1. ECE 1545
Service Curve Earliest Deadline Due (SCED) or How to construct a scheduler from a service curve

3. How does SCED work? Goal: Realize a minimum service curve , ie.,
For an arrival at , compute
Set deadline of arrival to
Transmit all backlogged traffic in the order of deadlines
If , service curve condition is satisfied
Traffic
Time

4. Conceptual issue Computation of amounts to computing a pseudo-inverse:
SCED becomes more intuitive if expressed using max-plus algebra
Max-plus and min-plus formulations of SCED are equivalent, … … as long as we use use real-valued notions of time and traffic
 Fluid-flow SCED

5. Summary of duality of min-plus and max-plus network calculus
[Liebeherr `17]

14. Now back to SCED …. (max-plus version)

15. Max-plus SCED Goal: Realize a max-plus service curve , ie.,
For bit value , compute deadline:
Transmit all backlogged traffic in the order of deadlines
Then:
Time
Traffic