ONU buffer reduction for power efficiency in Passive Optical Networks

Power efficiency will be one of the primary factors dictating the choice of future network deployments. Passive Optical Networks (PONs) in general consume less power and are well positioned to be the technology of choice for future access networks. In a PON, the Optical Network Units (ONUs), that provide the interface between the end user and the Optical Line Terminal (OLT), consume a substantial amount of power. Typically, 2 MB or more buffer capacity is used in an ONU for holding upstream packets. This consumes around 1.29 W of leakage power when idle. In the current work, we show the relationship between buffer capacity and leakage power consumption. This motivated us to propose buffer reduction as a strategy to reduce power consumption of an ONU. We propose three schemes viz. Zero Buffers (ZBs), Node Proportional Buffers (NBs) and Rate Proportional Buffers (RBs). They impose aggressive buffer capacity restrictions on the ONU to reduce power consumption. Having said that, these schemes cannot be realized without modifications to the basic network operation. We propose mechanisms required to support the buffer reduction schemes. Through simulations we explore the relationship between power consumption and network performance. We also present the comparison of the proposed schemes in terms of network performance with different network loads. Simulation results indicate that despite buffer size reduction, an acceptable level of application level performance can be achieved. We show that buffer reduction as a strategy is viable and can cut down more than 90% of leakage power consumed by packet buffers at the ONU.