Radio communication system, base station apparatus, base station control apparatus, method of controlling transmission power of base station, and computer readable medium

• US 8,805,398 B2
• Filed: 11/24/2010
• Issued: 08/12/2014
• Est. Priority Date: 12/08/2009
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Morita, Motoki, Hamabe, Kojiro
• Primary Examiner(s): PATEL, MAHENDRA R
• Application Number:
  US13/514,455
• Publication Number:
  US 20120252479A1
• Time in Patent Office: 1,357 Days
• Field of Search: 455/436, 455/456.1, 455/104, 455/423, 455/525, 455/444, 455/502, 455/437, 455/561, 455/422.1, 455/456.5, 455/452.2, 455/522, 370/328, 370/338, 370/331, 370/329, 370/352, 370/254, 370/311, 709/213, 726/4, 726/7
• US Class Current: 455/452.2
• CPC Class Codes: H04B 17/327 Received signal code power [RSCP]
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• CPC Class Codes: H04B 17/382 for resource allocation, admission control or handover
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/16 Deriving transmission power values from another channel
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/242 taking into account path loss
• CPC Class Codes: H04W 52/245 taking into account received signal strength
• CPC Class Codes: H04W 52/283 Power depending on the position of the mobile
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels

Abstract

A base station (1) includes a radio communication unit (10) for performing radio communication with at least one mobile station (6), and a controller (11) for controlling transmission power of the radio communication unit (10). The controller (11) controls transmission power of an own cell signal by the radio communication signal (10) so that reception quality of the own cell signal transmitted from the radio communication unit (10) exceeds a second standard at a position of a mobile station at which reception quality of a peripheral cell signal is lower than a first standard based on a measurement result of reception quality by the mobile station (6) of a peripheral cell signal reached from a peripheral cell. Accordingly, it is possible to efficiently suppress occurrence of dead areas at cell boundaries.

Claims

1. A radio communication system comprising:

at least one first base station which transmits a first downlink radio signal;

a second base station which transmits a second downlink radio signal;

at least one radio terminal configured to receive the first downlink radio signal and the second downlink radio signal;

wherein the second base station comprises a control unit that controls a transmission power of the second downlink radio signal based on a calculated difference between the reception quality of the second downlink radio signal and the reception quality of the first downlink radio signal measured by the at least one radio terminal, such that a reception quality of the second downlink radio signal exceeds a second predetermined value of reception quality at a position of the at least one radio terminal at which a reception quality of the first downlink radio signal is lower than a first predetermined value of reception quality based on a measurement value of the reception quality of the first downlink radio signal by the at least one radio terminal;

wherein, when the at least one radio terminal calculates the calculated difference between the reception quality of the second downlink radio signal and the reception quality of the first downlink radio signal at a position of the at least one radio terminal at which the reception quality of the first downlink radio signal exceeds the first predetermined value and the reception quality of the second downlink radio signal exceeds the reception quality of the first downlink radio signal, the control unit decreases the transmission power of the second downlink radio signal based on the calculated difference.

2. The radio communication system according to claim 1, wherein the control unit controls the transmission power of the second downlink radio signal so that the reception quality of the second downlink radio signal is equal to or smaller than the reception quality of the first radio signal at a position of the radio terminal at which the reception quality of the first radio signal exceeds the first predetermined value.

3. The radio communication system according to claim 1, wherein

the at least one radio terminal is configured to measure the reception quality of the second downlink radio signal and the reception quality of the first downlink radio signal.

4. The radio communication system according to claim 3, wherein

the control unit obtains a statistical representative value based on a plurality of calculated differences when the reception quality of the first downlink radio signal exceeds the first predetermined value and the reception quality of the second downlink radio signal exceeds the reception quality of the first radio signal, and

the control unit decreases the transmission power of the second downlink radio according to the statistical representative value.

5. The radio communication system according to claim 4, wherein the statistical representative value comprises a maximum value of the plurality of calculated differences, a minimum value of the plurality of calculated differences, an average value of the plurality of calculated differences, or an X percent value (where 0≦

X≦

100) of the plurality of calculated differences.

