Improving uplink performance for a beam-forming antenna configuration

• US 9,124,333 B1
• Filed: 10/17/2014
• Issued: 09/01/2015
• Est. Priority Date: 10/17/2014
• Status: Active Grant

• Current Assignee: T-Mobile Innovations LLC (Deutsche Telekom AG)
• Original Assignee: Sprint Communications Company LP (Deutsche Telekom AG)
• Inventors: Mansour, Nagi A., Tailor, Pinal, Pawlowski, Aaron
• Primary Examiner(s): Flores, Leon
• Application Number:
  US14/517,444
• Time in Patent Office: 319 Days
• US Class Current: 1/1
• CPC Class Codes: H04B 7/0837 using pre-detection combining H04B7/0868 takes precedence
• CPC Class Codes: H04B 7/0874 using subgroups of receive antennas
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04W 72/046 the resource being in the space domain, e.g. beams

Abstract

A method, system, and medium are provided for improving uplink performance of an antenna array configured for downlink beam forming. Beam forming requires an antenna element spacing that results in correlated downlink signals. Uplink reception preferably uses an element spacing such that uplink signals are uncorrelated. For an eight-element antenna configured for beam forming, using eight-branch combining to produce a single resultant signal is thus less than optimal. In an embodiment, non-adjacent elements in the antenna array, which receive uncorrelated signals, may be combined in pairs with two-branch combining. The four resultant signals may then be combined using four-branch combining to provide a single resultant signal.

Claims

1. One or more non-transitory computer-readable media having embodied thereon computer-usable instructions that, when executed by one or more processing devices, perform a method for combining uplink signals received via an antenna array that includes a plurality of elements, the method comprising:

for each of a plurality of element pairs within the antenna array, wherein each element pair contains two non-adjacent elements separated by a single element within the antenna array, wherein each element in the element pair receives an uplink signal, utilizing two-branch combining to combine the uplink signals from the elements within the element pair, thereby providing a resultant two-branch-combined uplink signal for each of the plurality of element pairs; and

utilizing n-branch combining to combine the resultant two-branch-combined uplink signals, wherein n is finite and corresponds to the number of element pairs within the antenna array.

2. The media of claim 1, wherein the n-branch combining of the resultant two-branch-combined signals is utilized to combine the resultant two-branch-combined signals into a single resultant uplink signal.

3. The media of claim 1, wherein the uplink signals are received via the antenna array that is physically configured for down-link beam forming.

4. The media of claim 3, wherein the antenna array that is physically configured for down-link beam forming comprises the elements spaced at a distance of λ

/2 or 0.65λ

, wherein λ

is the wavelength of a carrier signal associated with the uplink signals.

5. The media of claim 1, wherein the two-branch combining comprises a two-branch receive diversity technique and the n-branch combining comprises an n-branch receive diversity technique.

6. The media of claim 1, wherein the two-branch combining comprises maximum ratio combining.

7. The media of claim 1, wherein the n-branch combining comprises maximum ratio combining.

8. The media of claim 1, wherein the element pairs are non-overlapping element pairs.

9. The media of claim 1, wherein the antenna array includes at least eight elements.

10. A method for combining uplink signals received via an antenna array that includes eight antenna elements configured as four sets of cross-polarized dipoles that are configured for downlink beam forming, comprising:

using a two-branch combining technique to combine pairs of uncorrelated uplink signals received from non-overlapping pairs of elements in the antenna array, thereby providing four resultant two-branch-combined signals corresponding respectively to the non-overlapping pairs of elements;

using a four-branch combining technique to combine the four resultant two-branch-combined signals, thereby providing a four-branch-combined signal; and

utilizing the four-branch-combined signal to receive uplink communication.

11. The method of claim 10, wherein the two-branch combining technique comprises maximum ratio combining and the four-branch combining technique comprises maximum ratio combining.

12. The method of claim 10, wherein the plurality of elements configured for downlink beam forming are spaced within the antenna array such that signals received from adjacent elements are correlated.

13. The method of claim 12, wherein the plurality of elements configured for downlink beam forming are spaced at a distance of λ

/2 or 0.65λ

, wherein λ

is the wavelength of a carrier signal associated with the uplink signals.

14. The method of claim 12, wherein the elements within each non-overlapping pair of elements are nonadjacent in the antenna array.

15. The method of claim 10, wherein the antenna array includes at least eight elements.

16. A base station, comprising:

an antenna array that includes eight antenna elements configured as four sets of cross-polarized dipoles, wherein the antenna array is configured with the antenna elements spaced at one-half wavelength for downlink beam forming, and wherein the antenna array is further configured to provide a received uplink signal from each element; and

a signal processing module configured to;

A) perform two-branch combining of pairs of uplink signals received from non-overlapping pairs of nonadjacent elements spaced at one wavelength in the antenna array, thereby providing four resultant two-branch-combined uplink signals corresponding respectively to the non-overlapping pairs of nonadjacent elements, and

B) perform four-branch combining of the four resultant two-branch-combined uplink signals to provide a four-branch-combined uplink signal.

17. The method of claim 16, wherein the two-branch combining technique comprises maximum ratio combining.

18. The method of claim 16, wherein the four-branch combining technique comprises maximum ratio combining.

19. The method of claim 16, wherein the antenna array configured for downlink beam forming comprises an element spacing of λ

/2 or 0.65λ

, wherein λ

is the wavelength of a carrier signal associated with the uplink signals.

20. The method of claim 16, wherein the antenna array includes at least eight elements.