METHOD OF PREVENTING INTERFERENCE OF ADJACENT FREQUENCIES IN A CELLULAR SYSTEM BY SELECTION BETWEEN ADJACENT CARRIER FREQUENCY AND NON-ADJACENT CARRIER FREQUENCY

• US 20020111163A1
• Filed: 03/26/1999
• Published: 08/15/2002
• Est. Priority Date: 03/27/1998
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: HAMABE, KOJIRO
• Granted Patent: US 6,574,456 B2
• Time in Patent Office: Days
• US Class Current: 455/425
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 72/541 using the level of interference

Abstract

A method of preventing interference of adjacent frequencies which selects and uses a carrier frequency which is not adjacent to another carrier frequency is disclosed. A cellular system A is composed of a plurality of base stations and a mobile station, and a cellular system B is composed of a plurality of other base stations and another mobile station. For cellular system A, a carrier frequency adjacent to a carrier frequency used in cellular system B and a carrier frequency not adjacent thereto are determined. If a received power of a perch channel sent by a base station of cellular system B is larger than a threshold value, the mobile station uses the carrier frequency which is not adjacent to carrier frequency used in cellular system B.

Claims

1. A method of preventing interference of adjacent frequencies wherein two cellular systems comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and signal for the uplink channel used by a mobile station of one cellular system may cause interference of adjacent frequencies to a base station of the other cellular system, said method comprising the steps of:

at the mobile station of said one cellular system;

measuring a received power of signals transmitted from the base station of the other cellular system; and

at the base station and the mobile station of said one cellular system;

if the measured value is larger than a threshold value, using a carrier frequency that is not adjacent to that of said other cellular system as a carrier frequency of an uplink channel.

2. The method according to claim 1, wherein said threshold value is determined depending on the amount of suppression of leakage power to an adjacent frequency of said mobile station.

3. The method according to claim 1, wherein said threshold value is determined depending on the received power of the transmitting signals transmitted from said base station of said one cellular system.

4. The method according to claim 1, wherein said threshold value is determined depending on a difference between a transmission power of the transmitting signals transmitted from a base station from which a channel is established to said mobile station and transmission power of transmitting signals transmitted from a base station of the other cellular system.

12. The method according to claim 1, wherein said step of measuring a received power includes the step of measuring a received power of signals transmitted from said base station of the other cellular system, using information, transmitted from the base station of same cellular system, of central frequencies of signals for the downlink channel used by a base station of the other cellular system.

13. The method according to claim 1, wherein said step of measuring a received power includes the step of measuring a received power of signals transmitted from said base station of the other cellular system, using information, possessed forehand by said mobile station, of central frequencies of signals for the downlink channel used by a base station of the other cellular system.

14. The method according to claim 1, wherein said one cellular system is a micro-structured cellular system in which the transmission power of each base station is smaller than a predetermined value, and the other cellular system is a macro-structured cellular system in which the transmission power of each base station is larger than said predetermined value.

15. The method according to claim 1, wherein said one cellular system is a macro-structured cellular system in which the transmission power of each base station is larger than a predetermined value, and the other cellular system is a micro-structured cellular system in which the transmission power of each base station is smaller than said predetermined value.

18. The method according to claim 1, wherein said step of measuring a received power includes the step of measuring a perch channel in signals transmitted from the base station of the other cellular system.

19. The method according to claim 1, wherein said step of using a carrier frequency includes a step of using a carrier frequency not adjacent to a carrier frequency of downlink channel of the other cellular system as a carrier frequency of a downlink channel, if said mobile station and said base station use a carrier frequency not adjacent to a carrier frequency of the other cellular system as a carrier frequency of an uplink channel.

5. A method of preventing interference of adjacent frequencies wherein two cellular systems comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and signal for the uplink channel used by a mobile station of one cellular system may cause interference of adjacent frequencies to a base station of the other cellular system, said method comprising the steps of:

at the mobile station of said one cellular system;

using preferentially a carrier frequency that is not adjacent to a carrier frequency of the uplink channel used by the other cellular system when a signal for the downlink channel is continuously received;

measuring a received power of signals transmitted from a base station of the other cellular system when a signal of the downlink channel is intermittently received; and

at the base station and the mobile station of said one cellular system;

if the measured value is larger than a threshold value, using a carrier frequency that is not adjacent to that of said other cellular system as a carrier frequency of an uplink channel.

