Mikael Asplund

Emerging Information Infrastructures: Cooperation in Disasters

Disasters are characterised by their devastating effect on human lives and the societys ability to function. Unfortunately, rescue operations and the possibility to re-establish a working society after such events is often hampered by the lack of functioning communication infrastructures. This paper describes the challenges ahead in creating new communication networks to support post-disaster operations, and sets them in the context of the current issues in protection of critical infrastructures. The analysis reveals that while there are some common concerns there are also fundamental differences. The paper serves as an overview of some promising research directions and pointers to existing works in these areas.

A Partition-Tolerant Manycast Algorithm for Disaster Area Networks

Information dissemination in disaster scenarios requires timely and energy-efficient communication in intermittently connected networks. When the existing infrastructure is damaged or overloaded, we suggest the use of a manycast algorithm that runs over a wireless mobile ad hoc network, and overcomes partitions using a store-and-forward mechanism. This paper presents a random walk gossip protocol that uses an efficient data structure to keep track of already informed nodes with minimal signaling. Avoiding unnecessary transmissions also makes it less prone to overloads. Experimental evaluation shows higher delivery ratio, lower latency, and lower overhead compared to a recently published algorithm.

Anomaly detection and mitigation for disaster area networks

One of the most challenging applications of wireless networking are in disaster area networks where lack of infrastructure, limited energy resources, need for common operational picture and thereby reliable dissemination are prevalent. In this paper we address anomaly detection in intermittently connected mobile ad hoc networks in which there is little or no knowledge about the actors on the scene, and opportunistic contacts together with a store-and-forward mechanism are used to overcome temporary partitions. The approach uses a statistical method for detecting anomalies when running a manycast protocol for dissemination of important messages to k receivers. Simulation of the random walk gossip (RWG) protocol combined with detection and mitigation mechanisms is used to illustrate that resilience can be built into a network in a fully distributed and attack-agnostic manner, at a modest cost in terms of drop in delivery ratio and additional transmissions. The approach is evaluated with attacks by adversaries that behave in a similar manner to fair nodes when invoking protocol actions.

Exploiting Bro for Intrusion Detection in a SCADA System

Supervisory control and data acquisition (SCADA) systems that run our critical infrastructure are increasingly run with Internet-based protocols and devices for remote monitoring. The embedded nature of the components involved, and the legacy aspects makes adding new security mechanisms in an efficient manner far from trivial. In this paper we study an anomaly detection based approach that enables detecting zero-day malicious threats and benign malconfigurations and mishaps. The approach builds on an existing platform (Bro) that lends itself to modular addition of new protocol parsers and event handling mechanisms. As an example we have shown an application of the technique to the IEC-60870-5-104 protocol and tested the anomaly detector with mixed results. The detection accuracy and false positive rate, as well as real-time response was adequate for 3 of our 4 created attacks. We also discovered some additional work that needs to be done to an existing protocol parser to extend its reach.

Resource Footprint of a Manycast Protocol Implementation on Multiple Mobile Platforms

Wireless communication is becoming the dominant form of communication and ad hoc wireless connections are posed to play a role in disaster area networks. However, research efforts on wireless ad hoc communication protocols do not pay enough attention to measurable and reproducible indications of the mobile footprint including power consumption. Protocols and applications are initially designed and studied in a simulation environment and are hard to test in in-field experiments. In this work we report a multi-platform implementation of Random-Walk Gossip, a many cast protocol designed for message dissemination in disaster areas. Our work is focused in studying the resource footprint and its impact on performance on commercially available devices. We show both how different aspects of the protocol contributes to the footprint and how this in turn affects the performance. The methodologies used here can be applied to other protocols and applications, aiding in future optimisations.

Why is fingerprint-based indoor localization still so hard?

Wireless indoor localization systems and especially signal strength fingerprinting techniques have been the subject of significant research efforts in the last decades. However, most of the proposed solutions require a costly site-survey to build the radio map which can be used to match radio signatures with specific locations. We investigate a novel indoor localization system that addresses the data collection problem by progressively and semi-autonomously creating a radio-map with limited interaction cost. Moreover, we investigate how spatiotemporal and hardware properties-based variations can affect the RSSI values collected and significantly influence the resulting localization. We show the impact of these fluctuations on our system and discuss possible mitigations.

Trust Evaluation for Participatory Sensing

Participatory sensing, combining the power of crowd and the ubiquitously available smart phones, plays an important role to sense the urban environment and develop many exciting smart city applications to improve the quality of life and enable sustainability. The knowledge of the participatory sensing participants’ competence to collect data is vital for any effective urban data collection campaign and the success of these applications. In this paper, we present a methodology to compute the trustworthiness of the participatory sensing participants as the belief on their competence to collect high quality data. In our experiments, we evaluate trust on the sensing participants of BusWatch, a participatory sensing based bus arrival time prediction application. Our results show that our system effectively computes the sensing participants’ trustworthiness as the belief on their competence to collect high quality data and detect their dynamically varying sensing behavior.

Measuring Availability in Optimistic Partition-Tolerant Systems with Data Constraints

Replicated systems that run over partitionable environments, can exhibit increased availability if isolated partitions are allowed to optimistically continue their execution independently. This availability gain is traded against consistency, since several replicas of the same objects could be updated separately. Once partitioning terminates, divergences in the replicated state needs to be reconciled. One way to reconcile the state consists of letting the application manually solve inconsistencies. However, there are several situations where automatic reconciliation of the replicated state is meaningful. We have implemented replication and automatic reconciliation protocols that can be used as building blocks in a partition-tolerant middleware. The novelty of the protocols is the continuous service of the application even during the reconciliation process. A prototype system is experimentally evaluated to illustrate the increased availability despite network partitions.

A Formal Approach to Autonomous Vehicle Coordination

Increasing demands on safety and energy efficiency will require higher levels of automation in transportation systems. This involves dealing with safety-critical distributed coordination. In this paper we demonstrate how a Satisfiability Modulo Theories (SMT) solver can be used to prove correctness of a vehicular coordination problem. We formalise a recent distributed coordination protocol and validate our approach using an intersection collision avoidance (ICA) case study. The system model captures continuous time and space, and an unbounded number of vehicles and messages. The safety of the case study is automatically verified using the Z3 theorem prover.

Software-related energy footprint of a wireless broadband module

Energy economy in mobile devices is becoming an increasingly important factor as the devices become more advanced and rich in features. A large part of the energy footprint of a mobile device comes from the wireless communication module, and even more so as the amount of traffic increases. In this paper we study the energy footprint of a mobile broadband hardware module, and how it is affected by software, by performing systematic power consumption measurements. We show that there are several cases where the software does not properly take into account the effect that data communication has on the power consumption. This opens up for potential energy savings by creating better applications that are aware of the energy characteristics of the communication layer.