6. The radio communication system according to claim 1, wherein the control unit controls the transmission power of the second downlink radio signal so that the reception quality of the second downlink radio signal is equal to or smaller than the second predetermined value at a position of the radio terminal at which the reception quality of the first downlink radio signal exceeds the first predetermined value.

7. The radio communication system according to claim 1, wherein the control unit selects, from among a plurality of measurement values of the reception quality of the first downlink radio signal, a selected measurement value at which the reception quality of the first downlink radio signal is equal to or larger than the first predetermined value and the closest of the plurality of measurement values to the first predetermined value and controls the transmission power of the second downlink radio signal so that the reception quality of the second downlink radio signal at the position of the radio terminal approaches the selected measurement value of the reception quality of the first downlink radio signal.

8. The radio communication system according to claim 1, wherein the control unit controls the transmission power of the second downlink radio signal according to a calculated difference between the second predetermined value and the reception quality of the second downlink radio signal at a position of the radio terminal at which the reception quality of the first downlink radio signal is equal to the first predetermined value.

9. The radio communication system according to claim 1, wherein the control unit controls the transmission power of the second downlink radio signal so that the reception quality of the second downlink radio signal approaches the second predetermined value at a position of the radio terminal at which the reception quality of the first downlink radio signal is lower than the first predetermined value.

10. The radio communication system according to claim 9, wherein the control unit selects, from among a plurality of measurement values of the reception quality of the first downlink radio signal, a selected measurement value at which the reception quality of the first downlink radio signal is equal to or smaller than the first predetermined value and the closest of the plurality of measurement values to the first predetermined value and controls the transmission power of the second downlink radio signal so that the reception quality of the second downlink radio signal at a position of the radio terminal approaches the second predetermined value.

11. The radio communication system according to claim 1, wherein the control unit stops transmission of the second downlink radio signal when a statistical representative value exceeds the first predetermined value, wherein the statistical representative value is based on a plurality of measurement values of the reception quality of the first downlink radio signal measured by the at least one radio terminal.

12. The radio communication system according to claim 11, wherein the control unit stops transmission of the second downlink radio signal by gradually reducing transmission power of the second downlink radio signal.

13. The radio communication system according to claim 11, wherein the control unit continues transmission of the second downlink radio signal is continued when the statistical representative value is lower than the first predetermined value.

14. The radio communication system according to claim 11, wherein the statistical representative value comprises a maximum value of the plurality of measurement values, a minimum value of the plurality of measurement values, an average value of the plurality of measurement values, or an X percent value (where 0≦

X≦

100) of the plurality of measurement values.

15. The radio communication system according to claim 1,

wherein the at least one radio terminal transmits a plurality of measurement values of the reception quality of the first downlink radio signal to the second base station;

and

wherein the control unit continues transmission of the second downlink radio signal when a measurement value is lower than the first predetermined value standard is included in the plurality of measurement values.

16. The radio communication system according to claim 1, wherein

the at least one first base station comprises a plurality of first base stations which transmit a plurality of first downlink radio signals,

each of the at least one radio terminal measures reception qualities of each of the plurality of first downlink radio signals, and

the control unit determines a selected base station from among the plurality of first base stations, wherein a reception quality of the first downlink radio signal from the selected base station is the best reception quality of the plurality of first downlink radio signals, and

the control unit controls the transmission power of the second downlink radio signal so that the reception quality of the second downlink radio signal exceeds the second predetermined value at a position of the at least one radio terminal at which the reception quality of the first downlink radio signal from the selected base station is lower than the first predetermined value.

17. The radio communication system according to claim 1, wherein

the at least one radio terminal transmits control information indicating whether it is necessary to adjust the transmission power of the second downlink radio signal based on the reception quality of the first downlink radio signal, and

the control unit controls the transmission power of the second downlink radio signal based on the control information.

