Cellular system

• US 6,842,616 B2
• Filed: 03/14/2002
• Issued: 01/11/2005
• Est. Priority Date: 03/14/2001
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Hamabe, Kojiro, Takano, Nahoko
• Primary Examiner(s): Tran, Congvan
• Application Number:
  US10/096,833
• Publication Number:
  US 20020132621A1
• Time in Patent Office: 1,034 Days
• Field of Search: 455/435.1, 455/435.2, 455/522, 455/524, 455/525, 455/161.3, 455/67.11, 455/67.13, 455/67.14, 455/115.1, 455/115.3, 370/328, 370/331, 370/332, 370/333
• US Class Current: 455/435.2
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 36/30 by measured or perceived connection quality data
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 88/12 Access point controller devices
• CPC Class Codes: H04W 92/12 between access points and access point controllers

Abstract

A cellular system includes a mobile station and base stations, wherein the mobile station establishes a communication line with N first base stations wherein N is an integer (1≦N), measures receipt quality in pilot signals transmitted from the N first base stations, determines M second base stations to make communication therethrough among the N first base stations, based on measurement results of the receipt quality, wherein M is an integer (1≦M≦N), and transmits an designation signal to the M second base stations through upward line to designate the M second base stations as a base station through which the mobile station makes communication, and each of the base stations makes communication with the mobile station, if designated by the designation signal, and does not make communication with the mobile station, if not designated. The cellular system further includes a first apparatus for varying a signal-receipt error rate in the designation signal to be transmitted through upward line in accordance with a target signal-receipt error rate in downward line.

Claims

1. A cellular system comprising at least one mobile station and a plurality of base stations,

wherein said mobile station establishes a communication line with N first base stations wherein N is an integer equal to or greater than one (1≦

N), measures receipt quality in pilot signals transmitted from said N first base stations, determines M second base stations to make communication therethrough among said N first base stations, based on measurement results of said receipt quality, wherein M is an integer equal to or greater than one, but equal to or smaller than N(1≦

M≦

N), and transmits an designation signal to said M second base stations through upward line to designate said M second base stations as a base station through which said mobile station makes communication, and

each of said base stations makes communication with said mobile station, if designated by said designation signal as a base station through which said mobile station makes communication, and does not make communication with said mobile station, if not designated by said designation signal,

said cellular system further includes a first apparatus for varying a signal-signal-receipt error rate in said designation signal to be transmitted through upward line in accordance with a target signal-signal-receipt error rate in downward line.

2. The cellular system as set forth in claim 1, wherein said first apparatus determines a transmission ratio for transmitting said designation signal, in accordance with said target signal-signal-receipt error rate in downward line, to control said signal-signal-receipt error rate in said designation signal in said base stations making communication with said mobile station.

3. The cellular system as set forth in claim 1, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus therein.

4. The cellular system as set forth in claim 1, wherein each of said base stations includes first said apparatus.

5. The cellular system as set forth in claim 1, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus constituted as an apparatus which determines said target signal interference ratio in said upward line in said base stations in accordance with said target signal-signal-receipt error rate in said downward line, while a power at which said mobile station transmits a signal is controlled in a closed-loop such that receipt quality in said upward line reaches a target signal interference ratio.

6. The cellular system as set forth in claim 1, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus constituted as an apparatus which determines a higher target signal interference ratio in said upward line for a lower target signal-signal-receipt error rate in said downward line.

7. The cellular system as set forth in claim 1, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus constituted as an apparatus which determines a power at which said mobile station transmits said designation signal, in accordance with a target signal-signal-receipt error rate in said downward line.

8. The cellular system as set forth in claim 1, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus constituted as an apparatus which, when said mobile station transmits both a control signal to which said designation signal is multiplexed and an information signal to said base stations, determines a higher ratio of said control signal to said information signal with respect to a power at which said mobile station transmits said control and information signals, for a smaller target receipt rate in said downward line.

