Early Wake-Up Decision Algorithm for ONUs in TDM-PONs With Sleep Mode

Abstract

Abstract-Recent IEEE and ITU-T standards for TDM-Passive Optical Network (TDM-PON) with sleep mode recommend that the Optical Line Terminal (OLT) in a TDM-PON should be in charge of invoking an Optical Network Units (ONU) to move into sleep state in absence of frames. It is considered that, on upstream frame arrival, a sleeping ONU can leave sleep state, in which an ONU turns off its transmitter or both transmitter and receiver immediately, prior to its assigned sleep interval length. In this paper, we refer to this approach as immediate early wakeup (IMEW). According to the standards, the OLT may or may not allow an ONU to trigger early wake-up function (EWF) on upstream frames arrival. If the OLT does not allow EWF (not support early wake-up (NSEW)), an ONU should stay in sleep state during its assigned sleep duration and buffer all the upstream frames while it is in this state. In IMEW, upstream frames experience small delay but ONU's energy consumption increases remarkably. Conversely, in NSEW, an ONU consumes less energy compared to IMEW at the price of increasing upstream frame delay and possibility of its buffer overflow. In this paper, the limitations of IMEW and NSEW have motivated us to propose a novel Early Wake-up Decision (EWuD) algorithm which aims at meeting upstream frame delay requirement while reducing ONUs' energy consumption as much as possible. The role of EWuD algorithm is to select an appropriate time for triggering EWF taking into consideration two factors: (1) buffer overflow probability and (2) delay requirement violation of upstream frames. We evaluate EWuD performances using our TDM-PON OPNET Modular based simulation model under wide range of scenarios. Findings demonstrate that our proposed EWuD can successfully meet delay requirement of all upstream frames while reducing ONU's energy consumption significantly.

Energy Conservation in Passive Optical Networks: A Tutorial and Survey

“…The early wake-up function of an ONU is supported under both OLT and ONU initiated power saving mechanisms in SIEPON, as stated in IEEE Std 1904.1 [39]. When the OLT allows early wake-up of an ONU, it needs to periodically assign a gratuitous grant (a small uplink grant) to the ONU during each uplink DBA cycle [294]. The OLT uses the GATE MPCPDU message to notify the ONUs periodically regarding uplink transmission grant information, as shown in Fig.…”

“…Therefore, here, an ONU may experience frequent sleep interruption as the uplink traffic arrival increases, resulting in reduced energy saving opportunity. To avoid frequent sleep interruption, a traffic priority class-based sleep interruption decision could have been considered (as proposed in [294]).…”

Simulations of Grant Allocation in NG-PON2 Networks Using OPNET Modeler

“…Furthermore, our model proves a novel dynamic bandwidth allocation with modification of Max-Min fair algorithm in which a free grant size is spread to heavily loaded ONU (Optical Network Unit). At this time, several implementations for EPON passive optical network are available in OPNET [4], [5], [6]. However, communication in networks defined by the ITU take place in a different way.…”