IDLE CONNECTION STATE POWER CONSUMPTION REDUCTION IN A WIRELESS LOCAL AREA NETWORK USING VARIABLE BEACON DATA ADVERTISEMENT

• US 20080170552A1
• Filed: 01/09/2008
• Published: 07/17/2008
• Est. Priority Date: 01/16/2007
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Zaks, Artur
• Granted Patent: US 7,961,659 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A novel and useful apparatus for and method of improving idle connection state power consumption in wireless local area network (WLAN) system using variable Beacon data advertisements. The invention takes advantage of the fact that Beacon contents to not change significantly between consecutive messages. Access points determine the size of the variable portion of their Beacon messages and include this size information in a special Variable Beacon Data Information Element in the Beacon message itself. The station reads the contents of this information element and uses the size information to determine at what point it is able to abort the reception of the Beacon message and turn off it'"'"'s receive radio thereby saving power.

Claims

1. A method for use in an access point in a wireless local area network (WLAN) system, said method comprising the steps of:

preparing a beacon transmission buffer with information elements to be transmitted in a beacon message;

determining the size of a variable section of said beacon transmission buffer; and

inserting said size of said variable section in said beacon message.

2. The method according to claim 1, wherein said size of said variable section is transmitted in a variable beacon data information element.

3. The method according to claim 1, wherein said step of determining comprises comparing the current contents of said beacon transmission buffer with a most recently transmitted beacon message, and determining the size of the variable section as a function of the offset of the information element immediately following the last information element that differs therebetween.

4. The method according to claim 3, wherein said offset is calculated starting from the first byte of the beacon frame stored in said beacon transmission buffer

5. The method according to claim 1, further comprising the step of calculating a checksum only on the contents of said variable section and transmitting said checksum in said beacon message.

6. The method according to claim 5, wherein said checksum is transmitted in a variable beacon data information element.

7. A method for use in an access point in a wireless local area network (WLAN) system, said method comprising the steps of:

preparing a Beacon transmission buffer with information elements to be transmitted in a current Beacon message;

calculating the size of a variable portion of said Beacon transmission buffer that changed from the contents of a previous Beacon message; and

advertising said size of said variable portion in said current Beacon message thereby permitting recipient stations to abort Beacon reception once receipt of said variable portion of said current Beacon message is complete.

8. The method according to claim 7, wherein said size of said variable portion is transmitted in a variable beacon data information element within said current Beacon message.

9. The method according to claim 7, wherein said step of calculating comprises comparing the contents of said beacon transmission buffer with the contents of said previous Beacon message, and determining the size of said variable portion as a function of the offset of the information element immediately following the last information element that differs therebetween.

10. The method according to claim 9, wherein said offset is calculated starting from the first byte of the beacon frame stored in said Beacon transmission buffer

11. The method according to claim 7, further comprising the step of calculating a checksum only on the contents of said variable portion and transmitting said checksum in said current Beacon message.

12. The method according to claim 11, wherein said checksum is transmitted in a variable beacon data information element.

13. A method for use in a station in a wireless local area network (WLAN) system, said method comprising the steps of:

detecting the start of a beacon message;

beginning reception of said beacon message and reading a size of a variable portion of said beacon message therefrom; and

aborting reception of said beacon message immediately after reception of said variable portion.

14. The method according to claim 13, wherein said size comprises the number of bytes in said variable portion of said beacon message to be read.

15. The method according to claim 13, wherein said step of aborting beacon message reception comprises turning off a radio receiver.

16. The method according to claim 13, further comprising the step of verifying the integrity of said received beacon message.

17. The method according to claim 16, wherein said step of verifying comprises the steps of:

calculating a checksum only on the contents of said variable portion;

comparing said calculated checksum with a checksum value extracted from said received beacon message; and

considering beacon data received correctly if said calculated checksum equals said extracted checksum.

18. The method according to claim 13, further comprising the steps of:

setting a previous beacon receive correct flag true if a checksum calculated on the contents of the variable portion of said beacon message matches the checksum extracted from the received beacon message; and

receiving only the variable portion of said beacon message if said previous beacon receive correct flag is true.

19. The method according to claim 13, further comprising the steps of:

setting a previous beacon receive correct flag true if a checksum calculated on the contents of the variable portion of said beacon message matches the checksum extracted from the received beacon message; and

receiving the complete beacon message if said previous beacon receive correct flag is false.

20. A method for use in a station in a wireless local area network (WLAN) system, said method comprising the steps of:

beginning reception of a beacon message;

detecting a variable beacon data information element and extracting a size of a variable portion of the beacon message therefrom;

continuing to receive said beacon message up to an including said variable portion; and

aborting reception of said beacon message immediately after reception of said variable portion is complete.

21. The method according to claim 20, wherein said step of aborting beacon message reception comprises turning off a radio receiver.

22. The method according to claim 20, further comprising the step of verifying the integrity of said received beacon message.

23. The method according to claim 22, wherein said step of verifying comprises the steps of:

calculating a checksum only on the contents of said variable portion;

comparing said calculated checksum with a checksum value extracted from said received beacon message; and

considering beacon data received correctly if said calculated checksum equals said extracted checksum.

24. A mobile communication device, comprising:

a cellular radio;

a WLAN radio;

a processor communicatively coupled to said WLAN radio and said cellular radio, said processor operative to;

detect the start of a beacon message;

begin reception of said beacon message and read a size of a variable portion of said beacon message therefrom; and

abort reception of said beacon message immediately after reception of said variable portion.

25. The mobile communications device according to claim 24, wherein said size of said variable section is transmitted in a variable beacon data information element.