Tim Wegner

A workflow-driven approach to integrate generic software modules in a Trusted Third Party

BackgroundCohort studies and registries rely on massive amounts of personal medical data. Therefore, data protection and information security as well as ethical aspects gain in importance and need to be considered as early as possible during the establishment of a study. Resulting legal and ethical obligations require a precise implementation of appropriate technical and organisational measures for a Trusted Third Party.MethodsThis paper defines and organises a consistent workflow-management to realize a Trusted Third Party. In particular, it focusses the technical implementation of a Trusted Third Party Dispatcher to provide basic functionalities (including identity management, pseudonym administration and informed consent management) and measures required to meet study specific conditions of cohort studies and registries. Thereby several independent open source software modules developed and provided by the MOSAIC project are used. This technical concept offers the necessary flexibility and extensibility to address legal and ethical requirements of individual scenarios.ResultsThe developed concept for a Trusted Third Party Dispatcher allows mapping single process steps as well as individual requirements and characteristics of particular studies to workflows, which in turn can be combined to model complex Trusted Third Party processes. The uniformity of this approach permits unrestricted re-combination of the available functionalities (depending on the applied software modules) for various research projects.ConclusionThe proposed approach for the technical implementation of an independent Trusted Third Party reduces the effort for scenario specific implementations as well as for maintenance. The applicability and the efficacy of the concept for a workflow-driven Trusted Third Party could be confirmed during the establishment of several nationwide studies (e.g. German Centre for Cardiovascular Research and the National Cohort).

Simulation of thermal behavior for Networks-on-Chip

Due to increasing integration densities and the emergence of nanotechnology, especially reliability and power related design aspects become critical for chip design. Since the arising problems are enforced by high circuit temperatures, the need for a possibility to model thermal behavior of a system in an accurate and physically correct way becomes inevitable. Hence, in this paper VulcaNoCs, a SystemC-based simulation environment for systems based on NoCs, is introduced. VulcaNoCs is designed to enable simultaneous execution of both high-level system simulation and dynamic modeling of temperature distributions in NoC-based systems. To emulate a systems thermal properties equivalent RC-circuits are used, exploiting the dualism between heat flow and electrical phenomena. To verify the temperature model, VulcaNoCs is compared to a more commonly used SPICE-based approach, exhibiting significant increases in simulation performance of up to 98,5% for modeling a 2×2 NoC, for example.

System level power estimation of system-on-chip interconnects in consideration of transition activity and crosstalk

As technology reaches nanoscale order, interconnection systems account for the largest part of power consumption in Systemson-Chip. Hence, an early and sufficiently accurate power estimation technique is needed for making the right design decisions. In this paper we present a method for system-level power estimation of interconnection fabrics in Systems-on-Chip. Estimations with simple average assumptions regarding the data stream are compared against estimations considering bit level statistics in order to include low level effects like activity factors and crosstalk capacitances. By examining different data patterns and traces of a video decoding system as a realistic example, we found that the data dependent effects are not negligible influences on power consumption in the interconnection system of nanoscale chips. Due to the use of statistical data there is no degradation of simulation speed in our approach.

Impact of proactive temperature management on performance of Networks-on-Chip

With the progress of deep submicron technology power consumption and temperature related issues have become dominant factors for chip design. Therefore, very large-scale integrated systems like Systems-on-Chip (SoCs) are exposed to an increasing thermal stress. On the one hand, this necessitates effective mechanisms for thermal management. On the other hand, appliance of thermal management is accompanied by disturbance of system integrity and degradation of system performance. In this paper we propose to precompute and proactively manage on-chip temperature of systems based on Networks-on-Chip (NoCs). Thereby, traditional reactive approaches, utilizing the NoC infrastructure to perform thermal management, can be replaced. This results not only in shorter response times for appliance of management measures and therefore in a reduction of temperature and thermal imbalances, but also in less impairment of system integrity and performance. Simulations show that proactive management achieves improvements of nearly 150% regarding reduction of average temperature inside a 3×3 NoC compared to identical reactive approaches, while mitigating additional delay for packet transmission by more than 50 %.

