Multicast communication method, accompanied with the relay node and wireless network system design

A relay node, for relaying a multicast packet from a first member node to a plurality of second member nodes in a wireless network, wherein the second member nodes and the first member node belong to a same group, the relay node comprising:

• a radio frequency (RF) antenna, for receiving and transmitting the multicast packet;
• a memory, for storing a number and distances of the second member nodes;
• and
• a multicast unit, electrically connected to the memory and the RF antenna, for calculating a monitoring parameter according to the number and the distances of the second member nodes and determining a waiting time according to the monitoring parameter,
• wherein the multicast unit monitors whether at least one other node broadcasts the multicast packet during the waiting time, and when the at least one other node broadcasts the multicast packet, the multicast unit determines whether the multicast packet broadcasted by the at least one other node is transmitted to all the second member nodes,
• wherein if the multicast packet broadcasted by the at least one other node is already transmitted to all the second member nodes, the multicast unit does not broadcast the received multicast packet;
• otherwise, the multicast unit broadcasts the received multicast packet after the waiting time elapses.

A wireless network system, comprising:

• a plurality of member nodes, comprising a plurality of member relay nodes;
• and
• a plurality of non-member nodes, comprising a plurality of non-member relay nodes, wherein a wireless network is formed within a communication range between the member nodes and the non-member nodes,
• wherein each of the non-member nodes and member nodes records a number and distances of the communicable member nodes, calculates a corresponding monitoring parameter according to the number and distances of the communicable member nodes, and determines a corresponding waiting time according to the corresponding monitoring parameter,
• wherein when one of the member nodes transmits a multicast packet to the other member nodes, each of the member relay nodes or non-member relay nodes which receives the multicast packet monitors whether other member relay node or non-member relay node broadcasts the multicast packet during the corresponding waiting time, determines whether the other member relay node or non-member relay node which broadcasts the multicast packet already transmits the multicast packet to all the communicable member nodes when the other member relay node or non-member relay node broadcasts the multicast packet, and stops to broadcast the received multicast packet if the multicast packet is already transmitted to all the communicable member nodes and otherwise, broadcasts the received multicast packet after the waiting time elapses.