Multichannel communication protocol configured to extend the battery life of an implantable device

• US 6,472,991 B1
• Filed: 06/15/2001
• Issued: 10/29/2002
• Est. Priority Date: 06/15/2001
• Status: Active Grant

• Current Assignee: Alfred E. Mann Foundation For Scientific Research
• Original Assignee: Alfred E. Mann Foundation For Scientific Research
• Inventors: Folkman, Dan, DeRocco, Paul D., Karr, Lawrence J., Schulman, Joseph H., Gord, John C., Barber, Andrew
• Primary Examiner(s): TRIEU, VAN THANH
• Application Number:
  US09/882,603
• Time in Patent Office: 501 Days
• Field of Search: 340/635, 340/636, 128/898, 128/899, 128/903, 128/904, 604/20, 604/21, 604/890.1, 604/891.1, 607/1, 607/2, 607/4, 607/9, 607/16
• US Class Current: 340/995.1
• CPC Class Codes: A61N 1/37276 characterised by means for reducing power consumption during telemetry
• CPC Class Codes: A61N 1/3787 from an external energy source
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A communication protocol that is configured to extend the battery life of devices that monitor and/or affect body parameters and is particularly useful in a system comprised of a system control unit (SCU) and one or more implanted devices. Each such implanted device is configured to be monitored and/or controlled by the SCU via a wireless communication channel. The time between battery rechargings is determined by the battery capacity and the device'"'"'s power consumption. Accordingly, the present invention reduces their average power consumption by reducing the usage duty cycle of their power consuming transmit and receive modes used to communicate with the SCU. By dedicating addressable time slots to each of the implantable devices in the system and limiting their use of receive and transmit modes to time periods proximate to these time slots, the average power consumption is accordingly reduced.

Claims

1. A communication protocol for communicating between a system control unit and a plurality of battery-powered, implantable stimulation/sensor devices that is configured to extend the battery life of said implantable devices by reducing their average power consumption, wherein each said implantable device has an address, said communication protocol comprising:

a system control time period for transmitting a system control data message from said system control unit to said plurality of implantable devices, wherein said system control data message contains addressable data to said implantable devices which are selectively enabled to operate in a receive mode in a selected receive portion of said system control time period related to the address of each implantable device, wherein said implantable devices additionally consume a first incremental amount of power when operating in said receive mode, each said selected receive portion of said system control time period being less than 75% of said system control time period and the average power consumption of said implantable devices is reduced accordingly;

a response time period following each system control time period for enabling selected ones of said implantable devices to individually operate in a transmit mode to transmit data to said system control unit in a selected transmit portion of said response time period related to the address of each implantable device, wherein said implantable devices additionally consume a second incremental amount of power when operating in said transmit mode;

a response delay time period between said system control time period and said response time period; and

wherein

said system control time period, said response time period and said response time period define a communication cycle which periodically repeats at a repetition rate.

2. The communication protocol of claim 1 wherein each said selected transmit portion of said response time period is less than 75% of said response time period and the average power consumption of said implantable devices is reduced accordingly.

3. The communication protocol of claim 1 wherein each said selected transmit portion defines a time slot and at least one said selected transmit portion of said response time period used by at least one said implantable device to transmit data to said system control unit is related to the address of said implantable device and data within said system control data message.

4. The communication protocol of claim 3 wherein at least one of said implantable devices is assigned to a selected one of said time slots by data transmitted from said system control unit.

5. The communication protocol of claim 3 wherein each time slot additionally comprises a guard band for providing a time period between adjacent time slots when adjacently assigned implantable devices do not transmit data.

6. The communication protocol of claim 1 wherein:

in a first mode of operation at least one said selected transmit portion of said response time period is used for responses from a single implantable device; and

in a second mode of operation at least one said selected transmit portion of said response time period is configurable to be shared during alternate communication cycles for transmitting responses to said system control unit from a plurality of said implantable devices, thereby extending the battery life of said implantable devices that are configured to share said selected response time period portions.

7. The communication protocol of claim 1 wherein said addressable data of said system control data message is transmitted at a rate defining a bit rate and said transmitted bit rate of said system control data message determines timing of said selected transmit portions of said response time period for transmitting data from said implantable devices to said system control unit.