P-DONAS: A P2P-Based Domain Name System in Access Networks

The domain name system (DNS) includes infrastructures deployed by Internet service providers (ISPs) and third-party suppliers to ensure high responsiveness, resilience, and load sharing. This equipment implies high effort and energy for 24/7 operation. To facilitate cost reductions in this regard, P-DONAS—a peer-to-peer (P2P)-based DNS—organizes access nodes (ANs) of an ISP’s access network, which possess available resources, into a decentralized, self-organizing distributed hash table--based P2P network. Each AN acts as traditional DNS server and solely stores a piece of DNS data. DNS requests issued to an AN are resolved via P2P lookups while maintaining full compatibility with traditional DNS. The article discusses the application of P-DONAS as both a complement and an alternative to traditional DNS. Results from both simulations and a practical test arrangement prove P-DONAS’ high scalability and its performance comparable to that of a commercial DNS name server relieving this name server by 53% to 75% of DNS traffic.

Low overhead in situ aging monitoring and proactive aging management

Post-Dennard scaling CMOS technologies suffer from considerable degradation due to increasing electrical fields caused by the lack of further reduction of the supply voltage. This aspect of aging is widely disregarded so far and cannot be addressed at design time by adding static margins anymore. Instead, it needs to be counteracted effectively at run time over the entire device lifetime. For this purpose, dynamic runtime approaches for aging management are required, relying on detailed in formation regarding the current system state. In this paper we propose a novel aging monitoring mechanism providing that crucial information at a marginal resource overhead. The current device degradation is measured via the aging-dependent delay variation, which can be quantified in situ with built-in tests exploiting the strictly monotonic relation between supply voltage and propagation delay. Furthermore, we suggest to utilize the information gained this way for a proactive aging-aware task mapping.

Centralized and Software-Based Run-Time Traffic Management Inside Configurable Regions of Interest in Mesh-Based Networks-on-Chip

This work proposes the introduction of multiple spatially independent network interfaces in order to connect computational resources to mesh-based Networks-on-Chip (NoCs). Furthermore, a flexible system for traffic monitoring is introduced supporting runtime reconfigurability as well as software-based centralized data aggregation and evaluation. These approaches are combined to form a sophisticated framework for runtime traffic management of NoC-based many-core systems exploiting the dual-path options of the underlying network.

Performance Analysis of Temperature Management Approaches in Networks-on-Chip

With the progress of deep submicron technology, power consumption and temperature related issues have become dominant factors for chip design. Therefore, very large-scale integrated systems like Systems-on-Chip (SoCs) are exposed to an increasing thermal stress. On the one hand, this necessitates effective mechanisms for thermal management. On the other hand, application of thermal management is accompanied by disturbance of system integrity and degradation of system performance. In this paper the authors propose to precompute and proactively manage on-chip temperature of systems based on Networks-on-Chip (NoCs). Thereby, traditional reactive approaches, utilizing the NoC infrastructure to perform thermal management, can be replaced. This results not only in shorter response times for application of management measures and a reduction of temperature and thermal imbalances, but also in less impairment of system integrity and performance. The systematic analysis of simulations conducted for NoC sizes ranging from 2x2 to 4x4 proves that under certain conditions the proactive approach is able to mitigate the negative impact of thermal management on system performance while still improving the on-chip temperature profile. DOI: 10.4018/jertcs.2012100102 20 International Journal of Embedded and Real-Time Communication Systems, 3(4), 19-41, October-December 2012 Copyright

Monitoring and Control of Temperature in Networks-on-Chip

Increasing integration densities and the emergence of nanotechnology cause issues related to reliability and power consumption to become dominant factors for the design of modern multi-core systems. Since the arising problems are enforced by high circuit temperatures, monitoring and control of on-chip temperature profiles need to be considered during design phase as well as during system operation. Hence, in this paper different approaches for the realization and integration of a monitoring system for temperature in multi-core systems based on Networks-on-Chip (NoCs) in combination with Dynamic Frequency Scaling (DFS) are investigated. Results show that both combinations using event-driven and time-driven forwarding more than double overall execution time and considerably reduce throughput of application data. Regarding performance of notification and reaction to temperature development event-driven forwarding clearly outperforms time-driven forwarding.