Systems and Methods for Indicating Buffered Data at an Access Point Using an Embedded Traffic Indication Map

• US 20090010191A1
• Filed: 03/12/2008
• Published: 01/08/2009
• Est. Priority Date: 07/05/2007
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Wentink, Maarten Menzo
• Granted Patent: US 8,233,414 B2
• Time in Patent Office: Days
• US Class Current: 370/311
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Stations in standby mode periodically wake up to check for buffered data at the access points. Traditionally, the information is available by checking the periodic beacon frame for a traffic indication map (TIM). Unfortunately, the length of beacons has steadily increased with the progression of the various wireless standards requiring stations to wake up for longer periods to merely check for buffered data. Several approaches are disclosed which address this shortcoming, including the broadcast of TIM frames, the partial reception of beacon frames and the use of an embedded TIM frame within a beacon frame.

Claims

1. An informational element comprising:

a check beacon indication field;

a bitmap control field; and

a partial virtual bitmap field.

2. The informational element of claim 1, further comprising an error detection field.

3. The informational element of claim 1, wherein the check beacon indication field comprises means for indicating a critical change in the beacon frame.

4. The informational element of claim 1, wherein the check beacon indication field comprises a counter which is incremented after each critical change in the beacon frame.

5. The informational element of claim 1, wherein the check beacon indication field comprises means for indicating a significant change in the beacon frame.

6. The informational element of claim 1, wherein the check beacon indication field comprises a counter which is incremented after each significant change in the beacon frame.

7. The informational element of claim 1, wherein the error detection field comprises a parity check.

8. The informational element of claim 1, wherein the error detection field comprises a cyclic redundancy code (CRC).

9. The informational element of claim 1, wherein the error detection field comprises a hash.

10. The informational element of claim 1, further comprising a second bitmap control field and a second partial virtual bitmap.

11. A method for indicating buffered data comprising, broadcasting a beacon frame comprising the informational element of claim 1, wherein the informational element is placed near the beginning of the beacon frame.

12. The method of claim 11, wherein the beacon frame is a delivery traffic indication map (DTIM) beacon frame.

13. A method in a station for retrieving buffered data from an access point comprising:

partially receiving a beacon frame, said partially receiving comprising receiving an embedded traffic indication map (ETIM) informational element, wherein the ETIM informational element comprises;

a check beacon indication field;

a bitmap control field; and

a partial virtual bitmap field.

if the partial virtual bitmap is indicative that the access point has buffered data for the station, receiving the buffered data; and

if the check beacon indication field indicates a critical or significant change in the beacon frame, receiving the remainder of the beacon frame.

14. The method of claim 13, wherein the ETIM informational element further comprises an error detection field.

15. The method of claim 13, wherein the check beacon indication field comprises a means for indicating a critical change in the beacon frame, a means for indicating a significant change in the beacon frame, or both.

16. The method of claim 13, wherein the check beacon indication field comprises a first counter which is incremented after each critical change in the beacon frame, a second counter which is incremented after each significant change in the beacon frame, or both.

17. The method of claim 13, wherein the error detection field comprises a parity check, a CRC, a hash or a combination thereof.

18. A station comprising a processor, a wireless network interface device and a memory comprising instructions, said instructions causing the processor and the wireless network interface device to perform the method of claim 13.

19. The method of claim 14, further comprising discarding the partially received beacon frame if the error detection field indicates an error.

20. A station comprising a processor, a wireless network interface device and a memory comprising instructions, said instructions causing the processor and the wireless network interface device to perform the method of claim 19.

21. An access point comprising:

a processor;

a wireless network interface device; and

a memory comprising instructions;

said instructions causing the processor to cause the wireless network interface device to broadcast a beacon frame comprising an ETIM element,

wherein the ETIM element is placed near the beginning of the beacon frame;

said ETIM element comprising;

a check beacon indication field;

a bitmap control field; and

a partial virtual bitmap field.

22. The access point of claim 21, wherein the ETIM element further comprises an error detection field.

23. The access point of claim 21, wherein the ETIM element immediately follows a capability field in the beacon frame

24. The access point of claim 21, wherein the ETIM element comprises a second bitmap control field and a second partial virtual bitmap.

25. The access point of claim 21, wherein the check beacon indication field comprises a means for indicating a critical change in the beacon frame, a means for indicating a significant change in the beacon frame, or both.

26. The access point of claim 21, wherein the check beacon indication field comprises a first counter which is incremented after each critical change in the beacon frame, a second counter which is incremented after each significant change in the beacon frame, or both.

27. The access point of claim 21, wherein the error detection field comprises a parity check, a CRC, a hash or a combination thereof.

28. The method of claim 21, wherein the beacon frame is a DTIM beacon frame.