Journal Paper

Faces in the Clouds: Long-Duration, Multi-User, Cloud-Assisted Video Conferencing

Submitted by richard on Mon, 02/27/2017 - 09:27
Transactions on Cloud Computing (to appear)

This paper is a simulation based study of cloud assisted multi-user video streaming. It is based upon two use cases (one related to video poker the other related to MOOCs). The paper looks at strategies for placing cloud locations to facilitate streaming using Amazon EC2 cloud locations. The paper compares a strategy that dynamically picks new locations for cloud hosts as time goes on. Interestingly this seems to provide little benefit compared with simply having a good initial choice of sites even when users may drop into and out of a cloud chat session over the course of many hours.

On rate limitation mechanisms for TCP throughput: a longitudinal analysis

Submitted by richard on Tue, 12/13/2016 - 17:00
Computer Networks

This paper is a considerably expanded version of the INFOCOM paper.

Again it argues that TCP is no longer mainly controlled by loss and congestion but instead by algorithms and settings under the control of the sender or receiver deliberately or accidentally designed to restrict throughput for a variety of reasons (for example limiting video sending to the rate at which the viewer is watching).

It contains extended discussion of the methodology and in particular how flight and RTT data was extracted from passive traces.

Likelihood-based assessment of dynamic networks

Submitted by richard on Thu, 12/24/2015 - 11:36
Journal of Complex Networks

This paper used a likelihood based framework to create a rigorous way to assess models of networks. Network evolution is broken down into an operation model (it decides the 'type' of change to be made to the network, e.g. "add node" "add link" "remove node" "remove link") and an object model (that decides the exact change -- which node/link to add).

The system is shown to be able to recover known parameters on artificial models and to be useful in analysis of real data.

This work can generate graphs from a very large family with the aim of fitting those graph to parameters of real data sets.

Software-defined network support for transport resilience

Submitted by richard on Tue, 02/18/2014 - 22:06
IEEE/IFIP Network Operations and Management Symposium

This paper is a development of the earlier ideas in PREFLEX -- http://www.richardclegg.org/node/18

In this case the focus is resilience within a data centre. In particular resilience at the network layer. If several paths are available to a destination the system known as INFLEX can support fail over between paths seamlessly using OpenFlow. In this case the system is tested using Openvswitch.

Criticisms of modelling packet traffic using long-range dependence (extended version)

Submitted by richard on Sun, 10/27/2013 - 16:16
Journal of Computer and System Sciences, 77(5)

This paper looks at the phenomenon of long-range dependence. It shows that certain long-range dependent models give answers which contain infinities and also that this behaviour will not be detected by a naive modelling approach. The work is an extension of an earlier published PMECT paper.

A practical system for improved efficiency in frequency division multiplexed wireless networks

Submitted by richard on Thu, 10/17/2013 - 18:40
IET Communications, Volume 6, issue 4, p. 449-457

This paper looks at the problem of sending data using a variation on Orthogonal Frequency Division Multiplexing. In this variant frequencies are packed slightly closer. This means the frequencies are no longer orthogonal but more may be packed into a given amount of spectrum.