Base station, mobile station and control method therefor

• US 20060046765A1
• Filed: 08/30/2005
• Published: 03/02/2006
• Est. Priority Date: 09/01/2004
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Kogure, Yuki
• Granted Patent: US 7,693,536 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/28 using user profile, e.g. mobile speed, priority or network state, e.g. standby, idle or non transmission
• CPC Class Codes: H04W 52/282 taking into account the speed of the mobile
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 52/285 taking into account the mobility of the user
• CPC Class Codes: H04W 52/362 Aspects of the step size
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

An exemplary method for a communication network according to the present invention includes detecting movement of a mobile station, and modifying a control for the communication network based on the detection of the movement. In an exemplary embodiment, a transmit power control may be increased or decreased based the movement of the mobile station which is detected. Further, the network may determine a base station among plurality of base stations which provides the best communication path, taking into account a movement state of the mobile station. Accordingly, a stable hand over process may be realized, providing favorable communication quality and minimizing the occurrence of disconnection of the mobile terminal from a base station.

Claims

1. A method for a communication network in which a mobile station transmits and receives wireless signals to and from a plurality of base stations, the method comprising:

detecting movement of a mobile station; and

modifying, at a first base station among the plurality of base stations, a transmit power control based on the detection of the movement of the mobile station, the transmit power control comprising controlling transmit power of a wireless signal to the mobile station based on a transmit power control signal which is received from the mobile station, and the transmit power control signal requesting increase or decrease of the transmit power.

2. The method according to claim 1, further comprising

detecting whether a first reception quality at the mobile station of a wireless signal transmitted from the first base station is the highest value among reception qualities of wireless signals from the plurality of base stations;

wherein

the transmit power control is modified based on both the movement of the mobile station and the detection regarding the first reception quality in the modifying the transmit power control.

3. The method according to claim 1, wherein the transmit power control comprises at least increasing the transmit power by a first predetermined control step or decreasing the transmit power by a second predetermined control step, and the modified transmit power control comprises at least:

raising at least the first predetermined control step or the second predetermined control step; and

increasing the transmit power if the first base station receives a first predetermined number of transmit power control signals requesting to increase the transmit power in sequence and decreasing the transmit power if the first base station receives a second predetermined number of transmit power control signals requesting to decrease the transmit power in sequence, the second predetermined number being equal to or more than the first predetermined number.

4. The method according to claim 1, wherein the transmit power control is modified if the mobile station approaches the first base station.

5. The method according to claim 1, wherein the detecting the movement comprises detecting whether the mobile station approaches the first base station.

6. The method according to claim 5, wherein the movement of the mobile station is detected based on at least one of:

reception timing of a wireless signal from the mobile station;

distances from the mobile station to a respective base station;

positional information of the mobile station obtained by using a satellite based positioning system; and

reception power at the mobile station of a pilot signal which is transmitted by the first base station at fixed transmit power.

7. The method according to claim 2, wherein the transmit power control comprises at least increasing the transmit power by a first predetermined control step or decreasing the transmit power by a second predetermined control step, and the modified transmit power control comprises at least:

raising at least the first predetermined control step or the second predetermined control step; and

increasing the transmit power if the base station receives a first predetermined number of transmit power control signals requesting increase of the transmit power in sequence and decreasing the transmit power if the base station receives a second predetermined number of transmit power control signals requesting decrease of the transmit power in sequence, the second predetermined number being equal to or more than the first predetermined number.

8. The method according to claim 2, wherein the transmit power control is modified if the first reception quality is not the highest value among reception qualities of wireless signals from the plurality of base stations.

9. The method according to claim 2, wherein the detection regarding the first quality is based on at least one of:

a notification, transmitted from the mobile station, that the first reception quality is the highest value among the reception qualities;

information regarding the first reception quality transmitted from the mobile station; and

whether the mobile station controls transmit power of a wireless signal transmitted to the first base station based on transmit power control signal transmitted to the mobile station from the first base station.

10. The method according to claim 1, further comprising detecting whether the mobile station performs a soft handover,

wherein the transmit power control is modified if the mobile station performs the soft handover.

