Cross-correlation reduction for control signals

• US 10,742,353 B2
• Filed: 04/05/2019
• Issued: 08/11/2020
• Est. Priority Date: 04/09/2018
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Lin, Jamie Menjay, Mallik, Siddhartha, Kadous, Tamer
• Primary Examiner(s): Tu, Christine T.
• Application Number:
  US16/376,895
• Publication Number:
  US 20190312671A1
• Time in Patent Office: 494 Days
• CPC Class Codes: H04J 11/0023 Interference mitigation or co-ordination direct sequence spread spectrum [DSSS] systems H04B1/7097; frequency hopping H04B1/713; allocation criteria for ingress interference avoidance H04L5/0062; frequency allocation criteria for requirements on out-of-channel emissions H04L5/0066; arrangements for removing intersymbol interference or baseband equalisers H04L25/03006; peak power aspects in multicarrier modulation H04L27/2614; power management H04W52/00; traffic scheduling H04W72/54, H04W72/541
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04L 1/001 applied to control information
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0072 Error control for data other than payload data, e.g. control data
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/26035 Maintenance of orthogonality, e.g. for signals exchanged between cells or users, or by using covering codes or sequences using different training sequence per antenna H04B7/0684; code allocation H04J13/16
• CPC Class Codes: H04L 27/2605 Symbol extensions, e.g. Zero Tail, Unique Word [UW]
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/026 using code division

Abstract

Methods, systems, and devices for wireless communications are described. In accordance with the described techniques, communicating devices (e.g., an encoder and decoder) may apply an orthogonal cover code to a polar codeword to reduce cross-correlation between different codewords. For example, such techniques may reduce power consumption at a decoding device by providing for earlier decoding termination (e.g., as a result of the reduced cross-correlation). Techniques for generating the cover codes (e.g., on a per-aggregation level basis) and applying the cover codes (e.g., within a search space) are described. Additionally or alternatively, the described techniques may relate to seeding of reference signals used to support decoding of the codewords. Improved orthogonality between reference signal seeds may further suppress codeword recipient ambiguity.

Claims

1. A method for wireless communications at a wireless device, comprising:

determining symbol information associated with a candidate codeword of a control channel, the candidate codeword encoded according to a forward error correction code;

applying an orthogonal cover code to the symbol information to obtain demasked symbol information for the candidate codeword;

descrambling the demasked symbol information with a scrambling code to obtain descrambled symbol information for the candidate codeword;

performing a decoding operation on the descrambled symbol information according to the forward error correction code; and

communicating with a second wireless device based at least in part on a result of the decoding operation.

2. The method of claim 1, wherein the candidate codeword comprises a plurality of candidate codewords of a search space set for the control channel, wherein each of the plurality of candidate codewords is associated with an aggregation level of a plurality of aggregation levels of the search space set.

3. The method of claim 2, wherein applying the orthogonal cover code comprises:

applying a plurality of orthogonal cover codes to the plurality of candidate codewords, each of the plurality of orthogonal cover codes determined based at least in part on one of a plurality of base orthogonal cover codes, each of the plurality of base orthogonal cover codes associated with one of the plurality of aggregation levels.

4. The method of claim 3, wherein applying the plurality of orthogonal cover codes comprises:

aligning the plurality of base orthogonal cover codes to an initial resource for the search space set within the control channel;

repeating the plurality of base orthogonal cover codes to span resources for the search space set within the control channel; and

determining the plurality of orthogonal cover codes from the aligned and repeated plurality of base orthogonal cover codes.

5. The method of claim 3, further comprising:

applying a second plurality of orthogonal cover codes to a second plurality of candidate codewords of a second search space set of a plurality of search space sets, wherein the search space set is a first search space set of the plurality of search space sets configured for the wireless device.

6. The method of claim 3, wherein applying the orthogonal cover code comprises:

applying a user-specific orthogonal cover code to each of the plurality of candidate codewords.

7. The method of claim 1, further comprising:

determining the orthogonal cover code by concatenating a plurality of constituent codes, each of the plurality of constituent codes based at least in part on one of a plurality of base orthogonal cover codes.

8. The method of claim 7, wherein each of the plurality of constituent codes has a length corresponding to an exponential function of a base number.

9. The method of claim 1, further comprising:

determining the orthogonal cover code by sampling a continuous waveform function according to a length of the orthogonal cover code, the continuous waveform function selected from a set of mutually orthogonal continuous waveform functions.

10. The method of claim 1, wherein performing the decoding operation comprises:

performing at least one estimation operation based at least in part on the descrambled symbol information.

11. The method of claim 10, wherein performing the at least one estimation operation comprises:

terminating the decoding operation prior to sequential decoding of all sub-channels of the forward error correction code based at least in part on the descrambled symbol information.

