Apparatus and method for adding and removing a base station from a cellular communications system

• US 5,584,049 A
• Filed: 08/31/1995
• Issued: 12/10/1996
• Est. Priority Date: 09/12/1994
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Bender, Paul E., Weaver, Lindsay A. Jr.
• Primary Examiner(s): FAILE, ANDREW I
• Application Number:
  US08/521,673
• Time in Patent Office: 467 Days
• Field of Search: 455/9, 455/33.1, 455/33.2, 455/53.1, 455/54.2, 455/56.1, 455/63, 455/67.1, 455/115, 379/59-60
• US Class Current: 455/67.11
• CPC Class Codes: H04B 7/2628 using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04W 16/06 Hybrid resource partitioning, e.g. channel borrowing
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

An apparatus and method for adding and removing a target base station from a network of base stations, which includes base stations adjacent the target base station. The apparatus is comprised of two attenuators: a first for setting an artificial receive noise power level and a second for setting a transmit level. The transmit level determines the forward link coverage area of the base station. The artificial noise level sets the reverse link coverage area of the base station when a base station is added, initially the transmit power is low and the artificial receive noise power is high such that the forward and reverse kink coverage areas are collocated in close proximity to the base station. As the base station blossoms into full operation, the artificial receive noise power is decreased and the transmit level is increased such that the two coverage areas of the base station remain balanced as the coverage areas expand. When a base station is to be removed from a system, the same attenuators are used to wilt the two coverage areas in unison as the power level transmitted from the base station decreases.

Claims

1. In a system having a plurality of base stations for bi-directional communication with a remote unit wherein information is communicated to said remote unit from said plurality of base stations on a forward link and information is communicated to said plurality of base stations from said remote unit on a reverse link and wherein each base station defines a forward link coverage area and a reverse link coverage area, a method of adding a new base station having a new reverse link and a new forward link coverage area to said plurality of base stations comprising the steps of:

increasing gradually a receive sensitivity of said new base station such that said new reverse link coverage area of said new base station is gradually expanding; and

adjusting a forward link power level at said new base station based on said receive sensitivity to preserve a balance of a location of said new reverse link coverage area in relation to a location of said new forward link coverage area.

2. A method of adding a new base station of claim 1 wherein the product of a reverse link power level at said new base station and said forward link power level at said new base station is equal to a constant during said steps of increasing gradually said receive sensitivity and adjusting said forward link power level.

3. In a system having a plurality of base stations, each of said plurality of base stations having a corresponding forward link coverage area and a corresponding reverse link coverage area wherein each of said plurality of base stations is for communicating to a remote unit located within said corresponding forward link coverage area and each of said plurality of base stations is for receiving communication from a remote unit located within said corresponding reverse link coverage area, a method of adding a new base station to said plurality of base stations having a first forward link coverage area and a first reverse link coverage area comprising the steps of:

increasing gradually a level of transmit power of said new base station to expand a location of said first forward link coverage area; and

decreasing gradually a level of artificial loading of said first reverse link coverage area to expand a location of said first reverse link coverage area;

wherein said location of said first forward link coverage area and said location of said first reverse link coverage area are co-located during said steps of increasing and decreasing.

4. The method of adding a new base station of claim 3 wherein a total reverse link power level sets said location of said first reverse link coverage area wherein said total reverse link power level comprises energy received from a set of remote units located within said expanding first reverse link coverage area and said level of artificial loading.

5. The method of adding a new base station of claim 4 wherein said total reverse link power level of said first reverse link coverage area further comprises energy received from a non system user and a set of remote units located within a reverse link coverage area corresponding to a second base station.

6. The method of adding a new base station of claim 3 wherein said step of decreasing gradually said level of artificial loading of said first reverse link coverage area is limited to a maximum coverage area boundary.

7. A method for beginning communication with an additional base station in a system comprising a plurality of operating base stations comprising the steps of:

transmitting a forward link signal at a first selected power level from said additional base station defining a first forward link coverage area;

receiving a reverse link signal at a first power level at said additional base station defining a first reverse link coverage area;

transmitting a forward link signal at a selected power level from a first operating base station defining a second forward link coverage area, wherein said first forward link coverage area and said second forward link coverage area intersect to define a first forward link equality location at which a mobile unit receives communication with the same performance level with said additional base station and said first operating base station;

receiving a reverse link signal at a power level at said first operating base station defining a second reverse link coverage area, wherein said first reverse link coverage area and said second reverse link coverage area intersect to define a first reverse link equality location wherein said additional base station and said first operating base station receive communication from a mobile unit at said first reverse link equality location with the same performance level and wherein said first forward link equality location and said first reverse link equality location are the same;

transmitting from said additional base station said forward link signal at a slightly higher power level defining a slightly larger first forward link coverage area and a second forward link equality location such that said second forward link equality location is closer to said first operating base station than said first forward link equality location; and

receiving at said first base station said reverse link signal at a slightly lower power level thereby defining a slightly larger first reverse link coverage area of said additional base station and defining a new reverse link equality location in the same location as said second forward link equality location.

