Interference alignment for transmitter/receiver pairs in wireless communication systems

• US 9,445,285 B2
• Filed: 10/15/2013
• Issued: 09/13/2016
• Est. Priority Date: 10/15/2013
• Status: Active Grant

• Current Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Original Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Inventors: Maddah-Ali, Mohammadali, Ntranos, Vasileios
• Primary Examiner(s): ADHAMI, MOHAMMAD SAJID
• Application Number:
  US14/054,654
• Publication Number:
  US 20150103753A1
• Time in Patent Office: 1,064 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04J 11/0046 using joint detection algorithms
• CPC Class Codes: H04J 11/0059 Out-of-cell user aspects
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• 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 24/02 Arrangements for optimising operational condition

Abstract

Interference is mitigated in a wireless communication system using interference alignment techniques to cancel inter-cell interference based on a decoding order while using joint decoding to cancel intra-cell interference. Second transmitter-receiver pairs proximate a first transmitter-receiver pair may be selected so that the first transmitter-receiver pair is in a first cell and the second transmitter-receiver pairs are not in the first cell. Signals transmitted by the second transmitter-receiver pairs may be aligned to be received by the first transmitter-receiver pair in a first subspace of channels. A second subspace of the channels is free of the signals transmitted by the second transmitter-receiver pairs.

Claims

1. A method comprising:

selecting second transmitter-receiver pairs proximate to a first transmitter-receiver pair, wherein the first transmitter-receiver pair is in a first cell and the second transmitter-receiver pairs are not in the first cell, and wherein the first and second transmitter-receiver pairs form a first group;

canceling interference caused by signals in one direction between the first transmitter-receiver pair and the second transmitter-receiver pairs,

in response to canceling the interference caused by the signals in one direction, aligning beamforming vectors of signals for transmission by the second transmitter-receiver pairs to be received by the first transmitter-receiver pair in a first subspace of channels defined by channel matrices between the first transmitter-receiver pair and the second transmitter-receiver pairs, wherein a second subspace of the channels is free of the signals transmitted by the second transmitter-receiver pairs; and

aligning beamforming vectors of signals in a second group of transmitter-receiver pairs relative to at least one beamforming vector associated with at least one transmitter-receiver pair that is a member of the first group and the second group.

2. The method of claim 1, wherein canceling the interference comprises:

decoding messages in the signals transmitted by the first transmitter-receiver pair at a first receiver and the second transmitter-receiver pairs at a second receiver; and

providing the decoded messages for canceling interference caused by the signals in one direction between the first transmitter-receiver pair and the second transmitter-receiver pairs.

3. The method of claim 2, further comprising:

assigning a decoding order to the first transmitter-receiver pair and the second transmitter-receiver pairs, wherein providing the decoded messages comprises providing the decoded messages to the first transmitter-receiver pair or the second transmitter-receiver pairs based on the decoding order.

4. The method of claim 3, wherein aligning signals transmitted by the second transmitter-receiver pairs comprises precoding the signals transmitted by the second transmitter-receiver pairs using estimates of channels between the first and second transmitter-receiver pairs so that the precoded signals are elements of the first subspace.

5. The method of claim 4, wherein precoding the signals comprises precoding the signals to form the beamforming vectors for the signals, wherein the beamforming vectors are defined relative to a direction of a predetermined beamforming vector used by one of the second transmitter-receiver pairs.

6. The method of claim 5, further comprising:

jointly decoding messages in signals received by the first transmitter-receiver pair and at least one third transmitter-receiver pair, wherein said at least one third transmitter-receiver pair is in the first cell.

7. The method of claim 6, wherein jointly decoding the messages comprises exchanging scalar observations of signals received by the first transmitter-receiver pair and said at least one third transmitter-receiver pair.

8. The method of claim 7, wherein jointly decoding the messages comprises combining the scalar observations received at the first transmitter-receiver pair and said at least one third transmitter-receiver pair with vector observations of signals received by the first transmitter-receiver pair and said at least one third transmitter-receiver pair.

