Hot spot with tailored range for extra frequency to minimize interference

• US 6,792,276 B1
• Filed: 06/28/2000
• Issued: 09/14/2004
• Est. Priority Date: 07/13/1999
• Status: Expired due to Term

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Johansson, Lars B., Muller, Walter, Blomberg, Petter, Butovitsch, Peter
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): MILLER, BRANDON J
• Application Number:
  US09/605,638
• Time in Patent Office: 1,539 Days
• Field of Search: 455/453, 455/436-437, 455/443-444, 455/13.4, 455/446, 455/448, 455/67.1, 455/63, 455/561, 370/332
• US Class Current: 455/453
• CPC Class Codes: H04W 16/02 Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 16/32 Hierarchical cell structures
• CPC Class Codes: H04W 36/06 Reselecting a communication resource in the serving access point

Abstract

A method and apparatus for minimizing interference in a wireless communication system. A base transceiver station transmits and receives over a first frequency band and a second frequency band. The maximum range of the first frequency band can be smaller than the maximum range of the second frequency band. Alternatively, the maximum range of the first frequency band can be larger than the maximum range of the second frequency band. Further, the maximum range of the second frequency band can vary based upon factors such as the capacity of the first frequency band and the amount of interference on the first frequency band. A control channel for the second frequency band which is measured for determining whether to handoff from the first frequency band to the second frequency band can be transmitted within the first frequency band.

Claims

1. A base transceiver station in a Code Division Multiple Access (CDMA) communications system, comprising:

a transmitter capable of transmitting signals over a first frequency band and a second frequency band, wherein said first and second frequency bands are traffic channels;

interference measuring means for determining whether said first frequency band has sufficient capacity for all current connections (mobile stations);

activation means for activating said second frequency band if interference in said first frequency band exceeds a predetermined threshold; and

means for effecting a soft handoff of a mobile station between said first frequency band and said second frequency band for reducing interference in said first frequency band, wherein the range of said second frequency band overlaps said first frequency band that is transmitted from an adjoining base transceiver station.

2. The base transceiver station of claim 1, wherein said first frequency band has a first maximum range that defines the boundaries of a first cell.

3. The base transceiver station of claim 1, wherein said first frequency band has a first maximum range that defines the boundaries of one sector in a multi-sector cell.

4. The base transceiver station of claim 1, wherein said base transceiver station transmits a control channel for said second frequency band on said first frequency band.

5. The base transceiver station of claim 1, wherein said base transceiver station transmits information regarding said first frequency band and said second frequency band to said mobile station and said mobile station calculates an offset value based on said transmitted information.

6. The base transceiver station of claim 1, wherein said base transceiver station calculates an offset value as a function of the difference in power levels between said first frequency band and said second frequency band.

7. The base transceiver station of claim 6, wherein said base transceiver station calculates a pathloss estimate for the control channel for said second frequency on said first frequency band.

8. The base transceiver station of claim 4, wherein said mobile station calculates a pathloss estimate for the control channel for said second frequency band on said first frequency band.

9. The base transceiver station of claim 6, wherein said mobile station calculates the pathloss estimate using the offset value.

10. The base transceiver station of claim 1, wherein said first frequency band and said second frequency band each comprise a plurality of frequencies.

11. The base transceiver station of claim 10, wherein the plurality of frequencies in said first frequency band are exclusive of the plurality of frequencies in said second frequency band.

12. A Code Division Multiple Access (CDMA) cellular communication system, comprising:

a base transceiver station of a first cell capable of;

transmitting signals over a first frequency band and a second frequency band, said first frequency band having a first maximum range; and

said second frequency band having a second maximum range, said second frequency band maximum range overlapping said first frequency band that is transmitting from an adjoining base transceiver station, wherein said first and second frequency bands are traffic channels; and

adjusting said maximum range of each of said first and second frequency band;

a mobile station capable of communicating over said first and second frequency bands;

interference measuring means for determining whether said first frequency band has sufficient capacity for all current connections;

activation means for activating said second frequency band if interference in said first frequency band exceeds a predetermined threshold; and

means for effecting a soft handoff of said mobile station between said first frequency band and said second frequency band in said first cell prior to crossing a boundary between said first cell and a second cell to lower said interference in said first frequency band.

13. The cellular communication system of claim 12 further comprising at least one other base transceiver station which transmits signals across said first frequency band with said first maximum range and across said second frequency band with said second maximum range, wherein said first and second maximum ranges overlap and wherein said second maximum range is smaller than said first maximum range.

14. The cellular communications system of claim 12, wherein said second maximum range coverage area does not overlap coverage as from frequency bands associated with other base transceiver stations.

15. The cellular communication system of claim 12, wherein said first maximum range defines the boundaries of a first cell.

16. The cellular communication system of claim 12, wherein said first maximum range defines the boundaries of one sector in a multisector cell.

17. The cellular communication system of claim 12, wherein said base transceiver station transmits a control channel for said second frequency band on said first frequency band.

18. The cellular communication system of claim 12, wherein said base transceiver station calculates an offset value as a function of said difference in power levels between said first frequency band and said second frequency band.

19. The cellular communication system of claim 17, further comprising a mobile station, wherein said mobile station calculates a pathloss estimate for the control channel for said second frequency band on said first frequency band.

20. The cellular communication system of claim 18, further comprising a mobile station, wherein said mobile station calculates a pathloss estimate using the offset value.

21. The cellular communication system of claim 12, wherein said first frequency band and said second frequency band each comprise a plurality of frequencies.

22. The cellular communication system of claim 21, wherein the plurality of frequencies in said first frequency band are exclusive of the plurality of frequencies in said second frequency band.

23. In a base transceiver station in a Code Division Multiple Access (CDMA) communications system, a method for minimizing interference comprising the steps of:

determining whether a first frequency band has sufficient capacity for all current connections (mobile stations) by measuring the interference in said first frequency band;

activating a second frequency band if the interference in said first frequency band exceeds a predetermined threshold, wherein said first and second frequency bands are traffic channels;

reducing the number of mobile stations communicating on said first frequency band through soft handoff to said second frequency band; and

adjusting the ranges of said first and second frequency bands according to the number of connected mobile stations wherein said second frequency band is adjusted to overlap said first frequency band transmitting from an adjoining base transceiver station.

24. The method of claim 23, wherein said base transceiver station does not transmit over said second frequency band if said first frequency band has sufficient capacity.

25. The method of claim 23, wherein said first frequency band has sufficient capacity when additional connections on said first frequency band do not cause excessive interference to existing connections on said first frequency band.

26. The method of claim 23, wherein a maximum range of said second frequency band also varies based upon the location of said connected mobile stations.

27. A method for minimizing interference in a Code Division Multiple Access (CDMA) wireless communication system comprising the steps of:

transmitting signals across a first frequency band with a first maximum range;

transmitting signals across a second frequency band with a second maximum range wherein said first and second frequency bands are traffic channels; and

instructing a mobile station to handoff from said first frequency band to said second frequency band based upon a predetermined criteria, wherein the maximum range of the second frequency band is greater than said maximum range of said first frequency band and overlaps said first frequency band that is transmitting from an adjoining base transceiver station of said wireless communication system.

28. The method of claim 27, wherein said predetermined criteria comprises the speed at which a mobile station is traveling.

29. The method of claim 27, wherein said predetermined criteria is the proximity of a mobile station to a base transceiver station which transmits said first and second frequency bands.

30. The method of claim 27, wherein said predetermined criteria comprises the direction that a mobile station is traveling.