Concurrent multiple data rate communications in a wireless local area network

• US 5,912,921 A
• Filed: 08/20/1997
• Issued: 06/15/1999
• Est. Priority Date: 08/20/1997
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Intermec IP Corporation (Honeywell International Inc.)
• Inventors: Jovanovich, Alan F., Mensonides, John W., Warren, Bruce G.
• Primary Examiner(s): Vo, Don N.
• Assistant Examiner(s): JIANG, LENNY R
• Application Number:
  US08/915,260
• Time in Patent Office: 664 Days
• Field of Search: 375/220, 375/221, 375/222, 375/258, 375/225, 370/338, 370/241, 370/465, 370/245, 370/468, 370/247, 370/522, 370/251, 370/252, 370/253, 370/329, 370/332, 370/333, 370/335, 371/5.1, 371/5.3, 371/5.5, 455/67.1, 455/67.4, 455/422, 455/517
• US Class Current: 375/220
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04L 1/00 Arrangements for detecting or preventing errors in the information received correcting synchronisation H04L7/00
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0016 involving special memory structures, e.g. look-up tables
• CPC Class Codes: H04L 1/0025 Transmission of mode-switching indication
• CPC Class Codes: H04L 1/0036 arrangements specific to the receiver
• CPC Class Codes: H04L 12/28 characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks] wireless communication networks H04W ; arrangements for dividing the transmission path H04W40/00
• CPC Class Codes: H04W 28/22 Negotiating communication rate
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A wireless local area network (WLAN) provides optimal data throughput by operating at multiple data rates simultaneously. The WLAN includes a network master communicating with a plurality of remote client transceiver nodes. The network master maintains a table of active client transceiver nodes. The table includes a current data rate for each of the active client transceiver nodes. Periodic high-speed and low-speed beacon signals are transmitted from the network master to the active client transceiver nodes. Each of the active client transceiver nodes receives and processes the beacon signals to determine an optimal data rate. Then, each of the active client transceiver nodes transmits a return signal to the network master which designates the determined optimal data rate. Thereafter, the network master updates the table to reflect the optimal data rate for each of the active client transceiver nodes. Subsequent messages from the network master to the active client transceiver nodes are thereby transmitted at the current data rate for each respective one of the active client transceiver nodes.

Claims

1. A method for operating a wireless local area network having a network master communicating with a plurality of remote client transceiver nodes at plural data rates comprising the steps of:

maintaining a table of active client transceiver nodes at said network master, said table including a current data rate for each of said active client transceiver nodes;

transmitting an expected number of first beacon signals and second beacon signals;

receiving and processing a received number of said first and second beacon signals at each of said active client transceiver nodes;

determining an optimal data rate based upon a difference between said expected number of first and second beacon signals and said received number of first and second beacon signals;

transmitting a return signal from each of said active client transceiver nodes to said network master designating said determined optimal data rate; and

updating said table to reflect said optimal data rate as said current data rate for each of said active client transceiver nodes, wherein subsequent messages from said network master to said active client transceiver nodes are transmitted at said current data rate for each respective one of said active client transceiver nodes.

2. The method for operating a wireless local area network of claim 1, further comprising the step of maintaining a count of said received number of first and second beacons.

3. The method for operating a wireless local area network of claim 1, further comprising the steps of:

attempting to receive a plurality of messages at each of said active client transceiver nodes;

re-trying to receive ones of said plurality of messages not received during said attempting step; and

maintaining a count of said re-tried ones of said plurality of messages.

4. The method for operating a wireless local area network of claim 3, wherein the step of determining an optimal data rate further comprises the steps of:

selecting a data rate lower than said current data rate when said count of said re-tried ones of said plurality of messages exceeds a predetermined number of acceptable re-tried messages; and

selecting a data rate higher than said current data rate when said count of said re-tried ones of said plurality of messages is less than a predetermined number of acceptable re-tried messages.

5. The method for operating a wireless local area network of claim 1, further comprising the steps of:

transmitting a channel reservation message at a first data rate; and

receiving and processing subsequent messages at a second data rate a predetermined time period following said transmission of said channel reservation message.

6. The method for operating a wireless local area network of claim 1, wherein said first beacon signals are transmitted at a first data rate and said second beacon signals are transmitted at a second data rate.

7. The method for operating a wireless local area network of claim 1, wherein said table further includes a current modulation type for each of said active client transceiver nodes.

8. The method for operating a wireless local area network of claim 7, wherein said step of determining an optimal data rate further comprises determining an optimal modulation type based upon said difference between said expected number of first and second beacon signals and said received number of first and second beacon signals.

9. The method for operating a wireless local area network of claim 8, wherein said step of transmitting a return signal further comprises transmitting a return signal from each of said active client transceiver nodes to said network master designating said determined optimal modulation type.

10. The method for operating a wireless local area network of claim 9, wherein said step of updating said table further comprises updating said table to reflect said optimal modulation type as said current modulation type for each of said active client transceiver nodes, wherein subsequent messages from said network master to said active client transceiver nodes are transmitted at said current modulation type for each respective one of said active client transceiver nodes.

11. A wireless local area network operable at plural data rates comprising:

a network master having a table of active client transceiver nodes at said network master, said table including a current data rate for each of said active client transceiver nodes, said network master transmitting an expected number of first beacon signals and second beacon signals;

a plurality of client transceiver nodes adapted to receive and process a received number of said first and second beacon signals at each of said active client transceiver nodes, said client transceiver nodes determining an optimal data rate based upon a difference between said expected number of first and second beacon signals and said received number of first and second beacon signals, said client transceiver nodes transmitting a return signal to said network master designating said determined optimal data rate;

wherein, said network master updates said table to reflect said optimal data rate as said current data rate for each of said active client transceiver nodes, wherein subsequent messages from said network master to said active client transceiver nodes are transmitted at said current data rate for each respective one of said active client transceiver nodes.