9. The cellular system as set forth in claim 1, wherein said mobile station includes said first apparatus constituted as an apparatus which determines a power at which said mobile station transmits said designation signal, in accordance with a target signal-signal-receipt error rate in the downward line.

10. The cellular system as set forth in claim 1, wherein said mobile station includes said first apparatus constituted as an apparatus which, when said mobile station transmits both a control signal to which said designation signal is multiplexed and an information signal to said base stations, determines a higher ratio of said information signal to said control signal with respect to a power at which said mobile station transmits said information and control signals, for a smaller target receipt rate in said downward line.

11. The cellular system as set forth in claim 1, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus constituted as an apparatus which determines a signal length of said designation signal in accordance with a target signal-signal-receipt error rate in said downward line.

12. The cellular system as set forth in claim 1, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus constituted as an apparatus which determines higher redundancy of said designation signal for a smaller target signal-signal-receipt error rate in said downward line, if said designation signal is encoded for correcting errors.

13. The cellular system as set forth in claim 1, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus constituted as an apparatus which determines a longer signal interval between said designation signal and a next designation signal for a smaller target signal-signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed number in bits per a unit time.

14. The cellular system as set forth in claim 1, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus constituted as an apparatus which determines a higher number in bits per a unit time in said designation signal for a smaller target signal-signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed transmission interval.

15. The cellular system as set forth in claim 1, wherein said mobile station includes said first apparatus constituted as an apparatus which determines a signal length of said designation signal in accordance with said target signal-signal-receipt error rate in said downward line.

16. The cellular system as set forth in claim 1, wherein said mobile station includes said first apparatus constituted as an apparatus which determines higher redundancy of said designation signal for a smaller target signal-signal-receipt error rate in said downward line, if said designation signal is encoded for correcting errors.

17. The cellular system as set forth in claim 1, wherein said mobile station includes said first apparatus constituted as an apparatus which determines a longer interval between said designation signals for a smaller target signal-signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed number of bits per a unit time.

18. The cellular system as set forth in claim 1, wherein said mobile station includes said fit apparatus constituted as an apparatus which determines a higher number in bits per a unit time in said designation signal for a smaller target signal-signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed transmission interval.

19. A cellular system comprising at least one mobile station and a plurality of base stations,

wherein said mobile station establishes a communication line with N first base stations wherein N is an integer equal to or greater than one (1≦

N), measures receipt quality in pilot signals transmitted from said N first base stations, determines M second base stations to make communication therethrough among said N first base stations, based on measurement results of said receipt quality, wherein M is an integer equal to or greater than one, but equal to or smaller than N(1≦

M≦

N), and transmits an designation signal to said M second base stations through upward line to designate said M second base stations as a base station through which said mobile station makes communication, and

each of said base stations makes communication with said mobile station, if designated by said designation signal as a base station through which said mobile station makes communication, and does not make communication with said mobile station, if not designated by said designation signal,

said cellular system further includes a first apparatus for varying conditions to determine said second base stations, in accordance with a target signal-signal-receipt error rate in downward line, to control said second base stations in number.

20. The cellular system as set forth in claim 19, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus therein.

21. The cellular system as set forth in claim 19, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus constituted as an apparatus which, when said mobile station designates a base station which transmits said pilot signal having receipt quality equal to or higher than a predetermined threshold, as said second base station, determines a higher threshold for a smaller target signal-signal-receipt error rate in said downward line.

22. The cellular system as set forth in claim 19, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus constituted as an apparatus which determines a higher number of said second base stations for a smaller target signal-signal-receipt error rate in said downward line, when said mobile station designates a base station as said second base station by a predetermined number in the order of highness in said receipt quality of said pilot signal.

23. The cellular system as set forth in claim 19, further comprising a base station controller which controls said base stations making communication with said mobile station, and wherein said base station controller includes said first apparatus constituted as an apparatus which determines all of said base stations as said second base station, if said target signal-signal-receipt error rate in said downward line is equal to or smaller than a predetermined error rate.

