earticle

영어

Even though many wireless communication standards specify multicast as well as unicast traffic in layer 2, most parts in the specifications are contributed for unicast methods. In addition, while the wireless standards provide reliable unicast methods by using ARQ and retransmission, multicast packets are not reliably transmitted per the standards. To retransmit a multicast packet, the acknowledgements from the receivers need to be transmitted to the sender so that the sender knows whether or not the retransmission is required. However, transmitting an ACK from each group member degrades the network performance due to the overhead of multiple ACK packet transmissions and channel access processes for the ACKs. In this paper, States-of-the-arts in Layer-2 wireless multicast protocol are investigated in wide areas such as commercial communication standards as well as academic researches. Through the investigation, the research on reliable wireless multicast protocol is imposed.