Interference mitigation for downlink in a wireless communication system

• US 10,027,372 B2
• Filed: 01/08/2016
• Issued: 07/17/2018
• Est. Priority Date: 06/04/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gorokhov, Alexei Y., Agrawal, Avneesh
• Primary Examiner(s): Sinkantarakorn, Pao
• Assistant Examiner(s): JAHANGIR, KABIR U
• Application Number:
  US14/991,874
• Publication Number:
  US 20160119022A1
• Time in Patent Office: 921 Days
• Field of Search: 370310-350
• CPC Class Codes: H04B 1/7103 the interference being multiple access interference
• CPC Class Codes: H04B 2201/70702 Intercell-related aspects

Abstract

Techniques for mitigating interference in a wireless communication system are described. In an aspect, pertinent transmission parameters for a served UE may be sent to at least one interfered UE to support interference mitigation. In one design, information for at least one transmission parameter for a data transmission sent by a first cell to a first UE may be transmitted to at least one UE served by a second cell to enable the at least one UE to perform interference mitigation for the data transmission sent by the first cell to the first UE. The information may be transmitted by either the first cell or the second cell. In another aspect, a cell may send transmission parameters for a UE via a pilot. In yet another aspect, scrambling may be performed by a cell at symbol level to enable an interfered UE to distinguish between modulation symbols of desired and interfering transmissions.

Claims

1. A method for wireless communication, wherein the method is performed at a first user equipment, the method comprising:

obtaining at the first user equipment a received signal comprising a first data transmission sent by a first cell to the first user equipment and a second data transmission sent by a second cell to a second user equipment;

obtaining, from the second data transmission sent by the second cell, information for at least one transmission parameter for the second data transmission; and

performing symbol-level interference mitigation for the second data transmission, based on the information for the at least one transmission parameter, to recover the first data transmission sent to the first user equipment,

wherein the performing symbol-level interference mitigation comprises;

demodulating symbols for the second data transmission without decoding the second data transmission to recover any packet sent by the second cell to the second user equipment,

demodulating the received signal based on the information for the at least one transmission parameter to obtain demodulated symbols for the second data transmission,

estimating interference due to the second data transmission based on the demodulated symbols for the second data transmission,

subtracting the estimated interference from the received signal to obtain an interference-canceled signal, and

demodulating the interference-canceled signal to obtain demodulated symbols for the first data transmission.

2. The method of claim 1, wherein the performing symbol-level interference mitigation further comprises performing joint demodulation on the received signal based on the information for the at least one transmission parameter to obtain demodulated symbols for the first and second data transmissions.

3. The method of claim 1, wherein the performing symbol-level interference mitigation further comprises performing demodulation with symbol-level interference mitigation for a plurality of hypotheses, each hypothesis corresponding to a different set of one or more values for one or more of the at least one transmission parameter.

4. The method of claim 1, wherein the performing symbol-level interference mitigation further comprises

obtaining a channel estimate for a wireless channel from the second cell to the first user equipment based on information for one or more of the at least one transmission parameter, and

performing demodulation with symbol-level interference mitigation based further on the channel estimate to obtain the demodulated symbols for the first data transmission.

5. The method of claim 1, wherein the information for the at least one transmission parameter comprises at least one of:

a modulation order,

a modulation and coding scheme,

a traffic-to-pilot ratio,

precoding information,

a transmission rank, or

assigned resources for the second data transmission.

6. The method of claim 1, wherein the obtaining the information for the at least one transmission parameter comprises obtaining actual value of the at least one transmission parameter used by the second cell for the second data transmission.

7. The method of claim 1, wherein the obtaining the information for the at least one transmission parameter comprises obtaining a default value of the at least one transmission parameter likely to be used by the second cell for the second data transmission.

8. The method of claim 1, wherein the obtaining the information for the at least one transmission parameter comprises obtaining the information for the at least one transmission parameter from a pilot transmitted by the second cell to the second user equipment.

