Wireless networking communication methods, systems, and devices operable using harvested power
Example devices described herein include endpoint devices which may communicate with an access point device by modulating a channel associated with the wireless communication to encode transmit data. The channel modulation may be performed by utilizing a switch to control an impedance of an antenna at the endpoint device to either reflect or absorb wireless network communication signals received by the endpoint device. The access point device may extract the transmit data by decoding changes in the channel caused, at least in part, by the modulation. Access point devices may transmit a pattern of packets—the presence or absence of which may correspond with transmit data. Endpoint devices may decode this data by using an energy detector to differentiate between the presence or absence of a packet.
1. A device comprising:
an antenna, the antenna configured to receive wireless network communication signals provided by another device;
a channel modulator configured to modulate a channel associated with the wireless communication signals, wherein the channel modulator is configured to modulate the channel by adjusting an impedance of the antenna in accordance with transmit data for transmission to the another device, wherein a first time during which the channel is modulated for each bit of transmit data is greater than a second time required for transmission of a plurality of packets of the wireless network communication signals.
2. The device of claim 1 , wherein the channel modulator is configured to modulate the channel by altering channel measurements for the wireless network communication signals received by the another device.
3. The device of claim 1 , wherein the channel modulator is configured to modulate the channel responsive to a query by the another device.
4. The device of claim 1 , wherein the channel modulator comprises a switch configured to modify the impedance of the antenna in accordance with the transmit data.
5. The device of claim 1 , wherein the channel modulator is further configured to adjust a rate of modulation in accordance with wireless network traffic conditions.
6. The device of claim 5 , wherein the channel modulator is configured to adjust the rate of modulation by changing a duration of modulation for a bit of the transmit data.
7. The device of claim 6 , further comprising a power harvester configured to power the channel modulator using power harvested from an environment in which the device is located.
8. The device of claim 7 , wherein the power harvester is configured to power the channel modulator using power harvested from RF signals received by the antenna.
9. The device of claim 6 , wherein the another device comprises an access point device.
10. The device of claim 6 , further comprising an energy detector, the energy detector configured to detect a presence or absence of a transmitted packet in a time interval and output a first value corresponding to the presence of the transmitted packet and a second value corresponding to the absence of the transmitted packet.
11. The device of claim 10 , wherein the energy detector comprises an envelope detector, a peak finder, a set-threshold circuit and a comparator.
12. A method of wireless networking communication, the method comprising:
receiving, at an endpoint device, wireless networking communication signals provided by an access point device;
decoding, at the endpoint device, a query from the access point device, wherein the query is transmitted using a presence or absence of a packet to indicate a bit;
responding to the query by transmitting data to the access point device, at least in part by modulating a channel associated with the wireless networking communication signals, wherein a first time during which the channel is modulated for each bit of data is greater than a second time required for transmission of a plurality of packets of the wireless networking communication signals.
13. The method of claim 12 , wherein the wireless networking communication signals comprise signals.
14. The method of claim 12 , wherein the decoding occurs using an energy detector to differentiate between the presence and absence of a packet.
15. The method of claim 12 , wherein modulating the channel comprises absorbing or reflecting at least a portion of the wireless networking communication signals.
16. The method of claim 14 , wherein using the energy detector comprises:
detecting the presence or the absence of the packet in a time interval; and
outputting a first value corresponding to the presence of the packet and a second value corresponding to the absence of the packet.
17. The method of claim 14 , wherein the energy detector comprises an envelope detector, a peak finder, a set-threshold circuit and a comparator.
18. The method of claim 12 , wherein modulating the channel comprises altering channel measurements for the wireless networking communication signals received by the access point device.
19. The method of claim 12 , wherein modulating the channel comprises modifying an impedance of an antenna of the endpoint device in accordance with the data.
20. The method of claim 12 , wherein modulating the channel comprises adjusting a rate of modulation by changing a duration of modulation for a bit of the data.