18. The radio communication system according to claim 17, wherein

the control information indicates a continuation of transmission of the second downlink radio signal, and

the at least one radio terminal transmits the control signal when the reception quality of the first downlink radio signal is below the first predetermined value.

19. The radio communication system according to claim 17, wherein

the control information indicates a stop of transmission of the second downlink radio signal, and

the at least one radio terminal transmits the control signal when the reception quality of the first downlink radio signal exceeds the first predetermined value.

20. The radio communication system according to claim 17, wherein the control unit receives a plurality of transmissions of the control information from the at least one radio terminal, and controls the transmission power of the second downlink radio signal based on the plurality of transmissions of the control information.

21. The radio communication system according to claim 1, wherein

the at least one first base station uses a plurality of frequency channels, and the first downlink radio signal is transmitted in each of the plurality of frequency channels, and

the control unit controls transmission of the second downlink radio signal based on a measurement result of the reception quality of the first downlink radio signal transmitted in at least one of the plurality of frequency channels.

22. The radio communication system according to claim 1, wherein

the at least one first base station uses a plurality of frequency channels, and the first downlink radio signal is transmitted in each of the plurality of frequency channels, and

the control unit controls transmission of the second downlink radio signal based on a measurement result of the reception quality of the first downlink radio signal transmitted in a frequency channel which is the same as a frequency channel in which the second radio downlink signal is transmitted.

23. The radio communication system according to claim 1, wherein

the second base station is configured to measure the reception quality of the first downlink radio signal, and

the control unit continues transmission of the second downlink radio signal when the reception quality of the first downlink radio signal measured by the at least one radio terminal or a representative value thereof is lower than the first predetermined value, or when a measurement result of the first downlink radio signal measured by the second base station is lower than a third predetermined value.

24. The radio communication system according to claim 1, wherein

the second base station is configured measure the reception quality of the first downlink radio signal, and

the control unit controls stops transmission of the second downlink radio signal when the reception quality of the first downlink radio signal measured by the at least one radio terminal or a representative value thereof exceeds the first predetermined value and a measurement result of the first downlink radio signal measured by the second base station exceeds a third predetermined value.

25. The radio communication system according to claim 1, wherein the reception quality of the first downlink radio signal comprises the reception power of the first downlink radio signal.

26. The radio communication system according to claim 1, wherein the second predetermined value is equal to the first predetermined value.

27. The radio communication system according to claim 1, wherein the at least one radio terminal comprises a mobile radio station which is configured to interactively communicate with the first base station and the second base stations by radio, and a fixed radio station which receives the first downlink radio signal and the second downlink radio signal at a predetermined position.

28. A base station apparatus comprising:

a radio communication unit that performs radio communication with at least one mobile station; and

a control unit that controls transmission power of the radio communication unit,

wherein the control unit controls transmission power of a downlink radio signal transmitted by the radio communication unit, based on a calculated difference between the reception quality of the downlink radio signal and the reception quality of a peripheral cell downlink radio signal, measured by the at least one mobile station, so that a reception quality of the downlink radio signal exceeds a second predetermined value of reception quality at a position of the at least one radio terminal at which a reception quality of the peripheral cell downlink radio signal is lower than a first predetermined value of reception quality based on a measurement value of the reception quality of the peripheral cell downlink radio signal by the at least one mobile station, and

the control unit controls the transmission power of the downlink radio signal based on the calculated difference calculated at least one position of the mobile station at which the reception quality of the peripheral cell downlink radio signal exceeds the first predetermined value and the reception quality of the downlink radio signal exceeds the reception quality of the peripheral cell downlink radio signal, and the control unit controls the transmission power of the downlink radio signal to decrease the transmission power of the downlink radio signal according to the calculated difference.

29. The base station apparatus according to claim 28, wherein the control unit controls the transmission power of the downlink radio signal so that the reception quality of the downlink radio signal is equal to or smaller than the reception quality of the peripheral cell downlink radio signal at a position of the mobile station at which the reception quality of the peripheral cell downlink radio signal exceeds the first predetermined value.

