Lens antenna array with beam index modulation

1. A method of wireless communication for a lens antenna array system, comprising:

selecting a first subset of transmit antennas from an array of transmit antennas arranged in a focal region of a first lens;

transmitting from each transmit antenna in the first subset of transmit antennas to form a plurality of first RF signals that are directed through the first lens toward a second lens for a first symbol interval;

selecting a second subset of transmit antennas from the array of transmit antennas; and

transmitting from each transmit antenna in the second subset of transmit antennas to form a plurality of second RF signals that are directed through the first lens towards the second lens for a second symbol interval.

2. The method of wireless communication of claim 1 , wherein the first subset of transmit antennas contains a same number of transmit antennas as contained within the second subset of transmit antennas.

3. The method of wireless communication of claim 2 , wherein the number of transmit antennas in both the first subset of transmit antennas and in the second subset of transmit antennas is less than one-half of a total number of transmit antennas in the array of transmit antennas.

4. The method of wireless communication of claim 2 , wherein the number of transmit antennas in both the first subset of transmit antennas and in the second subset of transmit antennas is less than one-fourth of a total number of transmit antennas in the array of transmit antennas.

5. The method of wireless communication of claim 2 , wherein the number of transmit antennas in both the first subset of transmit antennas and in the second subset of transmit antennas is equal to one-half of a total number of transmit antennas in the array of transmit antennas.

6. The method of wireless communication of claim 1 , wherein the array of transmit antennas are arranged in the focal region of the first lens such that each transmit antenna corresponds to a unique angle-of-departure from the first lens, the method further comprising:

focusing the plurality of first RF signals through the second lens onto a first subset of receive antennas from an array of receive antennas arranged in a focal region of the second lens during the first symbol interval, and

focusing the plurality of second RF signals through the second lens onto a second subset of receive antennas from the array of receive antennas during the second symbol interval.

7. The method of wireless communication of claim 6 , further comprising:

detecting that the first subset of receive antennas received the plurality of first RF signals to decode a first symbol in a receiver coupled to the array of receive antennas; and

detecting that the second subset of receive antennas received the plurality of second RF signals to decode a second symbol.

8. The method of wireless communication of claim 6 , wherein a frequency of the plurality of first RF signals and of the plurality of second RF signals is between 100 GHz and 300 GHz.

9. The method of wireless communication of claim 8 , wherein a separation between the first lens and the second lens is such that the second lens is within a near-field region of the first lens.

10. The method of wireless communication of claim 1 , the method further comprising:

maintaining inactive each transmit antenna in the array of transmit antennas that does not belong to the first subset of transmit antennas during the first symbol interval; and

maintaining inactive each transmit antenna in the array of transmit antennas that does not belong to the second subset of transmit antennas during the second symbol interval.

11. A lens antenna array system, comprising:

an array of transmit antennas arranged in a focal region of a first lens;

an array of receive antennas arranged in a focal region of a second lens; and

one or more processors coupled with the array of transmit antennas and the array of receive antennas, wherein the one or more processors are configured to:

select a first subset of transmit antennas from the array of transmit antennas;

transmit through the first subset of transmit antennas to form a plurality of first RF signals that are directed through the first lens toward the second lens for a first symbol interval;

select a second subset of transmit antennas from the array of transmit antennas; and

transmit through the second subset of transmit antennas to form a plurality of second RF signals that are directed through the first lens towards the second lens for a second symbol interval.

12. The lens antenna array system of claim 11 , wherein the first subset of transmit antennas contains a same number of transmit antennas as contained within the second subset of transmit antennas.

13. The lens antenna array system of claim 12 , wherein the number of transmit antennas in both the first subset of transmit antennas and in the second subset of transmit antennas is less than one-half of a total number of transmit antennas in the array of transmit antennas.

14. The lens antenna array system of claim 12 , wherein the number of transmit antennas in both the first subset of transmit antennas and in the second subset of transmit antennas is less than one-fourth of a total number of transmit antennas in the array of transmit antennas.

15. The lens antenna array system of claim 12 , wherein the number of transmit antennas in both the first subset of transmit antennas and in the second subset of transmit antennas is equal to one-half of a total number of transmit antennas in the array of transmit antennas.

16. The lens antenna array system of claim 11 , wherein the array of transmit antennas is arranged in the focal region of the first lens such that each transmit antenna corresponds to a unique angle-of-departure from the first lens, wherein the lens antenna array system is configured to:

focus the plurality of first RF signals through the second lens onto a first subset of receive antennas from the array of receive antennas during the first symbol interval, and

focus the plurality of second RF signals through the second lens onto a second subset of receive antennas from the array of receive antennas during the second symbol interval.

17. The lens antenna array system of claim 16 , further comprising:

a receiver configured to:

detect that the first subset of receive antennas received the plurality of first RF signals to decode a first symbol in a receiver coupled to the array of receive antennas; and

detect that the second subset of receive antennas received the plurality of second RF signals to decode a second symbol.

18. The lens antenna array system of claim 16 , wherein a frequency of the plurality of first RF signals and of the plurality of second RF signals is between 100 GHz and 300 GHz.

19. The lens antenna array system of claim 18 , wherein a separation between the first lens and the second lens is such that the second lens is within a near-field region of the first lens.

20. The lens antenna array system of claim 11 , wherein the one or more processors are further configured to control the transmitter to:

maintain inactive each transmit antenna in the array of transmit antennas that does not belong to the first subset of transmit antennas during the first symbol interval; and

maintain inactive each transmit antenna in the array of transmit antennas that does not belong to the second subset of transmit antennas during the second symbol interval.