Frequency hopping medium access control protocol for a communication system having distributed synchronization

• US 6,466,608 B1
• Filed: 04/06/1995
• Issued: 10/15/2002
• Est. Priority Date: 03/03/1994
• Status: Expired due to Term

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Proxim Inc. (Proxim Corp.)
• Inventors: Giles, Rick R., Coleman, Arthur, Grau, Juan, Hong, Hilton
• Primary Examiner(s): LUTHER, WILLIAM A
• Application Number:
  US08/417,907
• Time in Patent Office: 2,749 Days
• Field of Search: 375/202, 375/356, 375/362, 375/211, 375/200, 375/201, 375/364, 375/137, 370/73, 370/74, 370/75, 370/94.2, 370/60, 370/16.1, 370/16, 370/103, 370/85.6, 370/335, 370/441, 370/342, 370/479, 370/515, 370/509, 370/513, 370/512, 370/514, 370/507, 380/21, 380/34, 380/48, 380/49, 340/825.06, 340/825.07, 340/825.08, 340/825.14, 340/825.2, 340/825.21, 340/825.5, 340/825.51, 340/825.73, 364/232.9, 395/200.19
• US Class Current: 375/137
• CPC Class Codes: H04B 1/7156 Arrangements for sequence synchronisation
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 74/00 Wireless channel access
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 84/20 Master-slave selection or change arrangements

Abstract

The present invention is directed to providing frequency hopping medium access control among a plurality of nodes (e.g., communication stations) in a wireless communication system. The present invention is directed to decentralized control of synchronization among the plural nodes. In accordance with exemplary embodiments, a node used to control synchronization of the communication system can switch from a first master node to a second master node.

Claims

1. Method for controlling communication of frequency hopped radio signals among a plurality of nodes in a communication system, comprising the steps of:

assigning each of said nodes a hierarchical designation representing a priority of the node to control wireless synchronization of the communication system;

initializing the communication system by synchronizing the nodes to a first node;

searching the communication system to locate a second node to control synchronization of the communication system; and

synchronizing the communication system to said second node if located.

2. Method according to claim 1, further including the steps of:

assigning each of said nodes one of at least first, second and third hierarchical designations, with said first hierarchical designation being of highest priority and with said third hierarchical designation being of lowest priority.

3. Method according to claim 2, wherein said first node is assigned said first priority, said step of initializing further including the steps of:

sending a synchronization signal from said first node without searching for other nodes of said first priority within said communication system.

4. Method according to claim 2, wherein said first node is assigned said second priority, said step of initializing further including the steps of:

scanning the communication system for a synchronization signal from another node of equal or higher priority;

synchronizing said first node to said another node if located; and

sending a synchronization signal from said first node if said another node is not located.

5. Method according to claim 2, wherein said first node is assigned said third priority, said step of initializing further including the steps of:

scanning the communication system for a synchronization signal from another node of higher priority;

synchronizing said first node to said another node if said another node is located; and

signalling that a synchronization signal was not detected if said another node is not located.

6. Method according to claim 2, further comprising the step of:

dynamically reconfiguring the communication system as nodes enter or depart communication range with remaining nodes of the communication system.

7. Method according to claim 2, wherein said first node is assigned said second priority, said step of searching the communication system further including the steps of:

scanning the communication system for a synchronization signal from another node of said first or said second priority;

continuing normal operation if said synchronization signal is not detected; and

synchronizing to a node of said first priority if a synchronization signal from a node of said first priority is detected.

8. Method according to claim 2, wherein said first node is assigned said second priority, said step of searching the communication system further including the steps of:

scanning the communication system for a synchronization signal from another node of said first or said second priority;

continuing normal operation if said synchronization signal is not detected; and

synchronizing to a node of said second priority if a synchronization signal from a node of said second priority is detected and if a synchronization signal from a node of said first priority is not detected.

9. Method according to claim 1, wherein said step of synchronizing the nodes to said second node further includes the steps of:

sending a synchronization signal from said first node to each of said nodes, said synchronization signal indicating a hop number of said second node.

10. Method according to claim 1, wherein said step of synchronizing further includes a step of:

broadcasting a resynchronization request to inform all nodes of the communication system to synchronize to said second node.

11. Method for synchronizing frequency hopping communication among plural nodes in a communication system, wherein said communication system includes at least two nodes, each of said nodes being assigned at least one of three different hierarchical designations for determining when a node used to control wireless synchronization of the communication system is switched from a first one of said nodes to a second one of said nodes comprising the steps of:

transmitting a synchronization signal from a first node during a predetermined contention-free synchronization period;

synchronizing frequency hopping of at least a second node to said first node via said synchronization signal; and

searching for synchronization signals transmitted by other nodes of said communication system prior to said step of transmitting.

12. Method according to claim 11, wherein said step of transmitting further includes a step of:

transmitting said synchronization signal for a period sufficient for said plural nodes to scan all frequencies of said frequency hopping communication system.

13. A method according to claim 11, wherein said step of synchronizing frequency hopping of at least a second node to said first node further includes steps of:

scanning all frequencies of a frequency hopping sequence to detect said synchronization signal; and

locking a frequency of said second node to said synchronization signal upon detection of said synchronization signal by said second node.

14. Method according to claim 11, wherein said step of transmitting further includes a step of:

transmitting a synchronization signal which includes a fixed pattern preamble and a data packet for identifying a transmission frequency.

15. Method for controlling a first node of a communication system having a plurality of nodes using frequency hopped radio signals, each node of said communication system being assigned a hierarchical designation representing a priority of a node to control wireless synchronization of the frequency hopped radio signals, said method comprising the steps of:

(a) when said first node is of a first priority, sending a synchronization signal from said node without searching for other nodes of said first priority;

(b) when said first node is of a second priority, scanning the communication system for a synchronization signal from another node of equal or higher priority, synchronizing said first node to said another node if located, and sending a synchronization signal from said first node if said another node is not located; and

(c) when said first node is of a third priority, scanning the communication system for a synchronization signal from another node of a higher priority, synchronizing said first node to said another node if said another node is located, and signalling that a synchronization signal was not detected if said another node is not located.

16. Method according to claim 15, further comprising the step of:

dynamically reconfiguring said communication system to synchronize all nodes within communication range of said first node with said