System and method for interference mitigation in a wireless sensor network

• US 8,199,000 B2
• Filed: 09/27/2007
• Issued: 06/12/2012
• Est. Priority Date: 09/27/2007
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Ross, John Anderson Fergus, Davenport, David Michael
• Primary Examiner(s): Pham, Toan N
• Assistant Examiner(s): RUSHING, MARK S
• Application Number:
  US11/862,681
• Publication Number:
  US 20090088605A1
• Time in Patent Office: 1,720 Days
• Field of Search: 340/539.12, 340/539.22, 340/539.26, 340/572.1, 600/300, 600/301
• US Class Current: 340/539.12
• CPC Class Codes: A61B 2560/0271 using a remote monitoring unit
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: G16H 40/67 for remote operation
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A wireless patient monitoring system forms a Network Around a Patient (NAP) and includes sensor nodes configured to acquire patient data from a patient. A gateway device is in bi-directional wireless communication with the sensor nodes for a plurality of defined communication frames. The gateway device is configured to transmit a beacon message to the sensor nodes at each of a plurality of frequencies. The sensor nodes are further configured to receive the beacon message from the gateway device and transmit the acquired patient data to the gateway device at each of the plurality of frequencies.

Claims

1. A wireless patient monitoring system comprising:

a plurality of sensor nodes configured to acquire patient data from a patient; and

a gateway device in bi-directional wireless communication with the plurality of sensor nodes for a plurality of defined communication frames, the gateway device configured to transmit a beacon signal to each of the plurality of sensor nodes at each of a plurality of frequencies; and

wherein each of the plurality of sensor nodes are further configured to;

receive the beacon signal from the gateway device; and

transmit the acquired patient data to the gateway device at each of the plurality of frequencies;

wherein the plurality of frequencies comprises a first frequency and a second frequency and the plurality of sensor nodes are further configured to tune to the first frequency to receive the beacon signal and tune to the second frequency if the beacon signal transmitted at the first frequency is not received within a pre-determined time limit; and

wherein the gateway device is further configured to tune to the first frequency to receive the patient data and, if the patient data is not received within a pre-determined time limit, tune to the second frequency.

2. The wireless patient monitoring system of claim 1 wherein each of the gateway device and the plurality of sensor nodes are configured to retune to the first frequency at the end of each of the plurality of defined communication frames.

3. The wireless patient monitoring system of claim 1 wherein the first frequency and the second frequency are offset by one of a pre-determined fixed amount and a pseudo-random amount.

4. The wireless patient monitoring system of claim 1 further comprising a supervisor gateway to control the gateway device, the supervisor gateway device configured to cause the gateway device to shift at least one of the first frequency and the second frequency by a pre-determined amount between a first communication frame and a subsequent communication frame.

5. The wireless patient monitoring system of claim 1 wherein the plurality of sensor nodes further comprises at least a first sensor node and a second sensor node, the first sensor node and the second sensor node transmitting patient data in sequential order during each of the defined communication frames.

6. The wireless patient monitoring system of claim 5 wherein the first sensor node transmits patient data at the first frequency and then at the second frequency, the second sensor node subsequently transmits patient data at the first frequency and then at the second frequency, and any additional sensor nodes in the plurality of sensor nodes subsequently transmit patient data at the first frequency and then at the second frequency, and wherein the gateway device is synchronized with the switching between the first frequency and the second frequency of each of the sensor nodes.

7. The wireless patient monitoring system of claim 5 wherein the first sensor node transmits patient data at the first frequency and then at the second frequency, the second sensor node subsequently transmits patient data at the second frequency and then at the first frequency, and any additional sensor nodes in the plurality of sensor nodes subsequently transmit patient data at the first frequency and the second frequency in an opposite order from a previous sensor in the plurality of sensors, and wherein the gateway device is synchronized with the switching between the first frequency and the second frequency.

8. The wireless patient monitoring system of claim 1 wherein each of the plurality of defined communication frames further comprises a first sub-frame and a second sub-frame, and wherein each of the plurality of sensor nodes transmits patient data at the first frequency during the first sub-frame and transmits patient data at the second frequency during the second sub-frame.

9. The wireless patient monitoring system of claim 1 wherein each of the gateway device and the at least one sensor node comprises:

an integrated circuit radio transceiver to transmit and receive wireless signals at the first frequency and the second frequency; and

a micro-controller configured to switch the integrated circuit radio transceiver between transmission of the wireless signals at the first frequency and the second frequency and switch the integrated circuit radio transceiver between reception of the wireless signals at the first frequency and the second frequency.

10. The wireless patient monitoring system of claim 1 wherein the at least one sensor node comprises a wireless body worn sensor.

11. The wireless patient monitoring system of claim 1 wherein the gateway device comprises a wireless body worn device.

12. The wireless patient monitoring system of claim 1 wherein the gateway device is further configured to transmit information identifying available frequencies.

13. A method for patient monitoring, comprising:

arranging a plurality of wireless sensors on a patient to acquire health data therefrom during an operative frame;

associating the plurality of wireless sensors with a gateway controller by assigning each of the plurality of wireless sensors to a timeslot within the operative frame;

transmitting a beacon signal from the gateway controller to the plurality of wireless sensors to activate the wireless sensors during an operative frame;

transmitting the health data from the plurality of wireless sensors to the gateway controller via a plurality of data packets during the operative frame in response to the beacon signal; and

sequentially transmitting data packets at the first frequency and then at the second frequency within a first timeslot;

wherein at least one of the beacon signal and the data packets are transmitted over a first frequency channel and a second frequency channel during the operative frame;

wherein the step of transmitting the health data comprises;

in each subsequent timeslot, sequentially transmitting the first and second frequencies in a reverse order from an immediately preceding timeslot.

