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Energy efficiency and green communications have become well-established themes for next-generation communications systems, with specific regard to reducing carbon footprint, lowering environmental impact, and minimizing operational expenditures. Apart from conforming to the required societal green agenda, there are also many practical and financial advantages to creating solutions that exhibit such benefits. Extending the advantages of energy efficiency to access networks is paramount as it is the major contributor of energy consumption in the Internet. Among the various factors of energy consumption in access networks, optical network units (ONUs) at the customer's premises consume the bulk of energy: ONUs consume about 60-70% of the energy consumed in current fiber-to-the-home networks. In this paper, we propose a dynamic bandwidth allocation (DBA) algorithm for Ethernet passive optical networks (EPONs). The DBA algorithm exploits the sleep mode functionality, in which the optical network unit (ONU) is put into sleep according to the traffic load of the ONU. We explore the DBA paradigm for two kinds of ONUs: legacy (with large sleep overheads) and next generation (with small sleep overheads). We also extend the DBA algorithm with a variety of grant sizing (bandwidth allocation) schemes. The DBA algorithm achieves significant power savings in comparison to traditional power-ignore DBAs. |
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