System and method for reducing data loss during a serving cell change in a multi-flow HSDPA communication network
A method and apparatus for wireless communication may provide for reduced data loss during mobility events in a wireless communication network capable of downlink carrier aggregation. Some aspects of the disclosure provide for maintaining data corresponding to a flow in at least one buffer at a Node B when the Node B acts as a serving cell for the same UE both before and after a serving cell change. Another aspect of the disclosure provides for transferring buffered data from a Node B that acts as a serving cell for a UE before a serving cell change, to a Node B that acts as a serving cell for the UE after the serving cell change.
1. A method of wireless communication, comprising:
transmitting a downlink flow to a user equipment (UE) utilizing at least a first base station and a second base station to provide a first serving cell and a second serving cell, respectively, to be aggregated at the UE;
performing a serving cell change by replacing the first serving cell or the second serving cell with a third cell when a quality of the third cell is greater than the first serving cell and the second serving cell, wherein the first base station or the second base station continues to act as a serving cell to the UE after the serving cell change; and
forgoing to instruct the acting serving cell to flush data corresponding to the flow, so that the acting serving cell maintains the data corresponding to the flow before the serving cell change within a queue at the acting serving cell for transmission from the acting serving cell to the UE directly after the serving cell change.
2. The method of claim 1 , further comprising:
receiving a report from the UE ranking cell qualities of the first serving cell and the second serving cell, where the acting serving cell is selected based on strongest cell quality from the ranked cell qualities; and
wherein the acting serving cell is a primary serving cell and the non-selected serving cell is the secondary serving cell.
3. The method of claim 2 , wherein the report further includes ranking of the cell qualities of one or more neighboring cells including the third cell, provided by one or more base stations, upon an occurrence of a mobility event; and wherein the third cell is added to an active set associated with the UE when the cell quality of the third cell is stronger than the cell quality of the primary serving cell or the secondary serving cell upon the occurrence of the mobility event.
4. The method of claim 3 , further comprising:
performing a primary serving cell change by replacing the primary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the primary serving cell, the third cell becoming a new primary serving cell;
performing a secondary serving cell change by replacing the secondary serving cell with the primary serving cell when the cell quality of the primary serving cell is greater than the cell quality of the secondary serving cell, the primary serving cell becoming a new secondary serving cell;
maintaining the data corresponding to the flow within a queue at the new primary serving cell; and
flushing the data corresponding to the flow within a queue at the secondary serving cell.
5. The method of claim 3 , further comprising:
performing a primary serving cell change by replacing the primary serving cell with the secondary serving cell when the cell quality of the secondary serving cell is greater than the cell quality of the primary serving cell, the secondary serving cell becoming a new primary serving cell;
performing a secondary serving cell change by replacing the secondary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the secondary serving cell, the third cell becoming a new secondary serving cell;
maintaining the data corresponding to the flow within a queue at the new primary serving cell; and
flushing the data corresponding to the flow within a queue at the secondary serving cell.
6. The method of claim 3 , further comprising:
performing a primary serving cell change by replacing the primary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the primary serving cell, the third cell becoming a new primary serving cell;
maintaining the data corresponding to the flow within a queue at the new primary serving cell; and
flushing the data corresponding to the flow within a queue at the primary serving cell.
7. The method of claim 3 , further comprising:
removing the secondary serving cell from the active set associated with the UE when the cell quality of the secondary serving cell is below a predetermined threshold; and
flushing the data corresponding to the flow within a queue at the secondary serving cell.
8. The method of claim 3 , further comprising:
performing a primary serving cell change by replacing the primary serving cell with the secondary serving cell when the cell quality of the secondary serving cell is greater than the cell quality of the primary serving cell, the secondary serving cell becoming a new primary serving cell;
removing the primary serving cell from the active set associated with the UE when the cell quality of the primary serving cell is below a predetermined threshold; and
flushing the data corresponding to the flow within a queue at the primary serving cell.
