Integrated sleep mode for improving energy efficiency of NG-PONs

As the energy consumption of data communications networks and associated telecommunications devices has been increasing rapidly, improving the energy efficiency has become an important aspect of designing optical access networks to minimize their carbon footprint. In the context of energy saving, Green Interleaved Polling with Adaptive Cycle Time (G-IPACT) is proposed as a medium access control (MAC) scheme to improve the energy efficiency of next-generation passive optical networks (NG-PONs). For energy saving, the sleep mode of each Optical Network Unit (ONU) is activated considering packet queue lengths for both upstream and downstream traffic simultaneously. This integrated approach for sleep mode activation is in accordance with the desired QoS requirements and avoids needless ONU sleeping. The impact of the proposed integrated approach for improving energy efficiency is evaluated and compared with the baseline case in which the sleep mode is activated based on upstream traffic only. Simulation results validate the need of joint consideration of upstream and downstream traffic to avoid excessive delay in downstream and upstream transmissions. For the system performance, we examine the mean packet delay and the mean power consumption for various values of sleep periods.