8. The communication protocol of claim 1 wherein:

in a first mode of operation at least one of said selected implantable devices operates in a transmit mode during a single selected transmit portion of said response time period; and

in a second mode of operation at least one selected implantable device operates in a transmit mode during a plurality of selected transmit portions of said response time period, thereby increasing the amount of data that may be transmitted from said at least one selected implantable device during each communication cycle.

9. The communication protocol of claim 8 wherein in said second mode of operation at least one selected implantable device operates in a transmit mode during a plurality of consecutive selected transmit portions of said response time period.

10. The communication protocol of claim 1 wherein said communication cycle is essentially fixed and said communication protocol supports a predetermined number of communication slots, wherein said predetermined number of communication slots determines the average power consumption reduction;

and wherein

said system control time period and said response time period decrease and said response delay time period increases when an actual number of implantable devices within a system is decreased relative to said predetermined number of communication slots.

11. The communication protocol of claim 10 wherein when said actual number of implantable devices is less than said predetermined number of communication slots, a system having multiple system control units each operating according to said communication protocol is supported by sharing said increased response delay time periods associated with another one of said system control units.

12. The communication protocol of claim 1 wherein said system control data time period and said response data time period are each comprised of time slots and said system control message communicates in a first numerical time slot order with said implantable devices and said implantable devices communicate with said system control unit in a second numerical order wherein said second order is the opposite of said first order.

13. The communication protocol of claim 12 wherein said first numerical time slot order is in ascending order.

14. The communication protocol of claim 1 wherein each said selected transmit portion defines a time slot and each implantable device communicates with said system control unit using a different frequency during its associated time slot.

15. The communication protocol of claim 1 wherein the system control message is configurable to direct a plurality of addressable data portions to a selected one of said implantable devices, thereby increasing the communication rate from said system control unit to said selected implantable device.

16. The communication protocol of claim 15 wherein said selected implantable device is suitable for providing an auditory message to a patient.

17. A system for programmably controlling the operation of a plurality of battery-powered, implantable stimulation/sensor devices that is configured to extend the battery life of said implantable devices by reducing their average power consumption, said system comprising:

one or more battery-powered implantable device wherein each of said devices has an identification address;

a system control unit for periodically sending, during a system control time period, a system control message containing addressable data directed to each of said implantable devices, wherein each said system control message is followed by a response time period for enabling each of said implantable devices to transmit data to said system control unit, wherein said implantable devices are selectively enabled to operate in a receive mode in a selected receive portion of said system control time period related to the address of each implantable device, wherein said implantable devices additionally consume a first incremental amount of power when operating in said receive mode, each said selected receive portion of said system control time period being less than 75% of said system control time period and the average power consumption of said implantable devices is reduced accordingly; and

wherein

said implantable devices individually operate in a transmit mode to transmit data to said system control unit in a selected portion of said response data time period related to the address of each implantable device, wherein said implantable devices additionally consume a second incremental amount of power when operating in said transmit mode.

18. The system of claim 17 wherein each said selected transmit portion of said response time period is less than 75% of said response time period and the average power consumption of said implantable devices is reduced accordingly.

19. The system of claim 17 wherein at least one said selected transmit portion of said response time period used by at least one said implantable device to transmit data to said system control unit is related to the address of said implantable device and data within said system control data message.

20. The system of claim 17 wherein:

in a first mode of operation at least one said selected transmit portion of said response time period is used for responses from a single implantable device; and

in a second mode of operation at least one said selected transmit portion of said response time period is configurable to be shared during alternate communication cycles for transmitting responses to said system control unit from a plurality of said implantable devices, thereby extending the battery life of said implantable devices that are configured to share said selected response time period portions.

21. The system of claim 17 wherein said system control unit operates according to a system control unit clock and each said implantable devices operate according to an implantable device clock and wherein each of said clocks are relatively accurate to maintain communication timing between each of said devices.

22. The system of claim 17 wherein said addressable data of said system control data message is transmitted at a rate defining a bit rate timing and said transmitted bit rate timing of said system control data message determines timing of said selected transmit portions of said response time period for transmitting data from said implantable devices to said system control unit.

23. The system of claim 22 wherein each said implantable device additionally comprises a retiming controller for synchronizing its timing for selected transmit portions of said response time period to said transmitted bit rate timing of said system control data message.