8. The method for beginning communication with an additional base station of claim 7 wherein each of said plurality of operating base stations in said system transmits a pilot signal and wherein said forward link signal from said additional base station is said pilot signal corresponding to said additional base station.

9. The method for beginning communication with an additional base station of claim 7 wherein each of said plurality of operating base stations in said system transmits a pilot signal and message signals and wherein said forward link signal from said additional base station is said pilot signal and said message signals corresponding to said additional base station.

10. The method for beginning communication with an additional base station of claim 7 wherein the product of said first selected power level of said forward link signal from said additional base station and said first power level of said reverse link signal at said additional base station is equal to a constant and wherein the product of said slightly higher power level of said forward link signal from said additional base station and said slightly lower power level of said reverse link signal at said additional base station is equal to said constant.

11. The method for beginning communication with an additional base station of claim 10 wherein the product of said selected power level of said forward link signal from said first operating base station and said power level of said reverse link signal at said first operating base station is equal to said constant.

12. The method for beginning communication with an additional base station of claim 10 wherein said first power level of said reverse link signal at said additional base station comprises an amount of artificial power.

13. The method for beginning communication with an additional base station of claim 12 wherein said power level of said reverse link signal at said first operating base station comprises an amount of artificial power such that the product of said power level of said forward link signal from said first operating base station and said power level of said reverse link signal at said first operating base station is equal to said constant.

14. In a system having a plurality of base stations for bi-directional communication with a mobile unit wherein information is communicated to said mobile unit from said plurality of base stations on a forward link and information is communicated to said plurality of base stations from said mobile unit on a reverse link and wherein each base station defines a forward link coverage area and a reverse link coverage area, a method of removing a first base station having a first reverse link and a first forward link coverage area from said plurality of base stations comprising the steps of:

decreasing progressively a receive sensitivity of said first base station such that said new reverse link coverage area of said first base station is progressively contracting; and

adjusting a forward link power level at said first base station based on said receive sensitivity to preserve a balance of a location of said first reverse link coverage area in relation to a location of said first forward link coverage area.

15. A method of removing a first base station of claim 14 wherein the product of a reverse link power level at said first base station and said forward link power level at said first base station is equal to a constant during said steps of decreasing said receive sensitivity and adjusting said forward link power level.

16. In a system having a plurality of base stations, each of said plurality of base stations having a corresponding forward link coverage area and a corresponding reverse link coverage area wherein each of said plurality of base stations is for communicating to a mobile unit located within said corresponding forward link coverage area and each of said plurality of base stations is for receiving communication from a mobile unit located within said corresponding reverse link coverage area, a method of removing a wilting base station from said plurality of base stations having a wilting forward link coverage area and a wilting reverse link coverage area comprising the steps of:

decreasing non-instantaneously a level of transmit power of said wilting base station to contract a location of said wilting forward link coverage area; and

increasing non-instantaneously a level of artificial loading of said wilting reverse link coverage area to contract a location of said wilting reverse link coverage area;

wherein said location of said wilting forward link coverage area and said location of said wilting reverse link coverage area are co-located during said steps of increasing and decreasing.

17. The method of removing a wilting base station of claim 16 wherein a total reverse link power level sets said location of said wilting reverse link coverage area wherein said total reverse link power level comprises energy received from a set of mobile units located within said wilting reverse link coverage area and said level of artificial loading.

18. The method of removing a wilting base station of claim 17 wherein said total reverse link power level of said wilting reverse link coverage area further comprises energy received from a non system user and a set of mobile units located within a reverse link coverage area corresponding to a second base station.

19. The method of removing a wilting base station of claim 16 wherein said step of increasing non-instantaneously said level of artificial loading of said wilting reverse link coverage area is terminated when said wilting reverse link coverage area is virtually eliminated.

