SANES 2012 Abstracts


Full Papers
Paper Nr: 2
Title:

MITIGATION OF PERIODIC JAMMING IN A SPREAD SPECTRUM SYSTEM BY ADAPTIVE FILTER SELECTION

Authors:

Bruce DeBruhl and Patrick Tague

Abstract: Jamming has long been a problem in wireless communication systems. Traditionally, defense techniques have looked to raise the cost of mounting an equally effective jamming attack. One technique to raise the cost of jamming is direct sequence spread spectrum (DSSS) which spreads data over a wider bandwidth and has built-in error correction. To work around this, attackers have developed intelligent jamming techniques to minimize the cost of mounting attacks on these systems. To lower the cost of attacking a DSSS system, an attacker can use periodic jamming which alternates between an attacking and sleeping state. Previously, a digital filter has been used to mitigate a periodic jamming attack at the center frequency of the attacker. In this work, we expand this previous attack model by allowing an attacker to jam at any frequency and even to move to different frequencies in the channel. To defend against the more general attack, we propose the use of an adaptive filter selection technique. This technique monitors packet delivery ratio (PDR) at the receiver and uses this information to infer whether it is being attacked. If the receivers PDR is low, it activates a filter from a pre-defined filter bank and tests if performance improves. This process continues by activating different filters from the filter bank until adequate PDR performance is achieved. We show that this approach can search through a small set of filters and recover over 90% of packets with a search time of less than 3 seconds on average for an attacker who randomly chooses its center frequency.

Paper Nr: 4
Title:

TOWARDS EFFICIENT ON-LINE SCHEDULABILITY TESTS FOR ADAPTIVE NETWORKED EMBEDDED REAL-TIME SYSTEMS

Authors:

Klaus Becker, Marc Zeller and Gereon Weiss

Abstract: In networked embedded systems, runtime adaptive software promises an increase of flexibility, fault tolerance and extensibility. Often, this requires that software components have to be allocated dynamically to execution platforms at runtime. Hence, the platforms have to execute dynamically changing task sets. However, in real-time systems, a task set cannot be executed without previously checking its schedulability w.r.t. given timing constraints. Therefore, it has to be determined, whether or not the existing task set would be still schedulable including newly arriving tasks. In this paper, we propose a schedulability test algorithm for such systems, exploiting the situation of adding a new task to an existing task set. Therefore, we adapt existing schedulability tests to exploit the specific acceptance test use case. The benefits of the developed adaptations are shown by experimental investigations.

Paper Nr: 5
Title:

SELF-ADAPTIVE NOC POWER MANAGEMENT WITH DUAL-LEVEL AGENTS - Architecture and Implementation

Authors:

Syed M. A. H. Jafri, Liang Guang, Axel Jantsch, Kolin Paul, Ahmed Hemani and Hannu Tenhunen

Abstract: Architecture and Implementation of adaptive NoC to improve performance and power consumption is presented. On platforms hosting multiple applications, hardware variations and unpredictable workloads make static design-time assignments highly sub-optimal e.g. in terms of power and performance. As a solution to this problem, adaptive NoCs are designed, which dynamically adapt towards optimal implementation. This paper addresses the architectural design of adaptive NoC, which is an essential step towards design automation. The architecture involves two levels of agents: a system level agent implemented in software on a dedicated general purpose processor and the local agents implemented as microcontrollers of each network node. The system agent issues specific instructions to perform monitoring and reconfiguration operations, while the local agents operate according to the commands from the system agent. To demonstrate the system architecture, best-effort power management with distributed voltage and frequency scaling is implemented, while meeting run-time execution requirements. Four benchmarks (matrix multiplication, FFT, wavefront, and hiperLAN transmitter) are experimented on a cycle-accurate RTL-level shared-memory NoC simulator. Power analysis with 65nm multi-Vdd library shows a significant reduction in energy consumption (from 21 % to 36 %). The synthesis also shows minimal area overhead (4 %) of the local agent compared to the original NoC switch.

Paper Nr: 6
Title:

SELF-ADAPTATION IN AUTOMOTIVE EMBEDDED SYSTEMS USING A MULTI-LAYERED CONTROL APPROACH

Authors:

Marc Zeller and Christian Prehofer

Abstract: In this work, we present an approach for self-adaptation in automotive embedded systems using a hierarchical, multi-layered control approach. We model automotive systems as a set of constraints and define a hierarchy of control loops based on different criteria. Adaptations are performed at first locally on a lower layer of the architecture. If this fails due to the restricted scope of the control cycle, the next higher layer is in charge of finding a suitable adaptation. We compare different options regarding responsibility split in multi-layered control and a version with centralized control option, in a self-healing scenario with a setup adopted from automotive in-vehicle networks. We show that a multi-layer control architecture has clear performance benefits over a central control, even though all layers work on the same set of constraints. Furthermore, we show that a responsibility split w.r.t. network topology is preferable over a functional split.

Paper Nr: 7
Title:

DETERMINISTIC RUNTIME ADAPTATION FOR HARD REAL-TIME EMBEDDED SYSTEMS WITH PROCESSING CONSTRAINTS

Authors:

Fahad Bin Tariq

Abstract: Increasing the connectivity of systems at various levels gives rise to potential benefits that is addressed by trends such as the Internet of Things, Cyber-Physical Systems and Cyber-Biosphere. It is inevitable that the vast global network will consist of computationally constrained units. The ability of such systems to adapt while being connected to a global network presents new opportunities. Qualities such as fault tolerance and load sharing may be extended to nodes in the network that initially were devoid of them. On the other hand, an open adaptable system that does not limit its adaptation to pre-defined and pre-containing states needs to be connected to one or more sources that may provide the necessary behavioral units to switch to the new state. Extending computationally constrained nodes with the ability to adapt is in itself challenging, which increases when timely behavior is required due to real-time requirements. The system must then guarantee all deadlines implying the need for deterministic adaptation. The question of when to adapt becomes an important one with real-time deadlines involved. We present our work on a framework that aims to achieve deterministic runtime adaptation on single processor systems thereby enabling such computationally constrained systems to extend their functionality and non-functional qualities.