Martin Kupper

Providing multiple hard latency and throughput guarantees for packet switching networks on chip

In many-core architectures different distributed applications are executed in parallel. The applications may need hard guarantees for communication with respect to latency and throughput to cope with their constraints. Networks on Chip (NoC) are the most promising approach to handle these requirements in architectures with a large number of cores. Dynamic reservation of communication resources in virtual channel NoCs is used to enable quality of service for concurrent communication. This paper presents a router design supporting best effort and connection-oriented guaranteed service communication. The communication resources are shared dynamically between the two communication schemes. The key contribution is a concept for virtual channel reservation supporting different bandwidth and latency guarantees for simultaneous guaranteed service communication flows. Different to state-of-the-art, the used scheduling approach allows to give hard guarantees regarding throughput and latency. The concept enables to adjust the bandwidth and latency requirements of connections at run-time to cope with dynamically changing application requirements. Due to its distributed reservation process and resource allocation it offers good scalability for many-core architectures. The implementation of a router and the required extension of a network interface to support the proposed concept are presented. The software perspective is discussed. An algorithm is presented that is used to establish guaranteed service connections according to the applications bandwidth requirements. Simulation results are compared to state-of-the-art arbitration schemes and show significant improvements of latency and throughput, e.g. for an MPEG4 application. Synthesis results expose the low area overhead and impact on energy consumption which makes the concepts highly attractive for QoS-constraint many-core architectures.

Functional Fractional Calculus for System Identification of Battery Cells

Abstract This paper considers a fractional modelbased identification method with the objective to determine the aging of a battery cell. The method avoids lumped approximations of the fractional operator. Moreover with this approach it is possible to identify physically motivated battery cell parameters. The basic idea is to transfer the derivatives from the measurements to the so called modulating functions. With the help of simulations a robust behavior against measurement noise is shown. It is possible to use the method for online battery identification.

Rerouting: Scalable NoC self-optimization by distributed hardware-based connection reallocation

Networks-on-Chip (NoC) are the most promising candidates for scalable communication infrastructures in manycore architectures. To ensure scalability, distributed management of communication resources needs to replace centralized approaches. Hence, distributed adaptive routing schemes in combination with selection strategies are used to take semi-optimal routing decisions according to the current NoC utilization. Once these routing decisions are taken for guaranteed service connections, which are established for longer periods, the load situation can change during their lifetime. For such connections taken routing decisions might be poor at a later point in time due to dynamically changing communication workload. The proposed hardware-based mechanism called rerouting reacts on changing load conditions and reallocates existing connections transparently. This balances the NoC load and allows to increase the number of guaranteed service connections. Throughput and delay of existing connections can also be improved by rerouting. The concept is investigated using synthetic traffic patterns and distributed video processing applications. ASIC and FPGA synthesis results are presented to investigate the implementation costs.

Distributed and decentralized state estimation of Fractional order systems

This paper is about the decentralization and distribution of a Kalman filter for fractional order systems. A fractional order discrete state space is introduced for a global system and divided into different submodules. The distribution of the model and of the state estimation algorithm leads to small and scalable units, which do not need a central processing node. Each submodule performs its computation locally. All information required by other nodes is directly communicated between the nodes. Finally, an example is given to compare the Fractional Kalman Filter (FKF) for the overall system with the Distributed and Decentralized Fractional Kalman Filter (DDFKF).

Fractional Extended and Unscented Kalman Filtering for State of Charge Estimation of Lithium-Ion Batteries

Two state of charge estimation methods using fractional order extended and unscented Kalman filter and a nonlinear variable fractional order battery model are implemented. Both, battery model and Kalman filters are evaluated and compared using measurements of an actual lithium-ion polymer battery cell. The observability of the battery model and the influence of an initialization function on the estimation algorithms is investigated.

Distributed and decentralized Kalman filtering for Cascaded Fractional order systems

This paper presents a distributed Kalman filter algorithm for cascaded systems of fractional order. A functional distribution of a large scale system and of the state estimation algorithm leads to smaller and scalable nodes with reduced memory and computational effort. Since each subsystem performs its calculations locally, a central processing node is not needed. All data which are required by subsequent nodes are communicated to them unidirectionally. Also, a comparison between the Fractional Kalman Filter (FKF) and the Cascaded Fractional Kalman Filter (CFKF) is given by an example.