Carrier selection method

• US 20040157561A1
• Filed: 11/20/2003
• Published: 08/12/2004
• Est. Priority Date: 05/30/2001
• Status: Abandoned Application

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Akerberg, Dag
• Application Number:
  US10/478,314
• Publication Number:
  US 20040157561A1
• Time in Patent Office: Days
• US Class Current: 455/67.11
• CPC Class Codes: H04J 11/005 of intercell interference
• CPC Class Codes: H04W 36/20 for optimising the interference level

Abstract

The present invention discloses a carrier selection method for reducing interferences between mobile stations and/or base stations. A measure associated with a probability for a mobile station, having access to at least two carrier duplex entities, to produce interferences with adjacent external spectrum blocks is obtained. A candidate carrier duplex entity is then selected based on the interference measure. If the measure is lower than a first threshold value an inner carrier duplex entity should be selected as candidate carrier duplex entity. A mobile station in idle mode then locks to a downlink carrier of the candidate carrier duplex entity upon locking into a system. Mobile stations in an idle locked mode relocks to the downlink carrier of the carrier duplex entity, whereas mobile stations in an active mode perform a carrier handover to the candidate carrier duplex entity, unless already locked thereto.

Claims

1. A method of carrier reselection for a mobile station (11) in an idle locked mode of a cellular communication system (1) using a spectrum block (51) having at least a first (62, 63) and a second (61) carrier duplex entity, said carrier duplex entity (61, 62, 63) being defined as a number of carriers which together provides for both uplink and downlink communication, said number being equal or larger than one, comprising the steps of:

selecting a candidate carrier duplex entity for said mobile station (11); and

relocking.said mobile station (11) to a downlink carrier of said candidate carrier duplex entity if said downlink carrier is different from a downlink carrier, to which said mobile station (11) presently is locked, characterized by the step of;

obtaining a measure associated with a probability for said mobile station (11) to produce interference with adjacent external spectrum blocks (52) used by an external communication system (2), whereby a low value of said measure is connected to a high interference probability, said measure is obtained without any communication between said cellular communication system (1) and said external system (2) and based solely on measurement of a signal originating from said cellular communication system (1), said selecting step in turn comprises selecting said first carrier duplex entity (62, 63) as said candidate carrier duplex entity if said measure is lower than a first threshold value, said first carrier duplex entity (62, 63) having a larger frequency separation to said external spectrum blocks (52) than said second carrier duplex entity (61).

2. The method according to claim 1, characterized by the further step of:

performing any call set up and following traffic on the carrier duplex entity associated with the downlink carrier, to which said mobile station (11) is locked at the time for said call set up.

4. The method according to any of the claims 1 to 3, characterized in that said selecting step further comprises selecting said second carrier duplex entity (61) as said candidate carrier duplex entity if said measure. exceeds a second threshold value, said second threshold value being equal or larger than said first threshold value.

5. The method according to claim 4, characterized in that said second threshold value is larger than said first threshold value.

6. The method according to any of the claims 1 to 5, characterized by transmitting at least one of said first and second threshold values to said mobile station (11) upon request by said mobile station (11), or upon registering to said system (1).

7. The method according to any of the claims 1 to 6, characterized by transmitting notations of said first (62, 63) and second (61) carrier duplex entity to said mobile station (11) upon request by said mobile station (11), or upon registering to said system (1).

11. The method according to any of the claims 1 to 10, characterized by receiving at least one of said first and second threshold values as repeated broadcast information.

12. The method according to any of the claims 1 to 11, characterized by receiving notations of said first (62, 63) and second (61) carrier duplex entity as repeated broadcast information.

13. The method according to any of the claims 1 to 12, characterized in that said mobile station (11) has uplink power control and said measure is at least partly based on a propagation loss from a closest own base station (21).

14. The method according to claim 13, characterized in that said measure is dependent on a radio signal strength of a broadcast control channel.

15. The method according to any of the claims 1 to 14, characterized by adapting at least one of said first and second threshold values based on traffic load and recorded history of link quality and outage.

16. The method according to any of the claims 1 to 14, characterized by storing at least one of said first and second threshold values in hardware in said mobile station (11).

