Interference mitigation for downlink in a wireless communication system

Patent metadata

Field	Value
Publication number	US-2016119022-A1
Application number	US-201614991874-A
Country	US
Kind code	A1
Filing date	Jan 8, 2016
Priority date	Jun 4, 2009
Publication date	Apr 28, 2016
Grant date	—

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.

First claim

What is claimed is:

1 . A method for wireless communication, comprising:
obtaining at a 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 information for at least one transmission parameter for the second data transmission; and performing interference mitigation for the second data transmission, based on the information for the at least one transmission parameter and at least one scrambling sequence, to recover the first data transmission sent to the first user equipment.

2 . The method of claim 1 , wherein the performing interference mitigation comprises performing interference mitigation for the second data transmission at symbol level, without decoding the second data transmission to recover any packet sent by the second cell to the second user equipment.

3 . The method of claim 2 , wherein the performing interference mitigation comprises performing demodulation with interference mitigation.

4 . The method of claim 1 , wherein the performing interference mitigation comprises
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.

5 . The method of claim 1 , wherein the performing interference mitigation 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.

6 . The method of claim 1 , wherein the performing interference mitigation comprises performing demodulation with interference mitigation and decoding for a plurality of iterations, wherein an output of demodulation in each iteration is used for decoding in the iteration, and wherein an output of decoding in each iteration except for a final iteration is used for demodulation in next iteration.

7 . The method of claim 1 , wherein the performing interference mitigation comprises performing demodulation with 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.

8 . The method of claim 1 , wherein the performing interference mitigation 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 interference mitigation based further on the channel estimate to obtain demodulated symbols for the first data transmission.

9 . The method of claim 1 , wherein the information for the at least one transmission parameter comprises a modulation order, or a modulation and coding scheme, or a traffic-to-pilot ratio, or precoding information, or a transmission rank, or assigned resources for the second data transmission, or a combination thereof.

10 . 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.

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

12 . 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 signaling transmitted by the first cell or the second cell.

13 . 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.

14 . An apparatus for wireless communication, comprising:
means for obtaining at a 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 information for at least one transmission parameter for the second data transmission; and means for performing interference mitigation for the second data transmission, based on the information for the at least one transmission parameter and at least one scrambling sequence, to recover the first data transmission sent to the first user equipment.

15 . The apparatus of claim 14 , wherein the means for performing interference mitigation comprises means for performing interference mitigation for the second data transmission at symbol level, without decoding the second data transmission to recover any packet sent by the second cell to the second user equipment.

16 . The apparatus of claim 15 , wherein the means for performing interference mitigation comprises means for performing demodulation with interference mitigation.

17 . The apparatus of claim 14 , wherein the means for performing interference mitigation comprises:
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.

18 . The apparatus of claim 14 , wherein the means for performing interference mitigation 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.

19 . A method for wireless communication, comprising:
obtaining information for at least one transmission parameter for a data transmission sent by a first cell to a user equipment; and transmitting 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 interference mitigation for the data transmission sent by the first cell to the user equipment based on the at least one transmission parameter and at least one scrambling sequence.

20 . The method of claim 19 , wherein the information for the at least one transmission parameter comprises a modulation order, or a modulation and coding scheme or a traffic-to-pilot ratio, or precoding information, or a transmission rank, or assigned resources for the data transmission, or a combination thereof.

21 . The method of claim 19 , wherein the obtaining the information and the transmitting the in

Assignees

• Qualcomm Inc

Inventors

• Gorokhov Alexei Y
• Agrawal Avneesh

Classifications

• H04B1/7103 Primary

  the interference being multiple access interference · CPC title

• H04B7/0413

  MIMO systems · CPC title

• H04B2201/70702

  Intercell-related aspects · CPC title

• H04J11/0053

  using co-ordinated multipoint transmission/reception (co-ordinated antenna or beam-forming aspects H04B7/022) · CPC title

• H04B7/024

  Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems · CPC title