14. The method of claim 13 further comprising the steps of shifting at least one of the first frequency channel and the second frequency channel by a pre-determined amount between a first operative frame and a subsequent operative frame.

15. The method of claim 13 further comprising:

transmitting information identifying available frequencies from the gateway controller to the wireless sensors.

16. A method for patient monitoring, comprising:

arranging a plurality of wireless sensors on a patient to acquire health data therefrom during an operative frame;

associating the plurality of wireless sensors with a gateway controller by assigning each of the plurality of wireless sensors to a timeslot within the operative frame;

transmitting a beacon signal from the gateway controller to the plurality of wireless sensors to activate the wireless sensors during an operative frame;

transmitting the health data from the plurality of wireless sensors to the gateway controller via a plurality of data packets during the operative frame in response to the beacon signal; and

wherein at least one of the beacon signal and the data packets are transmitted over a first frequency channel and a second frequency channel during the operative frame;

wherein the step of transmitting the health data comprises;

sequentially transmitting the data packets from the plurality of wireless sensors during a first sub-frame within the operative frame and over the first frequency channel; and

sequentially transmitting the data packets from the plurality of wireless sensors during a second sub-frame within the operative frame and over the second frequency channel, the second sub-frame falling after the first sub-frame within the operative frame.

17. A method for patient monitoring, comprising:

arranging a plurality of wireless sensors on a patient to acquire health data therefrom during an operative frame;

associating the plurality of wireless sensors with a gateway controller by assigning each of the plurality of wireless sensors to a timeslot within the operative frame;

transmitting a beacon signal from the gateway controller to the plurality of wireless sensors to activate the wireless sensors during an operative frame;

transmitting the health data from the plurality of wireless sensors to the gateway controller via a plurality of data packets during the operative frame in response to the beacon signal;

tuning the plurality of wireless sensors to receive the beacon signal transmitted over the first frequency channel; and

tuning the plurality of wireless sensors to receive the beacon signal transmitted over the second frequency channel if the beacon signal transmitted over the first frequency channel is not received within a pre-determined time limit;

wherein at least one of the beacon signal and the data packets are transmitted over a first frequency channel and a second frequency channel during the operative frame.

18. A method for patient monitoring, comprising:

arranging a plurality of wireless sensors on a patient to acquire health data therefrom during an operative frame;

associating the plurality of wireless sensors with a gateway controller by assigning each of the plurality of wireless sensors to a timeslot within the operative frame;

transmitting a beacon signal from the gateway controller to the plurality of wireless sensors to activate the wireless sensors during an operative frame;

transmitting the health data from the plurality of wireless sensors to the gateway controller via a plurality of data packets during the operative frame in response to the beacon signal;

tuning the gateway controller to receive the data packets transmitted over the first frequency channel; and

tuning the gateway controller to receive the data packets transmitted over the second frequency channel if the data packets transmitted over the first frequency channel are not received within a pre-determined time limit;

wherein at least one of the beacon signal and the data packets are transmitted over a first frequency channel and a second frequency channel during the operative frame.

19. A wireless sensor communications system comprising:

a wireless sensor network configured to acquire system data from a monitored system;

a controller positioned in proximity to the sensor network and in wireless communication therewith;

wherein each of the sensor network and the controller are configured to sequentially transmit and receive wireless signals over a first frequency channel (F1) and over a second frequency channel (F2) and switch between the first frequency channel and the second frequency channel at least once during each of a plurality of communication frames, the wireless finals including an activation signal and system data; and

,

wherein the wireless sensor network is further configured to;

tune to F1 to receive the activation signal;

tune to F2 to receive the activation signal if the activation signal transmitted over F1 is not received within a pre-determined time limit; and

transmit the system data to the controller over each of F1 and F2 upon receipt of the activation signal.

20. The wireless sensor communications system of claim 19 wherein the wireless sensor network further comprises a plurality of sensor nodes, and wherein the plurality of sensor nodes are configured to transmit the system data to the controller within each of the plurality of communication frames in at least one of the following representative sequences:

(A) a first sensor transmitting at F1 then F2, a second sensor subsequently transmitting at F1 then F2, and all remaining sensors in the plurality of sensors subsequently transmitting at F1 then F2;

(B) a first sensor transmitting at F1 then F2, a second sensor subsequently transmitting at F2 then F1, and all remaining sensors in the plurality of sensors subsequently transmitting F1 and F2 in an opposite pattern from a previous sensor in the plurality of sensors; and

(C) all sensors in the plurality of sensors sequentially transmitting at F1 and then all sensors in the plurality of sensors sequentially transmitting at F2, the F1 transmissions occurring during a first sub-frame and the F2 transmissions occurring during a second sub-frame.

21. The wireless sensor communications system of claim 20 wherein the controller is configured to select one of the representative transmission sequences based on at least one of observation of data packet errors and sensing of outside radio sensors.

22. The wireless sensor communications system of claim 19 wherein the wireless sensor network comprises a body worn patient sensor network configured to acquire health data from a patient.

23. The wireless sensor communications systems of claim 19 wherein the controller is further configured to transmit information identifying available frequencies.