Using subarrays of a beamformer for transmissions in a forward link

• US 9,648,504 B2
• Filed: 12/10/2013
• Issued: 05/09/2017
• Est. Priority Date: 12/10/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Namgoong, June, Jayaraman, Srikant, Liu, Ruoheng
• Primary Examiner(s): DEAN, JR, JOSEPH E
• Application Number:
  US14/101,919
• Publication Number:
  US 20150163683A1
• Time in Patent Office: 1,246 Days
• CPC Class Codes: H04B 7/06 at the transmitting station
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/068 using space frequency diversity space-frequency coding H04L1/0606
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

Methods, systems, and devices are described for transmitting across a broad azimuth using an antenna array. In one example, a method is described that includes forming two subarrays from an antenna array. Beamforming weights are selected for each subarray to cause the radiation patterns to be complementary over a range of the azimuth of a cell. The beamforming weights may be selected according to a recursive relation based on the number of antenna elements in each subarray. Information may be encoded, scrambled, and mapped to modulation symbols. A Space Frequency Block Code (SFBC) such as an Alamouti Code may then be used to form two signals to be transmitted over the two subarrays.

Claims

1. A method for transmitting data over an angular range of an array antenna in a wireless communications system, comprising:

generating two parallel signals, each of the parallel signals associated with the data;

forming a first subarray from a first set of array elements of an array antenna;

forming a second subarray from a second set of array elements of the array antenna;

selecting a first set of beamforming weights for the first subarray and a second set of beamforming weights for the second subarray, the selected beamforming weights causing a power radiation pattern of the first subarray to be complementary to a power radiation pattern of the second subarray over the angular range of the array antenna, wherein the selected beamforming weights are based at least in part on a recursive relation that includes an iterative calculation that increases a calculated number of beamforming weights from an initial set of beamforming weights to a desired number of beamforming weights, the desired number of beamforming weights being equal to a number of elements in the respective subarray;

transmitting, according to the first set of beamforming weights, a first of the parallel signals over the angular range of the array antenna via the first subarray; and

transmitting, according to the second set of beamforming weights, a second of the parallel signals over the angular range of the array antenna via the second subarray.

2. The method of claim 1, wherein each repetition of the iterative calculation begins with an initial number of beamforming weights and calculates twice the initial number of beamforming weights.

3. The method of claim 1,

wherein the data comprises a control channel.

4. The method of claim 1,

wherein generating the two parallel signals is based at least in part on a space frequency block code (SFBC), the SFBC based at least in part on an Alamouti code.

5. The method of claim 1, wherein a sum of the power radiation pattern of the first subarray and the power radiation pattern of the second subarray is constant over the angular range of the array antenna.

6. The method of claim 1, wherein the first set of array elements and the second set of array elements comprise a same element pattern.

7. The method of claim 1, wherein at least one array element of the first subarray or the second subarray is omnidirectional over the angular range of the array antenna.

8. The method of claim 1, wherein the array antenna is a uniform linear array antenna.

9. The method of claim 1, wherein the recursive relation is based at least in part on at least one design parameter value.

10. The method of claim 9, wherein the at least one design parameter value is based at least in part one or more transmission conditions.

11. The method of claim 9, further comprising:

updating the first set of beamforming weights for the first subarray and the second set of beamforming weights for the second subarray, wherein the updating is based at least in part on an update of the at least one design parameter value.

12. An apparatus for transmitting data over an angular range of an array antenna in a wireless communications system, comprising:

means for generating two parallel signals, each of the parallel signals associated with the data;

means for forming a first subarray from a first set of array elements of an array antenna;

means for forming a second subarray from a second set of array elements of the array antenna;

means for selecting a first set of beamforming weights for the first subarray and a second set of beamforming weights for the second subarray, the selected beamforming weights causing a power radiation pattern of the first subarray to be complementary to a power radiation pattern of the second subarray over the angular range of the array antenna, wherein the selected beamforming weights are based at least in part on a recursive relation that includes an iterative calculation that increases a calculated number of beamforming weights from an initial set of beamforming weights to a desired number of beamforming weights, the desired number of beamforming weights being equal to a number of elements in the respective subarray

means for transmitting, according to the first set of beamforming weights, a first of the parallel signals over the angular range of the array antenna via the first subarray; and

means for transmitting, according to the second set of beamforming weights, a second of the parallel signals over the angular range of the array antenna via the second subarray.

