A bandwidth allocation algorithm for improving QoS in EPON with sleep mode

Recently, Ethernet Passive Optical Network (EPON) with sleep mode has been actively investigated to improve energy conservation in the broadband access network. EPON with cyclic sleep mode transmits up/downstream traffic at the same time and put into the sleep mode at idle time in Optical Network Unit (ONU). However, QoS requirement can be violated by the cyclic sleep mode. In this paper, we propose novel bandwidth allocation algorithm to maximize energy efficiency while satisfying QoS requirement. The main idea is to consider up/downstream traffic in order to determine suitable scheduling transmission period on Optical Line Terminal (OLT). To do this, it allocates bandwidth according to request from ONU, usually. However, when downstream traffic in OLT buffer exceeds predefined threshold, the proposed algorithm compares threshold to bandwidth request from ONU for reducing OLT traffic queuing delay. So, our proposed algorithm can satisfy both energy saving and QoS requirement. In order to evaluate the proposed algorithm, we perform simulation in terms of total and average sleep time of ONU, queuing delay of downstream traffic in OLT buffer.