Christoph Fuchs

Indoor tracking for mission critical scenarios: A survey

The availability of a reliable and precise tracking system for relief units operating in mission critical scenarios would drastically improve the situational awareness and thus facilitate the mission planning and accomplishment as well as increase the safety of human resources. Thus, the demand for such a system is very high both in the military and in the emergency and crisis intervention domain. While there are solutions like GPS for the localization in open areas, problems arise in urban scenarios and indoors due to insufficient or failed signal reception. For indoor use, multiple alternative localization concepts exist that are suited for different use cases and expose varying properties in precision, complexity and required preconditions. The deployment within mission critical scenarios implicates explicit restrictions and requirements so that only some of the techniques are adept or have the potential of being used here. This article identifies the commonly issued requirements to an indoor tracking in mission critical scenarios and introduces basic techniques for position estimation. Subsequently, existing indoor tracking systems specifically in the field of mission critical scenarios are reviewed with a focus on their capabilities in terms of reliability and accuracy. By doing so, an overview of current approaches in this field is given. Furthermore, the most adept techniques are classified with respect to the requirements within mission critical scenarios.

Detecting VoIP based DoS attacks at the public safety answering point

In the recent years Voice over IP (VoIP) telephony started to migrate from research to the market. In the future, All-IP networks will substitute the classical Public Switched Telephone Networks (PSTNs). Nowadays, there is no All-IP network yet, but many VoIP-providers already enable calls from VoIP to a PSTN and vice versa. Thus, critical infrastructures within the PSTN like the emergency call service, are accessible from the VoIP network (e.g. the Internet) and get exposed to new security threats. In particular, there is the risk of Denial of Service (DoS) attacks originating from the VoIP network. An attacker could jam the emergency call service by generating a massive load of faked emergency calls, which could lead to the loss of lives in the worst case. For us, this was the motivation to analyse the applicability of the concept of Intrusion Detection (ID) in the emergency call context and develop an adapted ID-architecture including its implementation. In an evaluation of the ID-architecture, using real emergency call traces from the fire department of Cologne, we show that the developed concept can reliably detect emerging DoS attacks from VoIP networks up to a certain VoIP diffusion rate.

STMP — Sensor data transmission and management protocol

Nowadays, networked sensors are deployed in various scenarios. To transmit sensor data like GPS, temperature, or vital signs data robust communication networks are needed. Different applications and sensor types may have specific requirements to the transmission of their data regarding loss-tolerance, timeliness, priority, or completeness. These requirements are typically met by appropriate transport protocols. At the lower layers, heterogeneous networks like wireless mesh networks or long thin networks lead to specific channel characteristics that may require the use of specifically adapted transport protocols. Additionally, the type of scenario can also affect the transport layer, e.g., a scenario with static nodes compared to moving nodes with high mobility. Of course, there are many variable requirements of different sensor data streams and applications. But there are also some basic functionalities that are common, such as registering sensors at a receiver, timestamping of sensor data as well as synchronization of all nodes. Thus, we specify a new protocol for sensor data transmission and management (STMP) that provides the basic functionalities required by many sensor data streams while at the same time allowing a flexible choice of the transport protocol to be used.

Nebula - generating syntactical network intrusion signatures

Signature-based intrusion detection is a state-of-the-art technology for identifying malicious activity in networks. However, attack trends change very fast nowadays, making it impossible to keep up with manual signature engineering. This paper describes a novel concept for automatic signature generation based on efficient autonomous attack classification. Signatures are constructed for each class from syntactical commonalities and go beyond a single, contiguous substring. Each part of a signature is combined with positional information, which drastically improves signature accuracy and matching performance. We argue that a general description of zero-day attacks is immanently restricted to syntactical features and outline how valid signatures for novel real-world attacks were successfully generated.

Evaluation of network effects on the Kalman filter and accumulated state density filter

Command and control applications are important especially in tactical scenarios. For such scenarios wireless multi-hop networks may be deployed as they can be used even when there is no infrastructure left. Due to the specific characteristics of these networks the problem of Out-of-Sequence (OoS) measurements for tracking applications arises. In this paper, we present an exhaustive, realistic evaluation of OoS measurements induced by network protocol effects. To this end, we compare a standard Kalman filter to an accumulated state density filter. The results show that in wireless multi-hop networks a filter that can deal with OoS measurements is needed.