12. The wireless local area network of claim 11, wherein said plurality of client transceiver nodes maintain a count of said received number of first and second beacons.

13. The wireless local area network of claim 11, wherein said plurality of client transceiver nodes attempt to receive a plurality of messages at each of said active client transceiver nodes, re-try to receive ones of said plurality of messages not received during said attempting step, and maintain a count of said re-tried ones of said plurality of messages.

14. The wireless local area network of claim 13, wherein the client transceiver nodes select a data rate lower than said current data rate when said count of said re-tried ones of said plurality of messages exceeds a predetermined number of acceptable re-tried messages, and select a data rate higher than said current data rate when said count of said re-tried ones of said plurality of messages is less than a predetermined number of acceptable re-tried messages.

15. The wireless local area network of claim 11, wherein the network master transmits a channel reservation message at a first data rate, and receives and processes subsequent messages at a second data rate a predetermined time period following said transmission of said channel reservation message.

16. The wireless local area network of claim 11, wherein said first beacon signals are transmitted at a first data rate and said second beacon signals are transmitted at a second data rate.

17. The wireless local area network of claim 11, wherein said table further includes a current modulation type for each of said active client transceiver nodes.

18. The wireless local area network of claim 17, wherein said client transceiver nodes determine an optimal modulation type based upon said difference between said expected number of first and second beacon signals and said received number of first and second beacon signals.

19. The wireless local area network of claim 18, wherein said client transceiver nodes transmit a return signal to said network master designating said determined optimal modulation type.

20. The wireless local area network of claim 19, wherein said network master updates said table to reflect said optimal modulation type as said current modulation type for each of said active client transceiver nodes, subsequent messages from said network master to said active client transceiver nodes thereby being transmitted at said current modulation type for each respective one of said active client transceiver nodes.

21. A wireless local area network having a network master communicating with a plurality of remote client transceiver nodes at plural data rates comprises:

means for maintaining a table of active client transceiver nodes at said network master, said table including a current data rate for each of said active client transceiver nodes;

means for transmitting an expected number of first beacon signals and second beacon signals;

means for receiving and processing a received number of said first and second beacon signals at each of said active client transceiver nodes;

means for determining an optimal data rate based upon a difference between said expected number of first and second beacon signals and said received number of first and second beacon signals;

means for transmitting a return signal from each of said active client transceiver nodes to said network master designating said determined optimal data rate; and

means for updating said table to reflect said optimal data rate as said current data rate for each of said active client transceiver nodes, wherein subsequent messages from said network master to said active client transceiver nodes are transmitted at said current data rate for each respective one of said active client transceiver nodes.

22. The wireless local area network of claim 21, further comprising means for maintaining a count of said received number of first and second beacons.

23. The wireless local area network of claim 21, further comprising:

means for attempting to receive a plurality of messages at each of said active client transceiver nodes;

means for re-trying to receive ones of said plurality of messages not received during said attempting step; and

means for maintaining a count of said re-tried ones of said plurality of messages.

24. The wireless local area network of claim 23, wherein the determining means further comprises:

means for selecting a data rate lower than said current data rate when said count of said re-tried ones of said plurality of messages exceeds a predetermined number of acceptable re-tried messages; and

means for selecting a data rate higher than said current data rate when said count of said re-tried ones of said plurality of messages is less than a predetermined number of acceptable re-tried messages.

25. The wireless local area network of claim 21, further comprising:

means for transmitting a channel reservation message at a first data rate; and

means for receiving and processing subsequent messages at a second data rate a predetermined time period following said transmission of said channel reservation message.

26. The wireless local area network of claim 21, wherein said first beacon signals are transmitted at a first data rate and said second beacon signals are transmitted at a second data rate.

27. The wireless local area network of claim 21, wherein said table further includes a current modulation type for each of said active client transceiver nodes.

28. The wireless local area network of claim 27, wherein said determining means further comprises means for determining an optimal modulation type based upon said difference between said expected number of first and second beacon signals and said received number of first and second beacon signals.

29. The wireless local area network of claim 28, wherein said means for transmitting a return signal further comprises means for transmitting a return signal from each of said active client transceiver nodes to said network master designating said determined optimal modulation type.

30. The wireless local area network of claim 29, wherein said means for updating said table further comprises means for updating said table to reflect said optimal modulation type as said current modulation type for each of said active client transceiver nodes, wherein subsequent messages from said network master to said active client transceiver nodes are transmitted at said current modulation type for each respective one of said active client transceiver nodes.

31. A wireless local area network comprises a network master adapted to communicate with a plurality of remote client transceiver nodes, said network master comprising a memory having a table defining status of each of said client transceiver nodes, said table including at least a current data rate for each of said client transceiver nodes, said network master transmitting a first beacon signal at a first data rate and a second beacon signal at a second data rate, each of said remote client transceiver nodes being adapted to determine an optimal data rate from said beacon signals and notify said network master of said optimal data rate, whereby said network master updates said table to reflect said optimal data rate for each of said active client transceiver nodes.

32. The wireless local area network of claim 31, wherein said remote client transceiver nodes are further adapted to maintain a count of a received number of first and second beacon signals.

33. The wireless local network of claim 31, wherein the first data rate is greater than the second data rate.