Network method for small data transmission termination and signaling

1 . An apparatus, comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:

receive, by a distributed unit of a target base station from a user equipment within a wireless network, during a multi-shot small data transmission transaction, an uplink multi-shot small data transmission packet;

determine whether the uplink multi-shot small data transmission packet is a terminal uplink multi-shot small data transmission packet; in response to the determination that the uplink multi-shot small data transmission packet is the terminal uplink multi-shot small data transmission packet,

generate termination data indicating a termination of the multi-shot small data transmission transaction; and

transmit the termination data to a central unit of a base station along a path within the wireless network, the termination data indicating a termination of the multi-shot small data transmission transaction,

wherein the base station is an anchor base station different from the target base station, the anchor base station being a last serving base station for the user equipment, and

wherein the path within the wireless network terminates at a control plane of a central unit of the anchor base station via a control plane of a central unit of the target base station.

2 . The apparatus as in claim 1 , wherein the at least one memory and the computer program code are further configured to cause the apparatus at least to:

after transmitting the termination data, receiving, from the control plane of the central unit of the anchor base station via the control plane of the central unit of the target base station within an XnAP message, radio resource control release data indicating that the multi-shot small data transmission transaction is closed; and

transmitting the radio resource control release data to the user equipment.

3 . The apparatus as in claim 1 , wherein the determining whether the uplink multi-shot small data transmission packet is a terminal uplink multi-shot small data transmission packet is based on at least one of:

the buffer status report data received from the user equipment, wherein the buffer status report data including an index indicating a condition by which an uplink multi-shot small data transmission packet is determined to be a terminal uplink multi-shot small data transmission packet, or

a threshold elapse of time since a previous uplink multi-shot small data transmission packet was received.

4 . The apparatus as in claim 1 , wherein the base station is an anchor base station different from the target base station, the anchor base station being a last serving base station for the user equipment, and wherein the path within the wireless network terminates at the anchor base station central unit control plane via the anchor base station central unit user plane.

5 . The apparatus as in claim 4 , wherein the at least one memory and the computer program code are further configured to cause the apparatus at least to:

receive downlink data from the anchor base station central unit user plane;

receive, from the anchor base station central unit control plane, radio resource control release data indicating that the multi-shot small data transmission transaction is closed; and

transmit the radio resource control release data to the user equipment after transmitting a downlink data packet.

6 . The apparatus as in claim 1 , wherein the base station is the target base station, and

wherein the path within the wireless network terminates at a control plane of the central unit of the target base station via the target base station central unit user plane.

7 . The apparatus as in claim 6 , wherein the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:

after determining that a uplink multi-shot small data transmission packet is the terminal uplink multi-shot small data transmission packet, receive, from the target base station central unit control plane, radio resource control release data indicating that the multi-shot small data transmission transaction is terminated; and

transmit the radio resource control release data to the user equipment.

8 . The apparatus as in claim 1 , wherein the base station is the target base station, and wherein the path within the wireless network terminates at the target base station central unit control plane directly from the distributed unit of the target base station.

9 . The apparatus as in claim 8 , wherein the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:

receive downlink data from the target base station central unit user plane;

receive, from the target base station central unit control plane, radio resource control release radio resource control release data indicating that the multi-shot small data transmission transaction is terminated; and

after transmitting the received DL downlink data packet, transmit the radio resource control release data to the user equipment UE.

10 . The apparatus as in claim 8 , wherein the at least one memory and the computer program code are further configured to cause the apparatus at least to:

after receiving an initial uplink multi-shot small data transmission packet of the transaction, receive, from a control plane of a central unit of the target base station, data representing a path by which the termination data is transmitted within the wireless network.

11 . The apparatus as in claim 8 , wherein the at least one memory and the computer program code are further configured to cause the apparatus at least to:

receive an inactive radio network temporary user equipment identifier;

generate a temporary user equipment context based on the above UE user equipment identifier; and

store the temporary user equipment context for a duration of the multi-shot small data transmission transaction.

12 . The apparatus as in claim 11 , wherein the at least one memory and the computer program code are further configured to cause the apparatus at least to:

receive, from the target base station central unit control plane, radio resource control release data indicating that the multi-shot small data transmission transaction is terminated;

transmit the radio resource control release data to the user equipment; and

after transmitting the radio resource control release data to the user equipment, discarding the temporary user equipment context.

13 . An apparatus, comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:

transmit, by a user equipment to a distributed unit of a base station, one or more uplink multi-shot small data transmission packets of a multi-shot small data transmission transaction; and

after transmitting the one or more of multi-shot uplink multi-shot small data transmission packets, receive, from the the distributed unit of the base station, radio resource control release data indicating that the multi-shot small data transmission transaction is terminated, the terminating of the multi-shot small data transmission transaction being determined by the distributed unit of the base station.

14 . The apparatus as in claim 13 , wherein the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:

initiate the multi-shot small data transmission transaction in response to obtaining a user plane packet in a buffer of the user equipment;

transmit an indication of a user equipment preference to terminate the multi-shot small data transmission transaction.

15 . The apparatus as in claim 14 , wherein the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:

transmit a buffer status report with an uplink multi-shot small data transmission to the distributed unit of the target base station, the buffer status report including an index indicating a condition by which a uplink multi-shot small data transmission packet is determined to be a terminal uplink multi-shot small data transmission packet, the condition indicating a termination of the multi-shot small data transmission transaction,

wherein the indication is transmitted in a radio link channel protocol data unit or in a media access channel control element.

16 . An apparatus, comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to:

receive, by an anchor base station central unit, control plane, termination data indicating an end of a small data transmission transaction; and

generate an radio resource control release data; and

transmit, to a user equipment, the radio resource control release data.

17 . The apparatus as in claim 16 , wherein the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to:

receive the termination data are further configured to cause the apparatus at least to receive the termination data from at least one of a target base station central unit control plane or an anchor base station central unit user plane;

transmit the radio resource control release data are further configured to cause the apparatus at least to transmit the radio resource control release data over at least one of an XnAP message to a target base station central control plane.

18 . The apparatus as in claim 16 , wherein the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to at least perform one of the following:

receive, at a target base station central unit control plane, termination data indicating an end of multi-shot small data transmission transaction, and generate and transmit radio resource control release data to a user equipment, or

receive, at a target base station central unit control plane, termination data indicating an end of multi-shot small data transmission transaction and propagate the termination data to an anchor base station central unit control plane, or

receive the termination data from a base station distributed unit.

19 . The apparatus as in claim 16 , wherein the at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to transmit the radio resource control release data are further configured to cause the apparatus at least to:

transmit the radio resource control release data over an F1-C message to the distributed units.