METHOD AND DEVICE FOR WIRELESS COMMUNICATION

1 . A first node for wireless communications, comprising:

a first receiver, receiving a first Packet Data Convergence Protocol (PDCP) Protocol Data Unit (PDU), the first PDCP PDU comprising a first PDCP sequence number; and

a first transmitter, in response to there existing PDCP Service Data Unit(s) (SDU(s)) indexed by X1 PDCP sequence number(s) in a target PDCP sequence number set not being correctly received, transmitting a first report;

wherein the first PDCP sequence number is used to determine the target PDCP sequence number set; the first report indicates that a PDCP SDU indexed by a first PDCP sequence number set is not received, the first PDCP sequence number set comprises the X1 PDCP sequence number(s), the target PDCP sequence number set comprises X PDCP sequence numbers, X1 being a positive integer not greater than X.

2 . The first node according to claim 1 , wherein the first PDCP PDU is used to bear a first service; the first PDCP PDU uses a first bearer; the first bearer comprises a multicast bearer transmitted in Point to point (PTP) method; the first bearer comprises a multicast bearer transmitted in Point to Multipoint (PTM) method.

3 . The first node according to claim 2 , wherein the first receiver receives a first signaling, the first signaling indicates X2;

wherein order of PDCP sequence numbers in the target PDCP sequence number set is continuous, and a number of PDCP sequence number(s) between a last PDCP sequence in the target PDCP sequence number set and the first PDCP sequence number is X2.

4 . The first node according to claim 3 , wherein when the first PDCP PDU is received, PDCP sequence numbers corresponding to all missing PDCP SDUs before n−X2+X1 are determined to belong to the target sequence number set.

5 . The first node according to claim 4 , wherein Quality of Service (QoS) requirements of the first service are used to determine X2.

6 . The first node according to claim 2 , comprising:

the first receiver, receiving a second signaling, the second signaling indicating X3 time unit(s);

wherein order of PDCP sequence numbers in the target PDCP sequence number set is continuous, and a time interval between a time for receiving a PDCP SDU indexed by any PDCP sequence number set in the target PDCP sequence number set and a time for receiving the first PDCP PDU is not less than the X3 time unit(s).

7 . The first node according to claim 6 , wherein X3 is equal to a length of inactive time of a discontinuous reception of the first service.

8 . The first node according to claim 7 , wherein the second signaling is transmitted in the method of broadcast and multicast.

9 . The first node according to claim 2 , wherein X1 is equal to X, order of a last PDCP sequence number in the target PDCP sequence number set and order of the first PDCP sequence number are continuous.

10 . The first node according to claim 2 , wherein a second PDCP sequence number belongs to the target PDCP sequence number set, and the second PDCP sequence number indexes a second PDCP SDU; the second PDCP sequence number is determined belonging to the target PDCP sequence number set, which is used to start a first timer;

an expiration of the first timer is used to trigger the behavior of the first transmitter transmitting the first report; the first PDCP sequence number set comprises the second PDCP sequence number.

11 . The first node according to claim 10 , wherein the first timer is related to outOfOrderDelivery, when a receiving PDCP entity of the first PDCP PDU is configured with outOfOrderDelivery, the first timer is started; a transmission method of the first service comprises PTM, the first timer is used.

12 . The first node according to claim 11 , wherein when the first timer expires, and if a state variable RX_DELIV of a PDCP entity receiving the first PDCP PDU<RX_NEXT, then re-starts the first timer.

13 . The first node according to claim 11 , wherein the first timer in a running state is used to prohibit a transmission of the first report; the first timer is related to reordering of a PDCP SDU.

14 . The first node according to claim 2 , wherein the first PDCP PDU is used to bear a first non-unicast service;

the first receiver, receives a third signaling, the third signaling is used to configure a discontinuous reception of the first non-unicast service; when the first report is transmitted, a reception of the first non-unicast service is in inactive state; the first node is in Radio Resource Control (RRC) Inactive state.

15 . The first node according to claim 2 , wherein when a transmission method of the first service is switched from PTM to PTP, the first report is transmitted.

16 . The first node according to claim 15 , wherein the first report comprises a PDCP status report; the first bearer comprises an Unacknowledged Mode (UM bearer); MBS data transmitted through PTM uses Hybrid Automatic Repeat reQuest (HARQ); the first PDCP PDU is used to carry a first service, and the first service comprises a Multicast/Broadcast Service (IVIES).

17 . The first node according to claim 15 , wherein the first report comprises a PDCP status report; the first bearer comprises a UM bearer; MB S data transmitted through PTM does not use HARQ; the first PDCP PDU is used to carry a first service, and the first service comprises a Multicast/Broadcast Service (MBS).

18 . The first node according to claim 2 , wherein when a transmission method of the first service is switched from PTP to PTM, the first report is transmitted.

19 . A second node for wireless communications, comprising:

a second transmitter, transmitting a first PDCP PDU, the first PDCP PDU comprising a first PDCP sequence number;

a second receiver, receiving a first report; a transmitter of the first report, in response to there existing PDCP SDU(s) indexed by X1 PDCP sequence number(s) in a target PDCP sequence number set not being correctly received, transmitting the first report;

wherein the first PDCP sequence number is used to determine the target PDCP sequence number set; the first report indicates that a PDCP SDU indexed by a first PDCP sequence number set is not received, the first PDCP sequence number set comprises the X1 PDCP sequence number(s), the target PDCP sequence number set comprises X PDCP sequence numbers, X1 being a positive integer not greater than X.

20 . A method in a first node for wireless communications, comprising:

receiving a first PDCP PDU, the first PDCP PDU comprising a first PDCP sequence number;

in response to there existing PDCP SDU(s) indexed by X1 PDCP sequence number(s) in a target PDCP sequence number set not being correctly received, transmitting a first report;

wherein the first PDCP sequence number is used to determine the target PDCP sequence number set; the first report indicates that a PDCP SDU indexed by a first PDCP sequence number set is not received, the first PDCP sequence number set comprises the X1 PDCP sequence number(s), the target PDCP sequence number set comprises X PDCP sequence numbers, X1 being a positive integer not greater than X.