6. A method of preventing interference of adjacent frequencies wherein two cellular systems comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and signal for the uplink channel used by a mobile station of one cellular system may cause interference of adjacent frequencies to a base station of the other cellular system, said method comprising the steps of:

at the mobile station of said one cellular system;

measuring a received power of signals transmitted from said base stations of the other cellular system;

at the base station and the mobile station of said one cellular system;

determining from the measured value an upper value of a transmission power to limit the interference of adjacent frequencies below a permissible level; and

if said upper level is below a transmission power in the case of SIR at the base station of said one cellular system being a target value, using a carrier frequency that is not adjacent to that of said other cellular system as a carrier frequency of an uplink channel.

7. A method of preventing interference of adjacent frequencies wherein two cellular systems comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and signal for the uplink channel used by a mobile station of one cellular system may cause interference of adjacent frequencies to a base station of the other cellular system, said method comprising the steps of:

at said mobile station of said one cellular system;

measuring a received power of signals transmitted from the base station of the other cellular system;

at the base station and the mobile station of said one cellular system;

if the measured value is larger than a first threshold value, using a carrier frequency that is not adjacent to that of said other cellular system; and

if the measured value is smaller than or equal to a second threshold value which is smaller than said first threshold value, using a carrier frequency that is adjacent to that of said other cellular system as a carrier frequency of an uplink channel.

8. The method according to claim 7, wherein said first threshold value is determined based on a difference between a transmission power of signals transmitted from a base station from which a channel is established to said mobile station and a transmission power of signals transmitted from a base station of said other cellular system.

9. The method according to claim 7, wherein said first threshold value is determined based on a received power of signals transmitted from a base station of said one cellular system.

10. A method of preventing interference of adjacent frequencies wherein two cellular systems comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and signal for the uplink channel used by a mobile station of one cellular system may cause interference of adjacent frequencies to a base station of the other cellular system, said method comprising the steps of:

at said mobile station of said one cellular system;

estimating a speed with which said mobile station is on the move; and

at the base station and the mobile station of said one cellular system;

if the estimated movement speed is larger than a threshold speed, using a carrier frequency that is not adjacent to that of said other cellular system as a carrier frequency of an uplink channel.

11. The method according to claim 10, wherein said step of estimating a speed includes the steps of obtaining median of a received power of a perch channel transmitted from the base station, and counting the number of times that the value of said received power crosses said median for a certain period of time.

16. A method of preventing interference of adjacent frequencies wherein two cellular systems comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and signal for the uplink channel used by a mobile station of one cellular system may cause interference of adjacent frequencies to a base station of the other cellular system, said method comprising the steps of:

at the mobile station of said one cellular system;

measuring a received power of signals transmitted from the base station of the other cellular system in which a carrier frequency adjacent to a carrier frequency of said other cellular system is allocated as a carrier frequency of an uplink channel; and

at the base station and the mobile station of said one cellular system;

if the measured value is larger than a threshold value, using a carrier frequency that is not adjacent to that of said other cellular system as a carrier frequency of an uplink channel.

17. A method of preventing interference of adjacent frequencies wherein two cellular systems comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for a downlink channel are provided in a same service area, and signal for the downlink channel used by a base station of one cellular system may cause interference of adjacent frequencies to a mobile station of the other cellular system, said method comprising the steps of:

at the mobile station of said other cellular system;

measuring a received power of signals transmitted from the base station of said one cellular system; and

at the base station and the mobile station of said other cellular system;

if the measured value is larger than a threshold value, using a carrier frequency that is not adjacent to that of said one cellular system as a carrier frequency of a downlink channel.

20. A method of preventing interference of adjacent frequencies in a cellular system comprising the steps of:

at the mobile station;

measuring received power of the carrier frequencies directed in the carrier selection rule information at the time the mobile station starts communication with the base station;

reporting the measurement result to the base station using a non-adjacent carrier frequency that is not adjacent to the carrier frequency paired with the measured carrier frequency;

at the base station;

receiving the measurement result from the mobile station;

selecting a non-adjacent carrier frequency if the measured received power is larger than a threshold value and selecting an available carrier frequency if the measured received power is equal to or smaller than the threshold value;

sending a call-setup direction, and informing the mobile station of the selected carrier frequency;

at the mobile station;

starting communication using the selected carrier frequency;

measuring received power of carrier frequencies as directed in the carrier selection rule information at a certain time interval, and reporting the measurement result to the base station;

at the base station;

receiving the measurement result from the mobile station;

selecting a non-adjacent carrier frequency, and informing the mobile station of an inter-frequency handover direction, if the measured received power is larger than the threshold value and the mobile station is using an adjacent carrier frequency that is adjacent to the carrier frequencies paired with the measured carrier frequencies; and

at the mobile station;

starting inter-frequency handover to the selected carrier frequency.

