Methods and apparatuses relating to reporting of user plane interruption times

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 perform:

transmitting a message relating to a change or addition of a primary cell of a secondary cell group, the message including (i) information indicative of a first user plane interruption time experienced by the apparatus and associated with the change or addition of the primary cell, and (ii) an indication of a first data radio bearer type to which the first user plane interruption time relates; and

receiving, from a radio access node and prior to transmitting the message, a prior message including an indication of the first data radio bearer type for which the first user plane interruption time is to be reported by the apparatus.

2 . The apparatus of claim 1 , wherein the first user plane interruption time is indicative of a time elapsed between a) either receipt of a command to change or add the primary cell or receipt of a last user plane data packet prior to the change or addition of the primary cell, and b) a first user plane data packet received at the apparatus, via a data radio bearer of the first data radio bearer type, after the change or addition of the primary cell.

3 . The apparatus of claim 1 , wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform:

receiving, from a radio access node and prior to transmitting the message, an indication of a first threshold user plane interruption time for use by the apparatus in determining whether to generate, for reporting to the radio access node, the information indicative of the first user plane interruption time.

4 . The apparatus of claim 3 , wherein the message is generated responsive to a determination that the first user plane interruption time exceeds the first threshold user plane interruption time.

5 . The apparatus of claim 3 , wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform:

receiving, from the radio access node and prior to transmitting the message, an indication of a second threshold user plane interruption time for use by the apparatus in determining whether to generate, for reporting to the radio access node, information indicative of a second user plane interruption time associated with the change or addition of the primary cell and relating to a second data radio bearer type.

6 . The apparatus of claim 1 , wherein the prior message further includes an indication of a second data radio bearer type for which a second user plane interruption time is to be reported by the apparatus, the second user plane interruption time being associated with the change or addition of the primary cell and relating to the second data radio bearer type.

7 . The apparatus of claim 1 , wherein the prior message further includes an indication of a third data radio bearer type for which a third user plane interruption time, associated with the change or addition of the primary cell and relating to the third data radio bearer type, is not to be reported by the apparatus.

8 . The apparatus of claim 1 , wherein the message further includes a second user plane interruption time associated with the change or addition and an indication of a second data radio bearer type to which the second user plane interruption time relates.

9 . The apparatus of claim 1 , wherein the indication of the first data radio bearer type indicates one of a secondary cell group bearer, a master cell group bearer, and a split bearer.

10 . 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 perform:

receiving a message relating to a change or addition of a primary cell of a secondary cell group, the message including (i) information indicative of a first user plane interruption time experienced by a terminal device and associated with the change or addition of the primary cell and (ii) an indication of a first data radio bearer type to which the first user plane interruption time relates; and

transmitting, to the terminal device and prior to receiving the message, a prior message including an indication of the first data radio bearer type for which the first user plane interruption time is to be reported by the terminal device.

11 . The apparatus of claim 10 , wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform:

transmitting, to the terminal device and prior to receiving the message, an indication of a first threshold user plane interruption time for use by the terminal device in determining whether to generate, for reporting to the apparatus, the information indicative of the first user plane interruption time.

12 . The apparatus of claim 11 , wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform:

receiving, prior to transmission of the indication of the first threshold user plane interruption time to the terminal device, the indication of the first threshold user plane interruption time from a second radio access node, the second radio access node being associated with a target primary cell during the change or addition of the primary cell.

13 . The apparatus of claim 10 , wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform:

utilising the information indicative of the first user plane interruption time associated with the change or addition of the primary cell and the indication of the first data radio bearer type to which the first user plane interruption time relates in connection with at least one of:

a) identifying another target primary cell for a future change of the primary cell;

b) determining a radio data bearer type for a future change or addition of the primary cell;

c) determining whether to perform bearer remapping during a future change or addition of the primary cell; or

d) identifying another target primary cell for a future addition of a primary cell.

14 . The apparatus of claim 10 , wherein the message relates to the change of the primary cell, and wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform:

forwarding, to a further radio access node associated with the primary cell, the information indicative of the first user plane interruption time associated with the change of the primary cell, and the indication of the first data radio bearer type to which the first user plane interruption time relates.

15 . The apparatus of claim 14 , wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform:

receiving, from the further radio access node, an indication that a subsequent change of the primary cell is required and an indication of a bearer configuration to be utilised by a target primary cell, wherein the bearer configuration to be utilised by the target primary cell is determined by the further radio access node based on the information indicative of the first user plane interruption time associated with the change of the primary cell and the indication of the first data radio bearer type to which the first user plane interruption time relates.

16 . The apparatus of claim 15 , wherein the instructions, when executed by the at least one processor, further cause the apparatus to perform:

receiving, from the further radio access node, an indication of whether bearer remapping should be performed.

17 . A method comprising:

transmitting, by a terminal device, a message relating to a change or addition of a primary cell of a secondary cell group, the message including (i) information indicative of a first user plane interruption time experienced by the terminal device and associated with the change or addition of the primary cell, and (ii) an indication of a first data radio bearer type to which the first user plane interruption time relates; and

receiving, from a radio access node and prior to transmitting the message, a prior message including an indication of the first data radio bearer type for which the first user plane interruption time is to be reported by the terminal device.

18 . The method of claim 17 , wherein the first user plane interruption time is indicative of a time elapsed between a) either receipt of a command to change or add the primary cell or receipt of a last user plane data packet prior to the change or addition of the primary cell, and b) a first user plane data packet received at the apparatus, via a data radio bearer of the first data radio bearer type, after the change or addition of the primary cell.