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Publications in Scientific Journals:

J. Fabini, M. Abmayer:
"Delay Measurement Methodology Revisited: Time-slotted Randomness Cancellation";
IEEE Transactions on Instrumentation and Measurement, 62 (2013), 10; 2839 - 2848.



English abstract:
Operation of today´s networked applications and protocols depends to a large extent on accurate end-to-end delay measurements and estimations. Appropriate methodologies can significantly improve quality, accuracy and representativeness of delay samples acquired through measurements.
This paper focuses on limitations of state-of-the-art end-to-end delay measurement methodologies. Its central observation is that the first time-slotted link in a measurement path cancels start-time randomness of delay measurement samples. When leaving this first link, all measurement samples are time-synchronized with each other and potentially with global time modulo link period. Because of this effect, which the paper introduces as time-slotted randomness cancellation effect, random sampling is not possible beyond the first time-slotted link of measurement paths. End-to-end measurements therefore fail to capture the full delay range of subsequent time-slotted links in the path, measurement results being limited to a specific session setup.
Following a detailed discussion of theoretical models, the paper proposes a novel delay measurement methodology which adds artificial delay functionality to intermediate network nodes. Measurement packet headers include random seeds which are used by compatible ingress nodes of subsequent time-slotted network segments to re-generate start-time randomness. Samples acquired with this measurement methodology can assess a network path´s full delay range.
Practical applicability of the presented concept and methodology is demonstrated by a prototype implementation which assesses delay in public mobile cellular networks. Measurement results presented in this paper confirm that the proposed concept and methodology is generally applicable and that randomness re-generation can significantly improve quality and representativeness of delay measurement samples.

German abstract:
Operation of today´s networked applications and protocols depends to a large extent on accurate end-to-end delay measurements and estimations. Appropriate methodologies can significantly improve quality, accuracy and representativeness of delay samples acquired through measurements.
This paper focuses on limitations of state-of-the-art end-to-end delay measurement methodologies. Its central observation is that the first time-slotted link in a measurement path cancels start-time randomness of delay measurement samples. When leaving this first link, all measurement samples are time-synchronized with each other and potentially with global time modulo link period. Because of this effect, which the paper introduces as time-slotted randomness cancellation effect, random sampling is not possible beyond the first time-slotted link of measurement paths. End-to-end measurements therefore fail to capture the full delay range of subsequent time-slotted links in the path, measurement results being limited to a specific session setup.
Following a detailed discussion of theoretical models, the paper proposes a novel delay measurement methodology which adds artificial delay functionality to intermediate network nodes. Measurement packet headers include random seeds which are used by compatible ingress nodes of subsequent time-slotted network segments to re-generate start-time randomness. Samples acquired with this measurement methodology can assess a network path´s full delay range.
Practical applicability of the presented concept and methodology is demonstrated by a prototype implementation which assesses delay in public mobile cellular networks. Measurement results presented in this paper confirm that the proposed concept and methodology is generally applicable and that randomness re-generation can significantly improve quality and representativeness of delay measurement samples.

Keywords:
IP, Delay, Measurements, 3G, Time-slotted Randomness Cancellation


"Official" electronic version of the publication (accessed through its Digital Object Identifier - DOI)
http://dx.doi.org/10.1109/TIM.2013.2263914

Electronic version of the publication:
http://publik.tuwien.ac.at/files/PubDat_218309.pdf


Created from the Publication Database of the Vienna University of Technology.