Energy-efficient load adaptive polling sequence arrangement scheme for passive optical access networks

An energy-efficient scheme termed as load adaptive sequence arrangement (LASA) is introduced. Based on changing the polling sequence of optical network units (ONUs) according to traffic load, the scheme can improve the energy efficiency of passive optical access networks. The polling sequence arrangement is performed by processing a label that is added in the gate/report message and allocating each ONU an uneven idle time. When the polling sequence is changed, the ONUs that have been allocated longer idle times could sleep much longer. Theoretical analysis indicates that the polling sequence arrangement has a significant effect on the energy efficiency of the network. It can provide ONUs longer total sleeping time, and barely lengthen the average cycle time. Moreover, to optimize the energy consumption performance under a low-traffic scenario, the LASA scheme jointly working with the fixed minimal transmission time (FMT) of the ONU scheme, which is called the LASA-FMT scheme, is further investigated. By ensuring the minimal transmission time of an ONU, the LASA-FMT scheme further extends the total sleeping time of ONUs and improves the energy efficiency. The performance on packet delay of both the LASA scheme and the LASA-FMT scheme is acceptable to support delay sensitive services, which shows the practical value of the two schemes in green network progress.