Energy-efficient scheduling and energy-delay tradeoff in green hybrid fiber-coaxial networks

Hybrid Fiber Coaxial (HFC) networks support broadband Internet access with the existing cable TV systems. Recent advances on HFC networks have demonstrated effective improvements on the customers´ access speeds with the channel-bonding technology. In this paper, we develop a novel energy-efficient traffic scheduling algorithm for the HFC networks that support channel bonding. The proposed algorithm is compliant with the newly-released DOCSIS 3.0 standard. We come up with a system model of the channel-bonding transmitters (TXs) on a Cable Modem (CM), and then define several operation modes for them. At the beginning of each scheduling cycle, the proposed algorithm adjusts the TXs´ operation modes based on the traffic status. Both analytical analysis and numerical simulations are then developed to investigate the energy-saving and delay introduced by the algorithm. The results on energy-saving indicate that the energy-consumption of the TXs scales almost linearly with the input traffic load and effective energy-saving can be achieved. We also investigate the tradeoff between the energy-saving and the average delay to optimize the parameters for the energy-efficient scheduling, and to make sure that the traffic will not experience significant delay increase due to the energy-saving operations.