Delay and buffer bounds in time-sensitive networks based on deficit round robin schedulers

Contact: Ehsan Mohammadpour

Modern aircrafts heavily rely on communication between the various aircraft subsystems for a safe flight. The communication network spans the entire aircraft connecting the wings, cockpit, the wheels, etc. and comprises 50-1000 switches, depending on the size of the plane. This network routes about X packets per second, some of which are time-sensitive control packets, which need to be delivered within a strict deadline. The control packets share the network with less time-critical but high-bandwidth audio-video traffic. The challenge then is to ensure that all packets are delivered within their respective deadlines, and the switches are appropriately dimensioned with the required buffer size to ensure 0% packet loss.

In order to ensure that low-priority packets do not interfere with high-priority packets, real-time networks use schedulers that dictate when each packet must be forwarded at each switch. As the size of the network grows, ad-hoc methods cannot provide the required delay and buffer guarantees. To address this issue, they use Network Calculus, a deterministic queuing framework that provides mathematical bounds on the delays and buffer sizes.

In this project, we will analyse the network of Airbus A380 using a Deficit Round Robin (DRR) scheduler at each switch. We will derive an upper bound on the delay of the time-critical packets. This bound will be used to obtain a bound on the buffer size at each switch in the A380 network. We will show that the delay and buffer bounds are better than the existing pessimistic bounds, potentially saving aircraft manufacturers a large investment in network equipment.

Student profile


  • A good motivation to work and learn
  • Analytical skills


  1. Network Calculus Book
  2. Deficit Round Robin Scheduler

Supervised with Ehsan Mohammadpour