Mapping between ingress and egress backhaul RLC channels in integrated access backhaul (IAB) networks

1. A method performed by a centralized unit (CU) in an integrated access backhaul (IAB) network, the method comprising:

determining a first identifier of a first backhaul radio link control (BH RLC) channel between first and second nodes in the IAB network, wherein the second node is a child node of the first node; and

sending, to the second node, a second request to setup a second BH RLC channel between the second node and a third node in the IAB network, wherein:

the third node is a child node of the second node; and

the second request includes the first identifier for association with the second BH RLC channel.

2. The method of claim 1 , wherein at least one data radio bearer (DRB) between a user equipment (UE) and the CU is associated with the first BH RLC channel and with the second BH RLC channel.

3. The method of claim 1 , wherein:

the second request is a context setup request or context modification request associated with the UE; and

the first identifier is a logical channel identifier (LCID).

4. The method of claim 1 , further comprising sending, to the first node, a first request to setup the first BH RLC channel.

5. The method of claim 4 , wherein determining the first identifier comprises receiving the first identifier from the first node in response to the first request.

6. The method of claim 4 , wherein:

the first identifier is received from a distributed unit (DU) associated with the first node; and

the second request is sent to a DU associated with the second node.

7. The method of claim 4 , wherein:

the first request includes the first identifier; and

determining the first identifier comprises selecting the first identifier according to one of the following:

from a pool of available BH RLC identifiers;

same as an identifier of a further BH RLC channel, wherein the further BH RLC channel and the first BH RLC channel are associated with the same data radio bearer (DRB) between a user equipment (UE) and the CU; or

based on quality-of-service (QoS) parameters associated with the first BH RLC channel.

8. The method of claim 7 , wherein the second request is sent to the second node without waiting for a response from the first node to the first request.

9. The method of claim 1 , further comprising:

determining a second identifier of the second BH RLC channel; and

sending, to the third node, a third request to setup a third BH RLC channel between the third node and a fourth node in the IAB network, wherein:

the fourth node is a child node of the third node; and

the third request includes the second identifier for association with the third BH RLC channel.

10. The method of claim 9 , wherein determining the second identifier comprises receiving the second identifier from the second node in response to the second request.

11. The method of claim 9 , wherein:

the second request includes the second identifier; and

determining the second identifier comprises selecting the second identifier according to one of the following:

from a pool of available BH RLC identifiers;

same as the first identifier;

same as an identifier of a further BH RLC channel, wherein the further BH RLC

channel and the second BH RLC channel are associated with the same data radio bearer (DRB) between a user equipment (UE) and the CU; or

based on quality-of-service (QoS) parameters associated with the second BH RLC channel.

12. A centralized unit (CU) configured to operate in an integrated access backhaul (IAB) network, the CU comprising:

communication interface circuitry configured to communicate with one or more nodes in the IAB network; and

processing circuitry operably coupled to the communication interface circuitry, whereby the processing circuitry and communication interface circuitry are configured to perform operations corresponding to the method of claim 1 .

13. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a centralized unit (CU) configured to operate in an integrated access backhaul (IAB) network, configure the CU to perform operations corresponding to the method of claim 1 .

14. A method performed by an intermediate node in an integrated access backhaul (IAB) network, the method comprising:

receiving, from a centralized unit (CU) in the IAB network, a request to setup a second radio link control (BH RLC) channel between the intermediate node and a child node in the IAB network, wherein the request includes a first identifier of a first BH RLC channel between the intermediate node and a parent node in the IAB network;

assigning a second identifier to the second BH RLC channel between the intermediate node and the child node in the IAB network; and

associating the first identifier and the second identifier with a data radio bearer (DRB) between a user equipment (UE) and the CU.

15. The method of claim 14 , further comprising:

receiving a data packet, associated with the DRB, via one of the first and second BH RLC channels; and

based on associating the first and second identifiers with the DRB, forwarding the data packet for transmission via the other of the first and second BH RLC channels.

16. The method of claim 15 , wherein:

the intermediate node includes a mobile terminal (MT) part and a distributed unit (DU) part;

the data packet is received by one of the MT and DU parts; and

the data packet is forwarded for transmission by the other of the MT and DU parts.

17. The method of claim 14 , wherein:

the request is a context setup request or context modification request associated with the UE; and

the first identifier is a logical channel identifier (LCID).

18. The method of claim 14 , wherein assigning the second identifier to the second BH RLC channel comprises receiving the second identifier in the request to setup the second BH RLC channel.

19. The method of claim 14 , wherein assigning the second identifier to the second BH RLC channel comprises selecting the second identifier according to one of the following:

from a pool of available BH RLC identifiers;

same as the first identifier;

same as an identifier of a further BH RLC channel associated with the DRB; or

based on quality-of-service (QoS) parameters associated with the second BH RLC channel.

20. The method of claim 19 , further comprising sending, to the CU, a response to the request to setup the second BH RLC channel, wherein the response includes the second identifier.

21. A network node configured to operate as an intermediate node in an integrated access backhaul (IAB) network, the network node comprising:

radio interface circuitry configured to communicate with a centralized unit (CU) and with one or more other IAB nodes; and

processing circuitry operably coupled to the radio interface circuitry, whereby the processing circuitry and radio interface circuitry are configured to perform operations corresponding to the method of claim 14 .

22. A non-transitory, computer-readable medium storing computer-executable instructions that, when executed by processing circuitry of a network node configured to operate as an intermediate node in an integrated access backhaul (IAB) network, configure the network node to perform operations corresponding to the method of claim 14 .