Database Architectures

Delis, Alex; Kanitkar, Vinay; Kollios, George

doi:10.1002/047134608x.w4302

Cited by 1 publication

(3 citation statements)

References 26 publications

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“…In order to address computationally intensive problems, NOWs have been used in a wide range of fields including large-scale databases, scientific computations, computer graphics, multimedia, wave propagation predictions, and telecommunication systems simulations [18,62,54,56,2,39,71,59]. …”

Section: Related Workmentioning

confidence: 99%

“…In this regard, the manager makes decisions about workload decomposition and job assignment. Traditionally, two types of decomposition methods have been used: data domain decomposition and control domain decomposition [18]. The former partitions data into non-overlapped subsets assigned by the manager to different sites; the latter divides the original computation into small and disjoint tasks assigned to workstations.…”

Section: Considerations For the Now-based Propagation Prediction Modelmentioning

confidence: 99%

“…With the exception of the first case, the trade-offs between communication overheads and memory consumption have to be examined under the assumption that in general accessing data over the network and/or from local disks takes at least an order of magnitude more time than from main memory [41,18]. In our control domain decomposition method, we move data to appropriate computation sites.…”

Section: Data Partitioning Techniquesmentioning

confidence: 99%

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Radio-wave propagation prediction using ray-tracing techniques on a network of workstations (NOW)

Chen¹,

Delis

Bertoni³

2004

Journal of Parallel and Distributed Computing

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Ray-tracing based radio wave propagation prediction models play an important role in the design of contemporary wireless networks as they may now take into account diverse physical phenomena including reflections, diffractions, and diffuse scattering. However, such models are computationally expensive even for moderately complex geographic environments. In this paper, we propose a computational framework that functions on a network of workstations (NOW) and helps speed up the lengthy prediction process. In ray-tracing based radio propagation prediction models, orders of diffractions are usually processed in a stage-by-stage fashion. In addition, various source points (transmitters, diffraction corners, or diffuse scattering points) and different ray-paths require different processing times. To address these widely varying needs, we propose a combination of the phase-parallel and manager/workers paradigms as the underpinning framework. The phase-parallel component is used to coordinate different computation stages, while the manager/workers paradigm is used to balance workloads among nodes within each stage. The original computation is partitioned into multiple small tasks based on either raypath-level or source-point-level granularity. Dynamic load-balancing scheduling schemes are employed to allocate the resulting tasks to the workers.We also address issues regarding main memory consumption, intermediate data assembly, and final prediction generation. We implement our proposed computational model on a NOW configuration by using the message passing interface (MPI) standard. Our experiments with real and synthetic building and terrain databases show that, when no constraint is imposed on the main memory consumption, the proposed prediction model performs very well and achieves nearly linear speedups under various workload. When main memory consumption is a concern, our model still delivers very promising performance rates provided that the complexity of the involved computation is high, so that the extra computation and communication overhead introduced by the proposed model do not dominate the original computation. The accuracy of prediction results and the achievable speedup rates can be significantly improved when 3D building and terrain databases are used and/or diffuse scattering effect is taken into account.Indexing Terms: Ray-tracing based radio propagation prediction model, Radio wave prediction model on Network of Workstations (NOW), Data or control domain decomposition, Dynamic workload-balancing scheduling schemes.

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