System and method for sharing a common communication channel between multiple systems of implantable medical devices

• US 8,050,297 B2
• Filed: 06/12/2008
• Issued: 11/01/2011
• Est. Priority Date: 03/03/2004
• Status: Active Grant

• Current Assignee: Alfred E. Mann Foundation For Scientific Research
• Original Assignee: Alfred E. Mann Foundation For Scientific Research
• Inventors: DelMain, Gregory J., Folkman, Dan, DeRocco, Paul, Karr, Lawrence J.
• Primary Examiner(s): Phung; Luat
• Application Number:
  US12/157,652
• Publication Number:
  US 20080255636A1
• Time in Patent Office: 1,237 Days
• Field of Search: 370/514, 370/509, 370/510, 370/512, 455/41.1, 455/41.2, 455/41.3, 128/899
• US Class Current: 370/514
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 2560/063 Devices specially adapted for delivering implantable medical measuring apparatus
• CPC Class Codes: A61B 2562/08 Sensors provided with means for identification, e.g. barcodes or memory chips
• CPC Class Codes: A61B 5/0008 Temperature signals
• CPC Class Codes: A61B 5/0024 for multiple sensor units attached to the patient, e.g. using a body or personal area network
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/053 Measuring electrical impedance or conductance of a portion of the body
• CPC Class Codes: A61B 5/07 Endoradiosondes
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/24 Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
• CPC Class Codes: A61B 5/681 Wristwatch-type devices
• CPC Class Codes: A61N 1/3727 characterised by the modulation technique
• CPC Class Codes: A61N 1/37288 Communication to several implantable medical devices within one patient
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 56/0015 one node acting as a reference for the others
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: H04W 92/02 Inter-networking arrangements

Abstract

A system and method that facilitates multiple systems of communicating devices, i.e., a master device and one or more implantable slave devices, to coexist on a common, e.g., RF, communication channel having a limited temporal bandwidth while maintaining the required update rate between each master device and its associated slave devices. In embodiments of the present invention, master devices periodically transmit one or more beacon messages that are suitable for identification by other such master devices at a communication range greater than the communication range that may cause interference between systems and thus enabling one or more systems to cause the position of its frame periods to be interleaved with the frame periods of other such systems in anticipation of systems moving in closer proximity and actually interfering with each other.

Claims

1. A method of enabling a plurality of systems (300-1, 300-2, 300-3) to communicate over a common communication channel wherein each system (300-1, 300-2, 300-3) is configured to enable communication during periodic and essentially temporally contiguous respective frame periods (409-1, 409-2, 409-3) determined essentially asynchronously by each said respective system (300-1, 300-2, 300-3) and having occupied temporal portions of each said frame period (409-1, 409-2, 409-3) comprised of transmission communication periods dedicated to each said respective system (300-1, 300-2, 300-3) and wherein each said frame period (409-1, 409-2, 409-3) has a start and an end that essentially spans the entire temporal bandwidth of said common communication channel, said method comprising the steps of:

transmitting during each said frame period (409-1, 409-2, 409-3) from each said respective system (300-1, 300-2, 300-3), at least one type of beacon message (454, 456 or 458) having a respective unique heavily-coded beacon marker code portion (460, 464 or 468),

wherein said step of transmitting at least one type of beacon message additionally comprises the step of transmitting at least one wandering beacon message having a moveable temporal offset from the start of its respective frame period;

receiving beacon messages (454, 456, 458) by each of said systems (300-1, 300-2, 300-3) according to said heavily-coded beacon marker code portions (460, 464, 468) from other said systems (300-2, 300-3), (300-1, 300-3), (300-1, 300-2) that are within communication range;

processing two or more of said received heavily-coded beacon marker code portions (460, 464, 468) of said respective beacon messages (454, 456, 458) to thereby determine the start of the frame period of another one of said systems; and

determining which received beacon messages uniquely correspond to other said systems according to uniquely defined temporal displacements between said received wandering beacon messages.

2. The method of claim 1 wherein said transmitting during each said frame period at least one type of beacon message additionally comprises transmitting a data portion within said beacon message.

3. The method of claim 2 additionally comprising the step of integrating data portions from said received beacon messages that correspond to other said systems over a plurality of frame periods to thereby increase the receive sensitivity and the effective communication range and thereby facilitating extracting said data portions.

4. The method of claim 1 wherein said step of transmitting at least one wandering beacon message having a moveable temporal offset from the start of its respective frame period comprises selecting said temporal offsets from a predetermined set of temporal offset values.

5. The method of claim 1 wherein said step of transmitting at least one beacon message additionally comprises transmitting a wandering beacon message type having temporal offset values selected from a predetermined set of temporal offset values for at least two different frame periods and wherein said method additionally comprises the step of determining in part which received beacon messages uniquely correspond to other said systems according to uniquely defined temporal displacements between received beacon messages by comparing the differences between temporal offset values of wandering beacon messages from other frame periods according to said predetermined set of temporal values.

6. The method of claim 1 wherein said step of transmitting at least one type of beacon message additionally comprises the step of periodically ceasing transmissions from said systems to facilitate said steps of receiving beacon messages and integrating data portions from said received beacon messages.

7. The method of claim 1 wherein said systems are comprised of a master device and one or more associated slave devices that communicate with said master device during said frame periods determined by each said master device, said method additionally comprising the steps of:

calculating the relative temporal displacements of the frame periods of other master devices;

determining whether at least one of said systems may interfere with communications of another one of said systems and accordingly calculating a new temporal placement for the frame period of a selected one of said systems according to said received beacon messages; and

causing said selected one of said systems comprised of a master device and one or more associated slave devices to temporally displace the start of its frame period to allow said occupied temporal portions of said selected one of said systems to be temporally interleaved with other occupied temporal portions of said systems across said common communication channel when said determining step has determined the potential for communication interference between two or more of said systems.

8. The method of claim 7 wherein each said master device has a unique identification code that is used within at least some of said beacon messages and said calculating step determines in part the new temporal placement for the frame period of a selected one Of said systems according to said received beacon messages and said unique identification codes.

9. The method of claim 7 wherein said calculating step determines in part the new temporal placement for the frame period of a selected one of said systems according to relative movement of the temporal placements of two or more sequential beacon messages received from another one of said master devices.

10. The method of claim 1 wherein the heavily-coded beacon marker code portion consists of:

a 31 baud long string of QPSK symbols;

a 63 baud long string of BPSK symbols;

or

a 62 bit code.