Arrangement For Improved Isolation Between Adjacent Cell Areas

• US 20110169713A1
• Filed: 08/28/2008
• Published: 07/14/2011
• Est. Priority Date: 08/28/2008
• Status: Active Grant

• Current Assignee: Optis Cellular Technology LLC (Brevet Capital)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Asplund, Henrik, Hagerman, Bo, Simonsson, Arne
• Granted Patent: US 8,942,766 B2
• Time in Patent Office: Days
• US Class Current: 343/893
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 21/205 providing an omnidirectional coverage turnstile aerials H01Q21/26
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity

Abstract

The present invention relates to a node in a wireless communication system, the node having a central point and comprising at least two antenna functions. Each antenna function is arranged to cover a corresponding sector area, the sector areas being positioned around the central point successively such that each sector area is adjacent to at least one other sector area separated by corresponding borders. The polarization of at least one of said antenna functions is variable between the borders of the corresponding sector area such that for each border, the polarizations of the antenna functions at each side of the border are essentially orthogonal at the border. The present invention also relates to a corresponding wireless communication system and corresponding antenna functions.

Claims

1. A node (1) in a wireless communication system (2), the node (1) having a central point (3) and comprising at least two antenna functions (4, 5, 6), each antenna function (4, 5, 6) being arranged to cover a corresponding sector area (7, 8, 9), the sector areas (7, 8, 9) being positioned around the central point (3) successively such that each sector area (7, 8, 9) is adjacent to at least one other sector area, two adjacent sector areas being separated by at least one corresponding border (10, 11, 12) extending from the central point (3) and running between the corresponding antenna functions (4, 5, 6), characterized in that the polarization of at least one of said antenna functions (4, 5, 6) is variable between the borders (10, 11, 12) of the corresponding sector area (7, 8, 9) such that for each border (10, 11, 12), the polarizations of the antenna functions (4, 5, 6) at each side of the border (10, 11, 12) are essentially orthogonal at the border (10, 11, 12).

2. A node (1) according to claim 1, characterized in that the node comprises an odd number of sector areas (7, 8, 9).

3. A node (1) according to claim 2, characterized in that the node comprises a first antenna function (4), second antenna function (5) and third antenna function (6), where each antenna function (4, 5, 6) is arranged to cover a corresponding first sector area (7), second sector area (8) and third sector area (9).

4. A node (1) according to any one of the previous claims, characterized in that the polarization of each antenna function (4, 5, 6) is continuously variable between the borders (10, 11, 12) of the corresponding sector area (7, 8, 9), such that the polarization for each antenna function (4, 5, 6) varies essentially equally from one border to the other in the corresponding sector area (7, 8, 9).

5. A node (1) according to any one of the previous claims, characterized in that each antenna function (4, 5, 6) with a continuously variable polarization comprises a first element (13) with a first polarization vector (v₁) and a second element (14) with a second polarization vector (v₂), the polarization vectors (v₁, v₂) presenting an angle (θ

) between them, where the elements (13, 14) radiate essentially equal radiation patterns (15, 16), the elements (13, 14) being separated by a distance (d).

6. A node (1) according to any one of the previous claims 1-4, characterized in that each antenna function (4, 5, 6) with a continuously variable polarization comprises a first element (17) with a first polarization vector (v₁′

) and a second element (18) with a second polarization vector (v₂′

), the polarization vectors (v₁′

, v₂′

) presenting an angle (θ

) between them, where the elements (17, 18) radiate unequal radiation patterns (19, 20).

7. A node (1) according to claim 6, characterized in that the elements have an essentially common phase centre (21).

8. A node (1) according to any one of the previous claims 5-7, characterized in that each one of the elements (13, 14;

15, 16) is fed with the same signal (x(t)), the signal being weighted by a certain weight (w1, w2) for each one of the elements (13, 14;

15, 16).

9. A node (1) according to any one of the previous claims 5-8, characterized in that the polarization vectors (v₁, v₂;

v₁′

, v₂′

) are essentially orthogonal to each other, the angle (θ

) being essentially 90°

.

10. A node (1) according to any one of the previous claims, characterized in that a user terminal (22) in one sector area (7) is equipped with means (23) for determining its angular position (α

) within the sector area (7) by measuring and evaluating the polarization of the signals received from said node (1), the angular position (α

) being defined within an angular interval (24) between the corresponding borders (10, 12), and having a certain accuracy.

