| Summary: | 碩士 === 國立成功大學 === 資訊工程學系碩博士班 === 100 === The number of users and the data rate are increasing in recent years. The access network needs more energy to satisfy the demands. The EPON is one of the most energy saving architecture in the access network. The ONU does not transmit or receive data all the time. There are three major sources for energy wasting including overhearing, control packet overhead, and idle listening. Therefore, the ONU can enter into sleep mode can save more energy.
There exist two implementation options for ONU’s transmitter and receiver. In option 1, the ONU’s transmitter and receiver are turned off simultaneously. The transmitter and receiver could be affected by each other. The transmitter or receiver could not be turned off separately when there is no data to transmit or receive. In option 2, the ONU’s transmitter or receiver is turned off or on separately to eliminate the option 1 problem.
When the ONU’s transmitter enters into sleep mode, it is easy for OLT to wake up the ONU’s transmitter through the upstream start time in the received GATE message. When the ONU’s receiver enters into sleep mode, the ONU can’t receive any data. Therefore, the OLT should assign sleep time for the ONU’s receiver before the ONU enters into sleep mode.
The thesis uses OLT’s downstream start time to calculate the sleep time of ONU’s receiver. The proposed method uses two different cases to predict downstream start time by the OLT. First, the OLT uses upstream scheduling result to predict the downstream start time. The OLT uses the two cases method simultaneously, and the result of longer is the sleep time of ONU’s receiver. In the simulation result, the sleep time of ONU’s receiver is increased and more power is saved. The downstream packet delay doesn’t increase because the sleep time isn’t too long.
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