24. The cellular system as set forth in claim 19, wherein said mobile station includes said first apparatus constituted as an apparatus which, when said mobile station designates a base station which transmits said pilot signal having receipt quality equal to or higher than a predetermined threshold, as said second base station, determines a higher threshold for a smaller target signal-signal-receipt error rate in said downward line.

25. The cellular system as set forth in claim 19, wherein said mobile station includes said first apparatus constituted as an apparatus which determines a higher number of said second base stations for a smaller target signal-signal-receipt error rate in said downward line, when said mobile station designates a base station as said second base station by a predetermined number in the order of highness in said receipt quality of said pilot signal.

26. The cellular system as set forth in claim 19, wherein said mobile station includes said first apparatus constituted as an apparatus which determines all of said base stations as said second base station, if said target signal-signal-receipt error rate in said downward line is equal to or smaller than a predetermined error rate.

27. A base station controller for controlling a mobile station and a base station in a cellular system,

wherein said mobile station establishes a communication line with N first base stations wherein N is an integer equal to or greater than one (1≦

N), measures receipt quality in pilot signals transmitted from said N first base stations, determines M second base stations to make communication therethrough among said N first base stations, based on measurement results of said receipt quality, wherein M is an integer equal to or greater than one, but equal to or smaller than N(1≦

M≦

N), and transmits an designation signal to said M second base stations through upward line to designate said M second base stations as a base station through which said mobile station makes communication, and

each of said base stations makes communication with said mobile station, if designated by said designation signal as a base station through which said mobile station makes communication, and does not make communication with said mobile station, if not designated by said destination signal,

said base station controller includes a first apparatus for varying a signal-signal-receipt error rate in said designation signal to be transmitted through upward line in accordance with a target signal-signal-receipt error rate in downward line.

28. The base station controller as set forth in claim 27, wherein said first apparatus determines a transmission ratio for transmitting said designation signal, in accordance with said target signal-signal-receipt error rate in downward line, to control said signal-signal-receipt error rate in said designation signal in said base stations making communication with said mobile station.

29. The base station controller as set forth in claim 27, wherein said first apparatus is constituted as an apparatus which determines said target signal interference ratio in said upward line in said base stations in accordance with said target signal-signal-receipt error rate in said downward line, while a power at which said mobile station transmits a signal is controlled in a closed-loop such that receipt quality in said upward line reaches a target signal interference ratio.

30. The base station controller as set forth in claim 27, wherein said first apparatus is constituted as an apparatus which determines a higher target signal interference ratio in said upward line for a lower target signal-signal-receipt error rate in said downward line.

31. The base station controller as set forth in claim 27, wherein said first apparatus is constituted as an apparatus which determines a power at which said mobile station transmits said designation signal, in accordance with a target signal-signal-receipt error rate in said downward line.

32. The base station controller as set forth in claim 27, wherein said first apparatus is constituted as an apparatus which, when said mobile station transmits both a control signal to which said designation signal is multiplexed and an information signal to said base stations, determines a higher ratio of said control signal to said information signal with respect to a power at which said mobile station transmits said control and information signals, for a smaller target receipt rate in said downward line.

33. The base station controller as set forth in claim 27, wherein said first apparatus is constituted as an apparatus which determines a signal length of said designation signal in accordance with a target signal-signal-receipt error rate in said downward line.

34. The base station controller as set forth in claim 27, wherein said first apparatus is constituted as an apparatus which determines higher redundancy of said designation signal for a smaller target signal-signal-receipt error rate in said downward line, if said designation signal is encoded for correcting errors.

35. The base station controller as set forth in claim 27, wherein said first apparatus is constituted as an apparatus which determines a longer signal interval between said designation signal and a next designation signal for a smaller target signal-signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed number in bits per a unit time.

