ADAPTATION OF MODULATION PARAMETERS FOR COMMUNICATIONS BETWEEN AN IMPLANTABLE MEDICAL DEVICE AND AN EXTERNAL INSTRUMENT

• US 20100198304A1
• Filed: 02/03/2009
• Published: 08/05/2010
• Est. Priority Date: 02/03/2009
• Status: Active Grant

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Wang, Yu
• Granted Patent: US 8,571,678 B2
• Time in Patent Office: Days
• US Class Current: 607/60
• CPC Class Codes: A61N 1/37235 Aspects of the external programmer
• CPC Class Codes: A61N 1/3727 characterised by the modulation technique
• CPC Class Codes: A61N 1/37276 characterised by means for reducing power consumption during telemetry

Abstract

External instruments and implantable medical devices communicate using modulation parameter settings that may be adapted during communication sessions based on a quality of the wireless communications link. An analysis of the quality of the link is performed and a request to change modulation parameters is sent to one of the devices by the other. The analysis may be based on measuring noise and interference during idle communication frames. The devices may then change the modulation parameter settings, for the uplink, downlink, or both. The devices may also employ a recovery operation to revert back to the previous modulation parameter settings if the transmissions are not properly received using the changed modulation parameter settings. The modulation parameter settings may include modulation type, modulation symbol rate, and the like.

Claims

1. A method of adapting communications between an implantable medical device and an external instrument, comprising:

transferring communication signals using a first initial modulation parameter setting over a telemetry link between the implantable medical device and the external instrument;

analyzing a quality metric of the communication signals that have been transferred;

selecting a second modulation parameter setting as a replacement for the first initial modulation parameter setting in response to the analysis; and

transferring communication signals using the second modulation parameter setting over the telemetry link between the implantable medical device and the external instrument.

2. The method of claim 1, wherein transferring a communication signal using the first initial modulation parameter setting over the telemetry link comprises:

transferring a first communication signal from the external instrument to the implantable medical device over the telemetry link; and

transferring a second communication signal from the implantable medical device to the external instrument in response to the first frame of data over the telemetry link.

3. The method of claim 2, wherein analyzing the quality metric occurs at the external device by analyzing the second communication signal.

4. The method of claim 3, wherein analyzing the quality metric further comprises measuring by the external device a received signal strength.

5. The method of claim 3, further comprising:

listening at the external device during a period of time when no communication signals are being sent by the implantable medical device to obtain a signal strength reference; and

wherein analyzing the quality metric further comprises comparing by the external instrument the signal strength reference to a signal strength of the second communication signal to obtain a signal-to-noise ratio for the telemetry link.

6. The method of claim 2, wherein the first communication signal and the second communication signal are sent using a same carrier frequency.

7. The method of claim 1, wherein the first initial modulation parameter setting comprises an initial modulation type and wherein the second modulation parameter setting comprises a first alternative modulation type.

8. The method of claim 7, wherein the initial modulation type comprises one of amplitude-shift keying (ASK), frequency-shift keying (FSK), quadrature amplitude modulation (QAM), phase-shift keying (PSK), binary phase-shift keying (BPSK), differential binary phase-shift keying (DBPSK), quadrature phase-shift keying (QPSK), and differential quadrature phase-shift keying (DQPSK).

9. The method of claim 8, wherein the first alternative modulation type comprises one of ASK, FSK, QAM, BPSK, DBPSK, QPSK, and DQPSK.

10. The method of claim 1, wherein the initial modulation parameter setting comprises an initial modulation symbol rate and wherein the second modulation parameter setting comprises a first alternative modulation symbol rate.

11. The method of claim 10, wherein the initial modulation symbol rate ranges from 1 to 300 kilosymbols per second.

12. The method of claim 11, wherein the first alternative modulation symbol rate ranges from 1 to 300 kilosymbols per second.

13. The method of claim 1, wherein selecting the second modulation parameter setting comprises performing a look-up of the link quality in a stored table that associates link quality to at least one modulation parameter setting.

14. The method of claim 1, wherein transferring communication signals using a first initial modulation parameter setting over a telemetry link between the implantable medical device and the external instrument further comprises using a second initial modulation parameter setting, the method further comprising selecting a third modulation parameter setting as a replacement for the second initial modulation parameter setting in response to the analysis, and wherein transferring communication signals using the second modulation parameter setting over the telemetry link between the implantable medical device and the external instrument further comprises using the third modulation parameter setting in addition to the second modulation parameter setting.

15. The method of claim 14, wherein the first initial modulation parameter setting comprises a modulation type and wherein the second initial modulation parameter setting comprises a modulation symbol rate.

16. The method of claim 1, further comprising:

analyzing a quality metric of the communication signals that have been transferred using the second modulation parameter setting;

selecting a fourth modulation parameter setting as a replacement for the second modulation parameter setting in response to the analysis; and

transferring communication signals using the fourth modulation parameter setting over the telemetry link between the implantable medical device and the external instrument.

17. The method of claim 1, further comprising:

sending between the external instrument and the implantable device a communication signal using the first initial modulation parameter setting that requests to change from the first initial modulation parameter setting to the second modulation parameter setting; and

in response to the communication signal that requests to change, sending a responsive communication signal using the first initial modulation parameter setting.

