Method and apparatus for synchronized communication over wireless backbone architecture

• US 5,875,179 A
• Filed: 10/29/1996
• Issued: 02/23/1999
• Est. Priority Date: 10/29/1996
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Proxim Inc. (Proxim Corp.)
• Inventors: Tikalsky, Terry L.
• Primary Examiner(s): Kizou, Hassan
• Application Number:
  US08/739,224
• Time in Patent Office: 847 Days
• Field of Search: 370/254, 370/255, 370/256, 370/315, 370/320, 370/335, 370/342, 370/350, 370/441, 370/479, 370/503, 370/516, 375/202, 375/205, 375/354, 375/356, 375/371, 455/507, 455/509
• US Class Current: 370/315
• CPC Class Codes: H04B 7/269 Master/slave synchronisation
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04J 3/0679 by determining clock distribution path in a network

Abstract

The present invention is directed to providing wireless communication among a plurality of nodes and repeaters that are synchronized for communication with a central hub that constitutes a master repeater. For example, the present invention is directed to a wireless network having a wireless backbone of repeaters which can use frequency hopping to automatically establish synchronization despite dynamic changes in the wireless communication system. Exemplary embodiments provide for control of synchronization whereby a repeater, when introduced to the system, automatically scans for, and synchronizes to another repeater, while at the same time continuing to listen for other repeater signals which identify either the master repeater, or another repeater which is closer to the master repeater (i.e., communicates to the master repeater through a more direct communication link).

Claims

1. A communication system comprising:

a first node having means for controlling synchronization of wireless communications between said first node and at least one additional node; and

a plurality of second nodes for communicating with said first node, at least one of said second nodes having means for determining a dynamic depth designation representing the number of nodes in a wireless communications path between said first node and said at least one second node, wherein said second node is configured to scan the communication system to dynamically update the dynamic depth designation.

2. A communication system according to claim 1, wherein said first node is a repeater of a radio backbone link in a wireless communications network.

3. A communication system according to claim 2, wherein said first node further includes:

a radio transceiver for communicating with other repeaters of the radio backbone link.

4. A communication system according to claim 3, wherein said first node further includes an additional transceiver for communicating with nodes that are not included in the backbone link.

5. A communication system according to claim 1, wherein said wireless communications path is an optical communications path.

6. A communication system according to claim 1, wherein said first node is a master repeater of a radio backbone link in the communications system, and said plurality of second nodes are access point repeaters which communicate with one another via said radio backbone link.

7. A communication system according to claim 6, wherein each of said plurality of second nodes has a dynamic depth designation representing the number of nodes located in a communications path to said first node.

8. A communication system according to claim 7, wherein said dynamic depth designations are determined by each of said plurality of second nodes during an initialization process, each of said plurality of second nodes being configured to repeatedly scan the communication system to dynamically update the dynamic depth designations.

9. A communication system according to claim 8, wherein each of said plurality of second nodes are configured to assume a lowest depth designation.

10. A communication system according to claim 1, wherein said first node and said plurality of second nodes communicate with one another using frequency hopping and plural communications channels, each of said plural communications channels including a hop sequence of frequencies wherein at least one frequency overlaps a frequency in the hop sequence of the remaining communications channels.

11. In a communication system having a first node and a second node, a method of dynamically assigning a depth to the second node, wherein a depth assigned to a given node represents a number of nodes between the given node and a master node, the method of assigning a depth to the second node comprising the steps of:

searching the communication system, from the second node, for a synchronization signal of the first node;

extracting a first depth of the first node from the synchronization signal of the first node; and

assigning a second depth to the second node which is one level higher than the first depth.

12. Method according to claim 11, wherein each of said first node and said second node are repeaters in a wireless backbone link.

13. Method according to claim 12, further including the steps of:

searching the communication system for a synchronization signal of a third node;

determining a third depth of the third node based on the synchronization signal of the third node;

determining whether the third depth is lower than the first depth; and

assigning a depth to the second node which is one level higher than the third depth when the third depth is lower than the first depth.

14. Method according to claim 13, further including steps of:

searching the communication system to locate a synchronization signal from the first node;

determining the first depth of the first node based on the synchronization signal of the first node; and

assigning a depth to the second node which is one depth level higher than that of the first node when the depth of the second node will be reduced from its present value.

15. A method for establishing synchronization between a first node and a second node, the method comprising the steps of:

selecting a first of plural communication channels for use by said first node, said first channel having a first hop sequence of frequencies;

assigning said second node any one of said plural communication channels, each of said plural communication channels having a hop sequence of frequencies wherein at least one frequency overlaps a frequency in said first hop sequence; and

detecting synchronization information during said frequency overlap to synchronize communications between said first and second nodes.

16. A communications network having a first node and a second node, said second node comprising:

means for sending communications to a first node using a first frequency hopping sequence; and

means for synchronizing communications between said first node and said second node by assigning said second node any one of plural communication channels, each of said plural communication channels having a hop sequence of frequencies wherein at least one frequency overlaps a frequency in said first frequency hopping sequence, said synchronizing means further detecting synchronization information during said frequency overlap to synchronize communications between said first and second nodes.