9. The method of claim 1, wherein the symbol-level interference mitigation is based in part on a scrambling sequence.

10. A first user equipment for wireless communication, comprising:

means for obtaining at the first user equipment a received signal comprising a first data transmission sent by a first cell to the first user equipment and a second data transmission sent by a second cell to a second user equipment;

means for obtaining, from the second data transmission sent by the second cell, information for at least one transmission parameter for the second data transmission; and

means for performing symbol-level interference mitigation for the second data transmission, based on the information for the at least one transmission parameter, to recover the first data transmission sent to the first user equipment, wherein the means for performing symbol-level interference mitigation comprises;

means for demodulating symbols for the second data transmission without decoding the second data transmission to recover any packet sent by the second cell to the second user equipment,

means for demodulating the received signal based on the information for the at least one transmission parameter to obtain demodulated symbols for the second data transmission,

means for estimating interference due to the second data transmission based on the demodulated symbols for the second data transmission,

means for subtracting the estimated interference from the received signal to obtain an interference-canceled signal, and

means for demodulating the interference-canceled signal to obtain demodulated symbols for the first data transmission.

11. The first user equipment of claim 10, wherein the means for performing symbol-level interference mitigation further comprises means for performing joint demodulation on the received signal based on the information for the at least one transmission parameter to obtain demodulated symbols for the first and second data transmissions.

12. The first user equipment for wireless communication of claim 10, wherein the symbol-level interference mitigation is based in part on a scrambling sequence.

13. A method for wireless communication, comprising:

obtaining information for at least one transmission parameter for a first data transmission sent by a first cell to a user equipment; and

transmitting, from the first cell, the information for the at least one transmission parameter to at least one user equipment served by a second cell to enable the at least one user equipment to perform symbol-level interference mitigation for the first data transmission sent by the first cell to the user equipment based on the at least one transmission parameter,

wherein the symbol-level interference mitigation comprises;

demodulating symbols in the first data transmission from the first cell without decoding the first data transmission from the first cell to recover any packet sent by the first cell to the user equipment,

demodulating a signal received from the second cell based on the information for the at least one transmission parameter to obtain demodulated symbols for the first data transmission,

estimating interference due to the first data transmission based on the demodulated symbols for the first data transmission,

subtracting the estimated interference from the received signal to obtain an interference-canceled signal, and

demodulating the interference-canceled signal to obtain demodulated symbols for a second data transmission from the second cell.

14. The method of claim 13, wherein the information for the at least one transmission parameter comprises at least one of:

a modulation order,

a modulation and coding scheme,

a traffic-to-pilot ratio,

precoding information,

a transmission rank, or

assigned resources for the first data transmission.

15. The method of claim 13, wherein the obtaining the information is performed by the first cell.

16. The method of claim 13, further comprising:

identifying the user equipment or the first cell as potential interferer to the at least one user equipment based on at least one of;

pilot measurement from the user equipment,

location of the user equipment,

pilot measurements from the at least one user equipment, or

location of the at least one user equipment.

17. An apparatus for wireless communication, comprising:

means for obtaining information for at least one transmission parameter for a first data transmission sent by a first cell to a user equipment; and

means for transmitting, from the first cell, the information for the at least one transmission parameter to at least one user equipment served by a second cell to enable the at least one user equipment to perform symbol-level interference mitigation for the first data transmission sent by the first cell to the user equipment based on the at least one transmission parameter,

wherein the symbol-level interference mitigation comprises;

demodulating symbols in the first data transmission from the first cell without decoding the first data transmission from the first cell to recover any packet sent by the first cell to the user equipment,

demodulating a signal received from the second cell based on the information for the at least one transmission parameter to obtain demodulated symbols for the first data transmission,

estimating interference due to the first data transmission based on the demodulated symbols for the first data transmission,

subtracting the estimated interference from the received signal to obtain an interference-canceled signal, and

demodulating the interference-canceled signal to obtain demodulated symbols for a second data transmission from the second cell.

18. The apparatus of claim 17, wherein the information for the at least one transmission parameter comprises at least one of:

a modulation order,

a modulation and coding scheme,

a traffic-to-pilot ratio,

precoding information,

a transmission rank, or

assigned resources for the first data transmission.