Poster: Deploying a mesh-based command and control sensing system in a disaster area maneuver

Wireless multi-hop networks meet the requirements of disaster area scenarios by their definition. Recently, different mesh and Wireless Sensor Network (WSN) testbeds were deployed. However, these deployments do not meet the specific characteristics of disaster area scenarios. Developing algorithms and protocols for public safety scenarios and deploying public safety networks is a huge challenge. We have developed BonnSens a commercial off-the-shelf (COTS)-based prototype of a mesh-based command and control sensing system for public safety scenarios. In this poster, we present experiences as well as first measurement results from an on-site deployment in a disaster area maneuver. Overall, our goal is to see which approaches are applicable for public safety networks and where further specific challenges are.

Extending ODMRP for on-site deployments in disaster area scenarios

One of the primary application scenarios for mobile wireless multi-hop networks are disaster areas. However, these pose specific challenges for routing, such as mobility and highly unpredictable links. The main applications for disaster area networks - group-based voice communication and group-oriented, map-based tracking - can be realized using multicast groups. Thus, we decided to implement ODMRP for disaster area deployments. In several disaster area maneuver on-site deployments, we identified the need for extensions, making the protocol more suitable for real-world deployments. In this paper, we propose three extensions to ODMRP: (1) link quality based routing, (2) prioritization of control messages, and (3) overhead reduction mechanisms. In simulations as well as in real-world measurements, we show the benefit of the extensions proposed.

An integrated simulation environment for sensor data fusion applications in wireless mesh networks

For the performance evaluation involving wireless mesh networks the concept of simulation is often used instead of measurements within a real environment. This is partly due to the lack of real-world testbeds but also caused by the unsteady nature of wireless mesh networks making it difficult to reproduce results. Typically, no real data is transmitted in simulations as for the calculation of network-related metrics like average throughput, delay, or loss rates, the knowledge of the packet sizes is sufficient. In order to evaluate the user level performance of a specific application that is subject to certain network conditions it is necessary, though, to use a set of application-related metrics. For the calculation of these metrics, the processing of the transmitted data in the time and order it has been received under the simulated network conditions is required.

Evaluating the Impact on Application-Related Metrics for Sensor Data with Concurrent Voice Transmission in Mobile Wireless Mesh Scenarios

The transmission of sensor data over wireless mesh networks in mobile scenarios is a strongly emerging application in the field of tactical and mission critical networking. In these scenarios, sensor data from the deployed units like GPSposition, vital and environmental data is transported over a wireless mesh network to a centralized command point. The inherently imprecise sensor measurements are processed at the command point using sensor data fusion algorithms in order to improve their precision and reliability. For evaluating the influence of node mobility and the effects of the wireless mesh network on the quality of the sensor data fusion result, it is not sufficient to only consider network-related metrics like throughput, delay or loss rate. Instead, application-related metrics must be considered that directly rate the precision of the processed data based on the fusion result. For this reason, we developed an integrated simulation and evaluation environment for sensor data fusion applications based on the popular network simulator ns-2 that allows for the inclusion and processing of real sensor data. In this paper, we present evaluation results for the transmission of GPS data in a typical tactical scenario. By doing so, we confirm that the quality of the fusion result can not be judged by evaluating network-related metrics only. Using the integrated simulation and evaluation environment, though, allows to analyze the effective impact on application level.

Demo: A mesh-based command and control sensing system for public safety scenarios

Public safety organizations need robust communication networks to transmit different kind of sensor information. These networks must be reliable even when all infrastructure has been destroyed. Wireless multi-hop networks (such as Mobile Ad-Hoc Networks (MANETs), Wireless Sensor Networks (WSNs), and Wireless Mesh Networks (WMNs)) are supposed to meet the requirements of (1) spontaneous deployment, (2) being independent of any kind of existing infrastructure, and (3) robustness in the sense of self-organization and self-healing by their very definition. These networks have been a topic in research for more than a decade now. Recently, real-world tests and deployments provide valuable insights concerning challenges and future research directions. There are different mesh and WSN testbeds (e.g., [4, 9, 10]) enabling the research community to run tests in static real-world networks. However, concerning public safety requirements, there are significant differences: (1) No spontaneous deployment, (2) no or at least no mobility typical for public safety, (3) no typical applications and traffic for public safety scenarios. Due to these characteristics, developing algorithms and protocols for public safety scenarios and deploying public safety networks is a huge challenge. To overcome this challenge, we developed a prototype based on commercial off-the-shelf (COTS) hardware. The prototype comprises typical public safety application and is spontaneously deployable. Furthermore, this prototype enables us to perform evaluations with real public safety endusers, e.g. by deploying the prototype in maneuvers. In our demo, we will demonstrate our COTS-based prototype.