13. The apparatus of claim 12

wherein the data comprises a control channel.

14. The apparatus of claim 12,

wherein the means for generating the two parallel signals is operable based at least in part on a space frequency block code (SFBC), the SFBC based at least in part on an Alamouti code.

15. The apparatus of claim 12, wherein a sum of the power radiation pattern of the first subarray and the power radiation pattern of the second subarray is constant over the angular range of the array antenna.

16. The apparatus of claim 12, wherein the first set of array elements and the second set of array elements comprise a same element pattern.

17. The apparatus of claim 12, wherein the array antenna is a uniform linear array antenna.

18. The apparatus of claim 12, wherein the recursive relation is based at least in part on at least one design parameter value.

19. The apparatus of claim 18, wherein the at least one design parameter value is based at least in part one or more transmission conditions.

20. The apparatus of claim 18, further comprising:

means for updating the first set of beamforming weights for the first subarray and the second set of beamforming weights for the second subarray, wherein the updating is based at least in part on an update of the at least one design parameter value.

21. An apparatus for transmitting data over an angular range of an array antenna in a wireless communications system, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory, the instructions being executable by the processor to;

generate two parallel signals, each of the parallel signals associated with the data;

form a first subarray from a first set of array elements of an array antenna;

form a second subarray from a second set of array elements of the array antenna;

select a first set of beamforming weights for the first subarray and a second set of beamforming weights for the second subarray, the selected beamforming weights causing a power radiation pattern of the first subarray to be complementary to a power radiation pattern of the second subarray over the angular range of the array antenna, wherein the selected beamforming weights are based at least in part on a recursive relation that includes an iterative calculation that increases a calculated number of beamforming weights from an initial set of beamforming weights to a desired number of beamforming weights, the desired number of beamforming weights being equal to a number of elements in the respective subarray

transmit, according to the first set of beamforming weights, a first of the parallel signals over the angular range of the array antenna via the first subarray; and

transmit, according to the second set of beamforming weights, a second of the parallel signals over the angular range of the array antenna via the second subarray.

22. The apparatus of claim 21, wherein the instructions are executable by the processor to:

generate the two parallel signals based at least in part on a space frequency block code (SFBC), the SFBC based at least in part on an Alamouti code.

23. The apparatus of claim 21, wherein the recursive relation is based at least in part at least one design parameter value.

24. The apparatus of claim 23, wherein the at least one design parameter value is based at least in part one or more transmission conditions.

25. The apparatus of claim 23, wherein the instructions are executable by the processor to:

update the first set of beamforming weights for the first subarray and the second set of beamforming weights for the second subarray, wherein the updating is based at least in part on an update of the at least one design parameter value.

26. A computer program product for transmitting data over an angular range of an array antenna in a wireless communications system, the computer program product comprising a non-transitory computer-readable medium storing instructions executable by a processor to:

generate two parallel signals, each of the parallel signals associated with the data;

form a first subarray from a first set of array elements of an array antenna;

form a second subarray from a second set of array elements of the array antenna;

select a first set of beamforming weights for the first subarray and a second set of beamforming weights for the second subarray, the selected beamforming weights causing a power radiation pattern of the first subarray to be complementary to a power radiation pattern of the second subarray over the angular range of the array antenna, wherein the selected beamforming weights are based at least in part on a recursive relation that includes an iterative calculation that increases a calculated number of beamforming weights from an initial set of beamforming weights to a desired number of beamforming weights, the desired number of beamforming weights being equal to a number of elements in the respective subarray

transmit, according to the first set of beamforming weights, a first of the parallel signals over the angular range of the array antenna via the first subarray; and

transmit, according to the second set of beamforming weights, a second of the parallel signals over the angular range of the array antenna via the second subarray.

27. The computer program product of claim 26, wherein the instructions are executable by the processor to:

generate the two parallel signals based at least in part on a space frequency block code (SFBC), the SFBC based at least in part on an Alamouti code.

28. The computer program product of claim 26, wherein the recursive relation is based at least in part on at least one design parameter value.

29. The computer program product of claim 28, wherein the at least one design parameter value is based at least in part one or more transmission conditions.

30. The computer program product of claim 28, wherein the instructions are executable by the processor to:

update the first set of beamforming weights for the first subarray and the second set of beamforming weights for the second subarray, wherein the updating is based at least in part on an update of the at least one design parameter value.