Reference Signal Interference Management in Heterogeneous Network Deployments

• US 20110319025A1
• Filed: 12/22/2010
• Published: 12/29/2011
• Est. Priority Date: 06/23/2010
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Siomina, Iana, Lindbom, Lars
• Granted Patent: US 8,489,029 B2
• Time in Patent Office: Days
• US Class Current: 455/63.1
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0613 using simultaneous transmission H04B7/0686 takes precedence
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0684 using different training sequences per antenna
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: Y02D 30/00 Reducing energy consumption in communication networks

Abstract

Methods and apparatus for enabling interference coordination in a communication network. A base station includes a plurality of antenna ports. Each antenna port is configured to transmit a reference signal, and each antenna port is associated with a respective cell. The base station determines a set of cells where transmissions of reference signals is to be performed from a reduced set of the plurality of antenna ports. The base station determines a subset of antenna ports in at least one cell of the determined set of cells to enable interference coordination in the network, and transmits the reference signal from the subset of antenna ports.

Claims

1. A method in a base station for enabling interference coordination in a communication network, the base station having a plurality of antenna ports that are each configured to transmit a reference signal and are each associated with a respective cell, the method comprising:

determining a set of cells where transmission of reference signals is to be performed from a reduced set of the plurality of antenna ports,

determining a subset of antenna ports in at least one cell of the set of cells to enable interference coordination in the communication network; and

transmitting the reference signal from the subset of antenna ports.

2. The method of claim 1, further comprising:

determining a time when the reference signal is to be transmitted from a reduced set of antenna ports, wherein the time is associated with low interference subframes, and the reference signal is transmitted from the subset of the antenna ports at the determined time.

3. The method of claim 2, further comprising:

informing a user equipment about the determined time.

4. The method of claim 3, further comprising:

informing a user equipment about the subset of antenna ports.

5. The method of claim 1, further comprising:

determining a time interval during which the subset of antenna ports shall apply.

6. The method of claim 5, further comprising:

informing a user equipment about the time interval.

7. The method of claim 1, further comprising:

re-initiating transmission of reference signals from the plurality of antenna ports.

8. The method of claim 7, further comprising:

informing a user equipment about re-initiated reference signal transmissions.

9. The method of claim 1, further comprising:

receiving measurements from a user equipment.

10. The method of claim 1, wherein the subset of antenna ports is configured to avoid interference from an interfering cell or reduce interference to another cell.

11. The method of claim 10, wherein the interference coordination is implemented with respect to a high interference area of a cell.

12. The method of claim 1, wherein the subset of antenna ports is pre-configured.

13. The method of claim 2, wherein at least one of the determined time and information of the subset of antenna ports is obtained from a network node in the communication network.

14. The method of claim 1, wherein transmissions from the reduced set of antenna ports apply to a part of a system bandwidth.

15. The method of claim 1, wherein transmissions from the reduced set of antenna ports in a cell are periodic or invoked by an event.

16. A base station for enabling interference coordination in a communication network, the base station having a plurality of antenna ports that are each configured to transmit a reference signal and are each associated with a respective cell, the base station comprising:

a processor configured to

determine a set of cells where transmission of reference signals is to be performed from a reduced set of the plurality of antenna ports, and

determine a subset of antenna ports in at least one cell of the set of cells to enable interference coordination in the communication network; and

a transmitter configured to transmit the reference signals from the subset of antenna ports.

17. A method in a user equipment in a communication network, the method comprising:

determining whether a reference signal is to be received from a subset of antenna ports associated with low interference subframes, which subset of antenna ports is included in a base station and is associated with at least one cell, and

receiving the reference signal from the subset of antenna ports.

18. The method of claim 17, further comprising:

receiving information from the base station about a time that indicates when the reference signal is received from a subset of antenna ports in at least one cell,

wherein the time is associated with low interference subframes; and

determining whether a reference signal is to be received from a subset of antenna ports is based on the information received from the base station about the time.

19. The method of claim 17, further comprising:

receiving information from the base station about the subset of antenna ports in at least one cell,

wherein determining whether a reference signal is to be received from a subset of antenna ports is based on received information about the subset of antenna ports.

20. The method of claim 18, further comprising:

receiving information from the base station about a time interval that indicates a time period during which the subset set of antenna ports shall apply for at least one cell,

wherein determining whether a reference signal is to be received from a subset of antenna ports is based on received information about the time interval.

21. The method of claim 20, wherein the information about the time interval comprises an indication of whether a subset of antenna ports applies or not in the time associated with low interference subframes.

22. The method of claim 17, further comprising:

receiving information from the base station about re-initiated reference signal transmissions.

23. The method of claim 17, further comprising:

performing measurements on the subset of antenna ports.

24. The method of claim 23, further comprising:

transmitting the measurements to the base station.

25. The method of claim 17, wherein the subset of antenna ports is pre-defined.

26. The method of claim 17, wherein the subset of antenna ports is pre-defined for a layer of nodes.

27. The method of claim 17, wherein determining whether a reference signal is to be received from a subset of antenna ports is based on at least one of a reference signal pattern and a set of active antenna ports in an interfering neighbor cell.

28. A user equipment for a communication network, comprising:

a processor configured to

determine whether a reference signal is to be received from a subset of antenna ports associated with low interference subframes, which subset of antenna ports is included in a base station and is associated with at least one cell; and

receive the reference signal from a subset of antenna ports.