21. A method of preventing interference of adjacent frequencies wherein two cellular systems comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and signal for the uplink channel used by a mobile station of one cellular system may cause interference of adjacent frequencies to a base station of the other cellular system, said method comprising the steps of:

at the mobile station of said one cellular system;

measuring a received power of a transmission signals transmitted from a base station of the other cellular system and transmitting a measured value of the received power to a base station of said one cellular system;

at said base station which said measured value is transmitted to;

selecting a carrier frequency that is not adjacent to that of said other cellular system if said measured value is larger than a threshold value and reporting said selected carrier frequency to said mobile station; and

at the mobile station of the one cellular system;

using said reported carrier frequency for an uplink channel.

22. The method according to claim 21, wherein said threshold value is determined depending on the amount of suppression of leakage power to an adjacent frequency of said mobile station.

23. The method according to claim 21, wherein further comprising the steps of:

at said mobile station of said cellular system;

measuring a received power of transmission signals transmitted from a base station of said one cellular system;

transmitting said measured value to said base station of said one cellular system;

at said base station of said one cellular system;

determining said threshold value based on said measured value.

24. The method according to claim 21, wherein said threshold value is determined depending on a difference between a transmission power of signals transmitted from a base station from which a channel is established to said mobile station and transmission power of signals transmitted from a base station of the other cellular system.

26. The method according to claim 25, wherein said step of using a carrier frequency includes a step of using a carrier frequency which is not adjacent to a carrier frequency of said other cellular system as a carrier frequency of a downlink channel, if said mobile station selects a carrier frequency not adjacent to a carrier frequency of said other cellular system as a carrier frequency of an uplink channel.

28. The method according to claim 27, wherein said step changing a carrier frequency of uplink channel includes a step of;

if a carrier frequency of an uplink channel is changed to a non-adjacent carrier frequency which is not adjacent to a carrier frequency of the other cellular system, when a carrier frequency adjacent to the carrier frequency of the other cellular system is used as a carrier frequency of a downlink channel, said mobile station changing also a carrier frequency of the downlink channel to a non-adjacent frequency not adjacent to a carrier frequency of the cellular system.

30. The cellular system according to claim 29, wherein said threshold value is determined depending on a amount of suppression of leakage power to an adjacent frequency of said mobile station.

32. The cellular system according to claim 29, wherein information of central frequencies of signals for the downlink channel used by a base station of the other cellular system is reported to said mobile station from a base station from which a channel is established to said mobile station.

33. The cellular system according to claim 29, wherein said threshold value is determined depending on a difference between a transmission power of transmitting signals transmitted from a base station from which a channel is established to said mobile station and a transmission power of transmitting signals transmitted from a base station of the other cellular system.

37. The cellular system according to claim 36, wherein said first threshold value is determined depending on a difference between a transmission power of transmitting signals transmitted from a base station from which a channel is established to said mobile station and a transmission power of transmitting signals transmitted from a base station of said other cellular system.

39. The cellular system according to claim 29, wherein using information of central frequencies of signals for the downlink channel used by a base station of the other cellular system, the information reported from the base station of a cellular system to which said mobile station belongs, said mobile station measures a received power of a transmission power of transmitting signals transmitted from said base station of the other cellular system.

40. The cellular system according to claim 29, wherein said mobile station measures a received power of transmitting signals transmitted from said base station of another cellular system, using information, possessed forehand by said mobile station, of central frequencies of signals for the downlink channel used by a base station of the other cellular system.

45. The cellular system according to claim 29, wherein said mobile station measures a received power of a perch channel in transmitting signals transmitted from a base station.

46. The cellular system according to claim 29, wherein when said mobile station uses a carrier frequency not adjacent to that of the other cellular system as a carrier frequency of an uplink channel, said mobile station uses a carrier frequency not adjacent to that of the other cellular system as a carrier frequency of a downlink channel.

