Abstract:
본 발명은 하이브리드 자동 반복 요구(Hybrid Automatic Repeat reQuest: HARQ) 방식을 지원하는 디바이스간 직접 통신(Device to Device: D2D) 무선 통신 시스템에서 기지국의 멀티캐스트 서비스 제공 방법에 있어서, 멀티캐스트 서비스 그룹에 포함되어 있는 이동 단말기들이 사용할 자동 재전송 횟수와, 멀티캐스트 서비스 데이터 패킷을 멀티캐스트하는 과정을 포함하며, 상기 자동 재전송 횟수는 상기 멀티캐스트 서비스 그룹에 포함되어 있는 이동 단말기들이 상기 멀티캐스트 서비스 데이터 패킷을 성공적으로 수신하였을 경우, 상기 멀티캐스트 서비스 데이터 패킷을 자동적으로 재전송하는 횟수를 나타냄을 특징으로 한다.
Abstract:
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