Inter-relay node discovery and measurements
During integrated access and backhaul (IAB) node setup, a distributed unit (DU) is configured to transmit synchronization signal blocks (SSBs) for inter-IAB-node discovery and measurement. In parallel to SSB transmission by the DU, user equipment (UEs) and IAB-mobile terminations may be configured to search for and measure on SSBs at specific time instance. In the IAB case, the DU and MT configuration are coordinated to enable inter-node SSB measurements subject to the half-duplex constraint.
1. A method for operating a base station (BS), comprising:
obtaining configuration data for a source integrated access and backhaul (IAB) logical radio node (gNB) of the base station, the configuration data specifying a timing framework for inter-relay gNB discovery and monitoring operations, by the IAB gNB, of target IAB gNBs of a cluster;
configuring the source IAB gNB, in response to obtaining the configuration data, for a synchronization signal block (SSB) transmission configuration (STC) window for inter-IAB gNB discovery, wherein the SSB comprises a physical broadcast channel (PBCH) transmission;
configuring the source IAB gNB, in response to obtaining the configuration data, for each target IAB gNB of the cluster, for an SSB monitoring timing configuration (SMTC) window for monitoring that target IAB gNB; and
causing SSB transmission by the source IAB gNB in accordance with the STC window and the SMTC window for each target IAB gNB of the cluster;
wherein the cluster comprises three IAB gNBs, including the source IAB gNB and two target IAB gNBs, and wherein the two target IAB gNBs are configured using the configuration data.
2. The method of claim 1 , wherein the configuration data specifies that the STC window of the source IAB gNB occurs at a same time as respective SMTC windows of the target IAB gNBs and each SMTC window of the source IAB gNB occurs at the same time that any respective STC window occurs for the target IAB gNBs.
3. The method of claim 2 , wherein the STC window and each SMTC window are configured within a periodicity of SSB windows for user equipment (UE) access.
4. The method of claim 1 , wherein the source IAB gNB of the cluster is configured to perform STC in a time-orthogonal manner with respect to the target IAB gNBs of the cluster.
5. The method of claim 1 , wherein the cluster is a first cluster, wherein a second cluster of IAB gNBs is configured using identical configuration data as the configuration data for the first cluster, and wherein the method further comprises:
configuring the source IAB gNB to exclude from consideration, within the discovery and monitoring operations, signals from the IAB gNBs in the second cluster.
6. The method of claim 1 , wherein the STC window is configured in accordance with an information element indicating a periodicity selected from a list of 80 ms, 160 ms, 320 ms, 640 ms, and 1280 ms and a duration selected from a list of 1, 2, 3, 4, or 5 sub-frames.
7. The method of claim 1 , wherein the SMTC window is configured in accordance with indicating a periodicity selected from a list of 80 ms, 160 ms, 320 ms, 640 ms, and 1280 ms and a duration selected from a list of 1, 2, 3, 4, or 5 sub-frames, and wherein the SMTC window is scheduled for each IAB gNB of the cluster.
8. A method for operating a cluster of integrated access and backhaul (IAB) gNBs each corresponding to a base station (BS), the method comprising:
configuring a first integrated access and backhaul (IAB) logical radio node (gNB) of the cluster for, during a first periodicity:
one synchronization signal block (SSB) transmission configuration (STC) window for inter-IAB gNB discovery, wherein the SSB comprises a physical broadcast channel (PBCH) transmission; and
two SSB monitoring timing configuration (SMTC) windows for measuring inter-group IAB gNBs of the cluster;
configuring a second IAB gNB of the cluster for:
two STC windows with respective periodicities for inter-IAB discovery;
two pairs of SMTC windows with the respective periodicities for measuring the IAB gNBs in the cluster;
causing SSB transmission by the first IAB gNB in accordance with the one STC windows and the two SMTC windows; and
causing SSB transmission by the second IAB gNB in accordance with the two STC windows and the two pairs of SMTC windows.
9. The method of claim 8 , wherein the first IAB gNB is further configured for two SSB windows for user equipment (UE) access or initial cell search with the first periodicity.
10. The method of claim 8 , wherein the first IAB gNB is a neighbor to each other gNB of the cluster.
11. He method of claim 8 , wherein the cluster comprises at least two groups of IAB gNBs in addition to the first IAB gNB, wherein the second IAB gNB is included a first group of the at least two groups of IAB gNBs.
12. The method of claim 11 , wherein, for the second IAB gNB,
a first STC window of the two STC windows is configured for discovery and measurement of IAB gNBs in a second group of the two groups of IAB gNBs, and
a second STC window of the two STC windows is configured for discovery and measurement of other IAB gNBs included in the first group.
13. The method of claim 11 , wherein, for the second IAB gNB,
a first pair of SMTC windows of the two pairs of SMTC windows are configured for measurement of the first IAB gNB and IAB gNBs in a second group of the two groups of IAB gNBs, and
a second pair of SMTC windows of the two pairs of SMTC windows are configured for measurement of other IAB gNBs included in the first group.
14. The method of claim 11 , wherein any two IAB gNBs in a group of the at least two groups are not neighboring IAB gNBs in the cluster.
15. The method of claim 8 , wherein the respective periodicities comprise the first periodicity and a second periodicity associated with a smaller frequency than the first periodicity.
16. The method of claim 8 , wherein an STC window is configured in accordance with an information element indicating a periodicity selected from a list of 80 ms, 160 ms, 320 ms, 640 ms, and 1280 ms and a duration selected from a list of 1, 2, 3, 4, or 5 sub-frames.
17. The method of claim 8 , wherein an SMTC window is configured in accordance with indicating a periodicity selected from a list of 80 ms, 160 ms, 320 ms, 640 ms, and 1280 ms and a duration selected from a list of 1, 2, 3, 4, or 5 sub-frames, and wherein the SMTC window is scheduled for each IAB gNB of the cluster.
18. A base station (BS), comprising:
one or more processors; and
memory storing instructions that, when executed by the one or more processors, cause the one or more processors to perform operations comprising:
obtaining configuration data for a source integrated access and backhaul (IAB) logical radio node (gNB) of the base station, the configuration data specifying a timing framework for inter-relay gNB discovery and monitoring operations, by the IAB gNB, of target IAB gNBs of a cluster;
configuring the source IAB gNB, in response to obtaining the configuration data, for a synchronization signal block (SSB) transmission configuration (STC) window for inter-IAB gNB discovery, wherein the SSB comprises a physical broadcast channel (PBCH) transmission;
configuring the source IAB gNB, in response to obtaining the configuration data, for each target IAB gNB of the cluster, for an SSB monitoring timing configuration (SMTC) window for monitoring that target IAB gNB; and
causing SSB transmission by the source IAB gNB in accordance with the STC window and the SMTC window for each target IAB gNB of the cluster;
wherein the cluster comprises three IAB gNBs, including the source IAB gNB and two target IAB gNBs, and wherein the two target IAB gNBs are configured using the configuration data.
19. The base station of claim 18 , wherein the configuration data specifies that the STC window of the source IAB gNB occurs at a same time as respective SMTC windows of the target IAB gNBs and each SMTC window of the source IAB gNB occurs at the same time that any respective STC window occurs for the target IAB gNBs.