APPARATUS AND METHOD FOR PROVIDING MULTICAST SERVICE IN DEVICE TO DEVICE COMMUNICATION RADIO COMMUNICATION SYSTEM SUPPORTING HYBRID AUTOMATIC REPEAT REQUEST SCHEME

摘要

A method for providing multi-cast services using a mobile terminal in a device to device (D2D) wireless communications system capable of supporting hybrid automatic repeat request (HARQ) method, comprises the steps of: receiving a multi-cast service data packet from a base station or a first mobile terminal which at least is another mobile terminal among mobile terminals included in the same multi-cast service group as the mobile terminal; receiving a negative acknowledgement signal (NACK) from a second mobile terminal which at least is another terminal except for the first mobile terminal among the mobile terminals in the same multi-cast service group as the mobile terminal when the decoding of the multi-cast service data packet is successful and the number of retransmission does not reach the maximum number of retransmission; generating an additional multi-cast service data packet using an modulation and coding scheme (MSC) level which is different from the MCS level applied to the multi-cast service data packet received from the base station when the decoded multi-cast service data packet is the multi-cast service data packet received from the base station; and transmitting the additional multi-cast service data packet to the second mobile terminal. [Reference numerals] (511) Receiving multicast service data packet; (513) Decoding successful?; (515,521) Reached the maximum number of retransmission?; (517) Determining reception failure; (519) Transmitting an NACK signal; (523) Standby for receiving the NACK signal; (525) NACK signal received?; (527) Transmitting additional multicast service data packet; (AA) Start; (BB,DD,GG,JJ) No; (CC,EE,FF,II) Yes; (HH,KK) End