36. The base station controller as set forth in claim 27, wherein said first apparatus is constituted as an apparatus which determines a higher number in bits per a unit time in said designation signal for a smaller target signal-signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed transmission interval.

37. A base station controller for controlling a mobile station and a base station in a cellular system,

wherein said mobile station establishes a communication line with N first base stations wherein N is an integer equal to or greater than one (1≦

N), measures receipt quality in pilot signals transmitted from said N first base stations, determines M second base stations to make communication therethrough among said N first base stations, based on measurement results of said receipt quality, wherein M is an integer equal to or greater than one, but equal to or smaller than N(1≦

M≦

N), and transmits an designation signal to said M second base stations through upward line to designate said M second base stations as a base station through which said mobile station makes communication, and

each of said base stations makes communication with said mobile station, if designated by said designation signal as a base station through which said mobile station makes communication, and does not make communication with said mobile station, if not designated by said designation signal,

said base station controller further includes a tenth apparatus for varying conditions to determine said second base stations, in accordance with a target signal-signal-receipt error rate in downward line, to control said second base stations in number.

38. The base station controller as set forth in claim 37, wherein said first apparatus is constituted as an apparatus which, when said mobile station designates a base station which transmits said pilot signal having receipt quality equal to or higher than a predetermined threshold, as said second base station, determines a higher threshold for a smaller target signal-signal-receipt error rate in said downward line.

39. The base station controller as set forth in claim 37, wherein said first apparatus is constituted as an apparatus which determines a higher number of said second base stations for a smaller target signal-receipt error rate in said downward line, when said mobile station designates a base station as said second base station by a predetermined number in the order of highness in said receipt quality of said pilot signal.

40. The base station controller as set forth in claim 37, wherein said first apparatus is constituted as an apparatus which determines all of said base stations as said second base station, if said target signal-receipt error rate in said downward line is equal to or smaller than a predetermined error rate.

41. A mobile station which defines a cellular system together with a plurality of base stations,

wherein said mobile station establishes a communication line with N first base stations wherein N is an integer equal to or greater than one (1≦

N), measures receipt quality in pilot signals transmitted from said N first base stations, determines M second base stations to make communication therethrough among said N first base stations, based on measurement results of said receipt quality, wherein M is an integer equal to or greater than one, but equal to or smaller than N(1≦

M≦

N), and transmits an designation signal to said M second base stations through upward line to designate said M second base stations as a base station through which said mobile station makes communication, and

said mobile station includes a first apparatus for varying a signal-receipt error rate in said designation signal to be transmitted through upward line in accordance with a target signal-receipt error rate in downward line.

42. The mobile station as set forth in claim 41, wherein said first apparatus is constituted as an apparatus which determines a power at which said mobile station transmits said designation signal, in accordance with a target signal-receipt error rate in said downward line.

43. The mobile station as set forth in claim 41, wherein said first apparatus is constituted as an apparatus which, when said mobile station transmits both a control signal to which said designation signal is multiplexed and an information signal to said base stations, determines a higher ratio of said control signal to said information signal with respect to a power at which said mobile station transmits said control and information signals, for a smaller target receipt rate in said downward line.

44. The mobile station as set forth in claim 41, wherein said first apparatus is constituted as an apparatus which determines a signal length of said designation signal in accordance with a target signal-receipt error rate in said downward line.

45. The mobile station as set forth in claim 41, wherein said first apparatus is constituted as an apparatus which determines higher redundancy of said designation signal for a smaller target signal-receipt error rate in said downward line, if said designation signal is encoded for correcting errors.

46. The mobile station as set forth in claim 41, wherein said first apparatus is constituted as an apparatus which determines a longer signal interval between said designation signal and a next designation signal for a smaller target signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed number in bits per a unit time.

47. The mobile station as set forth in claim 41, wherein said first apparatus is constituted as an apparatus which determines a higher number in bits per a unit time in said designation signal for a smaller target signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed transmission interval.