30. The base station apparatus according to claim 28, wherein

the at least one mobile station is configured to measure the reception quality of the downlink radio signal and the reception quality of the peripheral cell downlink radio signal.

31. The base station apparatus according to claim 30, wherein

the control unit obtains a statistical representative value based on a plurality of calculated differences when the reception quality of the peripheral cell downlink radio signal exceeds the first predetermined value and the reception quality of the downlink radio signal exceeds the reception quality of the peripheral cell downlink radio signal, and

the control unit decreases the transmission power of the downlink radio signal according to the statistical representative value.

32. The base station apparatus according to claim 28, wherein the control unit controls the transmission power of the downlink radio signal so that the reception quality of the downlink radio signal, as measured by the mobile station at a position at which the reception quality of the peripheral cell downlink radio signal exceeds the first predetermined value, is equal to or smaller than the second predetermined value.

33. The base station apparatus according to claim 28, wherein the control unit controls the transmission power of the downlink radio signal according to a difference between the second predetermined value and the reception quality of the downlink radio signal at a position of the mobile station at which the reception quality of the peripheral cell downlink radio signal is equal to the first predetermined value.

34. The base station apparatus according to claim 28, wherein the control unit controls the transmission power of the downlink radio signal so that the reception quality of the downlink radio signal approaches the second predetermined value at a position of the mobile station at which the reception quality of the peripheral cell downlink radio signal is lower than the first predetermined value.

35. The base station apparatus according to claim 34, wherein the control unit selects, from among a plurality of measurement values of the reception quality of the first downlink radio signal, a selected measurement value of the peripheral cell downlink signal at which the reception quality of the peripheral cell downlink signal is equal to or smaller than the first predetermined value and the closest of the plurality of measurement values to the first predetermined value and controls the transmission power of the downlink radio signal so that the reception quality of the downlink radio signal at a position of the mobile station approaches the second predetermined value.

36. The base station apparatus according to claim 28, wherein the control unit stops the transmission of the downlink radio signal when a statistical representative value based on a plurality of measurement values of the reception quality of the peripheral cell downlink radio signal measured by the at least one mobile station exceeds the first predetermined value.

37. The base station apparatus according to claim 36, wherein the control unit stops the transmission of the downlink radio by gradually reducing transmission power of the downlink radio signal.

38. The base station apparatus according to claim 36, wherein the control unit continues transmission of the downlink radio signal when the statistical representative value is lower than the first predetermined value.

39. The base station apparatus according to claim 28, wherein

the radio communication unit is configured to measure the reception quality of the peripheral cell downlink radio signal, and

the control unit stops transmission of the downlink radio signal when the reception quality of the peripheral cell downlink radio signal measured by the at least one mobile station or a representative value thereof exceeds the first predetermined value, and when the measurement result of the peripheral cell downlink radio signal measured by the radio communication unit exceeds a third predetermined value.

40. A control apparatus of a base station, the control apparatus comprising:

a control unit that controls transmission power of a downlink radio signal transmitted by the base station, based on a calculated difference between the reception quality of the downlink radio signal and the reception quality of a peripheral cell downlink radio signal, measured by at least one mobile station, so that a reception quality of the downlink radio signal transmitted from the base station exceeds a second predetermined value of reception quality, at a position of a mobile station at which a reception quality of the peripheral cell downlink radio signal is lower than a first predetermined value based on a measurement result by the at least one mobile station of the reception quality of the peripheral cell downlink radio signal, wherein the mobile station is in radio communication with the base station,

wherein the control unit controls the transmission power of the downlink radio signal based on the calculated difference calculated at least one position of the mobile station at which the reception quality of the peripheral cell downlink radio signal exceeds the first predetermined value and the reception quality of the downlink radio signal exceeds the reception quality of the peripheral cell downlink radio signal, and the control unit controls the transmission power of the downlink radio signal to decrease the transmission power of the downlink radio signal according to the calculated difference.

