4,812 research outputs found
On the combined effects of Bit Error Rate and delay-distribution tail on TCP performance
The original design of the TCP retransmission timeout was implemented ignoring the recent
measurement studies on the dynamics and features of network traffic and delay. Such studies have
reported the highly variable characteristics of network delay, considered to be heavy-tailed distributed.
Accordingly, depending on the heavy characteristics of the tail of the delay distribution, the actual
implementation of TCP's retransmission timeout might be too conservative, or rather insufficient.
This work aims to assess the optimal design of the retransmission timeout when heavy-tailed delay
profiles are present. In our experiments, we have considered the case of low-bit error rate scenarios
typical from wired networks as well as the high bit-error rates, typical from wireless networks. We show
that the current implementation of the retransmission timeout is in broad terms very conservative, except
in cases with extremely heavy tails
Weibull mixture model to characterise end-to-end Internet delay at coarse time-scales
Traces collected at monitored points around the Internet contain representative
performance information about the paths their probes traverse. Basic measurement
attributes, such as delay and loss, are easy to collect and provide a means to
both build and validate empirical performance models. However, the task of analysis
and extracting performance conclusions from measurements remains challenging.
Ideally, performance modelling aims to find a set of self-contained parameters to
describe, summarise, profile and easy display network performance status at a time.
This can result in the provision of meaningful information to address applications in
fault and performance management, hence providing input to network provisioning,
traffic engineering and performance prediction.
In this work we present the Weibull Mixture Model, a method to characterise endto-
end network delay measurements within a few simple, accurate, representative and
handleable parameters using a finite combination of Weibull distributions, with all the
aforementioned benefits. The model parameters are related tomeaningful delay characteristics,
such as average peak and tail behaviour in a daily profile, and can be optimally
found using an iterative algorithm known as Expectation Maximisation. Studies on
such parameter evolution can reflect current workload status and all possible network
events impacting packet dynamics, with further applications in network management.
In addition, a self-sufficient procedure to implement the Weibull Mixture Model is
presented, along with a set of matching examples to real GPS synchronised measurements
taken across the Internet, donated by RIPE NCC
Model-independent bounds probing on the electromagnetic dipole moments of the -lepton at the CLIC
We establish model independent bounds on the anomalous magnetic and electric
dipole moments of the tau-lepton using the two-photon processes and . We use of data
collected with the future linear collider such as the CLIC at
and we consider systematic
uncertainties of . Precise bounds at
C. L. on the anomalous dipole moments to the tau-lepton and
are set from our study. Our results show that the processes under consideration
are a very good prospect for probing the dipole moments of the tau-lepton at
the future linear collider at the mode.Comment: 38 pages, 26 figure
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