17. The method according to any of the claims 1 to 16, characterized by storing notations of said first (62, 63) and second (61) carrier duplex entity in hardware in said mobile station (11).

18. The method according to any of the claims 1 to 17, characterized in that said first (62, 63) and second (61) carrier duplex entity are self-contained with broadcast, uplink and downlink control channels and traffic channels.

19. The method according to any of the claims 1 to 18, characterized in that said communication system (1) is a code division multiple access (CDMA) based system.

20. The method according to claim 19, characterized in that said communication system (1) is a wideband code division multiple access (W-CDMA) based system.

21. The method according to any of the claims 1 to 20, characterized in that said cellular communication system (1) is a frequency division duplex (FDD) system.

22. The method according to claim 21, characterized in that a carrier duplex entity comprises at least two carriers, of which a first carrier provides uplink communication and a second carrier provides downlink communication.

23. The method according to any of the claims 1 to 20, characterized in that said cellular communication system (1) is a time division duplex (TDD) system.

24. The method according to claim 23, characterized in that a carrier duplex entity comprises a carrier, which provides both uplink and downlink communication.

25. The method according to any of the claims 1 to 24, characterized in that said cellular communication system (1) is a macro cell system.

26. The method according to any of the claims 1 to 25, characterized in that said external cellular communication system (2) having only one carrier duplex entity (60).

27. The method according to any of the claims 1 to 26, characterized in that said external cellular communication system (2) is a time division duplex (TDD) cellular communication system (2).

28. The method according to any of the claims 1 to 26, characterized in that said external cellular communication system (2) is a frequency division duplex (FDD) cellular communication system (2).

29. The method according to any of the claims 1 to 28, characterized in that said external cellular communication system (2) is a micro/pico cellular communication system (2).

3. A method of carrier handover for a mobile station (11) in an active mode of a cellular communication system (1) using a spectrum block having at least a first (62, 63) and a second (61) carrier duplex entity, said carrier duplex entity (61, 62, 63) being defined as a number of carriers which together provides for both uplink and downlink communication, said number being equal or larger than one, comprising the steps of:

selecting a candidate carrier duplex entity for said mobile station (11); and

performing a carrier handover to said candidate carrier duplex entity if said candidate carrier duplex entity is different from a carrier duplex entity presently used by said mobile station (11), characterized by the step of;

obtaining a measure associated with a probability for said mobile station (11) to produce interference with adjacent external spectrum blocks (52) used by an external communication system (2), whereby a low value of said measure is connected to a high interference probability, said measure is obtained without any communication between said cellular communication system (1) and said external system (2) and based solely on measurement of a signal originating from said cellular communication system (1), said selecting step in turn comprises selecting said first carrier duplex entity (62, 63) as said candidate carrier duplex entity if said measure is lower than a first threshold value, said first carrier duplex entity (62, 63) having a larger frequency separation to said external spectrum blocks (52) than said second carrier duplex entity (61).

8. A method of carrier selection for a mobile station (11) in an idle mode of a cellular communication system (1) using a spectrum block (51) having at least a first (62, 63) and a second (61) carrier duplex entity, said carrier duplex entity (61, 62, 63) being defined as a number of carriers which together provides for both uplink and downlink communication, said number being equal or larger than one, comprising the steps of:

selecting a candidate carrier duplex entity for said mobile station (11); and

locking said mobile station (11) to a downlink carrier of said candidate carrier duplex entity upon locking into said communication system (1) from said idle mode to an idle locked mode, characterized by the step of;

obtaining a measure associated with a probability for said mobile station (11) to produce interference with adjacent external spectrum blocks (52) used by an external communication system (2), whereby a low value of said measure is connected to a high interference probability, said measure is obtained without any communication between said cellular communication system (1) and said external system (2) and based solely on measurement of a signal originating from said cellular communication system (1), said selecting step in turn comprises selecting said first carrier duplex entity (62) as said candidate carrier duplex entity if said measure is lower than a first threshold value, said first carrier duplex entity (62, 63) having a larger frequency separation to said external spectrum blocks (52) than said second carrier duplex entity (61).