24. The system of claim 23 wherein said retiming controller comprises a phase locked loop.

25. The system of claim 17 wherein:

in a first mode of operation at least one of said selected implantable devices operates in a transmit mode during a single selected transmit portion of said response time period; and

in a second mode of operation at least one selected implantable device operates in a transmit mode during a plurality of selected transmit portions of said response time period, thereby increasing the amount of data that may be transmitted from said at least one selected implantable device during each response time period.

26. The system of claim 25 wherein in said second mode of operation at least one selected implantable device operates in a transmit mode during a plurality of consecutive selected transmit portions of said response time period.

27. The system of claim 17 wherein each said implantable device additionally comprises a magnetoresistive sensor for sensing a magnetic field from a source external to a patient'"'"'s body and wherein in response to sensing said magnetic field, operation of said implantable device is altered.

28. The system of claim 27 wherein said altered operation of said implantable device comprises removing power from one or more portions of said implantable device, thereby reducing the power consumption of said device.

29. The system of claim 17 wherein said system control unit comprises:

a system controller for controlling operation of said system control unit;

a transmitter for transmitting data from said system control unit to one or more of said implantable devices, wherein power is only supplied to said transmitter during said system control time period;

a receiver for receiving data from one or more or said implantable device, wherein power is only supplied to said receiver during said response time period; and

wherein

the average power consumption of said system control unit is reduced.

30. The system of claim 29 wherein said power supplied to said transmitter is supplied in a burst to enable data transmission during said system control time period and said power supplied to said receiver is supplied in a burst to enable data reception during said response time period.

31. The system of claim 29 wherein power consumption by said transmitter is minimized during time periods outside of said system control time period and power consumption of said receiver is minimized during time periods outside of said response time period.

32. The system of claim 29 wherein:

said system controller periodically instructs said transmitter to transmit an inquiry message to notify an other system controller of its presence and interrogates said receiver if an inquiry message has been received to determine the presence of said other system control unit; and

wherein

in response to receipt of an inquiry message said system control unit negotiates a communication parameter change with said other system control unit and notifies said associated implantable devices to alter said communication parameter to thereby avoid the effects of the presence of said other system control unit.

33. The system of claim 32 wherein each of said system control units has an identification value and said negotiated communication parameter change is dependent upon said identification values related to each of said system control units.

34. The system of claim 32 wherein at least one of said system control units additionally comprised a random number generator and said negotiated communication parameter change is dependent upon said at least one random number generator.

35. The system of claim 32 wherein said negotiated communication parameter change comprises a difference in communication phase with each system control unit and its associated implantable devices.

36. The system of claim 32 wherein said negotiated communication parameter change comprises a difference in communication frequency with each system control unit and its associated implantable devices.

37. The system of claim 32 wherein said negotiated communication parameter change comprises a time slot alteration for communication between at least one of said system control units and at least one of its associated implantable devices.

38. The system of claim 32 wherein said system control unit and said implantable devices operate across a first communication channel and communications between said system controllers is on a second communication channel separate from said first communication channel.

39. The system of claim 38 wherein said communication across said second communication channel comprises a higher radiated transmission power than across said first communication channel.

40. The system of claim 39 wherein said receiver in said system control unit has increased sensitivity to received data across said second communication channel.

41. The system of claim 38 wherein said communication across said second communication channel occurs within a different frequency range from said first communication channel.

42. The system of claim 17 wherein said system control unit and said implantable devices operate across a common communication frequency channel.

43. The system of claim 17 wherein said implantable devices communicate with said system control unit across a plurality of frequency channels.

44. A method of communicating between a system control unit and a plurality of addressable, battery-powered, implantable stimulation/sensor devices wherein said method is configured to extend the battery life of said implantable devices by reducing their average power consumption and wherein each said implantable device has an address, said method comprising the steps of:

periodically, during a system control time period, sending a system control message which defines addressable data that is to be directed to each of said plurality of implantable devices, wherein said implantable devices consume a base amount of power and additionally consume a first incremental amount of power when operating in a receive mode to receive data from said system control unit; and

waiting a response time period following each system control message for enabling each of said implantable devices to provide data to said system control unit in a selected transmit portion of said response time period related to the address of each implantable device, wherein said implantable devices additionally consume a second incremental amount of power when operating in said transmit mode, said selected transmit portion of said response time period being less than 75% of said response time period and the average power consumption of said implantable devices is reduced accordingly.

