Systems and methods of triggering interference mitigation without resource partitioning

• US 9,420,476 B2
• Filed: 02/12/2014
• Issued: 08/16/2016
• Est. Priority Date: 02/20/2013
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Koutsimanis, Chrysostomos, Kazmi, Muhammad, Lindbom, Lars
• Primary Examiner(s): Cho, Un C
• Assistant Examiner(s): Lou, Peian
• Application Number:
  US14/178,696
• Publication Number:
  US 20140233457A1
• Time in Patent Office: 916 Days
• US Class Current: 1/1
• CPC Class Codes: H04J 11/005 of intercell interference
• 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
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

Systems and methods for triggering interference mitigation at a wireless device in a cellular communications network are disclosed. In one embodiment, a node associated with a cellular communications network makes a determination to trigger interference mitigation at a wireless device based on a signal load in at least one interfering cell from which transmissions result in interference at the wireless device during reception from a desired cell, a relation between reference signals used in the desired cell and the at least one interfering cell, and a timing relation between at least one of a group consisting of: signals transmitted by the desired cell and the at least one interfering cell and signals received at the wireless device from the desired cell and the at least one interfering cell. In response to making the determination, the node triggers interference mitigation at the wireless device.

Claims

1. A method of operation of a node associated with a cellular communications network, comprising:

making a determination to trigger interference mitigation at a wireless device based on;

a signal load or interference level in at least one interfering cell from which transmissions result in interference at the wireless device during reception from a desired cell,

a relation between reference signals used in the desired cell and the at least one interfering cell, and

a timing relation between at least one of the group consisting of;

signals transmitted by the desired cell and the at least one interfering cell, and

signals received at the wireless device from the desired cell and the at least one interfering cell; and

triggering interference mitigation at the wireless device in response to making the determination to trigger interference mitigation at the wireless device.

2. The method of claim 1 wherein the desired cell is a serving cell of the wireless device.

3. The method of claim 1 wherein the desired cell is a measured cell of the wireless device.

4. The method of claim 1 wherein:

the node is the wireless device such that making the determination to trigger interference mitigation at the wireless device and triggering the interference mitigation are each performed by the wireless device.

5. The method of claim 4 further comprising:

receiving an indication from a network node of the cellular communications network that the wireless device is to perform interference mitigation;

wherein making the determination to trigger interference mitigation at the wireless device comprises making the determination in response to receiving the indication.

6. The method of claim 1 wherein:

the node is a network node of the cellular communications network such that making the determination to trigger interference mitigation at the wireless device and triggering the interference mitigation are each performed by the network node.

7. The method of claim 6 wherein the network node is a radio access node.

8. The method of claim 7 wherein the radio access node is a base station of a serving cell of the wireless device.

9. The method of claim 6 wherein triggering the interference mitigation at the wireless device comprises providing an implicit indication to the wireless device to perform interference mitigation.

10. The method of claim 9 wherein:

the network node is a base station of a serving cell of the wireless device; and

providing the implicit indication to the wireless device comprises sending information regarding the at least one interfering cell to the wireless device.

11. The method of claim 6 wherein triggering the interference mitigation at the wireless device comprises providing an explicit indication to the wireless device to perform interference mitigation.

12. The method of claim 11 wherein the explicit indication comprises information that informs the wireless device of signals on which the wireless device is to perform interference mitigation.

13. The method of claim 11 wherein the signals comprise one or more of:

a Cell-specific Reference Signal (CRS), a Secondary Synchronization Signal (SSS), a Primary Synchronization Signal (PSS), a Physical Broadcast Channel (PBCH), a Physical Downlink Shared Channel (PDSCH), a Physical Downlink Control Channel (PDCCH), a Physical Control Format Indicator Channel (PCFICH), and a Physical Hybrid-Automatic Repeat Request Indicator Channel (PHICH).

14. The method of claim 11 wherein the explicit indication further comprises one or more of the following:

a Boolean indicator indicating whether or not the wireless device is to perform interference mitigation;

information informing the wireless device of one or more physical channels for which the wireless device is to perform interference mitigation;

information informing the wireless device of one or more types of signal operations for which the wireless device is to perform interference mitigation; and

information informing the wireless device of one or more physical resources for which the wireless device is to perform interference mitigation.

15. The method of claim 1 wherein making the determination to trigger interference mitigation at the wireless device comprises making the determination to trigger interference mitigation at the wireless device if the signal load or interference level in the at least one interfering cell meets a predefined condition.

16. The method of claim 1 wherein making the determination to trigger interference mitigation comprises making the determination to trigger interference mitigation when predefined criteria are satisfied, wherein:

the predefined criteria are based on the signal load in the at least one interfering cell, the relation between the reference signals used in the desired cell and the at least one interfering cell, and the timing relation; and

the predefined criteria comprise;

a first criterion that the relation between the reference signals used in the desired cell and the at least one interfering cell be non-colliding, wherein the non-colliding reference signals do not overlap in time and frequency; and

a second criterion that the signal load in the at least one interfering cell be less than a predetermined threshold.

17. The method of claim 16 wherein the interference mitigation is Cell-Specific Reference Signal (CRS) interference mitigation, and the relation between the reference signals is a relation between CRSs used in the desired cell and the at least one interfering cell.

