中文摘要：

长距离无源光网络（Long-reach Passive Optical Networks,LR-PON）的覆盖范围超过100km,光网络单元（Optical Network Units,ONU）在一个轮询周期中处于空闲状态的时间较长。如果使处于空闲状态的ONU进入低功耗（休眠或假寐）模式,可以降低ONU的能耗。基于此,文章提出一种改进的节能动态带宽分配算法。该算法通过改变ONU的调度顺序,使得ONU在上下行传输结束后能够立刻进入休眠状态,而无需等待授权帧的到达,从而延长ONU的休眠时间。仿真结果表明：所提出算法能够降低ONU能耗和下行数据包平均时延。

英文摘要：

With a wide coverage of more than 100 km in long-reach passive optical networks（LR-PON）,there is longer idle time for optical network units（ONUs）in a polling cycle.It is beneficial to reduce the energy consumption of ONUs to make ONUs in idle state to enter low energy consumption mode（i.e.sleep or doze mode）.Based on which,an improved dynamic bandwidth allocation algorithm（IEDBA）was proposed.IEDBA makes ONUs sleep immediately after upward and downward transmission by changing the scheduling order without waiting for the arrival of gate frames,which can extend the ONUs＇ sleep time.The simulation results show that the proposed algorithm can achieve both low energy consumption of ONUs and low delay of downward packets.