20. A method for terminating communication with a target base station in a system comprising a plurality of operating base stations comprising the steps of:

transmitting a forward link signal at a first selected power level from said target base station defining a first forward link coverage area;

receiving a reverse link signal at a first power level at said target base station defining a first reverse link coverage area;

transmitting a forward link signal at a selected power level from a first operating base station defining a second forward link coverage area, wherein said first forward link coverage area and said second forward link coverage area intersect to define a first forward link equality location at which a mobile unit receives communication with the same performance level with said target base station and said first operating base station;

receiving a reverse link signal at a power level at said first operating base station defining a second reverse link coverage area, wherein said first reverse link coverage area and said second reverse link coverage area intersect to define a first reverse link equality location wherein said target base station and said first operating base station receive communication from a mobile unit at said first reverse link equality location with the same performance level wherein said first forward link equality location and said first reverse link equality location are the same;

transmitting from said target base station said forward link signal at a slightly lower power level defining a slightly smaller first forward link coverage area and a second forward link equality location such that said second forward link equality location is closer to said target base station than said first forward link equality location; and

receiving at said target base station said reverse link signal at a slightly higher first power level thereby defining a second slightly smaller reverse link coverage area of said target base station and defining a new reverse link equality location in the same location as said second forward link equality location.

21. The method for terminating communication with a target base station of claim 20 wherein each of said plurality of operating base stations in said system transmits a pilot signal and wherein said forward link signal from said target base station is said pilot signal corresponding to said target base station.

22. The method for terminating communication with a target base station of claim 20 wherein each of said plurality of operating base stations in said system transmits a pilot signal and message signals and wherein said forward link signal from said target base station is said pilot signal and said message signals corresponding to said target base station.

23. The method for terminating communication with a target base station of claim 20 wherein the product of said first selected power level of said forward link signal from said target base station and said first power level of said reverse link signal at said target base station is equal to a constant and wherein the product of said slightly lower first power level of said forward link signal from said target base station and said slightly higher first power level of said reverse link signal at said target base station is equal to said constant.

24. The method for terminating communication with a target base station of claim 23 wherein the product of said selected power level of said forward link signal from said first operating base station and said power level of said reverse link signal at said first operating base station is equal to said constant.

25. The method for terminating communication with a target base station of claim 20 wherein said slightly higher first power level of said reverse link signal at said target base station comprises an amount of artificial power.

26. The method for terminating communication with a target base station of claim 25 wherein said power level of said reverse link signal at said first operating base station comprises an amount of artificial power such that the product of said power level of said forward link signal from said first operating base station and said power level of said reverse link signal at said first operating base station is equal to said constant.

27. An apparatus for eliminating a forward link coverage area and a reverse link coverage area of a base station in a system of base stations for bi-directional communication with a set of mobile units comprising:

an antenna system having a wireline port providing an incoming signal at a receive power level and receiving a transmit signal at a transmit power level;

an artificial noise generator having an input coupled to said wireline port of said antenna system and having an output port providing a signal with an amount of artificial noise in addition to said receive power level;

a power detector having an input coupled to said output port of said artificial noise means and having an output providing a power level output indication proportional to the sum of said receive power level and said amount of artificial noise;

a variable attenuator having a power control signal input port coupled to said output of said power detector and having an input port receiving an information signal and having an output port providing a power controlled information signal coupled to wireline port of said antenna system thereby setting said transmit power level; and

a controller successively increasing said amount of artificial noise until said reverse link coverage area is virtually eliminated;

wherein said transmit power level is controlled to maintain balance in a location of said forward link coverage area with a location of said reverse link coverage area.

28. The apparatus for eliminating a forward link coverage area and a reverse link coverage area of a base station of claim 27 further comprising a scale and threshold block disposed between said power detector and said variable attenuator.

29. The apparatus for eliminating a forward link coverage area and a reverse link coverage area of a base station of claim 27 wherein said artificial noise generator is a variable attenuator.

30. An apparatus for adding a forward link coverage area and a reverse link coverage area of a base station in a system of base stations for bi-directional communication with a set of mobile units comprising:

an antenna system having a wireline port providing an incoming signal at a receive power level and receiving a transmit signal at a transmit power level;

an artificial noise generator having an input coupled to said wireline port of said antenna system and having an output port providing a signal with an amount of artificial noise in addition to said receive power level;

a power detector having an input coupled to said output port of said artificial noise means and having an output providing a power level output indication proportional to the sum of said receive power level and said amount of artificial noise;

a variable attenuator having a power control signal input port coupled to said output of said power detector and having an input port receiving an information signal and having an output port providing a power controlled information signal coupled to wireline port of said antenna system thereby setting said transmit power level; and

a controller gradually decreasing said amount of artificial noise such that said reverse link coverage area is expanded from nominal nonexistence to a full reverse link coverage area existence;

wherein said transmit power level is controlled to maintain balance in a location of said forward link coverage area with a location of said reverse link coverage area.