48. A mobile station which defines a cellular system together with a plurality of base stations,

wherein said mobile station establishes a communication line with N first base stations wherein N is an integer equal to or greater than one (1≦

N), measures receipt quality in pilot signals transmitted from said N first base stations, determines M second base stations to make communication therethrough among said N first base stations, based on measurement results of said receipt quality, wherein M is an integer equal to or greater than one, but equal to or smaller than N(1≦

M≦

N), and transmits an designation signal to said M second base stations through upward line to designate said M second base stations as a base station through which said mobile station makes communication, and

said mobile station includes a first apparatus for varying conditions to determine said second base stations, in accordance with a target signal-receipt error rate in downward line, to control said second base stations in number.

49. The mobile station as set forth in claim 48, wherein said first apparatus is constituted as an apparatus which, when said mobile station designates a base station which transmits said pilot signal having receipt quality equal to or higher than a predetermined threshold, as said second base station, determines a higher threshold for a smaller target signal-receipt error rate in said downward line.

50. The mobile station as set forth in claim 48, wherein said first apparatus is constituted as an apparatus which determines a higher number of said second base stations for a smaller target signal-receipt error rate in said downward line, when said mobile station designates a base station as said second base station by a predetermined number in the order of highness in said receipt quality of said pilot signal.

51. The mobile station as set forth in claim 48, wherein said first apparatus is constituted as an apparatus which determines all of said base stations as said second base station, if said target signal-receipt error rate in said downward line is equal to or smaller than a predetermined error rate.

52. A method of controlling power at which a signal is transmitted in a cellular system comprising a mobile station and a plurality of base stations, comprising the steps of:

(a) establishing a communication line with N first base stations wherein N is an integer equal to or greater than one (1≦

N);

(b) measuring receipt quality in pilot signals transmitted from said N first base stations;

(c) determining M second base stations to make communication therethrough among said N first base stations, based on measurement results of said receipt quality, wherein M is an integer equal to or greater than one, but equal to or smaller than N(1≦

M≦

N);

(d) transmitting an designation signal to said M second base stations through upward line to designate said M second base stations as a base station through which said mobile station makes communication;

(e) making communication with said mobile station, if designated by said designation signal as a base station through which said mobile station makes communication, and does not making communication with said mobile station, if not designated by said designation signal; and

(f) varying a signal-receipt error rate in said designation signal to be transmitted through upward line in accordance with a target signal-receipt error rate in downward line,

said steps (a), (b), (c) and (d) being to be carried out by said mobile station,

said step (e) being to be carried out by said base station.

53. The method as set forth in claim 52, wherein said step (f) includes the step of determining a transmission ratio for transmitting said designation signal, in accordance with said target signal-receipt error rate in downward line, to control said signal-receipt error rate in said designation signal in said base stations making communication with said mobile station.

54. The method as set forth in claim 52, further comprising the step of determining said target signal interference ratio in said upward line in said base stations in accordance with said target signal-receipt error rate in said downward line, while a power at which said mobile station transmits a signal is controlled in a closed-loop such that receipt quality in said upward line reaches a target signal interference ratio.

55. The method as set forth in claim 52, further comprising the step of determining a higher target signal interference ratio in said upward line for a lower target signal-receipt error rate in said downward line.

57. The method as set forth in claim 52, further comprising the step of, when said mobile station transmits both a control signal to which said designation signal is multiplexed and an information signal to said base stations, determining a higher ratio of said control signal to said information signal with respect to a power at which said mobile station transmits said control and information signals, or a smaller target receipt rate in said downward line.

58. The method as set forth in claim 52, further comprising the step of determining a power at which said mobile station transmits said designation signal, in accordance with a target signal-receipt error rate in the downward line, said step being to be carried out by said mobile station.

59. The method as set forth in claim 52, further comprising the step of, when said mobile station transmits both a control signal to which said designation signal is multiplexed and an information signal to said base stations, determining a higher ratio of said information signal to said control signal with respect to a power at which said mobile station transmits said information and control signals, for a smaller target receipt rate in said downward line.

