Performance and energy efficiency analysis in NGREEN optical network

We model the end to end delay and energy efficiency in the optical network architecture NGREEN. As the architecture is based on an optical ring, the random part of the delay comes from the random times needed to build an optical container from arriving Data Units and the insertion of the optical container on the ring. We first build a DTMC (Discrete Time Markov Chain) to model the filling of the optical container with Data Units. We take into account a deadline (to have a small latency) and a constraint on a minimal filling of the container (to be energy efficient). We obtain through a numerical analysis using an ad-hoc algorithm we proved, the distribution of the container filling and the distribution of the time needed to build a container. Then, we use this distribution to model the inter arrival of optical containers at a station on the ring. Through simulations and numerical analysis of Markov chains, we obtain the insertion delays and the occupancy of the queue before insertion. The relevance of the paper is to propose a trade-off between energy efficiency and latency for both opportunistic and reservation insertion modes into the ring.