9. The method of claim 3 , wherein the mobility event is a UE measurement of E c /I 0 for a particular cell that reaches a predetermined threshold and maintains the predetermined threshold for a predetermined time.
10. The method of claim 3 , wherein the mobility event is a UE measurement of E c /I 0 for a particular serving cell falls that below a predetermined threshold and maintains the predetermined threshold for a predetermined time.
11. An apparatus for wireless communication, comprising:
means for transmitting a downlink flow to user equipment (UE) utilizing at least a first base station and a second base station to provide a first serving cell and a second serving cell, respectively, to be aggregated at the UE;
means for performing a serving cell change by replacing the first serving cell or the second serving cell with a third cell when a quality of the third cell is greater than the first serving cell and the second serving cell, wherein the first base station or the second base station continues to act as a serving cell to the UE after the serving cell change; and
means for forgoing to instruct the acting serving cell to flush data corresponding to the flow, so that the acting serving cell maintains the data corresponding to the flow before the serving cell change within a queue at the acting serving cell for transmission from the acting serving cell to the UE directly after the serving cell change.
12. The apparatus of claim 11 , further comprising:
means for receiving a report from the UE ranking cell qualities of the first serving cell and the second serving cell, where the acting serving cell is selected based on strongest cell quality from the ranked cell qualities; and
wherein the acting serving cell is a primary serving cell and the non-selected serving cell is the secondary serving cell.
13. The apparatus of claim 12 , wherein the report further includes ranking of the cell qualities of one or more neighboring cells including the third cell, provided by one or more base stations, upon an occurrence of a mobility event; and wherein a the third cell is added to an active set associated with the UE when the cell quality of the third cell is stronger than the cell quality of the primary serving cell or the secondary serving cell upon the occurrence of the mobility event.
14. The apparatus of claim 13 , further comprising:
means for performing a primary serving cell change by replacing the primary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the primary serving cell, the third cell becoming a new primary serving cell;
means for performing a secondary serving cell change by replacing the secondary serving cell with the primary serving cell when the cell quality of the primary serving cell is greater than the cell quality of the secondary serving cell, the primary serving cell becoming a new secondary serving cell;
means for maintaining the data corresponding to the flow within a queue at the new primary serving cell; and
means for flushing the data corresponding to the flow within a queue at the secondary serving cell.
15. The apparatus of claim 13 , further comprising:
means for performing a primary serving cell change by replacing the primary serving cell with the secondary serving cell when the cell quality of the secondary serving cell is greater than the cell quality of the primary serving cell, the secondary serving cell becoming a new primary serving cell;
means for performing a secondary serving cell change by replacing the secondary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the secondary serving cell, the third cell becoming a new secondary serving cell;
means for maintaining the data corresponding to the flow within a queue at the new primary serving cell; and
means for flushing the data corresponding to the flow within a queue at the secondary serving cell.
16. The apparatus of claim 13 , further comprising:
means for performing a primary serving cell change by replacing the primary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the primary serving cell, the third cell becoming a new primary serving cell;
means for maintaining the data corresponding to the flow within a queue at the new primary serving cell; and
means for flushing the data corresponding to the flow within a queue at the primary serving cell.
17. The apparatus of claim 13 , further comprising:
means for removing the secondary serving cell from the active set associated with the UE when the cell quality of the secondary serving cell is below a predetermined threshold; and
means for flushing the data corresponding to the flow within a queue at the secondary serving cell.
18. The apparatus of claim 13 , further comprising:
means for performing a primary serving cell change by replacing the primary serving cell with the secondary serving cell when the cell quality of the secondary serving cell is greater than the cell quality of the primary serving cell, the secondary serving cell becoming a new primary serving cell;
means for removing the primary serving cell from the active set associated with the UE when the cell quality of the primary serving cell is below a predetermined threshold; and
means for flushing the data corresponding to the flow within a queue at the primary serving cell.
