Asymmetrical beams for spectrum efficiency

• US 8,311,582 B2
• Filed: 03/19/2007
• Issued: 11/13/2012
• Est. Priority Date: 03/17/2006
• Status: Active Grant

• Current Assignee: Communications Components Antenna Inc.
• Original Assignee: Tenxc Wireless Inc. (Communication Components, Inc.)
• Inventors: Trigui, Hafedh, Dean, Stuart J., Litva, John
• Primary Examiner(s): Eng, George
• Assistant Examiner(s): Gao, Jing
• Application Number:
  US12/094,299
• Publication Number:
  US 20090163214A1
• Time in Patent Office: 2,066 Days
• Field of Search: 455/562.1, 342/373, 342/374
• US Class Current: 455/562.1
• CPC Class Codes: H04W 16/24 Cell structures

Abstract

A method and apparatus for increasing capacity and performance of a base station for a sectorized cellular wireless network is disclosed in which one of the sector antennas is replaced or supplanted by a novel sub-sector antenna that generates a plurality of asymmetrical sub-sector coverage areas that collectively substantially cover the coverage area of the replaced sector antenna. The use of asymmetrical coverage areas permits the total coverage area to closely approximate the symmetrical sector coverage area without creating excessively large sub-sector handover zones or introducing severe degradation in the network performance. This in turn permits the selective replacement of a single sector antenna rather than the wholesale replacement of all sector antennas in a region, leading to lower transitional costs and the ability to provide a focused approach to capacity planning.

Claims

1. A method for increasing subscriber capacity in a sectorized cellular communications network having a plurality of subscribers and a base station supporting at least one sector, each of the at least one sector having one or more associated sector antennae at the base station having a critical coverage area extending therefrom and overlapping neighbouring sectors thereof in a sector handover zone, the method comprising a step of:

replacing the associated one or more sector antennae for a given sector with a split-sector antenna having a plurality of sub-sector coverage areas extending therefrom, at least one of which is asymmetrical, each corresponding to a sub-sector and overlapping a neighbouring sub-sector coverage area in a sub-sector handover zone, whereby a total critical coverage area provided by the plurality of sub-sector coverage areas is substantially equivalent to a critical coverage area of the replaced one or more associated sector antennae, wherein said at least one asymmetrical sub-sector coverage area reduces overlap with said neighbouring sub-sector coverage area comparing to overlap of the replaced antennae while maintaining the critical coverage area of the replaced antenna.

2. The method according to claim 1, further comprising a step of allocating different control resources to neighbouring sub-sector coverage areas.

3. The method according to claim 1, further comprising a step of allocating a common control resource to a pair of sub-sector coverage areas, each neighbouring a third sub-sector coverage area having a different allocated control resource.

4. The method according to claim 1, further comprising a step of allocating to the replaced one or more sector antennae a task of broadcasting control information.

5. The method according to claim 1, further comprising a step of transferring a task of broadcasting control information from the replaced one or more sector antennae to the split-sector antenna, and of removing the replaced one or more sector antennae.

6. The method according to claim 1, further comprising a step of allocating to the split-sector antenna a task of handling traffic from at least one of the subscribers.

7. The method according to claim 1, wherein the plurality of sub-sector coverage areas comprise a multiple of 2 asymmetrical sub-sector coverage areas.

8. The method according to claim 7, wherein the plurality of sub-sector coverage areas further comprise a symmetrical central sub-sector coverage area.

9. The method according to claim 1, wherein the plurality of sub-sector coverage areas comprise two sub-sector coverage areas, each one of which having a half power beam width of about half that of the critical coverage area of the replaced one or more associated sector antennae.

10. The method according to claim 9, wherein the critical coverage area of the replaced one or more associated sector antennae has a half power beam width selected from a group consisting of:

approximately 65°

, 90°

, 105° and

120°

.

11. The method of claim 1, wherein said at least one asymmetrical sub-sector coverage area has smaller overlapping area in the sub-sector handover zone with respect to an adjacent sub-sector in the plurality of sub-sector coverage areas, than overlapping areas that exist between a pair of symmetrical sectors.

