Blindly decoding interfering cell PDCCH to acquire interfering cell PDSCH transmission information

• US 8,989,121 B2
• Filed: 10/30/2012
• Issued: 03/24/2015
• Est. Priority Date: 11/02/2011
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Luo, Tao, Wei, Yongbin, Gaal, Peter, Malladi, Durga Prasad, Chen, Wanshi
• Primary Examiner(s): LY, ANH VU H
• Application Number:
  US13/663,912
• Publication Number:
  US 20130121168A1
• Time in Patent Office: 875 Days
• Field of Search: None
• US Class Current: 370/329
• CPC Class Codes: H04L 1/0046 Code rate detection or code type detection H04L1/0038 takes precedence; detection of the data rate H04L25/0262; for packet format H04L1/0091
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• 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 72/541 using the level of interference

Abstract

Certain aspects of the present disclosure relate to a technique for blindly decoding interfering cell Physical Downlink Control Channel (PDCCH) to acquire interfering cell Physical Downlink Shared Channel (PDSCH) transmission information. A UE may determine, for one or more aggregation levels, sets of CCEs that potentially include the PDCCH, based on available CCEs for each aggregation level and identify a set of decoding candidates based on the determination. Once the decoding candidates are decoded, the UE may perform an error correcting procedure on decoded candidates and prune out unlikely candidates. Likely decoded candidates may be further pruned based on comparison of CRC calculated using information bits only and possible Radio Network Temporary Identifiers (RNTIs). The UE may then interpret content of the PDCCH of the interfering cell based on surviving candidates. The UE may then use the interpreted PDCCH information to determine PDSCH information.

Claims

1. A method for wireless communications, comprising:

determining, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level, wherein the determining comprises;

performing a traffic to pilot ratio (TPR) estimation for resource element groups (REGs); and

determining the sets of CCEs based on results of the TPR estimation;

identifying a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination;

evaluating the set of candidates to determine one or more surviving candidates to be used for decoding the control channel;

decoding the control channel from the determined one or more surviving candidates;

interpreting information from the decoded control channel; and

using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell.

2. The method of claim 1, wherein one of the constraints comprises a constraint that limits, for each aggregation level, available starting CCEs for the control channel.

3. The method of claim 1, wherein evaluating the candidates comprises:

attempting to derive radio network temporary identifiers (RNTIs) for candidates based on cyclic redundancy check (CRC) values calculated from decoded information bits and decoded CRC bits; and

reducing the number of candidates in the candidate set by eliminating candidates for which an RNTI cannot be derived.

4. The method of claim 3, wherein using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell comprises:

using a derived RNTI to decode transmissions in the interfering cell for use in performing the interference cancellation.

5. The method of claim 1, wherein identifying the set of one or more decoding candidates comprises:

determining a set of possible payload sizes for the control channel based on at least one of system bandwidth of the interfering cell, a number of transmit antennas, or a type of carrier.

6. The method of claim 5, further comprising attempting to decode the decoding candidates of the control channel for each of the determined payload sizes and a plurality of aggregation levels.

7. The method of claim 1, wherein determining the sets of CCEs comprises:

deriving information regarding the CCEs based on an identifier of the interfering cell and information obtained by decoding a broadcast channel.

8. The method of claim 1, wherein the control channel comprises a Physical Downlink Control Channel (PDCCH) and the transmissions in the interfering cell comprise a Physical Downlink Shared Channel (PDSCH) corresponding to the PDCCH.

9. The method of claim 8, wherein using the interpreted information to decode transmissions in the interfering cell comprises using the interpreted information to determine resource block (RB) allocation, modulation order, and rank of the PDSCH.

10. A method for wireless communications, comprising:

determining, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level;

identifying a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination;

evaluating the set of candidates to determine one or more surviving candidates to be used for decoding the control channel, wherein evaluating the candidates comprises;

attempting to derive radio network temporary identifiers (RNTIs) for candidates based on cyclic redundancy check (CRC) values calculated from decoded information bits and decoded CRC bits; and

reducing the number of candidates in the candidate set by eliminating candidates for which an RNTI cannot be derived;

decoding the control channel from the determined one or more surviving candidates;

interpreting information from the decoded control channel;

using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell;

deriving a User Equipment (UE)-specific search space including a desirable set of CCEs corresponding to a derived RNTI, based on the derived RNTI and an assumed aggregation level;

declaring a CRC fail if an assumed set of CCEs corresponding to a decoded candidate for the derived RNTI is not a subset of or equal to the desirable set of CCEs; and

discarding the decoded candidate in response to the declaration of the CRC fail.

