TRANSMISSION METHOD FOR COMMUNICATION SYSTEM SUPPORTING MULTICAST MODE, PARTICULARLY FOR CHANGING A METHOD FOR TRANSMITTING MULTICAST MESSAGES AND SIGNAL MESSAGE RESPONSES BASED ON THE NUMBER OF RECEIVERS OF THE MESSAGE

摘要

PURPOSE: A transmission method for a communication system supporting a multicast mode is provided to reduce transmission errors through communication links when conditions for errors of a message are strict. CONSTITUTION: A threshold value(Th) is set to evaluate the size(S) of a group of users(S404). If the size of the group is the same as or greater than the threshold value(S406), the group receives a multicast message by the N number of times of re-transmission(S408). The users of the group transmit a signaling message that can be implemented as a positive ACK or negative NACK packet in response to the received multicast message(S410). If the size of the group is smaller than the threshold value(S406), the users of the group transmit an ACK/NACK packet for instructing reception of a multicast message(S412).