Secure channel state information with adaptive obfuscation

1. A privacy-enhancing wireless communication method for use by a transceiver device, the method comprising:

obtaining a frame preamble that includes a predetermined pattern enabling unauthorized detection of the transceiver device's movement or lack thereof via measurement of channel state information;

modifying the predetermined pattern to include amplitude or phase distortion that masks said movement or lack thereof;

transmitting a frame using the frame preamble with the modified pre-determined pattern;

instructing two or more receiving devices to respond according to a schedule with frame preambles that include predetermined patterns adjusted with amplitude or phase distortions to concurrently mask the movement or lack thereof of said two or more receiving devices.

2. A privacy-enhancing wireless communication method for use by a transceiver device, the method comprising:

obtaining a sequence of frames each having a preamble that includes a pre-determined pattern enabling unauthorized detection of the transceiver device's movement or lack thereof via measurement of channel state information;

modifying the predetermined pattern of each frame preamble in the sequence to include amplitude or phase distortion that masks said movement or lack thereof, with at least some of the frame preambles having modified predetermined patterns with different amplitude or phase distortion from the modified pre-determined patterns of other frame preambles; and

transmitting the sequence of frames using the frame preambles with the modified predetermined patterns.

3. The method of claim 2 , wherein the amplitude or phase distortion varies between frames to falsely indicate movement of the transceiver device.

4. The method of claim 2 , wherein the amplitude or phase distortion varies between frames to falsely indicate random movement of the transceiver device.

5. The method of claim 2 , wherein the amplitude or phase distortion varies between frames to falsely indicate that the transceiver device is not moving.

6. The method of claim 2 , wherein the amplitude or phase distortion varies between frames to falsely indicate communication from the transceiver device to another electronic device that is moving.

7. The method of claim 2 , wherein the transceiver device is at least one of an access point, a station, a repeater, and a mesh node.

8. The method of claim 2 , further comprising: instructing two or more receiving devices to respond according to a schedule with frame preambles that include predetermined patterns adjusted with amplitude or phase distortions to concurrently mask the movement or lack thereof of said two or more receiving devices.

9. The method of claim 2 , wherein the predetermined pattern is a training sequence.

10. The method of claim 2 , further comprising transmitting to a receiving device decoding parameters for operating on the frame preambles with the modified predetermined patterns to extract the channel state information.

11. The method of claim 2 , wherein said modifying includes multiplying each predetermined pattern with a corresponding obfuscation matrix, and wherein the method further comprises coordinating with a receiving device before said modifying to determine which obfuscation matrix to use.

12. The method of claim 2 , wherein said modifying includes multiplying each predetermined pattern with a corresponding obfuscation matrix, and wherein the obfuscation matrix varies according to time.

13. The method of claim 2 , wherein said modifying includes introducing a time delay or a phase shift between antenna streams, and wherein a magnitude of the time delay or a magnitude of the phase shift varies according to time.

14. A wireless transmitter that comprises:

one or more antennas;

a processor coupled to the one or more antennas; and

a memory storing instructions that when executed by the processor cause the processor to:

obtain a sequence of frames each having a preamble that includes a predetermined pattern enabling unauthorized detection of the wireless transmitter's movement or lack thereof via measurement of channel state information;

modify the predetermined pattern of each frame preamble in the sequence to include amplitude or phase distortion that masks said movement or lack thereof, with at least some of the frame preambles having modified predetermined patterns with different amplitude or phase distortion from the modified predetermined patterns of other frame preambles; and

transmit the sequence of frames using the frame preambles with modified predetermined patterns.

15. The transmitter of claim 14 , wherein the amplitude or phase distortion varies between frames to falsely indicate movement of the transmitter.

16. The transmitter of claim 14 , wherein the amplitude or phase distortion varies between frames to falsely indicate random movement of the transmitter.

17. The transmitter of claim 14 , wherein the amplitude or phase distortion varies between frames to falsely indicate that the transmitter is not moving.

18. The transmitter of claim 14 , wherein the amplitude or phase distortion varies between frames to falsely indicate communication from the transmitter to another electronic device that is moving.

19. The transmitter of claim 14 , wherein the instructions further cause the processor to: instruct two or more receiving devices to respond according to a schedule with frame preambles that include predetermined patterns adjusted with amplitude or phase distortions to concurrently mask the movement or lack thereof of said two or more receiving devices.

20. The transmitter of claim 14 , wherein as part of modifying the pre-determined pattern, the instructions cause the processor to introduce a time delay or a phase shift between antenna streams, and wherein a magnitude of the time delay or a magnitude of the phase shift varies according to time.