Use of uplink MU-MIMO grouping efficiency as basis to control split-uplink-mode operation for dual-connectivity service

1. A method for controlling operation in a wireless communication system having a first access node that provides service on a first air interface and a second access node that provides service on a second air interface, wherein the first and second access nodes support cooperatively providing dual-connectivity service in (i) a single-connection-uplink mode, with uplink user-plane communication being carried on just the second air interface and (ii) a split-uplink mode, with the uplink user-plane communication being split between the first air interface and the second air interface, the method comprising:

determining an uplink Multi-User Multiple-Input-Multiple-Output (MU-MIMO) grouping efficiency of the second air interface; and

based on the determined uplink MU-MIMO grouping efficiency of the second air interface, controlling whether to provide the dual-connectivity service in the single-connection-uplink mode or rather in the split-uplink mode,

wherein the uplink MU-MIMO grouping efficiency of the second air interface represents an extent to which the second access node provides uplink MU-MIMO service.

2. The method of claim 1 , wherein determining the uplink MU-MIMO grouping efficiency of the second air interface comprises receiving from the second access node an indication of the uplink MU-MIMO grouping efficiency.

3. The method of claim 1 , wherein the uplink MU-MIMO grouping efficiency of the second air interface is based on historical data, over one or more past days, for a current time of day.

4. The method of claim 1 , wherein controlling, based on the determined uplink MU-MIMO grouping efficiency of the second air interface, whether to provide the dual-connectivity service in the single-connection-uplink mode or rather in the split-uplink mode comprises:

making a determination of whether the determined uplink MU-MIMO grouping efficiency of the second air interface is at least as high as a predefined threshold level;

if the determination is that the determined uplink MU-MIMO grouping efficiency of the second air interface is not at least as high as the predefined threshold level, then, based at least on the determination, causing the dual-connectivity service to be provided in the split-uplink mode rather than the single-connection-uplink mode; and

if the determination is that the determined uplink MU-MIMO grouping efficiency of the second air interface is at least as high as the predefined threshold level, then, based at least on the determination, causing the dual-connectivity service to be provided in the single-connection-uplink mode rather than the split-uplink mode.

5. The method of claim 4 , wherein making the determination of whether the determined uplink MU-MIMO grouping efficiency of the second air interface is at least as high as a predefined threshold level comprises comparing the determined uplink MU-MIMO grouping efficiency of the second air interface with the predefined threshold level.

6. The method of claim 4 , wherein the first access node has an operational setting that governs whether split-uplink mode is enabled or rather disabled, and wherein:

causing the dual-connectivity service to be provided in the split-uplink mode rather than the single-connection-uplink mode comprises configuring the operational setting to have the split-uplink mode be enabled; and

causing the dual-connectivity service to be provided in the single-connection-uplink mode rather than the split-uplink mode comprises configuring the operational setting to have the split-uplink mode be disabled.

7. The method of claim 1 , wherein the determining and controlling are carried out at least in part by the first access node.

8. The method of claim 1 , wherein the determining and controlling are carried out at least in part by an element management system.

9. The method of claim 1 , wherein the first access node is a 4G Long Term Evolution (LTE) evolved Node-B (eNB), wherein the second access node is a 5G New Radio (NR) next-generation Node-B (gNB), and wherein the dual-connectivity service is EUTRA-NR Dual Connectivity (EN-DC) service.

10. A computing system operable to control dual-connectivity service in a wireless communication system having a first access node that provides service on a first air interface and a second access node that provides service on a second air interface, wherein the first and second access nodes support cooperatively providing the dual-connectivity service in (i) a single-connection-uplink mode, with uplink user-plane communication being carried on just the second air interface and (ii) a split-uplink mode, with the uplink user-plane communication being split between the first air interface and the second air interface, the computing system comprising:

a network communication interface;

a processing unit;

non-transitory data storage; and

program instructions stored in the non-transitory data storage and executable by the processing unit to cause the computing system to carry out operations including:

determining an uplink Multi-User Multiple-Input-Multiple-Output (MU-MIMO) grouping efficiency of the second air interface, and

based on the determined uplink MU-MIMO grouping efficiency of the second air interface, controlling whether the dual-connectivity service will be provided in the single-connection-uplink mode or rather in the split-uplink mode,

wherein the uplink MU-MIMO grouping efficiency of the second air interface represents an extent to which the second access node provides uplink MU-MIMO service.

