Power-saving is significant in wireless networks.To remedy the shortcoming in the power-saving class II of the IEEE 802.16e standard that energy is unnecessarily expended by the idle mobile stations (MSs) that are prevented from sleeping by the fixed length of the listening window

a two-stage reliable multicasting scheme (TRMS) is proposed

which lets a base station (BS) multicast during the first stage and remulticast

in the second stage

the network coded packets that contains the lost packets in the first stage.The TRMS enables MSs to sleep as soon as they become idle and realizes reliable packet delivery under delay constraint.Simulation shows that TRMS achieves power saving and outperforms the traditional retransmission and acknowledgement mechanism in terms of duty cycle

energy consumption

throughput

and packet loss rate.