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IEEE 802.16 wireless MAN is expected to be the revolution of broadband wireless access technology. The grant/request mechanism in IEEE 802.16 MAC enables different QoS for different class of multimedia. Efficient resource management is essential in providing scalability in such large wireless network. The mixture of conventional voice traffic and fractal traffic make the resource management more complex...
Virtual channels (VCs) are a popular solution for the provision of quality of service (QoS). Current interconnect standards propose 16 or even more VCs for this purpose. However, most commercial implementations do not offer so many VCs because it is too expensive in terms of silicon area. Therefore, a reduction of the number of VCs necessary to support QoS can be very helpful in the switch design...
The increase in the bandwidth of wireless channels and the computing power of mobile devices increase the interest in video communications over ad-hoc wireless networks. However, the high error rate and the rapidly changing quality of the radio channels can be devastating for the transport of compressed video. In addition, the bounded playout delay for interactive video limits the effectiveness of...
In this paper, we address the problem of cross-layer optimization in medium access control (MAC) and network layers for wireless multicasting with multiple cooperative or competitive source nodes in a simple tandem network. We consider scheduled or random access in MAC layer and model network layer operations as network coding or plain routing. We separately look at the cooperative and competitive...
Multi-cluster schedulers can dramatically improve average job turn-around time performance by making use of fragmented node resources available throughout the grid. By carefully mapping job's across potentially many clusters, jobs that would otherwise wait in the queue for local cluster resources can begin execution much earlier; thereby improving system utilization and reducing average queue waiting...
Flexible resource management and scheduling policies require detailed system-state information. Traditional, monolithic operating systems with a centralized kernel derive the required information directly, by inspection of internal data structures or maintaining additional accounting data. In systems with distributed or multi-level resource managers that reside in different subsystems and protection...
In this paper, we propose a novel routing protocol, RASTER, that approximates shortest overlay routes between nodes in randomized DHTs. Unlike previously proposed routing protocols, RASTER encodes and aggregates routing information. Its simple bitmap-encoding scheme together with the proposed RASTER routing algorithm enable a performance edge over current overlay routing protocols. RASTER provides...
Clusters of PCs are being used as cost-effective alternative to large parallel computers. In most of them it is critical to keep the system running even in the presence of faults. As the number of nodes increases in these systems, the interconnection network grows accordingly. Along with the increase in components the probability of faults increases dramatically, and thus, fault-tolerance in the system,...
Emerging network technologies have complex network interfaces that have renewed concerns about network reliability. In this paper, we present an effective low-overhead failure detection technique, which is based on a software watchdog timer that detects network processor hangs and a self-testing scheme that detects interface failures other than processor hangs. The proposed adaptive and concurrent...
We design an efficient active queue management (AQM) algorithm, SF-RED, that aims to provide inter-server fairness service in a simple and scalable manner. In the TCP/IP network, it happens that one may intentionally, but in a legal way, generate many "flows" for the same job in order to grab more bandwidth. This leads to servers' bandwidth allocation being unfair, and thus makes ISP price-based...
In future interconnection networks, congestion management is likely to become a critical issue owing to increasing power consumption and cost concerns. As congested packets introduce head-of-line (HoL) blocking to the rest of packets, congestion spreads quickly. The best-known solution to HoL blocking, virtual output queues (VOQs), is not scalable at all or too costly when implemented in large networks...
As typical collaboration tools, group editors allow a distributed group of human users to view and edit shared documents simultaneously over a computer network. Fast local response and timely group awareness are accepted performance metrics in group editors. In this context, a family of optimistic concurrency control algorithms, called operational transformation (OT), has been well established. However,...
Maximum likelihood (ML) estimation is used during tomosynthesis mammography reconstruction. A single reconstruction involves the processing of high-resolution projection images, which is both compute-intensive and time-consuming. This workload is presently a bottleneck in the accurate diagnosis of breast cancer during screening. This paper presents our parallelization work on an ML algorithm using...
This paper focuses on energy-efficient and fault-tolerant resolution of topographic queries in dense, uniformly deployed, two-dimensional sensor systems. Our approach is based on construction of the topographic map of user-defined features in the network. Once constructed, the map is used to resolve a large number of topographic queries efficiently. We present a distributed algorithm for construction...
Providing guaranteed QoS for grid services using resource reservation and allocation is an important feature for today's service grid. Reservation requests with existing mechanisms are often rejected during the resource utilization peak and lead to resource capacity fragment problem. In this paper, we propose a flexible capacity reservation mechanism, called FIRST, which employs the slack time-enabled...
iDIBS is a peer-to-peer backup system which optimizes the distributed Internet backup system (DIBS). iDIBS offers increased reliability by enhancing the robustness of existing packet transmission mechanism. Reed-Solomon erasure codes are replaced with Luby transform codes to improve computation speed and scalability of large files. Lists of peers are automatically stored onto nodes to reduce recovery...
With increased network speeds and throughputs, multicomputers (a system of computers connected by a high-speed network) have become an attractive alternative to store important data in their collective random access memory. Erasure codes provide space-optimal data redundancy to protect this type of storage from node unavailability. They have been used in LH*RS, the scalable high availability, distributed...
When computationally feasible, mining extremely large databases produces tremendously large numbers of frequent patterns. In many cases, it is impractical to mine those datasets due to their sheer size; not only the extent of the existing patterns, but mainly the magnitude of the search space. Many approaches have been suggested such as sequential mining for maximal patterns or searching for all frequent...
We present a scalable parallel implementation for exact inference in Bayesian networks. We explore two levels of parallelization: top level parallelization which uses pointer jumping to stride across nodes; and node level parallelization which parallelizes the node level computations which are independent from each other. For a junction tree with n cliques, using p processors, the worst-case running...
This paper proposes a non-cooperative game theoretical replica allocation technique (NCOR) to reduce user perceived Web access delays. NCOR uses distributed agents that because of their local knowledge act in a self-interested manner in order to enhance the performance of the servers that they represent. This can lead to some performance gains for some servers but has the potential to negatively impact...
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