# Frontiers of Optoelectronics

 Front. Optoelectron.    2019, Vol. 12 Issue (4) : 422-432     https://doi.org/10.1007/s12200-019-0906-5
 RESEARCH ARTICLE
Heuristic polling sequence to enhance sleep count of EPON
Bhargav Ram RAYAPATI(), Nakkeeran RANGASWAMY
Department of Electronics Engineering, Pondicherry University, Pondicherry 605014, India
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 Abstract Next-generation passive optical networks (PONs) demand power conservation to create a green environment. A reduction in power consumption of the traditional Ethernet passive optical network (EPON) can be achieved by increasing the sleep count in optical network units (ONUs). In this paper, this is accomplished by introducing a first-in-last-out (FILO) polling sequence in the place of a fixed polling sequence to increase the number of ONUs entering sleep mode (sleep count). In a fixed polling sequence, the optical line terminal (OLT) allocates idle time to the ONUs based on the overall load of the ONUs. This leads to a situation that whenever the idle time does not meet the wakeup time threshold of sleep mode, the ONUs are put into doze/active mode, which consumes more power. In the FILO polling sequence, the first polled ONU in the current cycle is made to be polled last in the following cycle. Polling continues in this way, and by this rearrangement, the idle time of delayed poll ONUs increases; hence, it helps to reduce the power consumption. Additionally, a modified load adaptive sequence arrangement (MLASA) method is suggested, where the ONUs are categorized into doze ONUs and sleep ONUs. A numerical simulation of the FILO polling sequence with a vertical cavity surface emitting laser (VCSEL) ONU shows a maximum reduction in power consumption of 15.5 W and a 20% improvement in energy savings compared with the traditional fixed polling sequence. The MLASA method results in better power consumption with minimum delay than that of the proposed FILO and existing LASA methods. Corresponding Authors: Bhargav Ram RAYAPATI Just Accepted Date: 24 June 2019   Online First Date: 07 November 2019    Issue Date: 30 December 2019
 Cite this article: Bhargav Ram RAYAPATI,Nakkeeran RANGASWAMY. Heuristic polling sequence to enhance sleep count of EPON[J]. Front. Optoelectron., 2019, 12(4): 422-432. URL: http://journal.hep.com.cn/foe/EN/10.1007/s12200-019-0906-5 http://journal.hep.com.cn/foe/EN/Y2019/V12/I4/422
 Fig.1  Basic EPON architecture [2] Fig.2  Traditional fixed polling sequence [16] Fig.3  Idle time partition Fig.4  FILO polling sequence with n ONUs Tab.1 Tab.2  Parameters considered for analysis [6] Fig.5  Power cumulative of polling methods against idle time Fig.6  Energy savings of polling methods against idle time Tab.3  Performance comparison of different polling methods Fig.7  Performance evolution of the LASA method and MLASA method Fig.8  Delay exploration against idle time