Sebastian Subik

SPIDER: Enabling interoperable information sharing between public institutions for efficient disaster recovery and response

The interoperability of the data sharing across different organizations is key for the efficient management of large-scale incidents. The system introduced in this paper will provide multi-disciplinary rescue teams with an integrated and intelligent communication and information system for efficient data sharing and emergency process management before, during and after major incidents. The project SPIDER (Security System for Public Institutions in Disastrous Emergency scenaRios) is part of the national research initiative Scenario based Civil Security Research and substantially funded by the German government. It will (a) facilitate a standardized XML based interface for a service oriented interoperability architecture and (b) provide substantial new insight on how to enable components in distinct critical networks for secure collaboration. With respect to (a), these interfaces will be coupled with recommendations on the orchestration of the provided services. As heterogeneous crisis information systems require standardized gateways, SPIDER uses Web Services in order to mutually interact. Thus, a fail-save communication infrastructure (b) that interconnects the required components is indispensable. Especially the usage of modern systems and the consequential high demand to the data rate pose a challenge to the system. The combination of (a) and (b) will lead to a holistic approach for digital crisis management.

Performance Analysis of Highly Available Ad Hoc Surveillance Networks Based on Dropped Units

In emergency situations like an attack on a building, public networks are not sufficiently reliable. Hence field forces, who want to share multimedia mission information, have to build up their own multi-hop wireless network. To build up these ad hoc networks, battery driven wireless nodes with meshing capability, called dropped units, present a new technology option for homeland security applications. To ensure sufficient coverage, an excessive usage of dropped units seems to be an obvious solution, but leads to undesired effects, such as interference. To solve this dilemma, rules to find an optimal number of dropped units are presented in this paper. To derive guidelines for this, realistic homeland security scenarios were analyzed. A dedicated simulation environment provided a reliable prediction of the required number of dropped units. We analyzed the communication link of moving or movable wireless clients like surveillance and first responders devices. The simulation results lead to the conclusion that with a limited number of dropped units a practically 100% network availability can be achieved.

A system design framework for scalability analysis of geographic routing algorithms in large-scale mesh networks

It is important to evaluate the performance of large communication networks prior to their deployment, in particular if economic interests are involved. In wireless multi-hop mesh networks, a communication message is transferred from a source to a destination via multiple nodes. Typically the message can be transferred via multiple routes in a mesh network, because several nodes are in communication range. During the design phase of such a communication network, specific characteristics need to be considered in order to avoid boundaries like bottlenecks and dead-end problems of the deployed system. Hence these kinds of problems must be avoided prior to the network deployment. In this paper, we present a system design framework for the OMNeT++ simulation environment, which is able to identify potential bottlenecks and maximum loads of multi-hop networks. The process is presented via a realistic use case scenario for an Energy Management Application, in which geographic routing algorithms are used to identify the shortest route to a destination. The results of the performance evaluation enabled us to support the communication design process with information about reliability, data rate and routing schemes.

Integrated PMR-broadband-IP network for secure realtime multimedia information sharing

In this paper, the authors present a novel solution for the integration of TETRA-based PMR and IP based wireless broadband networks through a novel inter-system interface. This solution enables secure group communications based on PMR standards using heterogeneous devices ranging from a traditional PMR device to smart phones such as the iPhone. Thereby a Smart-phone user will be enabled to leverage on one hand the multimedia data capabilities of 3G and 4G wireless networks (UMTS, LTE) while at the same time be part of a PMR group communication. In other words, any authorized Smart-phone can become part of a PMR communication group by simply downloading the appropriate, dedicated Application. As a key benefit, homeland security personnel can be included in the disaster response actions instantaneously, without necessarily carrying around a PMR device and without the need for PMR coverage. In contrast to existing solutions, the proposed interface solution prevents the reduction of the voice quality when bridging system boundaries by tandem encoding with a TETRA-over-IP (ToIP) interconnection. The presented solutions include different interconnection setups including Trunked Mode (TMO) and Direct Mode (DMO) capabilities. To enable the group communications services as known in PMR systems, a dedicated protocol, the Push-to-X protocol developed by CNI, is leveraged. The results of performance evaluations show that the speech quality is still acceptable even under harsh conditions. The proposed system therefore paves the way towards a future, high performance PMR based on LTE, while preserving backwards compatibility with existing PMR systems.

Dynamic Link Classification Based on Neuronal Networks for QoS Enabled Access to Limited Resources

In this paper, the authors present a study of a network fingerprinting classification using monotone multilayer perceptron neuronal networks. It is part of an overall performance engineering approach. The classification is used to increase the performance of an active queue management on the quality of service for a next generation public safety communication system based on an IP overlay network. This network combines heterogeneous communication networks and technologies to increase the overall systems performance. Public safety users have higher requirements regarding coverage, data rates and quality of service than standard commercial ones. Main challenge for this study is the optimization of the overall system for voice group communication, which is still the most important communication within public safety scenarios. This paper shows that with the given parametrization, an ensemble of multi-layer perceptrons gives a satisfactory classification probability, if a setup of three technologies (EDGE, UMTS and LTE) is assumed to be in usage as communication technologies. This setup is practicable enough to have a chance to be implemented in a future system.

ADeM: Active Delay Management for critical group communication over heterogeneous public cellular networks

As the basis of Next Generation Public Safety Communication (PSC) systems for critical group communication, 4G (LTE) technologies have been chosen from the different stakeholder. Existing 2G and 3G equivalent technologies are and will be used to allow for a sufficient network coverage. Due to the long investment cycles within the public sector, for a long time small band 2G Professional Mobile Radio (PMR) networks will be the backbone of mission critical voice communication. To enable enhanced data exchange 4G networks will provide this capability as an add-on. It is a well known fact that every transmission technology has its own footprint of delay and delay-spread (jitter). This lead to challenges within heterogeneous system environments, because different behavior introduces unfairness into the system, negligent users in legacy networks. The proposed solution in this paper is based on the identification of the unique footprint of the used networks to increase the fairness. In this paper, the authors present an Active Delay Management (ADeM) PSC System that allows for critical group communication in next generation public safety communication network based on ×G technologies. Therefore, the performance limitations of an IP overlay for heterogeneous communication networks have been studied and analyzed for different mobile radio technologies, based on mobile field trials performed in commercial 2G, 3G and 4G networks. Build upon this study, the gathered information is used to classify the transmission networks to enable the proposed ADeM system to actively consider network dependent delays in its Active Queue Management (AQM) decisions. Thereby, enhanced fairness for the different information streams as well as an improved performance in critical communication scenarios can be achieved.

Adaptive multiplexing gateway for LMR-based group communications over high latency IP-based satellite backhaul links

In this paper, the authors present a proof-of concept demonstrator for an adaptive inter-system-interface gateway between LMR and IP based networks. To underline the flexibility of the proposed solution, a satellite link is utilized to enable the integration of an independent LMR cell or direct connected terminals (MicroSpot) into an existing infrastructure over long distances without the need for dedicated transport networks. This set-up is motivated by both, homeland security operations as well as industrial use-cases. The scenario consists of an isolated communication group which needs to be linked with a core network from a degraded area. To deploy such a system, a prior in depth analysis of the restrictions of the components is performed. These results are used for an overall usability analysis based on measurements with a demonstrator. Main challenge is a high variance in the delay, which inhibit a direct connection between a strictly timed TDMA LMR network and IP-based transport networks. The proposed gateway is based on an adaptive convergence layer multiplexer, which optimizes the LMR data stream for the transmission on a time variant channel like a satellite link. This enables homeland security organizations to operate independent from land based radio networks.