31. The apparatus for eliminating a forward link coverage area and a reverse link coverage area of a base station of claim 30 further comprising a scale and threshold block disposed between said power detector and said variable attenuator.

32. The apparatus for eliminating a forward link coverage area and a reverse link coverage area of a base station of claim 30 wherein said artificial noise generator is a variable attenuator.

33. In a cellular communication system having a plurality of base stations each defining a respective geographic coverage area and a plurality of remote stations, a method for adding an additional base station into said cellular communication system comprising the steps of:

locating said additional base station within a coverage area of at least one base station of said plurality of base stations;

increasing by degree a coverage area of said additional base station; and

decreasing by degree a coverage area of said at least one base station said additional base station is located within.

34. The method claim 33 wherein each of said respective geographic coverage areas is comprised of a forward link coverage area and a reverse link coverage area and wherein said step of increasing by degree said coverage area of said additional base station comprises the step of matching a forward link coverage area of said additional base station to a reverse link coverage area of said additional base station.

35. The method of claim 33 wherein each of said respective geographic coverage areas is comprised of a forward link coverage area and a reverse link coverage area and wherein said step of increasing by degree said coverage area of said additional base station comprises the step of by degree reducing an amount of artificial noise added to a received signal at said additional base station.

36. The method of claim 33 wherein said coverage area of said additional base station is bound at least in part by an equality location wherein a remote unit located at said equality location has equal communication abilities with said additional base station and said at least one base station.

37. In a cellular communication system having a plurality of base stations each defining a respective geographic coverage area and having a plurality of remote stations, a method for removing a first base station of said plurality of base station from said cellular communication system comprising the steps of:

decreasing non-instantaneously a coverage area of said first base station; and

increasing non-instantaneously a coverage area of at least one base station adjacent to said first base station; and

removing from service said first base station when said coverage area of first base station has been consumed at least in part by said at least one base station.

38. The method of claim 37 wherein each of said respective geographic coverage areas is comprised of a forward link coverage area and a reverse link coverage area and wherein said step of decreasing non-instantaneously said coverage area of said first base station comprises the step of matching a forward link coverage area of said first base station to a reverse link coverage area of said first base station.

39. The method of claim 37 wherein each of said respective geographic coverage areas is comprised of a forward link coverage area and a reverse link coverage area and wherein said step of increasing non-instantaneously said coverage area of said first base station comprises the step of non-instantaneously increasing an amount of artificial noise added to a received signal at said first base station.

40. The method claim 37 wherein said coverage area of said first base station is bounded at least in part by an equality location wherein a remote unit located at said equality location has equal communication abilities with said first base station and said at least one base station.

41. In a cellular communication system having a plurality of base stations each defining a respective geographic coverage area of service and having a plurality of remote user stations, a method for modifying the coverage area of at least one base station in the cellular communication system comprising the steps of:

providing a first base station having a coverage area of service;

providing a second base station within said first base station coverage area, said second base station lacking a second base station coverage area of service;

providing by said second base station a second base station coverage area of service within said first base station coverage area, said second base station coverage area initially substantially less than said first base station coverage area and progressively increasing within said first base station coverage area; and

providing by said first base station a decrease in said first base station coverage area at a rate corresponding to a rate of increase in said second base station coverage area.

42. The method of claim 41 further comprising the step of removing said first base station from providing service in said cellular communication system upon said second base station coverage area consuming in part said first base station coverage area.

43. The method of claim 41 further comprising the step of providing service to ones of said remote user stations respectively within said first and second base station coverage areas.

44. A cellular communication system for providing communication services with a at least one remote user station comprising:

a first base station having a first base station coverage area of service of service; and

a second base station located within said first base station coverage area, said second base station initially lacking a coverage area of service and subsequently introducing a second base station coverage area of service increasing in size at a first rate within said first base station coverage area of service as said first base station coverage area of service decreases in size at a rate commensurate with a rate of increase of said second base station coverage area of service.

45. The cellular communication system for providing communication services of claim 44 further comprising a third base station having a third base station coverage area of service overlapping with said first base station coverage area of service, said third base station coverage area of service decreasing in size when said second base station coverage area of service increases into said third base station coverage area of service.

46. The cellular communication system for providing communication services of claim 44 wherein said first base station service area is decreased upon said second base station coverage area consuming in part said first base station coverage area until said first base station is removed from providing service in said cellular communication system.

47. The cellular communication system for providing communication services of claim 44 wherein said first base station and said second base station provide communication with said at least one remote user station when said at least one remote user station is located within said first base station coverage area and said second base station coverage area respectively.