19. A first user equipment, comprising at least one processor configured to:

obtain a received signal comprising a first data transmission sent by a first cell to the first user equipment and a second data transmission sent by a second cell to a second user equipment;

obtain, from the second data transmission sent by the second cell, information for at least one transmission parameter for the second data transmission; and

perform symbol-level interference mitigation for the second data transmission, based on the information for the at least one transmission parameter, to recover the first data transmission sent to the first user equipment,

wherein performing symbol-level interference mitigation comprises;

demodulating symbols for the second data transmission without decoding the second data transmission to recover any packet sent by the second cell to the second user equipment,

demodulate the received signal based on the information for the at least one transmission parameter to obtain demodulated symbols for the second data transmission,

estimate interference due to the second data transmission based on the demodulated symbols for the second data transmission,

subtract the estimated interference from the received signal to obtain an interference-canceled signal, and

demodulate the interference-canceled signal to obtain demodulated symbols for the first data transmission.

20. The first user equipment of claim 19, wherein the symbol-level interference mitigation is based in part on a scrambling sequence.

21. A non-transitory computer-readable medium comprising:

code for causing a first user equipment to obtain a received signal comprising a first data transmission sent by a first cell to the first user equipment and a second data transmission sent by a second cell to a second user equipment;

code for causing the first user equipment to obtain, from the second data transmission sent by the second cell, information for at least one transmission parameter for the second data transmission; and

code for causing the first user equipment to obtain perform symbol-level interference mitigation for the second data transmission, based on the information for the at least one transmission parameter, to recover the first data transmission sent to the first user equipment,

wherein the code for causing the first user equipment to perform symbol-level interference mitigation comprises code for causing the first user equipment to;

demodulate symbols for the second data transmission without decoding the second data transmission to recover any packet sent by the second cell to the second user equipment,

demodulate the received signal based on the information for the at least one transmission parameter to obtain demodulated symbols for the second data transmission,

estimate interference due to the second data transmission based on the demodulated symbols for the second data transmission,

subtract the estimated interference from the received signal to obtain an interference-canceled signal, and

demodulate the interference-canceled signal to obtain demodulated symbols for the first data transmission.

22. A first cell, comprising at least one processor configured to:

obtain information for at least one transmission parameter for a first data transmission sent by the first cell to a user equipment; and

transmit, from the first cell, the information for the at least one transmission parameter to at least one user equipment served by a second cell to enable the at least one user equipment to perform symbol-level interference mitigation for the first data transmission sent by the first cell to the user equipment based on the at least one transmission parameter,

wherein the symbol-level interference mitigation comprises;

demodulating symbols in the first data transmission from the first cell without decoding the first data transmission from the first cell to recover any packet sent by the first cell to the user equipment,

demodulating a signal received from the second cell based on the information for the at least one transmission parameter to obtain demodulated symbols for the first data transmission,

estimating interference due to the first data transmission based on the demodulated symbols for the first data transmission,

subtracting the estimated interference from the received signal to obtain an interference-canceled signal, and

demodulating the interference-canceled signal to obtain demodulated symbols for a second data transmission from the second cell.

23. A non-transitory computer-readable medium comprising:

code for causing a first cell to obtaining information for at least one transmission parameter for a first data transmission sent by the first cell to a user equipment; and

code for causing the first cell to transmit the information for the at least one transmission parameter to at least one user equipment served by a second cell to enable the at least one user equipment to perform symbol-level interference mitigation for the first data transmission sent by the first cell to the user equipment based on the at least one transmission parameter,

wherein the symbol-level interference mitigation comprises;

demodulating symbols in the first data transmission from the first cell without decoding the first data transmission from the first cell to recover any packet sent by the first cell to the user equipment,

demodulating a signal received from the second cell based on the information for the at least one transmission parameter to obtain demodulated symbols for the first data transmission,

estimating interference due to the first data transmission based on the demodulated symbols for the first data transmission,

subtracting the estimated interference from the received signal to obtain an interference-canceled signal, and

demodulating the interference-canceled signal to obtain demodulated symbols for a second data transmission from the second cell.