Joint selection of antennas and transmission power level for wireless energy transfer
Apparatuses, methods, and systems for jointly selecting a plurality of antennas and a transmission power level, for transmitting a wireless energy transfer (WET) signal from a base station to a device are disclosed. One apparatus includes a base station, wherein the base station includes a plurality of N antennas configured to transmit and receive electromagnetic signals, and a controller connected to the plurality of N antennas through a plurality of RF (radio frequency) chains. The controller is configured to jointly select a plurality of M of the plurality of N antennas and a transmission power level, for transmitting a wireless energy transfer (WET) signal from the base station to a device based on an activation threshold of the device and a saturation level of the device.
1. A base station, comprising:
a plurality of N antennas configured to transmit and receive electromagnetic signals;
wherein the base station is configured to:
transmit electromagnetic signals to a device through the plurality of N antennas at a power level that is above a startup threshold;
receive an activation threshold and a saturation level of the device from the device after the base station transmits the electromagnetic signals through the N antennas at the power level above the startup threshold, wherein the startup threshold is greater than the saturation level;
a controller, wherein the controller is configured to:
jointly select a plurality of M of the plurality of N antennas and a transmission power level, for transmitting a wireless energy transfer (WET) signal from the base station to device based on the received activation threshold of the device and the received-saturation level of the device;
and wherein the base station is further configured to:
transmits the WET signal to the device at the selected transmission power level through the selected M antennas;
receive an uplink wireless information transfer (WIT) from the device through the selected M antennas.
2. The base station of claim 1 , wherein the activation threshold is a level of the wireless energy transfer signal needed to activate the device.
3. The base station of claim 1 , wherein the saturation level of the device is a level of the wireless energy transfer signal wherein wireless energy transfer signal energy above this level does not provide additional energy to the device.
4. The base station of claim 1 , wherein the base station receives the activation threshold of the device and the saturation level of the device based on the uplink WIT signal from the device.
5. The base station of claim 4 , wherein the base station is further configured to jointly select the plurality of M of the plurality of N antennas and the transmission power level based on a channel estimate of a communication channel between the base station and the device.
6. The base station of claim 5 , wherein the controller is further configured to determine the channel estimate based on a training signal within at least a portion of the uplink communication from the device to the base station.
7. The base station of claim 1 , wherein downlink wireless energy transfer (WET) signals and uplink wireless information transfer (WIT) signals are scheduled according to frames, wherein at least one of the scheduled frames is divided into a downlink WET signal, an uplink training signal, and an uplink WIT signals; and wherein the uplink training signal provides the base station with knowledge of the transmission channel.
8. The base station of claim 7 , wherein the base station is further configured to jointly select the plurality of M of the plurality of N antennas and the transmission power level based on a percentage or fraction of one or more of the frames that is allocated for WET signals.
9. The base station of claim 7 , wherein the base station is further configured to use the knowledge of the transmission channel to transmit beam formed energy to the device at the selected transmission power level through the selected M antennas, and wherein the base station uses the knowledge of the transmission channel to decode information in the uplink wireless information transfer (WIT) from the device through the selected M antennas.
10. The base station of claim 1 , wherein the base station is further configured to jointly select the plurality of M of the plurality of N antennas and the transmission power level based on a number of devices communicating with the base station.
11. The base station of claim 1 , wherein the base station is further configured to jointly select the plurality of M of the plurality of N antennas and the transmission power level based on a system bandwidth between base station and the device.
12. The base station of claim 1 , wherein the base station is further configured to jointly select the plurality of M of the plurality of N antennas and the transmission power level based on an efficiency of a power amplifier of the base station.
13. The base station of claim 1 , wherein a fraction of at least one scheduled frame is reserved the downlink WET signal, a fraction of the at least one scheduled frame is reserved the uplink training signal, and a fraction of the at least one scheduled frame is reserved the uplink WIT signals, wherein the fraction of the at least one scheduled frame reserved for the downlink WET signal, the fraction of the at least one scheduled frame reserved for the uplink training signal, and the fraction of the at least one scheduled frame reserved for the uplink WIT signals, sum to equal one.
14. A method, comprising:
transmitting, by one or more of a plurality of N antennas of a base station, an electromagnetic signal to a device at a power level above that is above a startup threshold;
receiving, by the base station, an activation threshold and a saturation level of the device from the device after the base station transmits the electromagnetic signals through the N antennas at the power level that is above the startup threshold, wherein the startup threshold is greater than the saturation level;
jointly selecting, by a controller of the base station, a plurality of M of the plurality of N antennas and a transmission power level, for transmitting a wireless energy transfer (WET) signal from the base station to the device based on the received activation threshold of the device and the received saturation level of the device; and
transmitting, by the base station, the WET signal to the device at the selected transmission power level through the selected M antennas.
15. The method of claim 14 , wherein the activation threshold of the device and the saturation level of the device are received based on uplink communication from the device to the base station.
16. The method of claim 14 , wherein the jointly selecting, by the controller of the base station, the plurality of M of the plurality of N antennas and the transmission power level is further based on a channel estimate of a communication channel between the base station and the device.
17. The method of claim 14 , wherein downlink wireless energy transfer (WET) signals and uplink wireless information transfer (WIT) signals are scheduled according to frames.
18. The method of claim 17 , wherein the jointly selecting, by the controller of the base station, the plurality of M of the plurality of N antennas and the transmission power level is further based on a percentage or fraction of one or more of the frames that is allocated for WET signals.
19. The method of claim 14 , wherein the jointly selecting, by the controller of the base station, the plurality of M of the plurality of N antennas and the transmission power level is further based on an efficiency of a power amplifier of the base station.