Integrated access and backhaul adaptation layer status report

1. A method, comprising:

receiving, by a source network entity, a trigger;

generating, in response to receiving the trigger, at least one adaptation layer status report identifying at least one adaptation layer protocol data unit, wherein the at least one adaptation layer protocol data unit is identified with at least one sequence number, wherein a length of the sequence number is signaled in at least one of an adaptation layer header, general packet radio service tunneling protocol user plane header, or F1 application protocol; and

transmitting the at least one adaptation layer status report to a parent network entity.

2. The method as in claim 1 , wherein the trigger is a radio link control status report received from user equipment for downlink data or a successful reception of an uplink protocol data unit at a donor next generation node B.

3. The method as in claim 1 , wherein the at least one adaptation layer status report includes at least one user equipment identifier or at least one user equipment bearer identifier.

4. The method as in claim 1 , wherein multiple adaptation layer status reports are multiplexed into a source network entity's radio link control bearer or radio link control channel for transmission.

5. An apparatus comprising:

at least one processor; and

at least one memory comprising computer program code,

the at least one memory and computer program code being configured, with the at least one processor, to cause the apparatus at least to:

receive a trigger;

generate, in response to receiving the trigger, at least one adaptation layer status report identifying at least one adaptation layer protocol data unit, wherein the at least one adaptation layer protocol data unit is identified with at least one sequence number, wherein a length of the sequence number is signaled in at least one of an adaptation layer header, general packet radio service tunneling protocol user plane header, or F1 application protocol; and

transmit the at least one adaptation layer status report to a parent network entity.

6. The apparatus as in claim 5 , wherein the trigger is a radio link control status report received from a user equipment for downlink data or a successful reception of an uplink protocol data unit at a donor next generation node B.

7. The apparatus as in claim 6 , wherein the radio link control status report indicates that a radio link control automatic repeat request retransmission procedure of an individual hop was unsuccessful by reaching a maximum number of transmissions.

8. The apparatus as in claim 5 , wherein the at least one adaptation layer status report includes at least one user equipment identifier or at least one user equipment bearer identifier.

9. The apparatus as in claim 5 , wherein the adaptation layer status report is an end-to-end adaptation layer status report when the trigger is a radio link control status report received from a user equipment.

10. The apparatus as in claim 5 , wherein the at least one adaptation layer status report is transmitted automatically after a trigger, without a trigger, or according to at least one configuration associated with the parent network entity.

11. The apparatus as in claim 5 , wherein the adaptation layer status report only positively acknowledges when the trigger is a radio link control status report received from a user equipment and only negatively acknowledges when the trigger is received from an intermediate node.

12. The apparatus as in claim 5 , wherein multiple adaptation layer status reports are multiplexed into the apparatus's radio link control bearer or radio link control channel for transmission.

13. The apparatus as in claim 5 , wherein the sequence number is specified in an outer header of a packet data convergence protocol protocol data unit.

14. An apparatus comprising:

at least one processor; and

at least one memory comprising computer program code,

the at least one memory and computer program code being configured, with the at least one processor, to cause the apparatus at least to:

receive at least one adaptation layer status report identifying at least one adaptation layer protocol data unit from a source network entity of unsuccessful delivery, wherein the at least one adaptation layer protocol data unit is identified with at least one sequence number, wherein a length of the sequence number is signaled in at least one of an adaptation layer header, general packet radio service tunneling protocol user plane header, or F1 application protocol;

determine whether the apparatus has data buffered;

transmit data associated with the at least one adaptation layer status report to a target network entity upon determining that the apparatus has data buffered; and

forward the at least one adaptation layer status report to the apparatus's parent network entity upon determining that the apparatus has no data buffered.

15. The apparatus as in claim 14 , wherein the at least one adaptation layer status report includes at least one user equipment identifier or at least one user equipment bearer identifier.

16. The apparatus as in claim 14 , wherein multiple adaptation layer status reports are multiplexed into the received adaptation layer status report from a source network entity's radio link control bearer or radio link control channel.

17. The apparatus as in claim 14 , wherein the sequence number is specified in an outer header of a packet data convergence protocol protocol data unit.

18. An apparatus comprising:

at least one processor; and

at least one memory comprising computer program code,

the at least one memory and computer program code being configured, with the at least one processor, to cause the apparatus at least to:

receive a trigger, wherein the trigger is a radio link control status report received from a user equipment for downlink data or a successful reception of an uplink protocol data unit at a donor next generation node B, and wherein the radio link control status report indicates that a radio link control automatic repeat request retransmission procedure of an individual hop was unsuccessful by reaching a maximum number of transmissions;

generate, in response to receiving the trigger, at least one adaptation layer status report identifying at least one adaptation layer protocol data unit; and

transmit the at least one adaptation layer status report to a parent network entity.