Wireless mesh network with locally activated fast active scheduling of wireless messages

• US 7,889,710 B2
• Filed: 05/16/2007
• Issued: 02/15/2011
• Est. Priority Date: 09/29/2006
• Status: Active Grant

• Current Assignee: Rosemount Incorporated (Emerson Electric Company)
• Original Assignee: Rosemount Incorporated (Emerson Electric Company)
• Inventors: Orth, Kelly M., Ostby, Philip G.
• Primary Examiner(s): Afshar; Kamran
• Assistant Examiner(s): Behrooz; Neda
• Application Number:
  US11/803,953
• Publication Number:
  US 20080080475A1
• Time in Patent Office: 1,371 Days
• Field of Search: 370229-236, 370277-282, 370/294, 370311-314, 370345-350, 370442-444, 370458-460, 370/465, 370/468, 370/478, 370/498, 370/503, 370507-509, 455/500, 455/507, 455/527, 455 68- 70, 455/88, 4553431-3435
• US Class Current: 370/350
• CPC Class Codes: H04L 47/26 using explicit feedback to the source, e.g. choke packets
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04W 28/0278 using buffer status reports dynamic wireless traffic scheduling definition H04W72/12
• CPC Class Codes: H04W 28/10 Flow control between communication endpoints
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling

Abstract

A wireless mesh network is formed by nodes having a regular active schedule for transmitting and receiving messages, and a fast active schedule mode that is locally activated when a demand exists for transmission of a larger number of messages. As each node transmits a message to another node, the transmitting node includes a message buffer queue parameter that indicates the number of messages in the transmitting nodes, pending message queue. The receiving node determines, based upon the message buffer queue parameter received and its own capacity, whether to continue on the regular schedule, or to activate the fast active schedule. If the fast active schedule is activated, the receiving node sends a special acknowledge message back to the sending node, so that both nodes will transmit and receive messages over a fast active schedule link until the message buffer of the sending node has been reduced and the fast active schedule can be deactivated in favor of the regular active schedule.

Claims

1. A method of operating a wireless mesh network having a plurality of nodes capable of transmitting and receiving messages, the method comprising:

synchronizing the nodes of the network to a global regular active schedule that defines when messages can be transmitted and received by the nodes; and

locally synchronizing a transmitting node and a receiving node to a fast active schedule based upon a level of a transmit queue of the transmitting node to send messages, wherein the fast active schedule links nodes for communicating messages more rapidly than with the global regular active schedule.

2. The method of claim 1 wherein locally synchronizing comprises:

transmitting a message containing a parameter that indicates a depth of a pending message queue in the transmitting node; and

determining at the receiving mode whether to operate in the fast active schedule with the transmitting node based on the parameter.

3. The method of claim 2 wherein locally synchronizing further comprises:

transmitting an acknowledgment from the receiving node to the transmitting node indicating whether the transmitting node can transmit a further message to the receiving node on the fast active schedule.

4. The method of claim 2 wherein the receiving node determines whether to operate in the fast active schedule based upon the parameter and power resources of the receiving node.

5. The method of claim 2 wherein locally synchronizing further comprises:

discontinuing the fast active schedule by the receiving node not acknowledging receiving a message from the transmitting node when a pending message queue of the receiving node is full.

6. The method of claim 1 and further comprising:

deactivating the fast active schedule of a node after a period of inactivity at that node.

7. The method of claim 6 and further comprising:

returning to the global regular active schedule at the node upon deactivating the fast active schedule at the node.

8. A method of communicating messages in a wireless mesh network having a plurality of nodes with transmit queues, the method comprising:

operating nodes to transmit and receive messages according to a global regular active schedule; and

locally activating a fast active schedule between a first, transmitting node and a second, receiving node based upon the queue depth of the first node, wherein the fast active schedule allows communicating messages between the first and second nodes more rapidly than with the global regular active schedule.

9. The method of claim 8 wherein locally activating comprises:

transmitting a message from the first node to the second node, the message including an indication of a number of messages the first node has ready to send; and

determining at the second node whether to activate the fast active schedule based upon the number of messages the first node has ready to send and resources of the second node to handle the messages.

10. The method of claim 9 wherein locally activating further comprises:

transmitting an acknowledgment from the second node to the first node indicating whether to use the fast active schedule for a next message.

11. The method of claim 8 and further comprising:

locally deactivating the fast active schedule.

12. The method of claim 11 wherein the second node locally deactivates the fast active schedule in response to a message indicating the first node has no further message ready to send.

13. The method of claim 11 wherein the second node locally deactivates the fast active schedule when a message queue of the second node is full.

14. The method of claim 11 wherein the second node locally deactivates the fast active schedule upon not receiving a message from the first node within a timeout period.

15. The method of claim 8 wherein the first and second nodes continue to operate in background according to the global regular active schedule while the fast active schedule is locally activated.

16. A wireless mesh network comprising a plurality of nodes capable of transmitting and receiving messages;

characterized by;

each transmitting node including, as part of a message, a parameter that indicates a depth of a pending message queue in the transmitting node; and

each receiving node determining if it will activate a fast active schedule for receiving future messages from the transmitting node based solely upon the parameter included in the message received from the transmitting node, wherein the fast active schedule allows communication of messages more rapidly than with a global regular active schedule.

17. The network of claim 16 wherein the receiving node locally activates the fast active schedule with an acknowledgment of the message received from the transmitting node.

18. The network of claim 16 wherein the receiving node locally deactivates the fast active schedule based upon at least one of message inactivity, an indication from the transmitting node that it has no further messages to send, and a queue of messages to be sent by the receiving node being full.

19. The network of claim 16 wherein the nodes operate according to the global regular active schedule for transmitting and receiving messages except where a fast active schedule has been locally activated between transmitting and receiving nodes based upon local demand.