Transmission path identification based on propagation channel diversity
Various embodiments of the present technology relate generally to wireless power systems. More specifically, some embodiments relate to the use of time reversal techniques utilizing time diversity (e.g., different multipath arrivals at the same antenna) to achieve coherency from the same transmission node. For example, instead of initiating outgoing transmissions (e.g., power signals) at the same time, various embodiments can initiate the outgoing signals from the various antennas in a staggered timing that is a reversal of the arrival times of an incoming signal. As a result of staggering the start of the outgoing signals, the signals will arrive at the destination at approximately the same time even though they have traveled different paths having different propagation delays.
1. A circuit comprising control circuitry configured to:
generate an arrival profile including two or more times of arrival at the circuit for a wireless signal transmitted by a device over multiple paths; and
based on the arrival profile, determine:
a first time for a first response signal to be transmitted to the device over a first path of the multiple paths; and
at least a second time after the first time for at least a second response signal to be transmitted to the device over at least a second path of the multiple paths, the first path having a path length greater than a path length of the at least a second path.
2. The circuit of claim 1 further comprising an antenna operably coupled to the control circuitry.
3. The circuit of claim 1 further comprising memory operably coupled to the control circuitry.
4. The circuit of claim 1 , wherein the control circuitry is further configured to cause data representative of the arrival profile to be stored in the memory.
5. The circuit of claim 4 , wherein to determine the first time and the at least a second time, the control circuitry is configured to cause the data representative of the arrival profile to be read from the memory.
6. The circuit of claim 1 , wherein the control circuitry is further configured to cause the first response signal, and the at least a second response signal, to be transmitted from the circuit to the device at the first time and the at least a second time, respectively.
7. The circuit of claim 6 , wherein the control circuitry is further configured to cause the first response signal and the at least a second response signal to be received at the device at the same time.
8. The circuit of claim 1 , wherein the arrival profile further includes:
a first received phase of the wireless signal transmitted via the first path; and
at least a second received phase of the wireless signal transmitted via the at least a second,
and wherein the control circuitry is further configured to determine, based on the arrival profile:
a first transmit phase for the first response signal to reverse the direction of the first path over which the wireless signal was received at the circuit; and
at least a second transmit phase for the at least a second response signal to reverse the direction of the at least a second path over whish the wireless signal was received at the circuit.
9. The circuit of claim 8 , wherein the control circuitry is further configured to:
cause the first response signal to be transmitted to the device at the first time and at the first transmit phase; and
cause the at least a second response signal to be transmitted to the device at the at least a second time and at the at least a second transmit phase.
10. The circuit of claim 8 , wherein to determine the first transmit phase, and the at least a second transmit phase, the control circuitry is further configured to compute a complex conjugate of the first received phase, and the at least a second received phase, respectively.
11. A method comprising:
generating an arrival profile including two or more times of arrival at a circuit for a wireless signal transmitted by a device over multiple paths; and
determining, based on the arrival profile:
a first time for transmitting a first response signal to the device over a first path of the multiple paths; and
at least a second time after the first time for transmitting at least a second response signal to the device over at least a second path of the multiple paths, the first path having a path length greater than a path length of the at least a second path.
12. The method of claim 11 further comprising causing the first response signal, and the at least a second response signal, to be transmitted from the circuit to the device at the first time and the at least a second time, respectively.
13. The method of claim 12 further comprising causing the first response signal and the at least a second response signal to collectively match a radiation and reception pattern of the device in a three-dimensional space proximate to the device.
14. The method of claim 12 further comprising causing the first response signal and the at least a second response signal to coherently combine at a point, or in a three-dimensional space, proximate to the device.
15. The method of claim 12 further comprising:
receiving, at the circuit, a signal indicative of motion of the device; and
modifying transmission of at least one of the first, and the at least a second, response signals to the device according to the signal.
16. The method of claim 11 , wherein the arrival profile further includes:
a first phase of the wireless signal transmitted via the first path; and
at least a second phase of the wireless signal transmitted via the at least a second, the method further comprising determining:
a first direction to the circuit for the first path based on the first phase; and
at least a second direction to the circuit for the at least a second path based on the at least a second phase.
17. The method of claim 16 further comprising:
causing the first response signal to be transmitted to the device at the first time and in a direction opposite the first direction; and
causing the at least a second response signal to be transmitted to the device at the at least a second time and in a direction opposite the at least a second direction.
18. The method of claim 11 further comprising monitoring for receipt of the wireless signal at the circuit.
19. The method of claim 18 , wherein the generating comprises generating the arrival profile in response to the wireless signal being received at the circuit.
20. One or more non-transitory computer readable media having stored thereon program instructions which, when executed by at least one processor, cause a machine to:
generate an arrival profile including two or more times of arrival at a circuit for a wireless signal transmitted by a device over multiple paths; and
determine, based on the arrival profile:
a first time for transmitting a first response signal to the device over a first path of the multiple paths; and
at least a second time after the first time for transmitting at least a second response signal to the device over at least a second path of the multiple paths, the first path having a path length greater than a path length of the at least a second path.