45. The method of claim 44 further comprising the step of switching between a first mode of operation where at least one said selected transmit portion of said response time period is used for responses from a single implantable device and a second mode of operation where said at least one selected transmit portion of said response time period is configurable to be alternately shared for sending responses to said system control unit from a plurality of said implantable devices, thereby extending the battery life of said implantable devices that are configured to share said selected response time period portions.

46. The method of claim 44 further comprising the step of determining the timing of said selected transmit portions of said response time period for providing data from said implantable devices to said system control unit according to a bit rate of said system control message.

47. The method of claim 44 further comprising the step of enabling said receive mode of said implantable devices during time periods proximate to selected portions of said system control message related to the address of each implantable device wherein each said receive mode of said implantable device is enabled for less than 75% of said system control message and the average power consumption of said implantable device is reduced accordingly.

48. The method of claim 47 further comprising the step of switching between a first mode of operation where said selected transmit portion of said response time period is used for responses from a single implantable device and a second mode of operation where said selected transmit portion of said response time period is configurable to be alternately shared for sending responses to said system control unit from a plurality of implantable devices, thereby extending the battery life of said implantable devices that are configured to share said selected response time period portions.

49. The method of claim 47 further comprising the step of determining the timing of said implantable devices entering into said receive mode according to a bit rate of said system control message.

50. The method of claim 44 additionally comprising the steps of:

periodically sending an inquiry message to an other system control unit;

periodically receiving any inquiry message from said other system control unit;

negotiating a communication parameter change with said other system control unit if said inquiry message is received; and

sending a message from said system control unit to said implantable devices to alter its negotiated communication parameter change to avoid the effects of the presence of said other system control unit.

51. The method of claim 44 additionally comprising the steps of:

periodically interrogating a predetermined frequency spectrum range to determine noise levels; and

periodically sending a message from said system control unit to said implantable devices to alter its communication frequency with said system control unit according to said determined noise levels.

52. A communication protocol for communicating between a system control unit and a plurality of addressable, battery-powered, implantable stimulation/sensor devices that is reconfigurable to alternatively extend the battery life of said implantable devices by reducing their average power consumption or increasing the effective communication rate between said system control unit and said implantable device, said communication protocol comprising:

a system control message for defining addressable data to be directed to each of said plurality of implantable devices operating in a receive mode, wherein said implantable devices consume a base amount of power and additionally consume a first incremental amount of power when operating in said receive mode;

a response time period following each system control message for enabling each of said implantable devices to individually operate in a transmit mode to provide data to said system control unit in a selected portion of said response time period related to the address of each implantable device, wherein said implantable devices additionally consume a second incremental amount of power when operating in said transmit mode, said selected portion of said response time period being less than 75% of said response time period and the average power consumption of said implantable devices is reduced accordingly; and

wherein

at least one selected implantable device is configurable via data within said system control message to occupy a plurality of said selected portions of said response time period to thereby increase the effective communication rate from said implantable device to said system control unit.

53. The communication protocol of claim 52 wherein:

in a first mode of operation at least one said selected portion of said response time period is used for responses from a single implantable device; and

in a second mode of operation said selected portion of said response time period is configurable to be alternately shared for sending responses to said system control unit from a plurality of implantable devices, thereby extending the battery life of said implantable devices that are configured to share said selected time response period portions.

54. The communication protocol of claim 52 wherein said addressable data of said system control message is transmitted at a rate defining a bit rate and said transmitted bit rate timing determines timing of said selected portions of said response time period for providing data from said implantable devices to said system control unit.

55. The communication protocol of claim 52 wherein a plurality of said implantable devices operate in said receive mode during selected portions of said system control message related to the address of each implantable device.

56. The communication protocol of claim 55 wherein:

in a first mode of operation at least one said selected portion of said response time period is used for responses from a single implantable device; and

in a second mode of operation said selected portion of said response time period is configurable to be alternately shared for sending responses to said system control unit from a plurality of implantable devices, thereby extending the battery life of said implantable devices that are configured to share said selected time period portions.

57. The communication protocol of claim 55 wherein said addressable data of said system control message is transmitted at a rate defining a bit rate and said transmitted bit rate timing determines timing of said implantable devices for entering into said receive mode.

58. The communication protocol of claim 52 wherein the system control message is configurable to direct a plurality of addressable data portions to a selected one of said implantable devices, thereby increasing the communication rate from said system control unit to said selected implantable device.