| Summary: | 碩士 === 國立東華大學 === 電機工程研究所 === 88 === Multicast is an efficient technique for transmitting data from a sender to a group of receivers, it allows copies of single packets to be passed to selected subsets of all possible destinations. In this Thesis, We focus on multicast in single channel Multi-access wireless local area networks comprising several cells. In such a system, a receiver cannot correctly receive a packet if two or more packet are sent to it at the same time, because the packets collision. Therefore, one has to ensure that only one node sends at a time.
We present a new approach to overcome the problem of feedback collision in single channel multi-access wireless LANs, both for the purpose of acquiring the channel and for reliability. Our approach involves the selection of a leader in a multicast group member and representative for the purpose of sending feedback to the sender by random delayed timer. For reliable multicast, on erroneous reception of the packet, the leader does not send an acknowledgement, prompting a retransmission. On erroneous reception of the packet at receivers other than the leader, our protocol allows negative acknowledgements from these receivers to collide with the acknowledgement from the leader, thus destroying the acknowledgement and prompting the sender to retransmit the packet.
Using analytical models, we can find that our protocol make higher throughput than other two protocols.
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