41. A method of controlling transmission power of a base station, the method comprising:

obtaining a reception quality of a peripheral cell downlink radio signal as measured by at least one mobile station in communication with the base station; and

controlling a transmission power of an downlink radio signal transmitted by the base station, based on a calculated difference between the reception quality of the downlink radio signal and the reception quality of the peripheral cell downlink radio signal, measured by the at least one mobile station, so that a reception quality of the downlink radio signal exceeds a second predetermined value of reception quality, as measured by the at least one mobile station at a position at which the reception quality of the peripheral cell downlink radio signal is lower than a first predetermined value of reception quality standard,

wherein the controlling the transmission power of the downlink radio signal further comprises controlling the transmission power of the downlink radio signal based on the calculated difference calculated at least one position of the mobile station at which the reception quality of the peripheral cell downlink radio signal exceeds the first predetermined value and the reception quality of the downlink radio signal exceeds the reception quality of the peripheral cell downlink radio signal, and the control unit controls the transmission power of the downlink radio signal to decrease the transmission power of the downlink radio signal according to the calculated difference.

42. A non-transitory computer readable medium storing a program for causing a computer to execute control processing regarding base station equipment that performs radio communication with a mobile station, wherein

the control processing comprises:

acquiring a reception quality of a peripheral cell downlink radio signal as measured by the mobile station in communication with the base station; and

controlling a transmission power of downlink radio signal transmitted by the base station, based on a calculated difference between the reception quality of the downlink radio signal and the reception quality of the peripheral cell downlink radio signal, measured by the at least one mobile station, so that a reception quality of the downlink radio signal exceeds a second predetermined value of reception quality, as measured by the mobile station at a position at which the reception quality of the peripheral cell downlink radio signal is lower than a first predetermined reception quality,

wherein the controlling the transmission power of the downlink radio signal further comprises controlling the transmission power of the downlink radio signal based on the calculated difference calculated at least one position of the mobile station at which the reception quality of the peripheral cell downlink radio signal exceeds the first predetermined value and the reception quality of the downlink radio signal exceeds the reception quality of the peripheral cell downlink radio signal, and the control unit controls the transmission power of the downlink radio signal to decrease the transmission power of the downlink radio signal according to the calculated difference.

43. A radio communication system comprising:

a base station comprising;

a radio communication unit which transmits a downlink radio signal to at least one mobile station;

a control unit which controls a transmission power of the downlink radio signal, based on a calculated difference between the reception quality of the downlink radio signal and the reception quality of a peripheral cell downlink radio signal, measured by the at least one mobile station, such that a reception quality of the downlink radio signal exceeds a second predetermined value of reception quality, as measured by the at least one mobile station at a position at which a reception quality of the peripheral cell downlink radio signal is less than a first predetermined value of reception quality,

wherein the control unit controls the transmission power of the downlink radio signal based on the calculated difference calculated at least one position of the mobile station at which the reception quality of the peripheral cell downlink radio signal exceeds the first predetermined value and the reception quality of the downlink radio signal exceeds the reception quality of the peripheral cell downlink radio signal, and the control unit controls the transmission power of the downlink radio signal to decrease the transmission power of the downlink radio signal according to the calculated difference.

44. The radio communication system according to claim 43, further comprising:

the at least one mobile station comprising;

a measurement unit which measures a reception quality of the downlink radio signal and a reception quality of the peripheral cell downlink radio signal; and

a report unit which reports the measured reception quality of the downlink radio signal and the measured reception quality of the peripheral cell downlink radio signal to the base station.

45. The radio communication system according to claim 43, further comprising:

the at least one mobile station comprising;

a measurement unit which measures a reception quality of the downlink radio signal and a reception quality of the peripheral cell downlink radio signal; and

a report unit which, when the measured reception quality of the peripheral cell downlink radio signal is greater than the first predetermined value, transmits a stop message to the base station, and which, when the measured reception quality of the peripheral cell downlink radio signal is less than the first predetermined value, transmits a continue message to the base station,

wherein, when the base station receives the stop message, the control unit stops transmission of the downlink radio signal, and when the base station receives the continue message, the control unit continues transmission of the downlink radio signal.