9. An apparatus comprising:

a memory coupled to at least one processor;

the at least one processor to;

select second transmitter-receiver pairs proximate to a first transmitter-receiver pair, wherein the first transmitter-receiver pair is in a first cell and the second transmitter-receiver pairs are not in the first cell, and wherein the first and second transmitter-receiver pairs form a first group;

cancel interference caused by signals in one direction between the first transmitter-receiver pair and the second transmitter-receiver pairs,

in response to cancelling the interference caused by the signals in one direction, align beamforming vectors of signals for transmission by the second transmitter-receiver pairs to be received by the first transmitter-receiver pair in a first subspace of channels defined by channel matrices between the first transmitter-receiver pair and the second transmitter-receiver pairs, wherein a second subspace of the channels is free of the signals transmitted by the second transmitter-receiver pairs, and

align beamforming vectors of signals n a second group of transmitter-receiver pairs relative to at least one beamforming vector associated with at least one transmitter-receiver pair that is a member of the first group and the second group.

10. The apparatus of claim 9, wherein the processor is to:

decode messages in the signals transmitted by the first transmitter-receiver pair and the second transmitter-receiver pairs; and

provide the decoded messages for canceling interference caused by the signals in one direction between the first transmitter-receiver pair and the second transmitter-receiver pairs.

11. The apparatus of claim 10, wherein the processor is to assign a decoding order to the first transmitter-receiver pair and the second transmitter-receiver pairs, and wherein the processor is to provide the decoded messages to the first transmitter-receiver pair or the second transmitter-receiver pairs based on the decoding order.

12. The apparatus of claim 11, wherein the processor is to precode the signals transmitted by the second transmitter-receiver pairs using estimates of channels between the first and second transmitter-receiver pairs so that the precoded signals are elements of the first subspace.

13. The apparatus of claim 12, wherein the processor is to precode the signals to form beamforming vectors for the signals, wherein the beamforming vectors are defined relative to a direction of a predetermined beamforming vector used by one of the second transmitter-receiver pairs.

14. The apparatus of claim 13, wherein the processor is to jointly decode messages in signals received by the first transmitter-receiver pair and at least one third transmitter-receiver pair, wherein said at least one third transmitter-receiver pair is in the first cell.

15. The apparatus of claim 14, wherein the processor is to jointly decode the messages using scalar observations of signals received by the first transmitter-receiver pair and said at least one third transmitter-receiver pair.

16. The apparatus of claim 15, wherein the processor is to combine the scalar observations received at the first transmitter-receiver pair and said at least one third transmitter-receiver pair with vector observations of signals received by the first transmitter-receiver pair and said at least one third transmitter-receiver pair.

17. A non-transitory computer readable medium embodying a set of executable instructions, the set of executable instructions to manipulate at least one processor to:

select second transmitter-receiver pairs proximate to a first transmitter-receiver pair, wherein the first transmitter-receiver pair is in a first cell and the second transmitter-receiver pairs are not in the first cell, and wherein the first and second transmitter-receiver pairs form a first group;

cancel interference caused by signals in one direction between the first transmitter-receiver pair and the second transmitter-receiver pairs;

in response to canceling the interference caused by the signals in one direction, align beamforming vectors of signals for transmission by the second transmitter-receiver pairs to be received by the first transmitter-receiver pair in a first subspace of channels defined by channel matrices between the first transmitter-receiver pair and the second transmitter-receiver pairs, wherein a second subspace of the channels is free of the signals transmitted by the second transmitter-receiver pairs, and

align beamforming vectors of signals in a second group of transmitter-receiver pairs relative to at least one beamforming vector associated with at least one transmitter-receiver pair that is a member of the first group and the second group.

18. The non-transitory computer readable medium set forth in claim 17, comprising a set of executable instructions to manipulate said at least one processor to jointly decode messages in signals received by the first transmitter-receiver pair and at least one third transmitter-receiver pair, wherein said at least one third transmitter-receiver pair is in the first cell.