Sleep mode mechanism with improved upstream performance for passive optical networks

With the proliferation of advanced and interactive services together with the high demand for premium quality of experience, upstream traffic in passive optical networks is growing fast in recent times. Motivated by this, a new power saving mechanism called the sleep-transmit mode (STM) is proposed, which enables the optical network units (ONUs) at customer premises to transmit upstream data during sleep periods without turning on the receiver, thus conserving energy and improving upstream transmission delay. These advantages are achieved by pre-allocating bandwidth for upstream transmission to ONU before it enters the sleep state. Our analysis results show that using STM (1) the power consumption of an ONU is reduced by up to 29% compared to interrupting the sleep mode, and (2) the average additional upstream packet delay due to sleep mode is reduced by up to 10-fold compared to transmitting the upstream packets only after the sleep duration expires.