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Research Information
Please submit a detailed thesis statement or abstract for each project, with a description of how the six-month-renewable OPNET Modeler or IT Guru software license will be used.

1. Provisioning of relative quality of service guarantees over wireless hop
Nowadays, advanced scheduling disciplines are more and more supported by commercial network devices in order to grant Quality of Service (QoS) to the Internet traffic.

The bursty characteristics of such traffic requires further studies on an effective deployment of packet schedulers, especially when dealing with wireless interfaces (that have extremely time-variant nature). A possibility is to dynamically adapt the scheduling configuration parameters or queue weights according to the target QoS requirements and the relative priority of each queue, considering the lower layers (from physical to network ones) as a whole in terms of provided performance.

The modelling process consists of implementing a modified version of WTP (Waiting Time Priority) called AWTP (Advanced WTP) that schedules packets according to their scheduling priority (namely, the priority time). The priority time is calculated taking into account the packet queuing delay, the packet size and the priority of the queue the traffic flow of the packet was assigned, as well as the current performance at physical and data-link layers.

The aim is to analyze the behaviour of a system where such a scheduler is deployed in all the router interfaces or just in those that transmitting on the air.

Initially, the models to be developed are: video traffic sources/receivers and a mechanism to dynamically tune the operating parameters of an AWTP scheduler (supported by a generic network node at IP layer) on the basis of real-time measurements of the performance at lower layers. More network components (i.e. routers) should be interconnected in order to build a scenario resembling a real telecommunication infrastructure to be properly analyzed.

Several statistics related to delay, loss and transmitting/receiving rate are also made available to evaluate the performance of the resulting system.

2. Simulation-driven testing of ultra-large-scale choreography
The goal is to carry out a simulation modeling analysis about the scalability property for adaptable QoS-aware ultra-large-scale choreographies (i.e. a type of software oriented architectures). The developed model shall be capable of representing all the intrinsic dynamism, heterogeneity, and complexity related to the network, in terms of topology, bandwidth, and latency and related to the computing nodes and user devices, as resulting from a trade-off between complexity and reliable representation of reality.

Starting from a formal specification of a choreography, a (semi-)automatic process should lead to the building of simulation model for it. The related simulation analysis should provide data about the non-functional properties of the system under study. That should be matched with the user requirements from which the choreography was created for.

Scripts should be used to generate simulation models of application- and network-level components, with statistics that collect quantitative data, such as service response time, reliability, accessibility and activity, for assessment purposes
.

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