9. The method according to claim 8, characterized in that said selecting step further comprises selecting said second carrier duplex entity (61) as said candidate carrier duplex entity if said measure exceeds a second threshold value, said second threshold value being equal or larger than said first threshold value.

10. The method according to claim 9, characterized in that said second threshold value is larger than said first threshold value.

30. A cellular communication system (1), comprising:

a number of base stations (21) having means for communication with mobile stations (11) and using a spectrum block (51) having at least a first (62, 63) and a second (61) carrier duplex entity, said carrier duplex entity (61, 62, 63) being defined as a number of carriers which together provides for both uplink and downlink communication, said number being equal or larger than one;

selecting means for selecting a candidate carrier duplex entity; and

at least one of the means of the following list;

means for locking mobile stations (11) being in an idle mode to a downlink carrier of said candidate carrier duplex entity;

means for relocking mobile stations (11) being an idle locked mode to a candidate carrier said candidate carrier duplex entity if said downlink carrier is different from a downlink carrier, to which said mobile stations (11) presently is locked to; and

means for performing a carrier handover to said candidate carrier duplex entity if said candidate carrier duplex entity is different from a carrier duplex entity presently used by said mobile stations (11), characterized by;

means for obtaining a measure associated with a probability for said mobile stations (11) to produce interference with adjacent external spectrum blocks (52) used by an external communication system (2), whereby a low value of said measure is connected to a high interference probability, said measure is obtained without any communication between said cellular communication system (1) and said external system (2) and based solely on measurement of a signal originating from said cellular communication system (1), said selecting means being connected to said means for obtaining said measure and being arranged for selecting said first carrier duplex entity (62, 63) as said candidate carrier duplex entity if said measure is lower than a first threshold value, said first carrier duplex entity (62, 63) having a larger frequency separation to said external spectrum blocks (52) than said second carrier duplex entity (61).

31. The system according to claim 30, characterized by means for performing any call set up and following traffic on the carrier duplex entity associated with the downlink carrier, to which mobile stations (11) being in an idle locked mode are locked at the time for said call set up.

32. The system according to claim 30 or 31, characterized in that said selecting means in turn comprises means for selecting said second carrier duplex entity (61) as said candidate carrier duplex entity if said measure exceeds a second threshold value, said second threshold value being equal or larger than said first threshold value.

33. The system according to claim 32, characterized in that said second threshold value is larger than said first threshold value.

34. The system according to any of the claims 30 to 33, characterized by uplink power control means and in that said measure is at least partly based on a propagation loss from a closest own base station (21).

35. The system according to claim 34, characterized in that said measure is dependent on a radio signal strength of a broadcast control channel.

36. The system according to any of the claims 30 to 35, characterized by transmitting means (228) transmitting at least one of said first and second threshold values and/or notations of said first (62, 63) and second (61) carrier duplex entity.

37. The system according to any of the claims 30 to 36, characterized by means (224) adapting at least one of said first and second threshold values based on traffic load and recorded history of link quality and outage.

38. The system according to any of the claims 30 to 37, characterized in that said first (62, 63) and second (61) carrier duplex entity are self-contained with broadcast, uplink and downlink control channels and traffic channels.

39. The system according to any of the claims 30 to 38, characterized in that said communication system (1) is a code division multiple access (CDMA) based system.

40. The system according to claim 39, characterized in that said communication system (1) is a wideband code division multiple access (W-CDMA) based system.

41. The system according to any of the claims 30 to 40, characterized in that said cellular communication system (1) is a frequency division duplex (FDD) system.

42. The system according to claim 41, characterized in that a carrier duplex entity comprises at least two carriers, of which a first carrier provides uplink communication and a second carrier provides downlink communication.

43. The system according to any of the claims 30 to 40, characterized in that said cellular communication system (1) is a time division duplex (TDD) system.

44. The system according to claim 43, characterized in that a carrier duplex entity comprises a carrier, which provides both uplink and downlink communication.

45. The system according to any of the claims 30 to 44, characterized in that said cellular communication system (1) is a macro cell system.