11. A method for wireless communications, comprising:

determining, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level;

identifying a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination;

evaluating the set of candidates to determine one or more surviving candidates to be used for decoding the control channel, wherein evaluating the candidates comprises;

attempting to derive radio network temporary identifiers (RNTIs) for candidates based on cyclic redundancy check (CRC) values calculated from decoded information bits and decoded CRC bits; and

reducing the number of candidates in the candidate set by eliminating candidates for which an RNTI cannot be derived;

decoding the control channel from the determined one or more surviving candidates;

interpreting information from the decoded control channel;

using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell;

if CRC pass is declared for multiple candidates for a same derived RNTI in a same subframe for a same cell, selecting a candidate with a largest metric and discarding the remaining candidates.

12. A method for wireless communications, comprising:

determining, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level;

identifying a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination;

evaluating the set of candidates to determine one or more surviving candidates to be used for decoding the control channel, wherein evaluating the candidates comprises;

attempting to derive radio network temporary identifiers (RNTIs) for candidates based on cyclic redundancy check (CRC) values calculated from decoded information bits and decoded CRC bits; and

reducing the number of candidates in the candidate set by eliminating candidates for which an RNTI cannot be derived;

decoding the control channel from the determined one or more surviving candidates;

interpreting information from the decoded control channel;

using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell;

if CRC pass is declared for multiple candidates having overlapping CCEs in a same subframe on a same cell, selecting a candidate with a largest metric and discarding the remaining candidates.

13. A method for wireless communications, comprising:

determining, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level;

identifying a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination;

evaluating the set of candidates to determine one or more surviving candidates to be used for decoding the control channel, wherein evaluating the candidates comprises;

attempting to derive radio network temporary identifiers (RNTIs) for candidates based on cyclic redundancy check (CRC) values calculated from decoded information bits and decoded CRC bits; and

reducing the number of candidates in the candidate set by eliminating candidates for which an RNTI cannot be derived;

decoding the control channel from the determined one or more surviving candidates;

interpreting information from the decoded control channel;

using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell;

if CRC pass is declared for a set of candidates for a same cell and if at least one Downlink Control Information (DCI) format is not associated with explicit Multiple User-Multiple Input Multiple Output (MU-MIMO) support, discarding at least one candidate with a lowest metric.

14. A method for wireless communications, comprising:

determining, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level;

identifying a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination;

evaluating the set of candidates to determine one or more surviving candidates to be used for decoding the control channel, wherein evaluating the candidates comprises;

reducing a number of candidates in the candidate set by eliminating candidates from consideration that do not satisfy tailbiting convolutional code (TBCC) metrics;

decoding the control channel from the determined one or more surviving candidates;

interpreting information from the decoded control channel;

using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell.

15. A method for wireless communications, comprising:

determining, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level;

identifying a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination;

evaluating the set of candidates to determine one or more surviving candidates to be used for decoding the control channel;

decoding the control channel from the determined one or more surviving candidates;

interpreting information from the decoded control channel;

using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell;

wherein the control channel comprises a Physical Downlink Control Channel (PDCCH) and the transmissions in the interfering cell comprise a Physical Downlink Shared Channel (PDSCH) corresponding to the PDCCH, the method further comprising;

performing Traffic to Pilot Ratio (TPR) detection for assigned PDSCH resource blocks (RBs) to detect a PDSCH transmission in each of the assigned PDSCH RBs; and

checking if the interpreted information of the PDCCH is correct based on a comparison of results of the TPR detection with the interpreted information.

