Methods and Apparatus for Physical Uplink Control Channel (PUCCH) Load Control by Physical Downlink Control Channel (PDCCH) Restrictions

• US 20110299490A1
• Filed: 01/16/2009
• Published: 12/08/2011
• Est. Priority Date: 01/16/2009
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Faronius, Carola, Johansson, Anders, Nordstrom, Bjorn
• Granted Patent: US 8,897,240 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04L 1/1861 Physical mapping arrangements for ACK signaling see also H04L5/0053
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0055 Physical resource allocation for ACK/NACK for physical mapping arrangements in ARQ protocols H04L1/1861
• CPC Class Codes: H04L 5/0058 Allocation criteria
• CPC Class Codes: H04L 5/0062 Avoidance of ingress interference, e.g. ham radio channels
• CPC Class Codes: H04L 5/0073 Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

Methods for scheduling downlink (DL) data on a downlink subframe from a base station directed to at least one wireless terminal in a wireless network are provided. The methods include selecting a control channel element (CCE) region for a physical downlink control channel (PDCCH) carried in a control region of the downlink subframe; determining whether a DL assignment corresponding to the DL data can be allocated on the selected CCE region based on a load imposed on a corresponding physical resource block (PRB) of a physical uplink control channel (PUCCH) of a future uplink subframe that will carry an ACK/NACK response corresponding to the DL assignment; and allocating the DL assignment on the selected CCE region when it is determined that the DL assignment can be allocated.

Claims

1. A method for scheduling downlink (DL) data on a downlink subframe from a base station directed to at least one wireless terminal in a wireless network, the method comprising:

selecting a control channel element (CCE) region for a physical downlink control channel (PDCCH) carried in a control region of the downlink subframe;

determining whether a DL assignment corresponding to the DL data can be allocated on the selected CCE region based on a load imposed on a corresponding physical resource block (PRB) of a physical uplink control channel (PUCCH) of a future uplink subframe that will carry an ACK/NACK response corresponding to the DL assignment; and

allocating the DL assignment on the selected CCE region when it is determined that the DL assignment can be allocated.

2. The method claim 1:

wherein the PDCCH is mapped to at least one CCE region of the control region; and

wherein each CCE region of the downlink control region maps to a PUCCH PRB of an uplink subframe such that for each DL assignment allocated on the CCE region, the mapped PUCCH PRB carries an ACK/NACK response from an intended recipient wireless terminal due to the DL assignment allocated on the CCE region.

3. The method of claim 1, further comprising:

determining if there are at least one other CCE region in the PDCCH to which the DL assignment may be allocated when it is determined that the DL assignment cannot be allocated on the selected CCE region; and

repeating the selecting, determining, and allocating when it is determined that there are at least one other CCE region.

4. The method of claim 1, wherein determining whether the DL assignment can be allocated on the selected CCE region comprises:

determining a downlink (DL) load of the selected CCE region; and

determining if the DL load of the selected CCE region is below a maximum DL load threshold,

wherein it is determined that the DL assignment can be allocated on the selected CCE region when the DL load of the selected CCE region is below the maximum DL load threshold; and

wherein it is determined that the DL assignment cannot be allocated on the selected CCE region when the DL load of the selected CCE region is not below the maximum DL load threshold.

5. The method of claim 4, wherein the DL load of the selected CCE region is determined based on an amount of resources in the selected CCE region already allocated to carry at least one other DL assignment that requires corresponding at least one ACK/NACK response from at least one recipient wireless terminal.

6. The method of claim 4, wherein the DL load of the selected CCE region is determined based on a number of at least one other DL assignment already allocated in the selected CCE region that require corresponding at least one ACK/NACK response from at least one recipient wireless terminal.

7. The method of claim 4, further comprising setting the maximum DL load threshold for the selected CCE region prior to determining whether the DL load of the selected CCE region is below the maximum DL load threshold.

8. The method of claim 7, wherein the step of setting the maximum DL load threshold for the selected CCE region comprises setting the maximum DL load threshold based on a consideration of at least one of:

a channel quality of the PUCCH of the future uplink subframe;

an amount of semi-statically allocated uplink control information resources already scheduled to be carried by the corresponding PUCCH PRB;

a total number of DL assignments for the downlink subframe; and

a total number of ACK/NACK responses expected to be carried on the future uplink subframe.

9. The method of claim 1, wherein the determining whether the DL assignment can be allocated on the selected CCE region comprises:

determining an uplink (UL) load of the corresponding PUCCH PRB; and

determining whether the UL load of the corresponding PUCCH PRB is below a maximum UL load threshold,

wherein it is determined that the DL assignment can be allocated on the selected CCE region when the UL load of the corresponding PUCCH PRB is below the maximum UL load threshold; and

wherein it is determined that the DL assignment cannot be allocated on the selected CCE region when the UL load of the corresponding PUCCH PRB is not below the maximum UL load threshold.

10. The method of claim 9, wherein the UL load of the corresponding PUCCH PRB is determined based on a number of ACK/NACK responses already scheduled to be carried by the corresponding PUCCH PRB.

11. The method of claim 9, further comprising setting the maximum UL load threshold for the corresponding PUCCH PRB prior to determining whether the UL load for the corresponding PUCCH PRB is below the maximum UL load threshold.