11. The method according to claim 2, further comprising detecting whether the mobile station performs a soft handover,

wherein the transmit power control is modified if the mobile station performs the soft handover.

12. A method for a communication network in which a mobile station transmits and receives wireless signals to and from a plurality of base stations, the method comprising:

receiving, at a mobile station, downlink dedicated wireless signals from base stations in an active set which are chosen from the plurality of base stations, the downlink dedicated wireless signals being transmitted from the base stations in the active set at dynamically controlled transmit power;

receiving, at the mobile station, pilot wireless signals from the plurality of base stations, the pilot wireless signals being transmitted from the plurality of base station at fixed transmit power;

detecting movement of the mobile station;

modifying a first reception power at the mobile station of a first pilot signal transmitted from a first base station among the plurality of base stations based on the detection of the movement; and

choosing the base stations in the active set from the plurality of base stations based on the modified first reception power.

13. The method according to claim 12, further comprising:

detecting whether a first reception quality at the mobile station of a downlink dedicated wireless signal which is transmitted from the first base station among the base stations in the active set is the highest value among reception qualities of downlink dedicated wireless signals from the base stations in the active set, wherein

the first reception power is modified based on both the detection of the movement and the detection regarding the first reception quality in the modifying the first reception power.

14. The method according to claim 12, wherein the modifying the first reception power comprises at least adding a predetermined value to the first reception power, subtracting a predetermined value from the first reception power or multiplying the first reception power by a predetermined value.

15. The method according to claim 14, wherein the modifying the first reception power further comprises varying the predetermined value based on the detection of movement and the detection regarding the first quality.

16. The method according to claim 15, wherein the predetermined value is increased if the mobile station approaches the first base station.

17. The method according to claim 15, wherein the predetermined value is increased if the first reception quality is the highest among reception qualities of downlink dedicated wireless signals from the base stations in the active set.

18. A method for a communication network in which a mobile station transmits and receives wireless signals to and from a plurality of base stations, the method comprising:

detecting movement of a mobile station;

modifying a value of a first reception quality at the mobile station of a wireless signal transmitted from a first base station among a plurality of base stations based on the detection of the movement.

19. The method according to claim 18, further comprising:

detecting whether the first reception quality is the highest value among reception qualities of wireless signals from the plurality of base stations, wherein the value of the first reception quality is modified based on both the detection of the movement and the detection regarding the first reception quality in the modifying the value of the first reception quality, and the modified value of the first reception quality is utilized for the decision regarding the first reception quality.

20. The method according to claim 19, wherein the modifying the first reception quality comprises at least adding a predetermined value to the first reception power, subtracting a predetermined value from the first reception power or multiplying the first reception power by a predetermined value.

21. The method according to claim 20, wherein the modifying the first reception quality further comprises varying the predetermined value based on the detection of movement and the decision regarding the first quality.

22. The method according to claim 21, wherein the predetermined value is increased if the mobile station approaches the first base station.

23. The method according to claim 20, wherein the predetermined value is increased if the first reception quality is the highest among reception qualities of wireless signals from the plurality base stations.

24. A base station in a communication network in which a mobile station transmits and receives wireless signals to and from a plurality of base stations, the base station comprising:

a transmitter which transmits a wireless signal to a mobile station;

a receiver which receives a transmit power control signal from the mobile station, the transmit power control signal requesting to increase or decrease transmit power of the wireless signal; and

a controller, coupled to the transmitter and the receiver, which;

detects movement of a mobile station; and

modifies a transmit power control based on the detection of the movement of the mobile station, the transmit power control comprising controlling the transmit power of the wireless signal to the mobile station based on the transmit power control signal.

25. The base station according to claim 24, wherein the controller detects whether a first reception quality at the mobile station of the wireless signal transmitted from the base station is the highest value among reception qualities of wireless signals from a plurality of base stations, and modifies the transmit power control based on both the detection of the movement and the detection regarding the first reception quality.

26. The base station according to claim 24, wherein

the controller at least increases the transmit power by a first predetermined control step or decreases the transmit power by a second predetermined control step as the transmit power control, and the controller at least:

raises at least the first predetermined control step or the second predetermined control step;

or

increases the transmit power if the base station receives a first predetermined number of transmit power control signals requesting increase of the transmit power in sequence and decreases the transmit power if the base station receives a second predetermined number of transmit power control signals requesting decrease of the transmit power in sequence, the second predetermined number being equal to or more than the first predetermined number, as the modification of the transmit power control.

