  Economical and environmental concerns necessitate network engineers to focus
on energy-efficient access network design. The optical network units (ONUs),
being predominantly responsible for the energy consumption of Ethernet Passive
Optical Network (EPON), motivates us towards designing a novel protocol for
saving energy at ONU. The proposed protocol exploits different low power modes
(LPM) and opts for the suitable one using traffic prediction. This scheme
provides a significant improvement of energy-efficiency especially at high load
(~ 40%) over existing protocols. A better understanding of the performance and
a deeper insight into several design aspects can only be addressed through a
detailed mathematical analysis. The proposed protocol involves traffic
prediction which infringes Markovian property. However, some pragmatic
assumptions along with a proper selection of observation instances and state
descriptions allow us to form a Discrete Time Markov Chain (DTMC) of the
proposed algorithm. Thus, the primary objective of this paper is to propose a
novel scheme for achieving energy-efficiency at ONU and mathematically analyze
the performance of it with the help of a DTMC. The analysis reveals that the
energy-efficiency is more sensitive to the power consumption of doze mode as
compared to other LPM while the effect of sleep-to-wake-up time is minor.