18. The method of claim 1 wherein the relation between the reference signals used in the desired cell and the at least one interfering cell comprises a colliding or non-colliding relation between the reference signals used in the desired cell and the at least one interfering cell, wherein a colliding relation exists between the reference signals if the reference signals fully or partly overlap in time or frequency.

19. The method of claim 18 wherein the reference signals are Cell-Specific Reference Signals (CRSs) used in the desired cell and the at least one interfering cell.

20. The method of claim 18 wherein making the determination to trigger interference mitigation comprises making the determination to trigger interference mitigation when predefined criteria are satisfied, wherein:

the predefined criteria are based on the signal load in the at least one interfering cell, the relation between the reference signals used in the desired cell and the at least one interfering cell, and the timing relation; and

the predefined criteria comprise a first criterion based on the colliding or non-colliding relation between the reference signals used in the desired cell and the at least one interfering cell.

21. The method of claim 1 wherein:

triggering the interference mitigation at the wireless device comprises triggering the interference mitigation such that the interference mitigation is performed by the wireless device prior to channel estimation; and

making the determination to trigger interference mitigation comprises making the determination to trigger interference mitigation when predefined criteria are satisfied, wherein;

the predefined criteria are based on the signal load in the at least one interfering cell, the relation between the reference signals used in the desired cell and the at least one interfering cell, and the timing relation; and

the predefined criteria comprise a first criterion that the relation between the reference signals used in the desired cell and the at least one interfering cell be colliding wherein the colliding reference signals partly or fully overlap in time and frequency.

22. The method of claim 1 wherein making the determination to trigger interference mitigation comprises making the determination to trigger interference mitigation when predefined criteria are satisfied, wherein:

the predefined criteria are based on the signal load in the at least one interfering cell, the relation between the reference signals used in the desired cell and the at least one interfering cell, and the timing relation; and

the predefined criteria comprise a first criterion that the timing relation be such that the wireless device can perform the interference mitigation using a single receiver.

23. The method of claim 1 wherein making the determination to trigger interference mitigation comprises making the determination to trigger interference mitigation when predefined criteria are satisfied, wherein:

the predefined criteria are based on the signal load in the at least one interfering cell, the relation between the reference signals used in the desired cell and the at least one interfering cell, and the timing relation; and

the predefined criteria comprise a first criterion that the timing relation be less than a predetermined threshold.

24. The method of claim 1 wherein making the determination to trigger interference mitigation is further based on one or more supplemental criteria.

25. The method of claim 24 wherein the one or more supplemental criteria comprises a criterion based on a signal operation type of the wireless device.

26. The method of claim 25 wherein the signal operation type is one of a group consisting of:

channel estimation, interference estimation, demodulation assessment, and Channel State Information (CSI) assessment.

27. The method of claim 25 wherein the signal operation type of the wireless device is interference estimation followed by channel estimation, and the at least one interfering cell comprises two or more interfering cells, and:

making the determination to trigger interference mitigation further comprises making a determination to trigger interference mitigation at the wireless device for at least one of the two or more interfering cells that is inactive prior to interference estimation and to trigger interference mitigation at the wireless device for at least one other of the two or more interfering cells that is active after interference estimation and prior to channel estimation; and

triggering interference mitigation comprises triggering interference mitigation at the wireless device for the at least one of the two or more interfering cells that is inactive prior to interference estimation and interference mitigation at the wireless device for the at least one other of the two or more interfering cells that is active after interference estimation and prior to channel estimation in response to making the determination.

28. The method of claim 24 wherein the one or more supplemental criteria comprise a criterion that interference mitigation is to be triggered depending upon a battery life of the wireless device.

29. The method of claim 24 wherein the one or more supplemental criteria comprise a criterion that interference mitigation is to be triggered if the desired cell and the at least one interfering cell correspond to a defined network deployment scenario.

30. The method of claim 24 wherein the one or more supplemental criteria comprise a criterion that interference mitigation is to be triggered if a location of the wireless device with respect to the at least one interfering cell satisfies one or more predefined conditions.

31. The method of claim 24 wherein the one or more supplemental criteria comprise a criterion that interference mitigation is to be triggered if a frequency error between the desired cell and the at least one interfering cell is less than a threshold.

32. A node associated with a cellular communications network, comprising:

a processor configured to;

make a determination to trigger interference mitigation at a wireless device based on;

a signal load in at least one interfering cell from which transmissions result in interference at the wireless device during reception from a desired cell,

a relation between reference signals used in the desired cell and the at least one interfering cell, and

a timing relation between at least one of the group consisting of;

signals transmitted by the desired cell and the at least one interfering cell, and

signals received at the wireless device from the desired cell and the at least one interfering cell; and

trigger interference mitigation at the wireless device in response to making the determination to trigger interference mitigation at the wireless device.

33. The node of claim 32 wherein the node is the wireless device.

34. The node of claim 32 wherein the node is a network node of the cellular communications network.

35. The node of claim 34 wherein the network node is a radio access node.

36. The node of claim 35 wherein the radio access node is a base station of a serving cell of the wireless device.