12. The method of claim 1, further comprising:

determining the orthogonal cover code based at least in part on a protocol type of the control channel.

13. The method of claim 1, wherein the orthogonal cover code comprises a user-specific orthogonal cover code.

14. The method of claim 1, wherein the orthogonal cover code comprises an orthogonal variable spreading factor code.

15. The method of claim 1, wherein the scrambling code comprises a Gold sequence.

16. The method of claim 1, wherein communicating with the second wireless device based at least in part on the result of the decoding operation comprises:

identifying control information based at least in part on a result of the decoding operation; and

communicating with the second wireless device according to the control information.

17. A method for wireless communications at a wireless device, comprising:

generating a codeword based at least in part on applying a forward error correction encoding operation to a bit vector, the bit vector comprising control information for a second wireless device;

scrambling symbols of the codeword with a scrambling code to obtain scrambled symbol information associated with the codeword;

applying an orthogonal cover code to the scrambled symbol information to generate masked scrambled symbol information associated with the codeword; and

transmitting the masked scrambled symbol information to the second wireless device in a control channel.

18. The method of claim 17, wherein transmitting the masked scrambled symbol information comprises:

transmitting the masked scrambled symbol information in a control candidate of a search space set of the control channel, the control candidate associated with an aggregation level of a plurality of aggregation levels of the search space set.

19. The method of claim 18, further comprising:

determining the orthogonal cover code based at least in part on a base orthogonal cover code associated with the aggregation level.

20. The method of claim 19, wherein determining the orthogonal cover code comprises:

aligning the base orthogonal cover code to an initial resource for the search space set within the control channel; and

repeating the base orthogonal cover code to span resources for the search space set within the control channel.

21. The method of claim 18, wherein the search space set is a first search space set of a plurality of search space sets configured for the second wireless device for the control channel.

22. The method of claim 21, further comprising:

applying a second orthogonal cover code to a second scrambled set of symbols of a second search space set of the plurality of search space sets.

23. The method of claim 18, wherein applying the orthogonal cover code comprises:

applying an aggregation level-specific orthogonal cover code and a user-specific orthogonal cover code to the scrambled symbol information.

24. The method of claim 17, further comprising:

determining the orthogonal cover code by concatenating a plurality of constituent codes, each of the plurality of constituent codes based at least in part on one of a plurality of base orthogonal cover codes.

25. The method of claim 17, further comprising:

determining the orthogonal cover code by sampling a continuous waveform function according to a length of the orthogonal cover code, the continuous waveform function selected from a set of mutually orthogonal continuous waveform functions.

26. The method of claim 17, further comprising:

determining the orthogonal cover code based at least in part on a protocol type of the control channel.

27. An apparatus for wireless communications, comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to;

determine symbol information associated with a candidate codeword of a control channel, the candidate codeword encoded according to a forward error correction code;

apply an orthogonal cover code to the symbol information to obtain demasked symbol information for the candidate codeword;

descramble the demasked symbol information with a scrambling code to obtain descrambled symbol information for the candidate codeword;

perform a decoding operation on the descrambled symbol information according to the forward error correction code; and

communicate with a second wireless device based at least in part on a result of the decoding operation.

28. The apparatus of claim 27, wherein the candidate codeword comprises a plurality of candidate codewords of a search space set for the control channel, wherein each of the plurality of candidate codewords is associated with an aggregation level of a plurality of aggregation levels of the search space set, and wherein the instructions to apply the orthogonal cover code are executable by the processor to cause the apparatus to:

apply a plurality of orthogonal cover codes to the plurality of candidate codewords, each of the plurality of orthogonal cover codes determined based at least in part on one of a plurality of base orthogonal cover codes, each of the plurality of base orthogonal cover codes associated with one of the plurality of aggregation levels.

29. An apparatus for wireless communications, comprising:

a processor,

memory in electronic communication with the processor; and

instructions stored in the memory and executable by the processor to cause the apparatus to;

generate a codeword based at least in part on applying a forward error correction encoding operation to a bit vector, the bit vector comprising control information for a second wireless device;

scramble symbols of the codeword with a scrambling code to obtain scrambled symbol information associated with the codeword;

apply an orthogonal cover code to the scrambled symbol information to generate masked scrambled symbol information associated with the codeword; and

transmit the masked scrambled symbol information to the second wireless device in a control channel.

30. The apparatus of claim 29, wherein the instructions to transmit the masked scrambled symbol information are executable by the processor to cause the apparatus to:

transmit the masked scrambled symbol information in a control candidate of a search space set of the control channel, the control candidate associated with an aggregation level of a plurality of aggregation levels of the search space set.