standard Bluetooth Low Energy (Bluetooth Smart) for mesh-enabled applications. To achieve this, a demonstrator application is used in multiple measurements to analyze the packet delivery ratio of different setups. Since no official mesh implementation for Bluetooth Low Energy (BLE) has been released to this date, the proprietary, BLE-based CSRmesh protocol is used in this study. Besides the measurement campaign, several simulations were performed in order to study the suitability of Bluetooth Mesh in large-scale networks. Our results show that Bluetooth Mesh is a promising technology for mesh applications but additional effort is required during the ongoing standardization process to exploit its full potential.

Challenges of applying DTN routing protocols in realistic disaster scenarios

Delay Tolerant Networks (DTNs) are used to deliver messages in cases of intermittent connectivity. Disaster scenarios with multiple Mobile Ad hoc Networks formed by the communication equipment of first responders are one example for such networks. In this paper, we evaluate different delay tolerant routing schemes based on realistic mobility models and traffic patterns. Both options are crucial as the routing schemes usually exploit the movement of the nodes in order to deliver the messages. Our results show that the choice of a routing protocol has an impact on the experienced delay, but a DTN-based communication system should also provide the necessary contact opportunities. Therefore, we present a solution to integrate additional nodes and efficient routing to address this.

Inter-domain routing and name resolution using border nodes

Stable and reliable communication is essential in disaster scenarios. Mobile Ad hoc Networks (MANETs) provide a network that is fast to setup and that works independently of possibly damaged infrastructure. This is important during disaster rescue and recovery missions. But single isolated MANETs are able to cover only a limited area. Therefore, it is necessary to interconnect these individual networks in order to provide communication throughout the whole disaster area. The resulting network is heterogeneous because each MANET might employ different routing protocols as well as other underlying network technologies. In this paper, we present an approach to couple such heterogeneous networks using multihomed border nodes. We show how network-wide route discovery and name resolution is achieved and also propose a solution to address possible collisions in such environments.