12. The method of claim 11, wherein setting the maximum UL load threshold for the corresponding PUCCH PRB comprises setting the maximum UL load threshold based on a consideration of at least one of:

a channel quality of the PUCCH of the uplink subframe;

an amount of semi-statically allocated uplink control information resources already scheduled to be carried by the corresponding PUCCH PRB;

a total number of DL assignments for the downlink subframe; and

a total number of ACK/NACK responses expected to be carried on the future uplink subframe.

13. The method of claim 1, wherein the wireless network is a 3GPP network.

16. The scheduler of claim 1, wherein the processing unit is configured to:

determine whether there are at least one other CCE region of the PDCCH to which the DL assignment may be allocated when it determines that the DL assignment cannot be allocated on the selected CCE region; and

when it determines that there are at least one other CCE region, repeat the process to select another CCE region, determine whether the DL assignment on the another CCE region is possible, and allocate the DL assignment on the another CCE region based on the result.

14. A scheduler of a base station of a wireless network configured to schedule a downlink (DL) data on a downlink subframe directed to at least one wireless terminal, the scheduler comprising:

a communication unit configured to receive downlink data for the at least one wireless terminal from a gateway node of the wireless network;

a storage unit configured to buffer the downlink data; and

a processing unit configured to control the communication unit and the storage unit to provide scheduling services, wherein the processing unit is configured to;

select a control channel element (CCE) region for a physical downlink control channel (PDCCH) carried in a control region of the downlink subframe;

determine whether a DL assignment corresponding to the DL data can be allocated on the selected CCE region based on a load that will be imposed on a corresponding physical resource block (PRB) of a physical uplink control channel (PUCCH) of a future uplink subframe that will carry an ACK/NACK response corresponding to the DL assignment; and

allocate the DL assignment on the selected CCE region when it determines that the DL assignment can be allocated.

15. The scheduler of claim 14,

wherein the PDCCH is mapped to at least one CCE region of the control region;

and

wherein each CCE region of the downlink control region maps to a PUCCH PRB of an uplink subframe such that for each DL assignment allocated on the CCE region, the mapped PUCCH PRB carries an ACK/NACK response from an intended recipient wireless terminal due to the DL assignment allocated on the CCE region.

17. The scheduler of claim 14, wherein the processing unit is configured to:

determine a downlink (DL) load of the selected CCE region;

determine that the DL assignment can be allocated on the selected CCE region when the DL load of the selected CCE region is below a maximum DL load threshold; and

determine that the DL assignment cannot be allocated on the selected CCE region when the DL load of the selected CCE region is not below the maximum DL load threshold.

18. The scheduler of claim 17, wherein the processing unit is configured to determine the DL load of the selected CCE region based on an amount of resources in the selected CCE region already allocated to carry at least one other DL assignment that require corresponding at least one ACK/NACK response from at least one recipient wireless terminal.

19. The scheduler of claim 17, wherein the processing unit is configured to determine the DL load of the selected CCE region based on a number of at least one other DL assignment already allocated in the selected CCE region that require corresponding ACK/NACK response from at least one recipient wireless terminal.

20. The scheduler of claim 17, wherein the processing unit is configured to set the maximum DL load threshold for the selected CCE region prior to determining whether the DL load of the selected CCE region is below the maximum DL load threshold.

21. The scheduler of claim 20, wherein the processing unit is configured to set the maximum DL load threshold based on a consideration of any at least one of:

a channel quality of the PUCCH of the future uplink subframe;

an amount of semi-statically allocated uplink control information resources already scheduled to be carried by the corresponding PUCCH PRB;

a total number of DL assignments for the downlink subframe; and

a total number of ACK/NACK responses expected to be carried on the future uplink subframe.

22. The scheduler of claim 14, wherein the processing unit is configured to:

determine an uplink (UL) load of the corresponding PUCCH PRB;

determine that the DL assignment can be allocated on the selected CCE region when the UL load of the corresponding PUCCH PRB is below a maximum UL load threshold; and

determine that the DL assignment cannot be allocated on the selected CCE region when the UL load of the corresponding PUCCH PRB is not below the maximum UL load threshold.

23. The scheduler of claim 22, wherein the processing unit is configured to determine the UL load of the corresponding PUCCH PRB based on a number of ACK/NACK responses already scheduled to be carried by the corresponding PUCCH PRB.

24. The scheduler of claim 22, wherein the processing unit is configured to set the maximum UL load threshold for the corresponding PUCCH PRB prior to determining whether the UL load for the corresponding PUCCH PRB is below the maximum UL load threshold.

25. The scheduler of claim 24, wherein the processing unit is configured to set the maximum UL load threshold for the corresponding PUCCH PRB in a consideration of at least one of:

a channel quality of the PUCCH of the uplink subframe;

an amount of semi-statically allocated uplink control information resources already scheduled to be carried by the corresponding PUCCH PRB;

a total number of DL assignments for the downlink subframe; and

a total number of ACK/NACK responses expected to be carried on the future uplink subframe.

26. The scheduler of claim 14, wherein the wireless network is a 3GPP network.