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.
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.
This paper describes a system for middleboxes that process application level data -- that is reconstructed TCP flows not packets. The system consists of three parts:
1) A language specific to middleboxes that can quickly express data formats and how to process them but in a "safe" way that allows middleboxes to co-exist on the same physical hardware.
2) An abstraction, the task graph, that breaks middlebox logic into small, parallelisable logical units (tasks) connected by channels through which data flows.
3) A system that allows the compiled code to execute in a performant way.
This talk describes FLICK a system for the application-specific middlebox. It consists of three parts:
1) A domain specific language for the middlebox that allows easy development of typical middlebox functions.
2) An abstraction, the task graph, that allows the breaking of middlebox functions into easily parallelisable work units.
3) The system -- this implements the compiled language, handles TCP connections and memory management.
The whole system is comparable in speed to a specialist implementation.
Proc. of International Conference on Telecommunications
This paper looks at a new way to use multiple channels in ad-hoc sensor networks. It consists of two parts:
1) A protocol that allows a node, when sent a particular message, to attempt to change channel (reliably with a fall-back if the new channel is subject to interference).
2) An algorithm run at a single "command" node that selects which nodes should change channel according to a graph colouring problem.
The work is tested in simulation using Cooja (which simulates Contiki based sensor nodes).
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.