27. The base station according to claim 24, wherein the controller modifies the transmit power control if the mobile station approaches the first base station.

28. The base station according to claim 24, wherein the controller detects whether the mobile station approaches the first base station in the detection of the movement.

29. The base station according to claim 28, wherein the movement of the mobile station is detected based on at least one of:

reception timing of a wireless signal from the mobile station;

distances from the mobile station to the respective base station;

positional information of the mobile station obtained by using a satellite based positioning system; and

reception power at the mobile station of a pilot signal transmitted by the first base station at fixed transmit power.

30. The base station according to claim 25, wherein

the controller at least increases the transmit power by a first predetermined control step or to decrease the transmit power by a second predetermined control step as the transmit power control, and the controller at least:

raises at least the first predetermined control step or the second predetermined control step;

or

increases the transmit power if the base station receives a first predetermined number of transmit power control signals requesting to increase the transmit power in sequence and decreases the transmit power if the base station receives a second predetermined number of transmit power control signals requesting decrease of the transmit power in sequence, the second predetermined number being equal to or more than the first predetermined number, as the modification of the transmit power control.

31. The base station according to claim 25, wherein the controller modifies the transmit power control if the first reception quality is not the highest value among the reception qualities of wireless signals from the plurality of base stations.

32. The base station according to claim 25, wherein the controller performs the detection regarding the first quality based on at least one of:

a notification, transmitted from the mobile station, that the first reception quality is the highest value among the reception qualities;

information regarding the first reception quality transmitted the mobile station; and

whether the mobile station controls transmit power of a wireless signal transmitted to the first base station based on a transmit power control signal transmitted to the mobile station from the first base station.

33. The method according to claim 24, wherein the controller detects whether the mobile station performs a soft handover, and to modify the transmit power control if the mobile station performs the soft handover.

34. The method according to claim 25, wherein the controller detects whether the mobile station performs a soft handover, and to modify the transmit power control if the mobile station performs the soft handover.

35. A mobile station in a communication network in which a plurality of base station transmit and receive wireless signals to and from a mobile station, the mobile station comprising:

a receiver which receives downlink dedicated wireless signals from base stations in an active set which is chosen from the plurality of base stations, and receives pilot wireless signals from the plurality of base stations, the downlink dedicated wireless signals being transmitted from the base stations in the active set at dynamically controlled transmit power, and the pilot wireless signals being transmitted from the plurality of base station at fixed transmit power; and

a controller, coupled to the receiver, which;

detects movement of the mobile station;

modifies first reception power at the mobile station of a first pilot signal transmitted from a first base station among the base stations in the active set based on the detection of the movement; and

chooses the base stations in the active set out of the plurality of base stations based on the modified first reception power.

36. The mobile station according to claim 35, wherein the controller detects whether a first reception quality at the mobile station of a downlink dedicated wireless signal transmitted from the base station is the highest value among reception qualities of downlink dedicated wireless signals from the base stations in the active set, and modifies the first reception power based on both the detection of movement and the detection regarding the first reception quality.

37. The mobile station according to claim 36, wherein the controller modifies the first reception power by at least one of adding a predetermined value to the first reception power, subtracting a predetermined value from the first reception power and multiplying the first reception power by a predetermined value.

38. The method according to claim 37, wherein the controller varies the predetermined value based on the detection of movement and the detection regarding the first quality.

39. The method according to claim 38, wherein the predetermined value is increased if the mobile station approaches the first base station.

40. The method according to claim 39, wherein the predetermined value is increased if the first reception quality is the highest value among the reception qualities of downlink dedicated wireless signals from the base stations in the active set.

41. A mobile station in a communication network in which a plurality of base stations transmit and receive wireless signals to and from a mobile station, the mobile station comprising:

a receiver which receives wireless signals from the plurality of base stations;

a controller, coupled to the receiver, which;

detects movement of a mobile station; and

modifies a value of a first reception quality at the mobile station of a wireless signal transmitted from a first base station among the plurality of base stations based on the detection of the movement.