46. The system according to any of the claims 30 to 45, characterized in that said external cellular communication system (2) having only one carrier duplex entity (60).

47. The system according to any of the claims 30 to 46, characterized in that said external cellular communication system (2) a time division duplex (TDD) cellular communication system (2).

48. The system according to any of the claims 30 to 46, characterized in that said external cellular communication system (2) a frequency division duplex (FDD) cellular communication system (2).

49. The system according to any of the claims 30 to 48, characterized in that said external cellular communication system (2) a micro/pico cellular communication system (2).

50. A mobile station (11) in of a cellular communication system (1) using a spectrum block (51) having at least a first (62, 63) and a second (61) carrier duplex entity, said carrier duplex entity (61, 62, 63) being defined as a number of carriers which together provides for both uplink and downlink communication, comprising:

selecting means (206) for selecting a candidate carrier duplex entity for said mobile station (11); and

at least one of the means of the following list;

means (200) for locking said mobile station (11) to a downlink carrier of said candidate carrier duplex entity upon locking into said communication system (1) from an idle mode to an idle locked mode;

means (202) for relocking said mobile station (11) to a downlink carrier of said candidate carrier duplex entity if said downlink carrier is different from a downlink carrier, to which said mobile station (11) presently is locked to; and

means (204) for performing a carrier handover to said candidate carrier duplex entity if said candidate carrier duplex entity is different from a carrier duplex entity presently used by said mobile station (11), characterized by;

means (208) for obtaining a measure associated with a probability for said mobile station (11) to produce interference with adjacent external spectrum blocks (52) used by an external communication system (2), whereby a low value of said measure is connected to a high interference probability, said measure is obtained without any communication between said cellular communication system (1) and said external system (2) and based solely on measurement of a signal originating from said cellular communication system (1), said selecting means (206) being connected to said means (208) for obtaining said measure and being arranged for selecting said first carrier duplex entity (62, 63) as said candidate carrier duplex entity if said measure is lower than a first threshold value, said first carrier duplex entity (62, 63) having a larger frequency separation to said external spectrum blocks (52) than said second carrier duplex entity (61).

51. The mobile station according to claim 50, characterized by means for performing any call set up and following traffic on the carrier duplex entity associated with the downlink carrier, to which said mobile station (11) is locked at the time for said call set up.

52. The mobile station according to claim 50 or 51, characterized in that said selecting means (206) in turn comprises means for selecting said second carrier duplex entity (61) as said candidate carrier duplex entity if said measure exceeds a second threshold value, said second threshold value being equal or larger than said first threshold value.

53. The mobile station according to claim 52, characterized in that said second threshold value is larger than said first threshold value.

54. The mobile station according to any of the claims 50 to 53, characterized by receiver means (214) for receiving at least one of said first and second threshold values and/or notations of said first (62, 63) and second (61) carrier duplex entity.

55. The mobile station according to any of the claims 50 to 54, characterized by uplink power control means (210) and in that said measure is at least partly based on a propagation loss from a closest own base station (21).

56. The mobile station according to claim 55, characterized in that said measure is dependent on a radio signal strength of a broadcast control channel.

57. The mobile station according to any of the claims 50 to 56, characterized by memory means (212) storing at least one of said first and second threshold values and/or notations of said first (62, 63) and second (61) carrier duplex entity.

58. The mobile station according to any of the claims 50 to 57, characterized in that said communication system (1) is a code division multiple access (CDMA) based system.

59. The mobile station according to claim 58, characterized in that said communication system (1) is a wideband code division multiple access (W-CDMA) based system.

60. The mobile station according to any of the claims 50 to 59, characterized in that said cellular communication system (1) is a frequency division duplex (FDD) system.

61. The mobile station according to claim 60, characterized in that a carrier duplex entity comprises at least two carriers, of which a first carrier provides uplink communication and a second carrier provides downlink communication.

62. The mobile station according to any of the claims 50 to 59, characterized in that said cellular communication system (1) is a time division duplex (TDD) system.

63. The mobile station according to claim 62, characterized in that a carrier duplex entity comprises a carrier, which provides both uplink and downlink communications.