11. A wireless communication system (2) comprising at least one node (1), said node (1) having a central point (3) and comprising at least two antenna functions (4, 5, 6), each antenna function (4, 5, 6) being arranged to cover a corresponding sector area (7, 8, 9), the sector areas (7, 8, 9) being positioned around the central point (3) successively such that each sector area (7, 8, 9) is adjacent to at least one other sector area, two adjacent sector areas being separated by at least one corresponding border (10, 11, 12) extending from the central point (3) and running between the corresponding antenna functions (4, 5, 6), characterized in that the polarization of at least one of said antenna functions (4, 5, 6) is variable between the borders (10, 11, 12) of the corresponding sector area (7, 8, 9), such that for each border (10, 11, 12), the polarizations of the antenna functions (4, 5, 6) at each side of the border (10, 11, 12) are essentially orthogonal at the border (10, 11, 12).

12. A wireless communication system (2) according to claim 11, characterized in that the node comprises an odd number of sector areas (7, 8, 9).

13. A wireless communication system (2) according to claim 12, characterized in that the node comprises a first antenna function (4), a second antenna function (5) and a third antenna function (6), where each antenna function is arranged to cover a corresponding first sector area (7), second sector area (8) and third sector area (9).

14. A wireless communication system (2) according to any one of the claims 11-13, characterized in that the polarization of each antenna function (4, 5, 6) is continuously variable between the borders (10, 11, 12) of the corresponding sector area (7, 8, 9), such that the polarization for each antenna function (4, 5, 6) varies essentially equally from one border to the other in the corresponding sector area (7, 8, 9).

15. A wireless communication system (2) according to any one of the claims 11-14, characterized in that it further comprises at least one user terminal (22) in one sector area (7), the user terminal (22) being equipped with means (23) for determining its angular position (α

) within the sector area (7) by measuring and evaluating the polarization of the signals received from said node (1), the angular position (a) being defined within an angular interval (24) between the corresponding borders (10, 12), and having a certain accuracy.

16. A wireless communication system (2) according to claim 15, characterized in that the obtained angular position (α

) is used for

improving cellular positioning;

improving Global Positioning System, GPS, coverage; and

/or

obtaining Very High Frequency, VHF, Omni-directional Radio, VOR, positioning functionality.

17. An antenna function (4, 5, 6) in a wireless communication system (2), the antenna function (4, 5, 6) being arranged to cover a corresponding sector area (7, 8, 9) having at least two borders (10, 11, 12) towards at least one other adjacent sector area, said adjacent sector area having a corresponding antenna function, characterized in that the polarization of the antenna function (4, 5, 6) is variable between said borders (10, 11, 12) such that along each border (10, 11, 12), the polarization of the antenna function (4, 5, 6) is essentially orthogonal to the polarization in the corresponding adjacent sector area.

18. An antenna function (4, 5, 6) according to claim 17, characterized in that it comprises a first element (13) with a first polarization vector (v₁) and a second element (14) with a second polarization vector (v₂), the polarization vectors (v₁, v₂) presenting an angle (θ

) between them, where the elements (13, 14) radiate essentially equal radiation patterns (15, 16), the elements (13, 14) being separated by a distance (d).

19. An antenna function (4, 5, 6) according to claim 17, characterized in that the antenna function (4, 5, 6) comprises a first element (17) with a first polarization vector (v₁′

), and a second element (18) with a second polarization vector (v₂′

), the polarization vectors (v₁′

, v₂′

) presenting an angle (θ

) between them, where the elements (17, 18) radiate unequal radiation patterns (19, 20).

20. An antenna function (4, 5, 6) according to claim 19, characterized in that the elements have an essentially common phase centre (21).

21. An antenna function (4, 5, 6) according to any one of the previous claims 18-20, characterized in that each one of the elements (13, 14;

15, 16) is fed with the same signal (x(t)), the signal being weighted by a certain weight (w1, w2) for each one of the elements (13, 14;

15, 16).

22. An antenna function (4, 5, 6) according to any one of the previous claims 18-21, characterized in that the polarization vectors (v₁, v₂;

v₁′

, v₂′

) are essentially orthogonal to each other, the angle (θ

) being essentially 90°

.