Using alternative paths of descendant nodes for backhaul-link failure reporting in integrated access

1. A child integrated access backhaul (IAB) node configured to communicate with a first parent IAB node and a descendant IAB node over a backhaul network, the child IAB node comprising:

processing circuitry configured to:

detect a backhaul link failure between the child IAB node and the first parent IAB node;

in response to the detected backhaul link failure, cause transmission of a radio link failure indication to the descendant IAB node, the radio link failure indication being configured to cause each descendant IAB node in an established communication path receiving the radio link failure indication to modify data transmission and remain on the established communication path to the child IAB node;

receive signaling indicating for the child IAB node to connect to a second parent IAB node; and

modify network topology at least in part by connecting to the second parent IAB node.

2. The child IAB node of claim 1 , wherein the radio link failure indication is a failure report that indicates at least one of:

a cause of the detected backhaul link failure;

IAB node identification;

failure report identifier;

backhaul link failure time; and

results of measurements performed by the child IAB node.

3. The child IAB node of claim 1 , wherein the radio link failure indication is a failure report that includes results of measurements performed by the child IAB node, the results of the measurements indicating at least one discoverable parent IAB node.

4. A method implemented by a child integrated access backhaul (IAB) node that is configured to communicate with a first parent IAB node and a descendant IAB node over a backhaul network, the method comprising:

detecting a backhaul link failure between the child IAB node and the first parent IAB node;

in response to the detected backhaul link failure, causing transmission of a radio link failure indication to the descendant IAB node, the radio link failure indication being configured to cause each descendant IAB node in an established communication path receiving the radio link failure indication to modify data transmission and remain on the established communication path to the child IAB node;

receiving signaling indicating for the child IAB node to connect to a second parent IAB node; and

modifying network topology at least in part by connecting to the second parent IAB node.

5. The method of claim 4 , wherein the radio link failure indication is a failure report that indicates at least one of:

a cause of the detected backhaul link failure;

IAB node identification;

failure report identifier;

backhaul link failure time; and

results of measurements performed by the child IAB node.

6. The method of claim 4 , wherein the radio link failure indication is a failure report that includes results of measurements performed by the child IAB node, the results of the measurements indicating at least one discoverable parent IAB node.

7. A donor integrated access backhaul (IAB) node in communication with a first parent IAB node, a child IAB node and at least one descendant IAB node over a backhaul network, the first parent IAB node being in communication with the child IAB node and the descendant IAB node, the donor IAB node comprising:

processing circuitry configured to:

receive a radio link failure indication from one of the at least one descendent IAB nodes, the radio link failure indication indicating a radio link failure between the child IAB node and the first parent IAB node, the radio link failure indication being configured to cause each descendant IAB node in an established communication path receiving the radio link failure indication to modify data transmission and remain on the established communication path to the child IAB node;

determine a second parent IAB node for the child IAB node to connect to based at least in part on the radio link failure indication; and

cause transmission of signaling to the child IAB node, the signaling indicating for the child IAB node to modify a network topology at least in part by connecting to the second parent IAB node.

8. The donor IAB node of claim 7 , wherein the indication is a failure report destined for a donor IAB node, the failure report indicates at least one of:

a cause of the radio link failure;

IAB node identification;

failure report identifier;

backhaul link failure time; and

results of measurements performed by the child IAB node.

9. The donor IAB node of claim 7 , wherein the radio link failure indication is a failure report including results of measurements performed by the child IAB node, the results of the measurements indicating at least one discoverable parent IAB node.

10. A method implemented by a donor integrated access backhaul (IAB) node that is in communication with a first parent IAB node, a child IAB node and at least one descendant IAB node over a backhaul network, the first parent IAB node being in communication with the child IAB node and the descendant IAB node, the method comprising:

receiving a radio link failure indication from one of the at least one descendent IAB node, the radio link failure indication indicating a radio link failure between the child IAB node and the first parent IAB node, the radio link failure indication being configured to cause each descendant IAB node in an established communication path receiving the radio link failure indication to modify data transmission and remain on the established communication path to the child IAB node;

determining a second parent IAB node for the child IAB node to connect to based at least in part on the radio link failure indication; and

causing transmission of signaling to the child IAB node, the signaling indicating for the child IAB node to modify a network topology at least in part by connecting to the second parent IAB node.

11. The method of claim 10 , wherein the radio link failure indication is a failure report destined for a donor IAB node, the failure report indicates at least one of:

a cause of the radio link failure;

IAB node identification;

failure report identifier;

backhaul link failure time; and

results of measurements performed by the child IAB node.

12. The method of claim 10 , wherein the radio link failure indication is a failure report including results of measurements performed by the child IAB node, the results of the measurements indicating at least one discoverable parent IAB node.

13. A descendant integrated access backhaul (IAB) node in communication with a donor IAB node via at least a first parent IAB node and a child IAB node over a backhaul network, the descendant IAB node comprising:

processing circuitry configured to:

receive a radio link failure indication;

in response to the radio link failure indication:

modify data transmission and remain on an established communication path to the child IAB node; and

cause transmission of the radio link failure indication to the donor node;

receive signaling from the donor IAB node, the signaling indicating for the child IAB node to modify network topology at least in part by connecting to a second parent IAB node; and

cause transmission the signaling to the child IAB node.

14. The descendant IAB node of claim 13 , wherein the processing circuitry is further configured to:

determine whether an alternate communication path from the descendant IAB node to the donor IAB node is configured; and

if the alternate communication path is configured, cause transmission of the radio link failure indication along the alternative communication path to the donor IAB node.

15. The descendant IAB node of claim 13 , wherein the radio link failure indication is a failure report destined for a donor IAB node, the failure report including results of measurements performed by the child IAB node, the results of the measurements indicating at least one discoverable parent IAB node.

16. A method implemented by a descendant integrated access backhaul (IAB) node that is in communication with a donor IAB node via at least a first parent IAB node and a child IAB node over a backhaul network, the method comprising:

receiving a radio link failure indication;

in response to the radio link failure indication:

modifying data transmission and remain on an established communication path to the child IAB node; and

causing transmission of the radio link failure indication to the donor IAB node;

receiving signaling from the donor IAB node, the signaling indicating for the child IAB node to modify network topology at least in part by connecting to a second parent IAB node; and

causing transmission of the signaling to the child IAB node.

17. The method of claim 16 , further comprising:

determining whether an alternate communication path from the descendant IAB node to the donor IAB node is configured; and

if the alternate communication path is configured, causing transmission of the radio link failure indication along the alternative communication path to the donor IAB node.

18. The method of claim 16 , further comprising:

determining whether an alternate communication path from the descendant IAB node to the donor IAB node is configured; and

if the alternate communication path is not configured, causing transmission of the radio link failure indication to another descendant IAB node.

19. The method of claim 16 , wherein the radio link failure indication is a failure report destined for a donor IAB node, the failure report indicates at least one of:

a cause of the radio link failure;

IAB node identification;

failure report identifier;

backhaul link failure time; and

results of measurements performed by the child IAB node.

20. The method of claim 16 , wherein the radio link failure indication is a failure report destined for a donor IAB node, the failure report including results of measurements performed by the child IAB node, the results of the measurements indicating at least one discoverable parent IAB node.