42. The mobile station according to claim 41, wherein the controller detects whether the first reception quality is the highest value among reception qualities of wireless signals from the plurality of base stations;

and modifies the first reception quality based on both the detection of the movement and the detection regarding to the first reception quality.

43. The mobile station according to claim 41, wherein the controller modifies the first reception quality by at least one of adding a predetermined value to the first reception power, subtracting a predetermined value from the first reception power and multiplying the first reception power by a predetermined value.

44. The mobile station according to claim 43, wherein the controller varies the predetermined value based on the detection of movement and the detection regarding the first quality.

45. The mobile station according to claim 44, wherein the predetermined value is increased if the mobile station approaches to the first base station.

46. The mobile station according to claim 43, wherein the predetermined value is increased if the first reception quality is the highest among reception qualities of wireless signals from the plurality base stations.

47. The mobile station according to claim 41, wherein the controller chooses base stations in an active set from the plurality of base station based on the modified value of the first reception quality.

48. The mobile station according to claim 41, wherein the controller set chooses a base station with which the mobile station performs a downlink transmit power control based on the modified value of the first reception quality.

49. A base station in a communication network in which a mobile station transmits and receives wireless signals to and from a plurality of base stations, the base station comprising:

transmitting means for transmitting a wireless signal to a mobile station;

receiving means for receiving a transmit power control signal from the mobile station, the transmit power control signal requesting increase or decrease of transmit power of the wireless signal; and

means, coupled to the transmitting means and the receiving means, for detecting movement of a mobile station;

means, coupled to the transmitting means and the receiving means, for modifying a transmit power control based on the detection of the movement of the mobile station, the transmit power control comprising controlling the transmit power of the wireless signal to the mobile station based on the transmit power control signal.

50. The base station according to claim 49, further comprising:

means, coupled to the transmitting means and the receiving means, for detecting whether a first reception quality at the mobile station of a wireless signal transmitted from the first base station is the highest value among reception qualities of wireless signals from the plurality of base stations, wherein

the means for modifying the transmit power control modifies the transmit power control based on both the detection of the movement and the detection of regarding the first reception quality.

51. A mobile station in a communication network in which a plurality of base stations transmit and receive wireless signals to and from a mobile station, the mobile station comprising:

receiving means for receiving downlink dedicated wireless signals from base stations in an active set that is chosen from the plurality of base stations, and for receiving pilot wireless signals from the plurality of base stations, the downlink dedicated wireless signals being transmitted from the base stations in the active set at dynamically controlled transmit power, and the pilot wireless signals being transmitted from the plurality of base station at fixed transmit power;

means, coupled to the receiving means, for detecting movement of the mobile station;

means, coupled to the receiving means, for modifying first reception power at the mobile station of a first pilot signal transmitted from a first base station among the base stations in the active set based on the detection of the movement; and

means, coupled to the receiving means, for choosing the base stations in the active set out of the plurality of base stations based on the modified first reception power.

52. The mobile station according to claim 51, further comprising:

means, coupled to the receiving means, for detecting whether a first reception quality at the mobile station of a downlink dedicated wireless signal transmitted from the first base station is the highest value among reception qualities of downlink dedicated wireless signals from the base stations in the active set, wherein

the means for modifying the first reception power which modifies the first reception power based on both the detection of the movement and the detection regarding the first reception quality.

53. A mobile station in a communication network in which a plurality of base stations transmit and receive wireless signals to and from a mobile station, the mobile station comprising:

receiving means for receiving wireless signals from the plurality of base stations;

means, coupled to the receiving means, for detecting movement of a mobile station;

means, coupled to the receiving means, for modifying a value of a first reception quality at the mobile station of a wireless signal transmitted from a first base station among the plurality of base stations based on the detection of the movement.

54. The mobile station according to claim 53, further comprising:

means, coupled to the receiving means, for detecting whether the first reception quality is the highest value among reception qualities of wireless signals from the plurality of base stations, wherein

the means for modifying the first reception quality modifies the first reception quality based on both the detection of the movement and the detection regarding the first reception quality.