29. The user equipment of claim 28, wherein the processor is further configured to receive information from the base station about a time that indicates when the reference signal is to be received from a subset of antenna ports, and to determine whether a reference signal is to be received from a subset of antenna ports based on received information about the time.

30. The user equipment of claim 28, wherein the processor is further configured to receive information from the base station about the subset of antenna ports, and to determine whether a reference signal is to be received from a subset of antenna ports based on received information about the subset of antenna ports.

31. A method in a user equipment in a cell of a plurality of cells in a communication network, the method comprising:

acquiring information about a set of interfering cells among the plurality of cells;

identifying a set of time-frequency resources affected by the set of interfering cells; and

performing puncturing on the set of time-frequency resources.

32. The method of claim 31, wherein the set of interfering cells is based on at least one of user equipment capability, cell grouping, a desired number of most critical interfering cells to account for puncturing, and impact on an interference level.

33. The method of claim 31, wherein the information about the set of interfering cells includes assistance data configured to assist the user equipment in the puncturing on the set of time-frequency resources.

34. The method of claim 33, wherein the assistance data comprises at least one of a set of physical layer cell identities, a transmit bandwidth of an interfering cell, channel-related information, and a number of antenna ports.

35. The method of claims 33, further comprising:

autonomously extracting the assistance data from acquired information.

36. The method of claim 31, wherein information about interfering cells is acquired from a serving cell or a network node in the communication network.

37. The method of claim 31, wherein the set of time-frequency resources is identified based on a reference signal transmit pattern.

38. The method of claim 31, wherein each cell in the set of interfering cells is associated with a strong interfering signal that has a signal strength above a threshold.

39. A user equipment for a cell of a plurality of cells in a communication network, the user equipment comprising:

a processor configured to

acquire information about a set of interfering cells among the plurality of cells,

identify a set of time-frequency resources affected by the set of interfering cells; and

perform puncturing on the set of time-frequency resources.

40. The user equipment of claim 39, wherein the set of interfering cells is based on at least one of user equipment capability, cell grouping, a desired number of most critical interfering cells to account for puncturing, and an impact on an interference level.

41. A method in a network node for enabling interference coordination in a communication network, the network node being associated with a cell, the method comprising:

acquiring information about a set of interfering cells among a plurality of cells; and

transmitting the information about the set of interfering cells to a user equipment to enable interference coordination in the communication network.

42. The method of claim 41, wherein the information about the set of interfering cells comprises assistance data.

43. The method of claim 42, wherein the assistance data comprises at least one of a set of physical layer cell identities, a transmit bandwidth of an interfering cell, channel-related information, and a number of antenna ports.

44. The method of claim 41, wherein transmitting the information about the set of interfering cells is triggered upon detecting predetermined interference conditions for user equipment in the communication network.

45. The method according to claim 41, wherein the network node is associated with an interfering macro cell.

46. A network node for enabling interference coordination in a communication network, the network node being associated with a cell, the network node comprising:

a processor configured to acquire information about a set of interfering cells among a plurality of cells; and

one or more antennas configured to transmit information about the set of interfering cells to a user equipment to enable interference coordination in the communication network, wherein the information transmitted is based on the information acquired.

47. The network node of claim 46, wherein the one or more antennas are further configured to transmit the information about the set of interfering cells when predetermined interference conditions for the user equipment are detected in the communication network.

48. A method in a network node for enabling interference coordination in a communication network, wherein the network node includes a plurality of antenna ports that are each configured to transmit a reference signal according to a signal pattern, the method comprising:

deciding an active set of antenna ports from the plurality of antenna ports based on a reserved subset of signal patterns associated with at least one layer of network nodes, the reserved subset of signal patterns being associated with low interference and reserved from a plurality of signal patterns or indications to signal patterns; and

transmitting reference signals from the active set of antenna ports according to the reserved subset of signal patterns, thereby enabling interference coordination in the communication network.

49. The method of claim 48, further comprising:

reserving a subset of signal patterns for at least one layer of network nodes, wherein the subset of signal patterns is reserved from the plurality of signal patterns or indications to signal patterns, and the subset of signal patterns is associated with low interference.

50. The method of claim 49, wherein the subset of signal patterns is reserved for a group of network nodes.

51. The method of claim 50, wherein the group network nodes belongs to a layer.

52. The method of claim 48, wherein the plurality of signal patterns or indications to signal patterns is pre-configured in the network node, obtained from a second network node, or obtained from a macro cell.

53. The method of claim 48, wherein the set of active antenna ports is decided based on low-interference subframes.

54. The method of claim 48, wherein the reserved subset of signal patterns is dynamically maintained by the communication network.

55. The method of claim 48, wherein the reserved subset of signal patterns is based on the set of active antenna ports to be used by another layer in low-interference subframes.

56. A network node for enabling interference coordination in a communication network, the network node having a plurality of antenna ports that are each configured to transmit a reference signal according to a signal pattern, the network node comprising:

a processor configured to decide an active set of antenna ports from the plurality of antenna ports based on a reserved subset of signal patterns associated with at least one layer of network node, wherein the subset of signal patterns is associated with low interference and is reserved from a plurality of signal patterns or indications to signal patterns; and

a transmitter configured to transmit reference signals from the active set of antenna ports according to the reserved subset of signal patterns, thereby enabling interference coordination in the communication network.

57. The network node of claim 56, wherein the plurality of signal patterns or indications to signal patterns is pre-configured in the network node or configured based on information received from a second network node in the communication network or configured based on information obtained from a macro cell associated with a base station.