Implantable medical device telemetry with adaptive frequency hopping

• US 8,185,204 B2
• Filed: 07/12/2006
• Issued: 05/22/2012
• Est. Priority Date: 07/12/2006
• Status: Active Grant

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Bange, Joseph E., Vallapureddy, Vineel
• Primary Examiner(s): Lavert, Nicole F
• Application Number:
  US11/456,937
• Publication Number:
  US 20080015655A1
• Time in Patent Office: 2,141 Days
• Field of Search: 607/30, 607/32, 607/60
• US Class Current: 607/32
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61N 1/37252 Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data
• CPC Class Codes: A61N 1/37254 Pacemaker or defibrillator security, e.g. to prevent or inhibit programming alterations by hackers or unauthorised individuals
• CPC Class Codes: G16H 40/63 for local operation
• CPC Class Codes: H04B 1/7093 Matched filter type
• CPC Class Codes: H04B 17/318 Received signal strength

Abstract

A far-field radio-frequency (RF) telemetry system transmits data between an implantable medical device and an external system using an active channel selected from a plurality of channels each representing a frequency band within a predetermined frequency range. One or more preferred channels are identified from the plurality of channels based on channel quality indicators produced for each of the channels. When channel hopping is needed, a hop channel is selected from the one or more preferred channels and becomes the active channel.

Claims

1. A cardiac rhythm management (CRM) system, comprising an external system to communicate with an implantable medical device, the external system including:

a telemetry circuit including;

a transceiver adapted to transmit and receive data using at least one active radio frequency (RF) channel, the at least one active RF channel selectable from a plurality of RF channels available for use by the transceiver, each of the RF channels representing a channel frequency band;

a channel selector coupled to the transceiver, the channel selector adapted to select at least one hop channel according to a sequence of prioritized RF channels;

a hop controller coupled to the channel selector, the hop controller adapted to make the at least one hop channel the active RF channel when the at least one hop channel is selected;

a channel quality analyzer coupled to the channel selector and adapted to produce an RF channel quality indicator for an RF channel, wherein the RF channel quality indicator includes at least a received signal strength indicator indicative of a strength of signal received through that channel, wherein the channel quality analyzer includes a quality parameter receiver configured to receive an RF channel quality indicator produced by a channel quality analyzer of the implantable medical device; and

a preferred channel identifier coupled to the channel quality analyzer, the preferred channel identifier adapted to prioritize the plurality of channels according to the produced and received RF channel quality indicators into the sequence of prioritized RF channels.

2. The system of claim 1, wherein the at least one active channel comprises an active transmission channel selected from the plurality of channels and an active receiving channel selected from the plurality of channels, the active transmission channel and the active receiving channel representing substantially different channel frequency bands, and the transceiver comprises:

a transmitter to transmit data using the active transmission channel;

a receiver to receive data using the active receiving channel; and

a transmit/receive switch to provide a connection between the antenna and one of the transmitter and the receiver.

3. The system of claim 1, wherein the telemetry circuit further comprises a telemetry quality monitor adapted to monitor quality of data transmission associated with the active channel and to produce the channel selection signal when the quality of data transmission fails to satisfy one or more criteria.

4. The system of claim 1, wherein the telemetry circuit further comprises a hop timer to produce the channel selection signal according to a predetermined schedule.

5. The system of claim 1, wherein the telemetry circuit further comprises a telemetry initiation module to produce the channel selection signal when or before the telemetry session begins.

6. The system of claim 1, wherein the channel quality indicators comprise noise floor indicators each associated with one channel of the plurality of channels and indicative of a noise floor of that channel, the channel quality analyzer comprises a noise detector adapted to produce the noise floor indicators, and the preferred channel identifier is adapted to identify the sequence of preferred channels from the plurality of channels using at least the received signal strength indicators and the noise floor indicators.

7. The system of claim 6, wherein the noise detector is adapted to produce the noise floor indicators by measuring a noise level associated with each channel of the plurality of channels when the external system is not communicatively coupled with the implantable medical device.