18. The method of claim 1, wherein selecting a second modulation parameter setting as a replacement for the first initial modulation parameter setting in response to the analysis comprises selecting the second modulation parameter setting for use by only the external instrument when transmitting and only the implantable medical device when receiving and wherein transferring communication signals using the second modulation parameter setting over the telemetry link between the implantable medical device and the external instrument comprises transmitting communication signals using the second modulation parameter setting over the telemetry link only by the external instrument and receiving communication signals using the second modulation parameter setting over the telemetry link only by the implantable medical device.

19. The method of claim 1, wherein selecting a second modulation parameter value as a replacement for the first initial modulation parameter setting in response to the analysis comprises selecting the second modulation parameter for use by only the implantable medical device when transmitting and only by the external instrument when receiving and wherein transferring communication signals using the second modulation parameter setting over the telemetry link between the implantable medical device and the external instrument comprises transmitting communication signals using the second modulation parameter setting over the telemetry link only by the implantable medical device and receiving communication signals using the second modulation parameter setting over the telemetry link only by the external instrument.

20. The method of claim 1, wherein transferring communication signals using the second modulation parameter setting over the telemetry link between the implantable medical device and the external instrument comprises transferring communication signals from the external instrument to the implantable medical device, the method further comprising:

listening at the external instrument for a response by the implantable medical device; and

when the external instrument does not receive a valid response by the implantable medical device, then selecting the first initial modulation parameter setting and at a subsequent time transferring communication signals from the external instrument to the implantable medical device using the first initial modulation parameter setting.

21. The method of claim 20, further comprising:

listening at the implantable medical device for communication signals using the second modulation parameter setting from the external instrument;

when the implantable medical device does not receive a valid communication signal that uses the second modulation parameter setting, then at a subsequent time listening at the implantable medical device for communication signals using the first initial modulation parameter setting.

22. The method of claim 1, further comprising:

analyzing the quality metric of the communication signals that have been transferred using the second modulation parameter setting and a second initial modulation parameter setting;

selecting a third modulation parameter setting as a replacement for the second initial modulation parameter setting in response to the analysis; and

transferring communication signals using the second modulation parameter setting and the third modulation parameter setting over the telemetry link between the implantable medical device and the external instrument.

23. The method of claim 22, wherein the second modulation parameter setting comprises a modulation type and wherein the third modulation parameter setting comprises a modulation symbol rate.

24. The method of claim 1, wherein transferring a communication signal using the first initial modulation parameter setting over the telemetry link comprises:

transferring a first communication signal from the external instrument to the implantable medical device over the telemetry link; and

transferring a second communication signal from the implantable medical device to the external instrument in response to the first frame of data over the telemetry link; and

wherein analyzing the quality metric occurs at the implantable medical device by analyzing the first communication signal.

25. The method of claim 1, wherein selecting a second modulation parameter setting as a replacement for the first initial modulation parameter setting in response to the analysis comprises choosing the second modulation parameter setting based on a type of application for the communication signals.

26. An external instrument for communicating with an implantable medical device, comprising:

communication circuitry with selectable modulation parameter settings for exchanging communication signals with the implantable medical device; and

analysis logic circuitry that is coupled to the communication circuitry and that performs a link quality analysis of communication signals that are received using a first initial modulation parameter setting and that selects a second modulation parameter setting to replace the first initial modulation parameter setting in subsequent exchanges of communication signals with the implantable medical device.

27. The external instrument of claim 26, further comprising programmer logic circuitry that is coupled to the communication circuitry and that generates operational instructions that are communicated to the implantable medical device.

28. The external instrument of claim 26, wherein the programmer logic circuitry generates a request to switch to the second modulation parameter setting and wherein the communication circuitry sends the request to the implantable medical device.

29. The external instrument of claim 26, wherein the communication circuitry operates according to a schedule of active and idle frames, wherein the communication circuitry sends communication signals during a first portion of an active frame and receives communication signals during a second portion of an active frame, wherein the communication circuitry listens during idle frames to obtain a noise reference, and wherein the analysis logic circuitry utilizes the noise reference when performing the link quality analysis.

30. An implantable medical device for communicating with an external instrument, comprising:

communication circuitry with selectable modulation parameter settings for exchanging communication signals with the external instrument;

medical application circuitry that performs medical tasks; and

control circuitry that is coupled to the communication circuitry to obtain operational instructions from received communication signals, that instructs the communication circuitry to utilize modulation parameter settings that are specified by the operational instructions that pertain to modulation, that is coupled to the medical application circuitry, and that instructs the medical application circuitry to utilize medical task parameter settings that are specified by the operational instructions.

31. The implantable medical device of claim 30, wherein the communication circuitry is using a first initial modulation parameter setting, wherein operational instructions are received using the first initial modulation parameter setting and request a change to a second modulation parameter setting, wherein the control circuitry sends a response message via the communication circuitry utilizing the first initial modulation parameter setting to confirm the switch to the second modulation parameter setting, and wherein after sending the response message the control circuit instructs the communication circuitry to begin using the second modulation parameter setting in place of the first initial modulation parameter setting.

32. The implantable medical device of claim 31, wherein upon instructing the communication circuitry to begin using the second modulation type the control circuitry begins listening for subsequent communications from the external instrument, and when subsequent communications from the external instrument are not received at the control circuitry, then the control circuitry then instructs the communication circuitry to begin using the first initial modulation parameter setting in place of the second modulation parameter setting.