摘要：Due to massive expansion of Information and Communication Technology sector, the power consumption of this sector is rapidly increasing. Besides GHG emissions, the increase in power consumption also leads to higher operating costs of these networks. Passive Optical networks (PON) is energy efficient compared to legacy copper based Access Networks and Active Optical Networks (AON) but still the power consumption of the PON is significant and requires further research. The main cause of higher power consumption of PON is optical network unit (ONU). In this study, we have surveyed the energy conservation schemes for present and next generation PON (TWDM and OFDM PONs) with a focus on ONU based schemes. The focus of the study are the medium access control (MAC) schemes as they are more economical and be adapted easily. The review shows that if cyclic sleep mode is efficiently configured, it is the most economical, efficient and delay aware scheme for current as well as Next Generation PONs for energy conservation with delay guarantees.