60. The method as set forth in claim 52, further comprising the step of determining a signal length of said designation signal in accordance with a target signal-receipt error rate in said downward line.

61. The method as set forth in claim 52, further comprising the step of determining higher redundancy of said designation signal for a smaller target signal-receipt error rate in said downward line, if said designation signal is encoded for correcting errors.

62. The method as set forth in claim 52, further comprising the step of determining a longer signal interval between said designation signal and a next designation signal for a smaller target signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed number in bits per a unit time.

63. The method as set forth in claim 52, further comprising the step of determining a higher number in bits per a unit time in said designation signal for a smaller target signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed transmission interval.

64. The method as set forth in claim 52, further comprising the step of determining a signal length of said designation signal in accordance with said target signal-receipt error rate in said downward line, said step being to be carried out by said mobile station.

65. The method as set forth in claim 52, further comprising the step of determining higher redundancy of said designation signal for a smaller target signal-receipt error rate in said downward line, if said designation signal is encoded for correcting errors, said step being to be carried out by said mobile station.

66. The method as set forth in claim 52, further comprising the step of determining a longer interval between said designation signals for a smaller target signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed number of bits per a unit time, said step being to be carried out by said mobile station.

67. The method as set forth in claim 52, further comprising the step of determining a higher number in bits per a unit time in said designation signal for a smaller target signal-receipt error rate in the downward line, when said designation signal is designed to have a fixed transmission interval, said step being to be carried out by said mobile station.

56. The method as set forth in clam 52, further comprising the step of determining a power at which said mobile station transmits said designation signal, in accordance with a target signal-receipt error rate in said downward line.

68. A method of controlling power at which a signal is transmitted in a cellular system comprising a mobile station and a plurality of base stations, comprising the steps of:

(a) establishing a communication line with N first base stations wherein N is an integer equal to or greater than one (1≦

N);

(b) measuring receipt quality in pilot signals transmitted from said N first base stations;

(c) determining M second base stations to make communication therethrough among said N first base stations, based on measurement results of said receipt quality, wherein M is an integer equal to or greater than one, but equal to or smaller than N(1≦

M≦

N);

(d) transmitting an designation signal to said M second base stations through upward line to designate said M second base stations as a base station through which said mobile station makes communication;

(e) making communication with said mobile station, if designated by said designation signal as a base station through which said mobile station makes communication, and does not making communication with said mobile station, if not designated by said designation signal; and

(f) varying conditions to determine said second base stations, in accordance with a target signal-receipt error rate in downward line, to control said second base stations in number,

said steps (a), (b), (c) and (d) being to be carried out by said mobile station,

said step (e) being to be carried out by said base station.

69. The method as set forth in claim 68, further comprising the step of, when said mobile station designates a base station which transmits said pilot signal having receipt quality equal to or higher than a predetermined threshold, as said second base station, determining a higher threshold for a smaller target signal-receipt error rate in said downward line.

70. The method as set forth in claim 68, further comprising the step of determining a higher number of said second base stations for a smaller target signal-receipt error rate in said downward line, when said mobile station designates a base station as said second base station by a predetermined number in the order of highness in said receipt quality of said pilot signal.

71. The method as set forth in claim 68, further comprising the step of determining all of said base stations as said second base station, if said target signal-receipt error rate in said downward line is equal to or smaller than a predetermined error rate.

72. The method as set forth in claim 69, wherein said step of determining a higher threshold for a smaller target signal-receipt error rate in said downward line is carried out by said mobile station.

73. The method as set forth in claim 70, wherein said step of determining a higher number of said second base stations for a smaller target signal-receipt error rate in said downward line is carried out by said mobile station.

74. The method as set forth in claim 71, wherein said step of determining all of said base stations as said second base station is carried out by said mobile station.