An aggressive ONU sleep control scheme that squeezes sleep time into time to transmit data

This paper proposes an aggressive ONU sleep control scheme that squeezes sleep time into the time used to transmit data for power saving in passive optical network systems. Unlike current schemes it is effective even in heavily congested situations. To expand the applicability of the ONU sleep control scheme, we propose three major changes to the sleep control and dynamic bandwidth assignment. The first is to change the sleep trigger from the existence of buffered data to the existence of permission to transmit data. The second is to increase the burst length to the limit of the allowable delay variation to increase the sleep time. The third is to compensate for the lack of bandwidth requests from ONUs during sleep time to realize bandwidth fairness. Using the proposed scheme, the results show a one hundred thousand-fold expansion in the applicable range of sleep control and a four-fold improvement in power saving on average under highly congested conditions. Finally, the relation between the ONU load and the minimum sleep time is also discussed. The realistic minimum sleep time required by the proposed scheme is clearly shown.