A Simple Method for Generating Correlated Binary Variates

Park, Chul Gyu; Park, Taesung; Shin, Dong Wan

doi:10.2307/2684925

Cited by 60 publications

(19 citation statements)

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“…where BW is given by (4) and h(i) are given by (5). Numerical results show that GP (x) is non-increasing in x: it is relatively flat for smaller values of x, but decreases sharply for values of x larger than pagg 1−pagg .…”

Section: B Pfec/rfec Provisioningmentioning

confidence: 98%

“…In this case, however, the packet loss events are correlated, and the degree of correlation is measured by a parameter θ; the correlated loss processes are generated according to the method described in [5]. In particular, the correlation is such that, for two paths numbered i and j, the probability that a packet loss in one path results in a packet loss in the other is equal to θ |i−j| , thereby simulating the scenario where paths that are further apart interfere to a lesser degree.…”

Section: E Effect Of Loss Correlationsmentioning

confidence: 99%

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A Transport Protocol to Exploit Multipath Diversity in Wireless Networks

Sharma

Kar

Ramakrishnan

et al. 2012

IEEE/ACM Trans. Networking

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Abstract-Wireless networks (including wireless mesh networks) provide opportunities for using multiple paths. Multihoming of hosts, possibly using different technologies and providers, also makes it attractive for end-to-end transport connections to exploit multiple paths. In this paper, we propose a multi-path transport protocol, based on a carefully crafted set of enhancements to TCP, that effectively utilizes the available bandwidth and diversity provided by heterogeneous, lossy wireless paths. Our Multi-Path LOss-Tolerant (MPLOT) transport protocol can be used to obtain significant goodput gains in wireless networks, subject to bursty, correlated losses with average loss-rates as high as 50%. MPLOT is built around the principle of separability of reliability and congestion control functions in an end-to-end transport protocol. Congestion control is performed separately on individual paths and the reliability mechanism works over the aggregate set of paths available for an end-to-end session.MPLOT distinguishes between congestion and link losses through Explicit Congestion Notification (ECN), and uses Forward Error Correction (FEC) coding to recover from data losses. MPLOT uses a dynamic packet mapping based on the current path characteristics to choose a path for a packet. Use of erasure codes and block level recovery ensures that in MPLOT, the receiving transport entity can recover all data as long as a necessary number of packets in the block are received, irrespective of which packets are lost. We present a theoretical analysis of the different design choices of MPLOT, and show that MPLOT chooses its policies and parameters such that a desirable tradeoff between goodput with data recovery delay is attained. We evaluate MPLOT, through simulations, under a variety of test scenarios and demonstrate that it effectively exploits path diversity in addition to efficiently aggregating path bandwidths, while remaining fair to a conventional TCP flow on each path.

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Section: B Pfec/rfec Provisioningmentioning

confidence: 98%

Section: E Effect Of Loss Correlationsmentioning

confidence: 99%

A Transport Protocol to Exploit Multipath Diversity in Wireless Networks

Sharma

Kar

Ramakrishnan

et al. 2012

IEEE/ACM Trans. Networking

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“…Global outcome data were then simulated. 20 We simulated groups of 600 and 1400 ischemic stroke patients (the approximate sizes of the NINDS rtPA trials and GAIN International, respectively). We applied 2 selection strategies to these groups: all patients (equivalent to using the entry criteria of the source trial) and patients with moderate prognosis (probability of favorable outcome between 0.2 and 0.8).…”

Section: Simulations and Selection Strategiesmentioning

confidence: 99%

Targeting Neuroprotection Clinical Trials to Ischemic Stroke Patients With Potential to Benefit From Therapy

Weir

Kaste²,

Lees³

2004

Stroke

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Background and Purpose-Clinical trials of neuroprotective drugs have had limited success. We investigated whether selecting patients according to prognostic features would improve the statistical power of a trial to identify an efficacious treatment. Methods-Using placebo data from the Glycine Antagonist in Neuroprotection (GAIN) International and National Institute of Neurological Disorders and Stroke (NINDS) recombinant tissue plasminogen activator (rtPA) clinical trials, we developed and validated simple prognostic models for stroke trial end points: Barthel Index Ն95, modified Rankin Scale Յ1, National Institutes of Health Stroke Scale Յ1, and Glasgow Outcome Scaleϭ1. Using these models, we simulated 1000 clinical trials and estimated, under several hypothetical treatment effect patterns of neuroprotection, the effect on statistical power of including only patients with moderate prognosis. We calculated the number of patients that would have to be enrolled to maintain the statistical power achieved in selecting the whole trial population. Reanalysis of actual data from the NINDS rtPA trials confirmed the results independently. Results-Selecting patients with moderate prognosis (predicted probability of favorable outcome 0.2 to 0.8) enabled a sample size reduction, without loss of statistical power, of between 54.6% (51.3% to 57.6%) and 68.6% (66.0% to 71.1%), depending on the treatment effect pattern and outcome measure. These benefits were largely due to the exclusion of patients with poor prognosis. Conclusions-Targeting patients with potential to benefit enables a substantial sample size reduction without compromising statistical power or duration of recruitment. As part of a broader trial design strategy, informed use of prognostic data available acutely would help in identifying effective neuroprotective treatments.

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“…Among the different established methods in the literature to simulate samples from binary random variables (e.g. Emrich and Piedmonte 1991; Park et al 1996;Lunn and Davies 1998), this research adopts an algorithm based on the general Dichotomized Gaussian Method (DGM). The DGM is preferred over the other methods for its general applicability, especially when negative correlations exist.…”

Section: Generating Realizations Of Correlated Bridge Failures (Stagementioning

confidence: 99%

Seismic Reliability Assessment of Aging Highway Bridge Networks with Field Instrumentation Data and Correlated Failures, I: Methodology

et al. 2014

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The state-of-the-practice in seismic network reliability assessment of highway bridges often ignores bridge failure correlations imposed by factors such as the network topology, construction methods, and present-day condition of bridges, amongst others. Additionally, aging bridge seismic fragilities are typically determined using historical estimates of deterioration parameters. This research presents a methodology to estimate bridge fragilities using spatially interpolated and updated deterioration parameters from limited instrumented bridges in the network, while incorporating the impacts of overlooked correlation factors in bridge fragility estimates. Simulated samples of correlated bridge failures are used in an enhanced Monte Carlo method to assess bridge network reliability, and the impact of different correlation structures on the network reliability is discussed. The presented methodology aims to provide more realistic estimates of seismic reliability of aging transportation networks and potentially helps network stakeholders to more accurately identify critical bridges for maintenance and retrofit prioritization.

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A Simple Method for Generating Correlated Binary Variates

Cited by 60 publications

References 0 publications

A Transport Protocol to Exploit Multipath Diversity in Wireless Networks

A Transport Protocol to Exploit Multipath Diversity in Wireless Networks

Targeting Neuroprotection Clinical Trials to Ischemic Stroke Patients With Potential to Benefit From Therapy

Seismic Reliability Assessment of Aging Highway Bridge Networks with Field Instrumentation Data and Correlated Failures, I: Methodology

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