Methods and systems for providing multiple access within a network

• US 8,379,539 B2
• Filed: 06/03/2009
• Issued: 02/19/2013
• Est. Priority Date: 06/03/2008
• Status: Expired due to Fees

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Bange, Joseph E., Koshiol, Allan T., Holmquist, Paul, Harris, Thomas J., Kramer, Karen M.
• Primary Examiner(s): NGUYEN, STEVEN H D
• Application Number:
  US12/477,754
• Publication Number:
  US 20090296602A1
• Time in Patent Office: 1,357 Days
• Field of Search: None
• US Class Current: 370/254
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 84/20 Master-slave selection or change arrangements

Abstract

Methods and systems for media access control allow master and slave nodes of a network to communicate using the same carrier while avoiding collisions of transmissions. At least one slave node is an implantable device. Master nodes initiate all data exchange sequences, and slave nodes are responsive to the data exchange sequences. The exchange sequences begin by master nodes contending for use of the carrier through a countdown procedure. A set order of communications occurs between a master node who won the contention and a slave node being communicated with by the master node to transfer a data frame. Contention is then repeated to determine the next master node that is allowed to transfer a data frame. New master nodes entering the network employ a discovery process to poll for existing devices in the network.

Claims

1. A method of discovering nodes to establish communication between a first master node and one or more nodes in a network medium used by a plurality of master nodes and slave nodes, wherein a slave node is an implantable medical device, wherein the plurality of master nodes contend for a carrier of the network medium, comprising:

at a first master node, gaining use of the carrier;

sending out a plurality of discovery access codes from the first master node;

at the first master node, sending out a request for request to send message containing a first discovery access code of the plurality of discovery access codes, wherein the request for request to send message begins the communication sequence to obtain any available data from another node;

at the first master node, listening for a request to send message containing the first discovery access code and sending out a clear to send message upon receiving the request to send message;

upon receiving a data send message in response to the clear to send message at the first master node, when the data send message is from a second master node and includes a list of session access codes in use by the second master node, excluding the list of session access codes in use by the second master node from a list of potential session access codes at the first master node; and

upon receiving the data send message in response to the clear to send message at the first master node, when the data send message is from a first slave node that includes identification information for the first slave node, storing the first slave node identification information in preparation for associating with a session access code that is not excluded from the list of potential session access codes at the first master node.

2. The method of claim 1, further comprising:

at the first master node, gaining use of the carrier after sending out the plurality of discovery access codes but before sending out a request for request to send message containing the first discovery access code.

3. The method of claim 1, further comprising:

after receiving the data send message, sending an acknowledge message from the first master node;

after sending the acknowledge message, sending out a second request for request to send message containing a second discovery access code of the plurality, listening for a request to send message containing the second discovery access code, and sending out a clear to send message upon receiving the request to send message;

upon receiving a data send message in response to the clear to send message at the first master node, when the data send message is from a third master node that includes a list of session access codes in use by the second master node, excluding the list of session access codes in use by the third master node from the list of potential session access codes at the first master node; and

upon receiving the data send message in response to the clear to send message at the first master node, when the data send message is from a second slave node that includes identification information for the second slave node, storing the second slave node identification information in preparation for associating with a session access code that is not excluded from the list of potential session access codes at the first master node and that has not been associated with a node other than the second slave node.

4. The method of claim 1, wherein sending out a plurality of discovery access codes from the first master node comprises sending a request to send message with a universal access code followed by a clear to send message followed by a data send message containing the discovery access codes as data followed by an acknowledge message.

5. The method of claim 1, further comprising repeating the sending and receiving actions to send out a new set of discovery access codes and receive responses from master and slave nodes that did not previously respond successfully and receive no responses when all master and slave nodes did previously respond successfully.

6. The method of claim 1, further comprising:

prior to contending for the carrier at the first master node, monitoring for the carrier until a valid frame on the carrier is detected until at least two polling intervals have expired;

when a valid frame on the carrier is been detected before the at least two polling intervals have expired, delaying contending for the carrier until a message exchange between other nodes is detected to be complete; and

when at least two polling intervals have expired before a valid frame is detected on the carrier, beginning contending for the carrier.

7. The method of claim 1, including determining by a third master node when the communication sequence of the first master node will end according to the RRTS message.

8. The method of claim 1, wherein the data send message indicates that the sending node has more data to send.

9. The method of claim 1, wherein the data send message indicates that the sending node has additional data to send and indicates the priority of the additional data.

10. The method of claim 1, including

transmitting an acknowledge message from the first master node is response to the data send message;

and

discarding the transmitted data at the transmitting node.

11. The method of claim 1, wherein gaining use of the carrier includes:

determining, by the first master node, whether the carrier is in use; and

contending for use of the carrier.

12. The method of claim 11, wherein determining whether the carrier is in use includes:

eavesdropping by the first master node on a current transmission of another node; and

determining by the first master node when the current transmission will end.

13. The method of claim 12, wherein contending for use of the carrier includes initiating a contention interval according to the determined transmission end.

14. The method of claim 13, wherein initiating a contention interval includes initiating a contention interval that will expire when a data send message is sent during a detected communication sequence.

15. The method of claim 13, wherein initiating a contention interval includes initiating a contention interval that will expire when an acknowledge message is sent during a detected communication sequence.

16. The method of claim 11, wherein contending for use of the carrier includes:

determining, by the first master node, a backoff value between a maximum back value and a minimum backoff value;

beginning, by the first master node, a count from the randomly chosen value towards a win value when the first master node detects that the carrier is not in use; and

transmitting the request for request to send message using the carrier when the count by the first master node reaches the win value.

17. The method of claim 14, wherein determining a backoff value includes determining a random value between the maximum back value and the minimum backoff value.

18. The method of claim 14, including:

determining, by the first master node, priority of data to be sent by the first master node; and

wherein determining a backoff value includes determining the backoff value according to the determined priority of data.

19. The method of claim 11, wherein contending for use of the carrier includes:

determining, by the first master node, a backoff value between a maximum back value and a minimum backoff value;

beginning, by the first master node, a count from the randomly chosen value towards a win value when the first master node detects that the carrier is not in use; and

pausing, by the first master node, counting towards the win value when it is determined that the carrier continues to be in use.

20. The method of claim 17, including:

continuing, by the first master node, the determining of whether the carrier is in use and the counting towards a win value according to the determined carrier use; and

transmitting the request for request to send message using the carrier when the count by the first master node reaches the win value.