11. The computing system of claim 10 , wherein determining the uplink MU-MIMO grouping efficiency of the second air interface comprises receiving from the second access node an indication of the uplink MU-MIMO grouping efficiency.

12. The computing system of claim 10 , wherein controlling, based on the determined uplink MU-MIMO grouping efficiency of the second air interface, whether to provide the dual-connectivity service in the single-connection-uplink mode or rather in the split-uplink mode comprises:

making a determination of whether the determined uplink MU-MIMO grouping efficiency of the second air interface is at least as high as a predefined threshold level;

if the determination is that the determined uplink MU-MIMO grouping efficiency of the second air interface is not at least as high as the predefined threshold level, then, based at least on the determination, causing the dual-connectivity service to be provided in the split-uplink mode rather than the single-connection-uplink mode; and

if the determination is that the determined uplink MU-MIMO grouping efficiency of the second air interface is at least as high as the predefined threshold level, then, based at least on the determination, causing the dual-connectivity service to be provided in the single-connection-uplink mode rather than the split-uplink mode.

13. The computing system of claim 10 , wherein the computing system is disposed at least in part at the first access node.

14. The computing system of claim 10 , wherein the computing system is disposed at least in part at an element management system.

15. The computing system of claim 10 , wherein making the determination of whether the determined uplink MU-MIMO grouping efficiency of the second air interface is at least as high as a predefined threshold level comprises determining the uplink MU-MIMO grouping efficiency of the second air interface,

wherein determining the uplink MU-MIMO grouping efficiency of the second air interface comprises receiving from the second access node an indication of the uplink MU-MIMO grouping efficiency.

16. The computing system of claim 10 , wherein the uplink MU-MIMO grouping efficiency of the second air interface is based on historical data, over one or more past days, for a current time of day.

17. The computing system of claim 10 , wherein the first access node has an operational setting that governs whether split-uplink mode is enabled or rather disabled, and wherein:

causing the dual-connectivity service to be provided in the split-uplink mode rather than the single-connection-uplink mode comprises configuring the operational setting to have the split-uplink mode be enabled; and

causing the dual-connectivity service to be provided in the single-connection-uplink mode rather than the split-uplink mode comprises configuring the operational setting to have the split-uplink mode be disabled.

18. In a wireless communication system having a first access node that provides service on a first air interface and a second access node that provides service on a second air interface, wherein the first and second access nodes support cooperatively providing dual-connectivity service in (i) a single-connection-uplink mode, with uplink user-plane communication being carried on just the second air interface and (ii) a split-uplink mode, with the uplink user-plane communication being split between the first air interface and the second air interface, the first access node comprising:

a wireless communication interface through which to engage in air-interface communication on the first air interface; and

a controller, wherein the controller is configured to cause the first access node to carry out operations including:

determining an uplink Multi-User Multiple-Input-Multiple-Output (MU-MIMO) grouping efficiency of the second air interface, and

based on the determined uplink MU-MIMO grouping efficiency of the second air interface, controlling whether to provide the dual-connectivity service in the single-connection-uplink mode or rather in the split-uplink mode,

wherein the uplink MU-MIMO grouping efficiency of the second air interface represents an extent to which the second access node provides uplink MU-MIMO service.

19. The first access node of claim 18 , wherein the controller comprises at least one processing unit, at least one non-transitory data storage, and program instructions stored in the at least one non-transitory data storage and executable by the at least one processing unit to cause the first access node to carry out the operations.

20. The first access node of claim 18 , wherein controlling, based on the determined uplink MU-MIMO grouping efficiency of the second air interface, whether to provide the dual-connectivity service in the single-connection-uplink mode or rather in the split-uplink mode comprises:

making a determination of whether the determined uplink MU-MIMO grouping efficiency of the second air interface is at least as high as a predefined threshold level;

if the determination is that the determined uplink MU-MIMO grouping efficiency of the second air interface is not at least as high as the predefined threshold level, then, based at least on the determination, causing the dual-connectivity service to be provided in the split-uplink mode rather than the single-connection-uplink mode; and

if the determination is that the determined uplink MU-MIMO grouping efficiency of the second air interface is at least as high as the predefined threshold level, then, based at least on the determination, causing the dual-connectivity service to be provided in the single-connection-uplink mode rather than the split-uplink mode.