IMD Wake-Up Signal and ID Request Protocol for Multi-Device Interference
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Solution Overview
Problem
Existing communication systems for implantable medical devices (IMDs) struggle to efficiently support communication with multiple leadless IMDs, especially during the phase out and phase in of therapy support, while avoiding interference that prevents data exchange with other IMDs or external devices.
Innovation Solution
A communication system that uses a predefined wake-up signal combined with an ID request message to initiate communication with an IMD, allowing the IMD to respond with an ID response message within a specific time slot determined by the IMD's processor based on the ID information read from a predefined memory address. This system enables efficient communication with multiple IMDs without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wake-up signal is sent to activate an IMD for communication, then the IMD becomes responsive and can exchange data, but legacy active IMDs may be forced into transmitting states that create incessant data spewing and deny support for other devices
Solution Approach 1:
The communication protocol is segmented into distinct phases: a wake-up signal phase followed by a controlled response phase. The wake-up signal uses a specific pattern (e.g., 32 kHz carrier with particular modulation) that triggers only leadless IMDs to respond, while legacy active IMDs remain in receive-only mode. This segmentation prevents harmful interference by ensuring that only the intended device type becomes transmissive.
Solution Approach 2:
The external device acts as an intermediary that mediates communication between multiple IMDs. It sends targeted wake-up signals to specific leadless IMDs based on their unique identifiers, and controls the timing and nature of responses. This intermediary control prevents legacy IMDs from entering transmitting states that would create interference, as the external device manages the communication flow and suppresses unwanted transmissions.
2Object-affected harmful factors
If the communication carrier rate is kept low (e.g., 32 kHz) to ease signal transmission through patient anatomy, then signal penetration is improved, but transmission and receipt interactions are prolonged creating a larger target for temporal overlap of competing transmissions
Solution Approach 1:
The communication system uses periodic action by implementing structured time slots and controlled transmission windows. Instead of continuous low-rate communication, the system employs brief, periodic transmission bursts at the low carrier rate (32 kHz), separated by idle periods. This allows signal penetration through anatomy while minimizing the total time occupied for communication, reducing the window for temporal overlap with other transmissions.
Solution Approach 2:
The external device performs preliminary actions by sending a wake-up signal and establishing communication parameters before actual data exchange begins. This preliminary phase configures the leadless IMD to be highly responsive and efficient during the subsequent data transfer, allowing faster completion of communication tasks despite the low carrier rate, thereby reducing overall time exposure.
3Adaptability or versatility
If multiple leadless IMDs are present in the communication range, then the system can support phased therapy transitions, but any single IMD may interfere with the external device's ability to communicate with other IMDs
Solution Approach 1:
The communication protocol implements local quality by assigning different communication characteristics to different device types. Leadless IMDs are configured to respond to specific wake-up signal patterns and transmit only during designated time windows, while legacy active IMDs maintain receive-only mode. This localized differentiation allows multiple leadless IMDs to coexist without interference, as each operates under the same controlled protocol that prevents simultaneous transmissions.
Solution Approach 2:
The system employs dynamics by making the communication behavior of IMDs adaptive and state-dependent. Leadless IMDs dynamically transition from a low-power state to an active transmitting state only when addressed by the external device's wake-up signal. This dynamic behavior ensures that multiple IMDs can share the communication medium without interference, as they become active only when needed and remain dormant otherwise.
Data Source
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AI summary
The invention is directed to a communication system (10) for a wireless message transfer between an implantable medical device (IMD, 40) and an external device (60), comprising an IMD (40) and an external device (60), wherein the IMD (40) is configured to monitor the health status of a patient and/or configured to deliver a therapy signal to the patient, wherein the IMD (40) comprises a processor, a memory module and a transceiver module configured to bi-directionally exchange the messages with the external device (60). In order to provide a communication system and method that enables a low-overhead means for supporting communication with a plurality of IMDs and facilitating targeted IMD-specific interactions as part of IMD assembly and in-clinic use, the external device (60) is configured to send a predefined wake-up signal (100) to the transceiver module of the IMD combined with an ID request message (200) following the wake-up signal within a predefined first time interval (T1A).