Ping pong beamforming

1. One or more non-transitory, computer-readable media having one or more instructions, the one or more instructions comprising instructions that, when executed, cause a first device to:

perform a ping-pong beamforming process, wherein the instructions that, when executed, cause the first device to perform the ping-pong beamforming process comprise instructions that, when executed, cause the first device to:

send a first training signal using a first weight vector to a second device;

receive, from the second device, a second training signal sent using a second weight vector;

estimate, based on the second training signal, an indexed signal, wherein an estimate of the indexed signal comprises a product of the second weight vector and a channel;

determine a third weight vector based on a complex conjugate of the estimate of the indexed signal; and

normalize the third weight vector; and

perform a first iteration of the ping-pong beamforming process using a transmission protocol to exchange one or more messages with the second device, the transmission protocol comprising a plurality of time slots, and an individual time slot selected from the plurality of time slots dedicated to one transmission direction and comprising a training period followed by a data period, wherein the first iteration of the ping-pong beamforming process comprises the send, the receive, the estimate, the determine, and the normalize.

2. The one or more non-transitory, computer-readable media of claim 1 , wherein the instructions further comprise additional instructions that, when executed, further cause the first device to:

perform one or more iterations of the ping-pong beamforming process until a convergence criterion is satisfied.

3. The one or more non-transitory, computer-readable media of claim 2 , wherein the convergence criterion is based on a comparison of a norm of a fourth weight vector to a predetermined threshold.

4. The one or more non-transitory, computer-readable media of claim 2 , wherein the first weight vector for the first iteration of the ping-pong beamforming process is a randomly chosen value or a value determined by a second iteration of the ping-pong beamforming process that precedes the first iteration.

5. The one or more non-transitory, computer-readable media of claim 1 , wherein the instructions further comprise additional instructions that, when executed, further cause the first device to:

determine the complex conjugate of the estimate of the indexed signal.

6. The one or more non-transitory, computer-readable media of claim 1 , wherein the instructions further comprise additional instructions that, when executed, further cause the first device to:

perform an initialization procedure to acquire the first weight vector in a first time slot; and

send the first training signal in a second time slot that follows the first time slot.

7. The one or more non-transitory, computer-readable media of claim 1 , wherein the instructions further comprise additional instructions that, when executed, further cause the first device to:

receive a training signal matrix that comprises a first weight vector portion and a first noise portion;

estimate a normalized matched filter, wherein an estimate of the normalized matched filter is based on the training signal matrix; and

perform noise suppression based on the estimate of the normalized matched filter.

8. The one or more non-transitory, computer-readable media of claim 1 , wherein the first device is a base station, wherein the second device is a user device, and wherein the instructions further comprise additional instructions that, when executed, further cause the base station to:

perform the ping-pong beamforming process in a multi-user multiple-input, multiple-output (MIMO) process.

9. An apparatus, comprising:

transceiver circuitry; and

control circuitry coupled with the transceiver circuitry, the control circuitry configured to perform a ping-pong beamforming process, wherein, to perform the ping-pong beamforming process, the control circuitry is configured to:

receive, from a device, a training signal transmitted using a first weight vector;

estimate, based on the training signal, an indexed signal, wherein an estimate of the indexed signal comprises a product of the first weight vector and a channel;

determine a second weight vector based on a complex conjugate of the estimate of the indexed signal; and

normalize the second weight vector;

wherein the control circuitry is to perform one or more iterations of the ping-pong beamforming process until a convergence criterion is satisfied, wherein the convergence criterion is based on a comparison of a norm of a third weight vector to a predetermined threshold.

10. The apparatus of claim 9 , wherein the apparatus is a base station and wherein the control circuitry is further configured to transmit, via the transceiver circuitry to the device, another training signal using a fourth weight vector, the other training signal transmitted to the device before the indexed signal is estimated.

11. The apparatus of claim 9 , wherein the control circuitry is further configured to:

determine the complex conjugate of the estimate of the indexed signal.

12. An apparatus, comprising:

transceiver circuitry; and

control circuitry coupled with the transceiver circuitry, the control circuitry configured to perform a ping-pong beamforming process, wherein, to perform the ping-pong beamforming process, the control circuitry is configured to:

receive, from a device, a training signal transmitted using a first weight vector;

estimate, based on the training signal, an indexed signal, wherein an estimate of the indexed signal comprises a product of the first weight vector and a channel;

determine a second weight vector based on a complex conjugate of the estimate of the indexed signal; and

normalize the second weight vector;

wherein the control circuitry is to perform one or more iterations of the ping-pong beamforming process, wherein at least one iteration of the one or more iterations is performed using a transmission protocol to exchange one or more messages with the device, the transmission protocol comprising a plurality of time slots, and an individual time slot selected from the plurality of time slots is dedicated to one transmission direction and comprises a training period followed by a data period.

13. The apparatus of claim 12 , wherein the control circuitry is further configured to:

perform an initialization procedure to acquire a third weight vector in a first time slot; and

send, via the transceiver circuitry and to the device, another training signal in a second time slot that follows the first time slot.

14. The apparatus of claim 9 , wherein the control circuitry is further configured to:

transmit, via the transceiver circuitry and in response the second weight vector being normalized, a data symbol using the second weight vector;

receive, via the transceiver circuitry, a data signal from the device; and

apply a normalized third weight vector to the data signal to recover the data symbol.

15. The apparatus of claim 9 , wherein the transceiver circuitry is further configured to perform matched filtering.

16. The apparatus of claim 9 , wherein the transceiver circuitry is further configured to perform zero-forcing filtering based on the first and second weight vectors.

17. The apparatus of claim 16 , wherein the transceiver circuitry is further configured to perform the zero-forcing filtering at a transmitter.

18. The apparatus of claim 16 , wherein the transceiver circuitry is further configured to perform the zero-forcing filtering at a receiver.

19. The apparatus of claim 9 , wherein the transceiver circuitry comprises a plurality of antennas and wherein the transceiver circuitry is further configured to provide millimeter wave communication.

20. A method of operating a first device, comprising:

sending a first training signal using a first weight vector to a second device;

receiving, from the second device, a second training signal sent using a second weight vector;

estimating, based on the second training signal, an indexed signal, wherein an estimate of the indexed signal comprises a product of the second weight vector and a channel;

determining a third weight vector based on a complex conjugate of the estimate of the indexed signal;

normalizing the third weight vector; and

performing one or more iterations of the sending, the receiving, the estimating, the determining, and the normalizing until a convergence criterion is satisfied, wherein the convergence criterion is based on a comparison of a norm of a fourth weight vector to a predetermined threshold.

21. One or more non-transitory, computer-readable media having one or more instructions, the one or more instructions comprising instructions that, when executed, cause a first device to:

perform a ping-pong beamforming process, wherein the instructions that, when executed, cause the first device to perform the ping-pong beamforming process comprise instructions that, when executed, cause the first device to:

send a first training signal using a first weight vector to a second device;

receive, from the second device, a second training signal sent using a second weight vector;

estimate, based on the second training signal, an indexed signal, wherein an estimate of the indexed signal comprises a product of the second weight vector and a channel;

determine a third weight vector based on a complex conjugate of the estimate of the indexed signal; and

normalize the third weight vector; and

perform one or more iterations of the ping-pong beamforming process until a convergence criterion is satisfied, the convergence criterion based on a comparison of a norm of a fourth weight vector to a predetermined threshold.

22. The one or more non-transitory, computer-readable media of claim 21 , wherein the first weight vector is a randomly chosen value or a value determined by a second iteration of the ping-pong beamforming process that precedes the first iteration.