25. A method of preventing interference of adjacent frequencies wherein two cellular systems comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and signal for the uplink channel used by a mobile station of one cellular system may cause interference of adjacent frequencies to a base station of the other cellular system, said method comprising the steps of:

at said mobile station;

measuring a received power Qp1 of a downlink carrier frequency of said one cellular system, and measuring a received power Qp2 of a downlink carrier frequency of the other cellular system; and

if a difference between the received power Qp1 and the received power Qp2 is larger than a threshold value, using a carrier frequency not adjacent to a carrier frequency of the other cellular system, as a carrier frequency of an uplink channel.

27. A method of preventing interference of adjacent frequencies wherein two cellular systems comprising a plurality of base stations and at least one mobile station utilizing frequency bands adjacent to each other for an uplink channel are provided in a same service area, and signal for the uplink channel used by a mobile station of one cellular system may cause interference of adjacent frequencies to a base station of the other cellular system, said method comprising the steps of:

at said mobile station;

if said mobile station is using a carrier frequency adjacent to a carrier frequency of said other cellular system as a carrier frequency of an uplink channel, measuring a received power Qp1 of a downlink carrier frequency of said one cellular system, and measuring a received power Qp2 of a downlink carrier frequency of the other cellular system; and

if a difference between the received power Qp1 and the received power Qp2 is larger than a threshold value, changing a carrier frequency of uplink channel to a carrier frequency not adjacent to a carrier frequency of the other cellular system.

29. A cellular system comprising:

a plurality of base stations; and

at least one mobile station for establishing an uplink channel and a downlink channel with one or more base stations to communicate therewith, measuring a received power of signals transmitted from a base station of another cellular system, and when the measured value is larger than a threshold value, using a carrier frequency not adjacent to that of the other cellular system as a carrier frequency of an uplink channel.

31. The cellular system according to 29, wherein said threshold value is determined depending on the received power of the transmitting signals transmitted from said base station from which a channel is established to said mobile station.

34. A cellular system comprising:

a plurality of base stations; and

at least one mobile station for establishing an uplink channel and a downlink channel with one or more base stations to communicate therewith, using a carrier frequency not adjacent to a carrier frequency of another cellular system preferentially at a time of receiving the downlink channel continuously as a carrier frequency of an uplink channel, measuring a received power of transmitting signals transmitted from a base station of the other cellular system at a time of receiving the downlink channel intermittently, and if the measured value of the received power is larger than a threshold value, using a carrier frequency not adjacent to that of said other cellular system as a carrier frequency of an uplink channel.

35. A cellular system comprising:

a plurality of base stations; and

at least one mobile station for establishing an uplink channel and a downlink channel with one or more base stations to communicate therewith;

measuring a received power of transmitting signals transmitted from a base station of another cellular system;

obtaining an upper limit value of a transmission power which allows an interference of adjacent frequencies to be equal to or less than an allowable value based on a measured value of the received power; and

if the upper limit value of the transmission power is equal to or less than a received power value at a time when a SIR in said base station is an target value, using a carrier frequency not adjacent to a carrier frequency of said other cellular system as a carrier frequency of an uplink channel.

36. A cellular system comprising:

a plurality of base stations; and

at least one mobile station for establishing an uplink channel and a downlink channel with one or more base stations to communicate therewith;

measuring a received power of transmitting signals transmitted from a base station of another cellular system;

if the measured value of the received power is larger than a first threshold value, using a carrier frequency not adjacent to that of said other cellular system as a carrier frequency of an uplink channel; and

if the measured value of the received power is equal to or less than a second threshold value smaller than said first threshold value, using a carrier frequency adjacent to that of said other cellular system as a carrier frequency of an uplink channel.

38. The cellular system according to 36, wherein said first threshold value is determined depending on the received power of the transmitting signals transmitted from said base station from which a channel is established to said mobile station.

41. A cellular system comprising:

a plurality of base stations; and

at least one mobile station for establishing an uplink channel and a downlink channel with one or more base stations to communicate therewith, estimating a movement speed and if the movement speed is larger than a certain threshold speed, using a carrier frequency not adjacent to that of said other cellular system as a carrier frequency of an uplink channel.