19. A computer program product, comprising:
a non-transitory computer-readable medium comprising:
instructions for causing a computer to transmit a downlink flow to user equipment (UE) utilizing at least a first base station and a second base station to provide a first serving cell and a second serving cell, respectively, to be aggregated at the UE;
instructions for causing a computer to perform a serving cell change by replacing the first serving cell or the second serving cell with a third cell when a quality of the third cell is greater than the first serving cell and the second serving cell, wherein the first base station or the second base station continues to act as a serving cell to the UE after the serving cell change; and
instructions for causing a computer to forgo to instruct the acting serving cell to flush data corresponding to the flow, so that the acting serving cell maintains the data corresponding to the flow before the serving cell change within a queue at the acting serving cell for transmission from the acting serving cell to the UE directly after the serving cell change.
20. The computer program product of claim 19 , wherein the computer-readable medium further comprises:
instructions for causing a computer to receive a report from the UE ranking cell qualities of the first serving cell and the second serving cell, where the acting serving cell is selected based on strongest cell quality from the ranked cell qualities; and
wherein the acting serving cell is a primary serving cell and the non-selected serving cell is the secondary serving cell.
21. The apparatus of claim 20 , wherein the report further includes ranking of the cell qualities of one or more neighboring cells including the third cell, provided by one or more base stations, upon an occurrence of a mobility event; and wherein the third cell is added an active set associated with the UE when the cell quality of the third cell is stronger than the cell quality of the primary serving cell or the secondary serving cell upon the occurrence of the mobility event.
22. The computer program product of claim 21 , wherein the computer-readable medium further comprises:
instructions for causing a computer to perform a primary serving cell change by replacing the primary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the primary serving cell, the third cell becoming a new primary serving cell;
instructions for causing a computer to perform a secondary serving cell change by replacing the secondary serving cell with the primary serving cell when the cell quality of the primary serving cell is greater than the cell quality of the secondary serving cell, the primary serving cell becoming a new secondary serving cell;
instructions for causing a computer to maintain the data, after cell change, corresponding to the flow within a queue at the new primary serving cell; and
instructions for causing a computer to flush the data corresponding to the flow within a queue at the secondary serving cell.
23. The computer program product of claim 21 , wherein the computer-readable medium further comprises:
instructions for causing a computer to perform a primary serving cell change by replacing the primary serving cell with the secondary serving cell when the cell quality of the secondary serving cell is greater than the cell quality of the primary serving cell, the secondary serving cell becoming a new primary serving cell;
instructions for causing a computer to perform a secondary serving cell change by replacing the secondary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the secondary serving cell, the third cell becoming a new secondary serving cell;
instructions for causing a computer to maintain the data corresponding to the flow within a queue at the new primary serving cell; and
instructions for causing a computer to flush the data corresponding to the flow within a queue at the secondary serving cell.
24. The computer program product of claim 21 , wherein the computer-readable medium further comprises:
instructions for causing a computer to perform a primary serving cell change by replacing the primary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the primary serving cell, the third cell becoming a new primary serving cell;
instructions for causing a computer to maintain the data corresponding to the flow within a queue at the new primary serving cell; and
instructions for causing a computer to flush the data corresponding to the flow within a queue at the primary serving cell.
25. The computer program product of claim 21 , wherein the computer-readable medium further comprises:
instructions for causing a computer to remove the secondary serving cell from the active set associated with the UE when the cell quality of the secondary serving cell is below a predetermined threshold; and
instructions for causing a computer to flush the data corresponding to the flow within a queue at the secondary serving cell.
26. The computer program product of claim 21 , wherein the computer-readable medium further comprises:
instructions for causing a computer to perform a primary serving cell change by replacing the primary serving cell with the secondary serving cell when the cell quality of the secondary serving cell is greater than the cell quality of the primary serving cell, the secondary serving cell becoming a new primary serving cell;
instructions for causing a computer to remove the primary serving cell from the active set associated with the UE when the cell quality of the primary serving cell is below a predetermined threshold; and
instructions for causing a computer to flush the data corresponding to the flow within a queue at the primary serving cell.