16. A method for wireless communications, comprising:

determining, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level;

identifying a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination;

evaluating the set of candidates to determine one or more surviving candidates to be used for decoding the control channel;

decoding the control channel from the determined one or more surviving candidates;

interpreting information from the decoded control channel;

using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell;

wherein the control channel comprises a Physical Downlink Control Channel (PDCCH) and the transmissions in the interfering cell comprise a Physical Downlink Shared Channel (PDSCH) corresponding to the PDCCH, the method further comprising;

performing blind detection for assigned PDSCH resource blocks (RBs) to determine corresponding PDSCH information; and

checking if the interpreted information of the PDCCH is correct based on a comparison of the determined PDSCH information with the interpreted information.

17. An apparatus for wireless communications, comprising:

means for determining, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level, wherein the means for determining is configured to;

perform a traffic to pilot ratio (TPR) estimation for resource element groups (REGs); and

determine the sets of CCEs based on results of the TPR estimation;

means for identifying a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination;

means for evaluating the set of candidates to determine one or more surviving candidates to be used for decoding the control channel;

means for decoding the control channel from the determined one or more surviving candidates;

means for interpreting information from the decoded control channel; and

means for using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell.

18. The apparatus of claim 17, wherein one of the constraints comprises a constraint that limits, for each aggregation level, available starting CCEs for the control channel.

19. The apparatus of claim 17, wherein the means for evaluating the candidates is configured to:

attempt to derive radio network temporary identifiers (RNTIs) for candidates based on cyclic redundancy check (CRC) values calculated from decoded information bits and decoded CRC bits; and

reduce the number of candidates in the candidate set by eliminating candidates for which an RNTI cannot be derived.

20. The apparatus of claim 19, wherein the means for using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell is configured to:

use a derived RNTI to decode transmissions in the interfering cell for use in performing the interference cancellation.

21. The apparatus of claim 17, wherein the means for identifying the set of one or more decoding candidates is configured to:

determine a set of possible payload sizes for the control channel based on at least one of system bandwidth of the interfering cell, a number of transmit antennas, or a type of carrier.

22. The apparatus of claim 21, further comprising means for attempting to decode the decoding candidates of the control channel for each of the determined payload sizes and a plurality of aggregation levels.

23. The apparatus of claim 17, wherein the control channel comprises a Physical Downlink Control Channel (PDCCH) and the transmissions in the interfering cell comprise a Physical Downlink Shared Channel (PDSCH) corresponding to the PDCCH.

24. The apparatus of claim 23, wherein the means for using the interpreted information to decode transmissions in the interfering cell is configured to use the interpreted information to determine resource block (RB) allocation, modulation order, and rank of the PDSCH.

25. An apparatus for wireless communications, comprising:

means for determining, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level;

means for identifying a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination;

means for evaluating the set of candidates to determine one or more surviving candidates to be used for decoding the control channel, wherein the means for evaluating the candidates is configured to;

reduce a number of candidates in the candidate set by eliminating candidates from consideration that do not satisfy tailbiting convolutional code (TBCC) metrics;

means for decoding the control channel from the determined one or more surviving candidates;

means for interpreting information from the decoded control channel; and

means for using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell.

26. An apparatus for wireless communications, comprising:

at least one processor configured to determine, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level, identify a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination, evaluate the set of candidates to determine one or more surviving candidates to be used for decoding the control channel, decode the control channel from the determined one or more surviving candidates, interpret information from the decoded control channel, and use the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell, wherein the at least one processor is configured to determine the sets of CCEs by performing a traffic to pilot ratio (TPR) estimation for resource element groups (REGs) and determining the sets of CCEs based on results of the TPR estimation; and

a memory coupled with the at least one processor.

27. A computer program product for wireless communications, comprising:

a non-transitory computer-readable medium comprising computer executable code for;

determining, for one or more aggregation levels, sets of control channel elements (CCEs) that potentially include a control channel, based on one or more constraints on available CCEs for each aggregation level, wherein the determining comprises;

performing a traffic to pilot ratio (TPR) estimation for resource element groups (REGs); and

determining the sets of CCEs based on results of the TPR estimation;

identifying a set of one or more decoding candidates for the control channel transmitted in an interfering cell based on the determination;

evaluating the set of candidates to determine one or more surviving candidates to be used for decoding the control channel;

decoding the control channel from the determined one or more surviving candidates;

interpreting information from the decoded control channel; and

using the interpreted information to decode transmissions in the interfering cell for use in performing interference cancellation to aid in decoding transmissions in a serving cell.