42. The cellular system according to claim 41, wherein said mobile station obtains a median of a received power of a perch channel transmitted from the base station, and counts the number of times that the value of said received power crosses said median for a certain period of time, thereby estimating the movement speed.

43. A cellular system comprising:

a plurality of base stations; and

at least one mobile station for establishing an uplink channel and a downlink channel with one or more base stations to communicate therewith;

measuring a received power of only a perch channel in transmitting signals transmitted from a base station other than a base station in which a carrier frequency adjacent to a carrier frequency of a signal for the uplink channel is not used among base stations of another cellular system; and

if a measured value of the received power is larger than a threshold value, using a carrier frequency not adjacent to that of the other cellular system as a carrier frequency of an uplink channel.

44. A cellular system comprising:

a plurality of base stations; and

at least one mobile station for establishing an uplink channel and a downlink channel with one or more base stations to communicate therewith;

measuring a received power of transmitting signals transmitted from a base station of another cellular system; and

if the measured value of the received power is larger than a threshold value, using a carrier frequency not adjacent to that of the other cellular system as a carrier frequency of a downlink channel.

48. The cellular system according to claim 47, wherein said threshold value is determined depending on the amount of suppression of leakage power to an adjacent frequency of said mobile station.

49. The cellular system according to claim 47, wherein said mobile station measures a received power of transmitting signals transmitted from a base station consisting a cellular system together with said mobile station, and sends the measured value of the received power to the base station constituting a cellular system together with said mobile station;

and said threshold value is determined depending on the measured value.

50. The cellular system according to claim 47, wherein information of central frequencies of signals for the downlink channel used by a base station of the other cellular system is reported to said mobile station from a base station constituting a cellular system together with said mobile station.

51. The cellular system according to claim 47, wherein said threshold value is determined depending on a difference between a transmission power of transmitting signals transmitted from a base station from which a channel is established to said mobile station and a transmission power of transmitting signals transmitted from a base station of the other cellular system.

47. A cellular system comprising:

at least one mobile station for measuring a received power of transmitting signals transmitted from a base station of another cellular system;

transmitting the measured value of the received power to a base station constituting a cellular system together with said mobile station; and

when a carrier frequency to be used is informed from the base station, using the carrier frequency reported as a carrier frequency of the uplink channel; and

a plurality of base stations for selecting a carrier frequency not adjacent to that of the other cellular system, if the measured value of the received power is larger than a threshold value, and informing said mobile station of the selected carrier frequency.

52. A cellular system comprising:

a plurality of base stations; and

at least one mobile station for establishing an uplink channel and a downlink channel with one or more base stations to communicate therewith;

measuring a received power Qp1 of a carrier frequency as an allocation candidate of a downlink channel;

measuring a received power Qp2 of a carrier frequency of a downlink channel of another cellular system; and

if a difference between the received power Qp1 and the received power Qp2 is larger than a threshold value, using a carrier frequency not adjacent to a carrier frequency of the other cellular system, as a carrier frequency of an uplink channel.

53. The cellular system according to claim 52, wherein if said mobile station uses a carrier frequency not adjacent to that of the other cellular system as a carrier frequency of an uplink channel, said mobile station does not use the carrier frequency adjacent to a carrier frequency of the other cellular system as a carrier frequency of a downlink channel.

54. A cellular system comprising:

a plurality of base stations; and

at least one mobile station for establishing an uplink channel and a downlink channel with one or more base stations to perform communication therewith;

when the communication is performed using a carrier frequency adjacent to a carrier frequency of another cellular system as a carrier frequency of an uplink channel, measuring a received power Qp1 of a carrier frequency used for the downlink channel;

measuring a received power Qp2 of a carrier frequency of a downlink channel of the other cellular system; and

if a difference between the received power Qp1 and the received power Qp2 is larger than a threshold value, changing the carrier frequency of the uplink channel to a carrier frequency not adjacent to that of the other cellular system.

55. The cellular system according to claim 54, wherein when a carrier frequency of the uplink channel is changed to a non-adjacent carrier frequency which is not adjacent to a carrier frequency of the other cellular system, if said mobile station uses a carrier frequency adjacent to that of the other cellular system as a carrier frequency of a downlink channel, said mobile station changes also a carrier frequency of the downlink channel to a carrier frequency not adjacent to that of the other cellular system.