Search results for "Network Topology"
showing 10 items of 192 documents
Does higher datarate perform better in IEEE 802.11-based multihop ad hoc networks?
2007
Due to the nature that high datarate leads to shorter transmission range, the performance enhancement by high datarate 802.11 WLANs may be degraded when applying high datarate to an 802.11 based multihop ad hoc network. In this paper, we evaluate, through extensive simulations, the performance of multihop ad hoc networks at multiple transmission datarates, in terms of the number of hops between source and destination, throughput, end-to-end delay and packet loss. The study is conducted based on both stationary chain topology and mesh topologies with or without node mobility. From numerical results on network performance based on chain topology, we conclude that there is almost no benefit by…
Multiprocessor SoC Implementation of Neural Network Training on FPGA
2008
Software implementations of artificial neural networks (ANNs) and their training on a sequential processor are inefficient because they do not take advantage of parallelism. ASIC and FPGA implementations employ specific hardware structures to exploit parallelism in order to improve processing speed; however, optimizing resource usage requires the use of fixed-point arithmetic, thereby losing precision, and the final system is restricted to a particular network topology. This paper presents a mixed approach based on a multiprocessor system-on-chip (SoC) on a FPGA. The use of software-driven embedded microprocessors with custom floating-point extensions for ANN related functions allows for gr…
A Communication-Aware Topological Mapping Technique for NoCs
2008
Networks---on---Chip (NoCs) have been proposed as a promising solution to the complex on-chip communication problems derived from the increasing number of processor cores. The design of NoCs involves several key issues, being the topological mapping (the mapping of the Intellectual Properties (IPs) to network nodes) one of them. Several proposals have been focused on topological mapping last years, but they require the experimental validation of each mapping considered. In this paper, we propose a communication-aware topological mapping technique for NoCs. This technique is based on the experimental correlation of the network model with the actual network performance, thus avoiding the need…
Novel Three-Phase Multi-Level Inverter with Reduced Components
2019
A new multilevel converter topology is proposed in this paper. Low component count and compact design are the main features of the proposed topology. Furthermore, the proposed converter is a capacitor-, inductor-, and diode-free configuration, allowing reducing the converter footprint, increasing the lifetime and simplifying the control strategy. Further, a comparative study is carried out to highlight the merits of the proposed circuit as compared to existing multilevel topologies. Finally, simulation results for the three-level version using different modulation strategies are presented.
SoC-Based Implementation of the Backpropagation Algorithm for MLP
2008
The backpropagation algorithm used for the training of multilayer perceptrons (MLPs) has a high degree of parallelism and is therefore well-suited for hardware implementation on an ASIC or FPGA. However, most implementations are lacking in generality of application, either by limiting the range of trainable network topologies or by resorting to fixed-point arithmetic to increase processing speed. We propose a parallel backpropagation implementation on a multiprocessor system-on-chip (SoC) with a large number of independent floating-point processing units, controlled by software running on embedded processors in order to allow flexibility in the selection of the network topology to be traine…
Improving topological mapping on NoCs
2010
Networks-on-Chip (NoCs) have been proposed as an efficient solution to the complex communications on System-on-chip (SoCs). The design flow of network-on-chip (NoCs) include several key issues, and one of them is the decision of where cores have to be topologically mapped. This thesis proposes a new approach to the topological mapping strategy for NoCs. Concretely, we propose a new topological mapping technique for regular and irregular NoC platforms and its application for optimizing application specific NoC based on distributed and source routing.
A Clustering Approach for Improving Network Performance in Heterogeneous Systems
2000
A lot of research has focused on solving the problem of computation-aware task scheduling on heterogeneous systems. In this paper, we propose a clustering algorithm that, given a network topology, provides a network partition adapted to the communication requirements of the applications running on the machine. Also, we propose a criterion to measure the quality of each one of the possible mappings of processes to processors based on that network partition. Evaluation results show that these proposals can greatly improve network performance, providing a basis of a communication-aware scheduling technique.
Energy Efficient Consensus Over Directed Graphs
2018
Consensus algorithms are iterative methods that represent a basic building block to achieve superior functionalities in increasingly complex sensor networks by facilitating the implementation of many signal-processing tasks in a distributed manner. Due to the heterogeneity of the devices, which may present very different capabilities (e.g. energy supply, transmission range), the energy often becomes a scarce resource and the communications turn into directed. To maximize the network lifetime, a magnitude that in this work measures the number of consensus processes that can be executed before the first node in the network runs out of battery, we propose a topology optimization methodology fo…
A Restricted-Weakly Connected Dominating Set for Role Assignment in a Multichannel MAC for Wireless Mesh Network
2009
International audience; We propose an efficient way of constructing the wireless mesh structure associated with Molecular MAC, a multichannel access method designed for efficient packet forwarding. We base our role assignment on a restricted Weakly Connected Dominating Set structure. After presenting a formal definition of the role assignment problem, we prove its NP-completeness. Then, we propose a centralized 2-approximation algorithm that maximizes the sum of radio link capacities in the molecular structure. Finally, we extend this protocol so that it can operate in a distributed way still providing the same guarantee. This distributed protocol is self-stabilizing thus robust to topology…
MCD: Overcoming the Data Download Bottleneck in Data Centers
2013
The data download problem in data centers describes the increasingly common task of coordinated loading of identical data to a large number of nodes. Data download is seen as a significant problem in exascale HPC applications. Uncoor-dinated reading from a central file server creates contention at the file server and its network interconnect. We propose and evaluation a reliable multicast based approach to solve the data download problem. The MCD system builds a logical multi-rooted tree based on the physical network topology and uses the logical view for a two-phase approach. In the first phase, the data is multicasted to all nodes. In the second phase, the logical tree is used for an effi…