8. The system of claim 6, wherein the noise detector is adapted to produce the noise floor indicators by measuring a noise level associated with each channel of the plurality of channels when no data is being transmitted between the external system and the implantable medical device through that channel.

9. The system of claim 1, wherein the channel quality indicators comprise frame exchange metrics each associated with one channel of the plurality of channels, the channel quality analyzer comprises a frame exchange analyzer adapted to produce the frame exchange metrics, and the preferred channel identifier is adapted to identify the sequence of preferred channels from the plurality of channels using at least the received signal strength indicators and the frame exchange metrics.

10. The system of claim 9, wherein the frame exchange analyzer comprises a success ratio producer adapted to calculate success ratios each associated with one channel of the plurality of channels, the success ratios each being a ratio of a number of successful frame exchanges to a total number of frame exchanges.

11. The system of claim 1, wherein the channel quality indicators comprise performance history indicators each associated with one channel of the plurality of channels and indicative of a history of the channel quality indicator of that channel, the channel quality analyzer comprises a performance history tracker adapted to produce the performance history indicators, and the preferred channel identifier is adapted to identify the sequence of preferred channels from the plurality of channels using at least the received signal strength indicators and the performance history indicators.

12. The system of claim 1, wherein the external telemetry module comprises the telemetry circuit, and wherein the channel selector is adapted to transmit data specifying one or more of the at least one hop channel and the sequence of preferred channels to the implantable medical device through the telemetry link.

13. The system of claim 12, wherein the quality parameter receiver is configured to receive at least one quality parameter of each of the channel quality indicators from the implantable medical device.

14. The system of claim 1, wherein the plurality of channels are distributed over one of a first frequency range of approximately 902.25-927.75 MHz, a second frequency range of approximately 863-870 MHz, and a third frequency range of approximately 402-405 MHz.

15. The system of claim 6, wherein the channel quality analyzer is adapted to produce signal-to-noise ratios each associated with one channel of the plurality of channels, the signal-to-noise ratios each being a ratio of the received signal strength indicator to the noise floor indicator for the one channel.

16. The system of claim 1, wherein the preferred channel identifier is adapted to identify the sequence of preferred channels from the plurality of channels using the received signal strength indicators and one or more of:

noise floor indicators each associated with one channel of the plurality of channels and indicative of a noise floor of that channel;

frame exchange metrics each associated with one channel of the plurality of channels and indicative of a ratio of a number of successful frame exchanges to a total number of frame exchanges for that channel; and

performance history indicators each associated with one channel of the plurality of channels and indicative of a history of the channel quality indicator of that channel.

17. The system of claim 16, wherein the preferred channel identifier is adapted to identify the sequence of preferred channels from the plurality of channels using the received signal strength indicators and the one or more of the noise floor indicators, the frame exchange metrics, and the performance history indicators each weighted by applying a predetermined weighting factor.

18. The system of claim 16, wherein the external telemetry module comprises the telemetry circuit, and the channel quality analyzer comprises a quality parameter receiver adapted to receive quality parameters from the implantable medical device, the received quality parameters including one or more of the received signal strength indicators, the noise floor indicators, the frame exchange metrics, and the performance history indicators.

19. The system of claim 16, wherein the preferred channel identifier is adapted to identify the sequence of preferred channels from the plurality of channels using the received signal strength indicators and the noise floor indicators or the performance history indicators prior to a start of the telemetry session when no data is being transmitted between the external system and the implantable medical device.

20. The system of claim 19, wherein the preferred channel identifier is adapted to identify the sequence of preferred channels from the plurality of channels using the received signal strength indicators and the frame exchange metrics during the telemetry session.

21. The system of claim 1, wherein the channel quality analyzer comprises:

a quality parameter receiver adapted to receive a second received signal strength indicator, produced by the implantable medical device, indicative of a strength of signal received through the channel, and

wherein the preferred channel identifier is adapted to prioritize the plurality of channels according to quality as indicated by the first and second received signal strength indicators, into the sequence of prioritized RF channels.