Apparatus and method for intelligent frequency-hopping discovery and synchronization

• US 20080267259A1
• Filed: 04/30/2007
• Published: 10/30/2008
• Est. Priority Date: 04/30/2007
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Budampati, Ramakrishna S., Gonia, Patrick S., Kolavennu, Soumitri N.
• Granted Patent: US 8,107,511 B2
• Time in Patent Office: Days
• US Class Current: 375/134
• CPC Class Codes: H04B 1/7156 Arrangements for sequence synchronisation

Abstract

A process control system or other system includes multiple nodes that communicate using frequency-hopping patterns. Each node may operate using its own frequency-hopping pattern. Each node may also broadcast information identifying its frequency-hopping pattern to other nodes, such as any neighboring nodes. Each node may further. receive information identifying the frequency-hopping patterns of any neighboring nodes. The nodes may then operate in a non-synchronized manner and use the frequency-hopping patterns of neighboring nodes to communicate. For example, each node may use the identified frequency-hopping pattern of a neighboring node to synchronize with and communicate data to the neighboring node. In this way, the nodes need not maintain synchronization at all times during operation. Also, different nodes may use different frequency channels at the same time, helping to increase the bandwidth available for wireless communications.

Claims

1. An apparatus comprising:

a transceiver operable to communicate with a node in a wireless network;

a memory operable to store information associated with a frequency-hopping pattern of the node; and

a controller operable to synchronize the transceiver with the node using the frequency-hopping pattern of the node.

2. The apparatus of claim 1, wherein the transceiver is operable to receive information identifying the frequency-hopping pattern of the node from the node.

3. The apparatus of claim 1, wherein the transceiver is operable to transmit information identifying a frequency-hopping pattern of the apparatus to the node.

4. The apparatus of claim 3, wherein:

the transceiver is operable to receive the information identifying the frequency-hopping pattern of the node using a frequency-hopping pattern of a gateway; and

the transceiver is operable to transmit the information identifying the frequency-hopping pattern of the apparatus using the frequency-hopping pattern of the gateway.

5. The apparatus of claim 1, wherein:

the transceiver is operable to receive one or more synchronization messages from a gateway using a frequency-hopping pattern of the gateway; and

the transceiver is operable to transmit one or more synchronization messages to the node using the frequency-hopping pattern of the gateway.

6. The apparatus of claim 1, wherein:

the controller is operable to identify one or more routes through the wireless network to a gateway; and

the transceiver is operable to transmit information identifying the one or more routes to the node.

7. The apparatus of claim 1, wherein the apparatus and the node form part of a process control system, the process control system operable to control an industrial process.

8. A system comprising:

a plurality of nodes forming a wireless network, each node operable to broadcast information identifying a frequency-hopping pattern of that node and to receive information identifying a frequency-hopping pattern of at least one other node, each node also operable to communicate with the at least one other node using the frequency-hopping pattern of the at least one other node.

9. The system of claim 8, wherein a first of the nodes comprises:

a transceiver operable to communicate with a second of the nodes;

a memory operable to store information associated with the frequency-hopping patterns of the first and second nodes; and

a controller operable to synchronize the transceiver with the second node using the frequency-hopping pattern of the second node.

10. The system of claim 8, wherein:

the system further comprises a gateway operable to facilitate communication between the nodes in the wireless network and a wired network; and

each node is operable to broadcast the information identifying its frequency-hopping pattern and to receive the information identifying the frequency-hopping pattern of the at least one other node using a frequency-hopping pattern of the gateway.

11. The system of claim 10, wherein:

a first of the nodes is operable to receive one or more synchronization messages from the gateway using the frequency-hopping pattern of the gateway; and

the first node is operable to transmit one or more synchronization messages to a second of the nodes using the frequency-hopping pattern of the gateway.

12. The system of claim 8, wherein:

a first of the nodes is operable to identify one or more routes through the wireless network to a gateway; and

the first node is operable to transmit information identifying the one or more routes to a second of the nodes.

13. The system of claim 8, further comprising a transmit-only node in the wireless network.

14. The system of claim 13, wherein at least one of the plurality of nodes is operable to:

estimate a transmission time of the transmit-only node;

synchronize to a frequency-hopping pattern of the transmit-only node; and

receive a transmission from the transmit-only node at or around the estimated transmission time.

15. The system of claim 14, wherein:

the at least one of the plurality of nodes is operable to estimate the transmission time of the transmit-only node using a duty cycle and a clock skew associated with the transmit-only node; and

the at least one of the plurality of nodes is operable to update the clock skew after one or more transmissions by the transmit-only node.

16. A method comprising:

scanning a plurality of frequency channels for messages from a gateway at a first node in a wireless network;

synchronizing the first node with a frequency-hopping pattern of the gateway using the messages;

transmitting information identifying a frequency-hopping pattern of the first node to a second node in the wireless network;

receiving information identifying a frequency-hopping pattern of the second node at the first node;

operating the first node using the frequency-hopping pattern of the first node; and

synchronizing the first node with the second node for wireless communication using the frequency-hopping pattern of the second node.

17. The method of claim 16, wherein:

the gateway transmits multiple messages for a specified time period on each of the frequency channels; and

scanning the plurality of frequency channels comprises scanning all frequency channels during each specified time period.

18. The method of claim 16, wherein transmitting the information identifying the frequency-hopping pattern of the first node and receiving the information identifying the frequency-hopping pattern of the second node comprise using the frequency-hopping pattern of the gateway.

19. The method of claim 16, further comprising:

identifying one or more routes from the first node to the gateway; and

transmitting information identifying the one or more routes to the second node.

20. The method of claim 19, wherein identifying the one or more routes comprises selecting at least two routes from a set of routes, the at least two routes selected based on one or more of:

a number of hops from the first node to the gateway, a quality of wireless links from the first node to the gateway, and a number of common intermediate nodes of the at least two routes.