27. An apparatus for wireless communication, comprising:
at least one processor; and
a memory coupled to the at least one processor,
wherein the at least one processor is configured to:
transmit a downlink flow to user equipment (UE) utilizing at least a first base station and a second base station to provide a first serving cell and a second serving cell, respectively, to be aggregated at the UE;
perform a serving cell change by replacing the first serving cell or the second serving cell with a third cell when a quality of the third cell is greater than the first serving cell and the second serving cell, wherein the first base station or the second base station continues to act as a serving cell to the UE after the serving cell change; and
forgo to instruct the acting serving cell to flush data corresponding to the flow, so that the acting serving cell maintains the data corresponding to the flow before the serving cell change within a queue at the acting serving cell for transmission from the acting serving cell to the UE directly after the serving cell change.
28. The apparatus of claim 27 , wherein the at least one processor is further configured to:
receive a report from the UE ranking cell qualities of the first serving cell and the second serving cell, where the acting serving cell is selected based on strongest cell quality from the ranked cell qualities; and
wherein the acting serving cell is a primary serving cell and the non-selected serving cell is the secondary serving cell.
29. The apparatus of claim 28 , wherein the report further includes ranking of the cell qualities of one or more neighboring cells including the third cell, provided by one or more base stations, upon an occurrence of a mobility event; and wherein the third cell is added an active set associated with the UE when the cell quality of the third cell is stronger than the cell quality of the primary serving cell or the secondary serving cell upon the occurrence of the mobility event.
30. The apparatus of claim 29 , wherein the at least one processor is further configured to:
perform a primary serving cell change by replacing the primary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the primary serving cell, the third cell becoming a new primary serving cell;
perform a secondary serving cell change by replacing the secondary serving cell with the primary serving cell when the cell quality of the primary serving cell is greater than the cell quality of the secondary serving cell, the primary serving cell becoming a new secondary serving cell;
maintain the data corresponding to the flow within a queue at the new primary serving cell; and
flush the data corresponding to the flow within a queue at the secondary serving cell.
31. The apparatus of claim 29 , wherein the at least one processor is further configured to:
perform a primary serving cell change by replacing the primary serving cell with the secondary serving cell when the cell quality of the secondary serving cell is greater than the cell quality of the primary serving cell, the secondary serving cell becoming a new primary serving cell;
perform a secondary serving cell change by replacing the secondary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the secondary serving cell, the third cell becoming a new secondary serving cell;
maintain the data corresponding to the flow within a queue at the new primary serving cell; and
flush the data corresponding to the flow within a queue at the secondary serving cell.
32. The apparatus of claim 29 , wherein the at least one processor is further configured to:
perform a primary serving cell change by replacing the primary serving cell with the third cell when the cell quality of the third cell is greater than the cell quality of the primary serving cell, the third cell becoming a new primary serving cell;
maintain the data corresponding to the flow within a queue at the new primary serving cell; and
flush the data corresponding to the flow within a queue at the primary serving cell.
33. The apparatus of claim 29 , wherein the at least one processor is further configured to:
remove the secondary serving cell from the active set associated with the UE when the cell quality of the secondary serving cell is below a predetermined threshold; and
flush the data corresponding to the flow within a queue at the secondary serving cell.
34. The apparatus of claim 29 , wherein the at least one processor is further configured to:
perform a primary serving cell change by replacing the primary serving cell with the secondary serving cell when the cell quality of the secondary serving cell is greater than the cell quality of the primary serving cell, the secondary serving cell becoming a new primary serving cell;
remove the primary serving cell from the active set associated with the UE when the cell quality of the primary serving cell is below a predetermined threshold; and
flush the data corresponding to the flow within a queue at the primary serving cell.