12. The method of claim 1, wherein the said split-sector antenna is configured to project its beam pattern for said asymmetrical sub-sector coverage area such that the total critical coverage area provided by the plurality of sub-sector coverage areas is substantially equivalent to the critical coverage area of the replaced one or more associated sector antennae.

13. A split-sector antenna for use in a sectorized cellular communications network having a plurality of subscribers and a base station supporting at least one sector, each of the at least one sector having one or more associated sector antennae at the base station having a critical coverage area extending therefrom and overlapping neighbouring sectors in a sector handover zone, the split-sector antenna being constructed and arranged for replacing the one or more associated sector antennae and having a plurality of sub-sector coverage areas extending therefrom, at least one of which is asymmetrical, each corresponding to a sub-sector and overlapping a neighbouring sub-sector coverage area in a sub-sector handover zone, whereby a total critical coverage area provided by the plurality of sub-sector coverage areas is substantially equivalent to a critical coverage area of the replaced one or more associated sector antennae, wherein said at least one asymmetrical sub-sector coverage area reduces overlap with said neighbouring sub-sector coverage area comparing to overlap of the replaced antennae while maintaining the critical coverage area of the replaced antenna.

14. The split-sector antenna according to claim 13, wherein the plurality of sub-sector coverage areas comprise a multiple of 2 asymmetrical sub-sector coverage areas.

15. The split-sector antenna according to claim 14, wherein the multiple of 2 asymmetrical sub-sector coverage areas comprise one or more pairs of same, a first area of a given pair being substantially a mirror image of a second area of the given pair.

16. The split-sector antenna according to claim 14, wherein the plurality of sub-sector coverage areas further comprise a symmetrical central sub-sector coverage area.

17. The split-sector antenna according to claim 13, wherein the split-sector antenna generates minimal side lobes associated with each asymmetrical sub-sector coverage area.

18. The split-sector antenna according to claim 13, wherein the plurality of sub-sector coverage areas comprise two sub-sector areas, each one of which having a half power beam width of about half that of the critical coverage area of the one or more associated sector antennae being replaced.

19. The split-sector antenna according to claim 13, wherein the sub-sector handover zone is substantially equal to the sector handover zone.

20. A sectorized cellular communications network having a plurality of subscribers, comprising:

one or more base stations each supporting at least one sector; and

one or more sector antenna associated with each of the at least one sector providing a critical coverage area extending therefrom and overlapping neighbouring sectors in a sector handover zone, wherein at least one sector antenna is replaced with a split-sector antenna having a plurality of sub-sector coverage areas extending therefrom, at least one of which is asymmetrical, each corresponding to a sub-sector and overlapping a neighbouring sub-sector coverage area in a sub-sector handover zone, whereby a total critical coverage area provided by the plurality of sub-sector coverage areas is substantially equivalent to a critical coverage area of the replaced one or more associated sector antennae, wherein said at least one asymmetrical sub-sector coverage area reduces overlap with said neighbouring sub-sector coverage area comparing to overlap of the replaced antennae while maintaining the critical coverage area of the replaced antenna.

21. The network according to claim 20, wherein the plurality of sub-sector coverage areas comprise a multiple of 2 asymmetrical sub-sector coverage areas.

22. The network according to claim 21, wherein the multiple of 2 asymmetrical sub-sector coverage areas comprise one or more pairs of same, a first area of a given pair being substantially a mirror image of a second area of the given pair.

23. The network according to claim 21, wherein the plurality of sub-sector coverage areas further comprises a symmetrical central sub-sector coverage area.

24. The network according to claim 20, wherein the sub-sector handover zone is substantially equal to the sector handover zone.

25. The network according to claim 20, wherein the split-sector antenna generates minimal side lobes associated with each asymmetrical sub-sector coverage area.

26. The network according to claim 20, further comprising a passive network for implementing the at least one asymmetrical sub-sector coverage area.

27. The network according to claim 20, further comprising an active network for implementing the at least one asymmetrical sub-sector coverage area.

28. The network according to claim 20, wherein the split-sector antenna generates two asymmetrical coverage areas each having a half power beam selected from a the group consisting of:

approximately 33°

, 45°

, 53° and

60°

.