Using mini-beacons in a wireless network

• US 20060285507A1
• Filed: 06/17/2005
• Published: 12/21/2006
• Est. Priority Date: 06/17/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Lam, Alex C.K., Kinder, Richard D.
• Granted Patent: US 7,787,401 B2
• Time in Patent Office: Days
• US Class Current: 370/310
• CPC Class Codes: H04W 48/12 using downlink control channel
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A method, apparatus, and software containing computer readable code to implement the method implemented in a first wireless device, e.g., an access point. The method includes, for a particular network identifier, e.g., BSSID, of at least one network identifier supported by the first wireless device that including a transmitter and modulator, each network identifier identifying a wireless network, e.g., an IEEE 802.11 BSS for which the first wireless device acts as an access point, transmitting full parent beacon frames periodically at the beacon frame rate for the particular network identifier; and transmitting at least one mini-beacon frames in between consecutive full parent beacon frames for the particular network identifier. Each mini beacon frame includes a subset of the information in a full parent beacon frame, and further including timing information indicative of when the next full parent beacon frame will be transmitted for the particular network identifier.

Claims

1. A method comprising:

for a particular network identifier of at least one network identifier active in a first wireless device that supports at least one network identifier, the first wireless device including a transmitter and modulator for transmitting, and MAC hardware coupled to the transmitter and modulator, each network identifier identifying an infrastructure wireless network for which the first wireless device acts as an access point;

transmitting from the first wireless device full parent beacon frames periodically at the beacon frame rate for the particular network identifier; and

transmitting from the first wireless device at least one mini-beacon frames in between consecutive full parent beacon frames for the particular network identifier, each mini beacon frame including a subset of the information in a full parent beacon frame, and further including timing information indicative of when the next full parent beacon frame will be transmitted for the particular network identifier,

such that a second wireless device for which the first wireless device acts as an access point can determine when the next full parent beacon frame is to be transmitted.

2. A method as recited in claim 1, wherein the full parent frame includes an indication that mini-beacons are to be transmitted.

3. A method as recited in claim 2, wherein the full parent frame includes a measure of the period of the mini beacons.

4. A method as recited in claim 1, wherein the mini-beacon for the particular network identifier includes a measure of the period of the mini beacons.

5. A method as recited in claim 1, wherein the mini-beacon for the particular network identifier includes the timestamp from the parent beacon frame such that a client receiving a mini-beacon can maintain time synchronization by the AP transmitting frames with timestamps at a first frequency higher than the frequency of sending parent beacon frames.

6. A method as recited in claim 1, wherein the information in a mini-beacon is selected such that an unassociated wireless station receiving the mini-beacon is relatively unlikely to attempt to associate with the access point of the particular network identifier.

7. A method as recited in claim 1, wherein the access point of the first wireless device substantially conform to the IEEE 802.11 standard, wherein each of the at least one network identifiers is a BSSID, wherein for the particular BSSID and the first device acting as an AP for the particular BSSID, the full parent beacon frame substantially conforms to an IEEE 802.11 beacon frame, and wherein the infrastructure wireless network for which the first wireless device acts an the access point is a basic service set.

8. A method as recited in claim 7, wherein the mini-beacon includes a BSSID field that contains the BSSID used in the mini-beacon is the same as that of the parent BSSID, with the locally administered bit of the address set.

9. A method as recited in claim 7, wherein the full parent frame includes an indication that mini-beacons are to be transmitted.

10. A method as recited in claim 1, wherein the first wireless device supports a plurality of network identifiers at the same time, such that the first wireless device can act as an access point for more than one wireless network at a time.

11. A method as recited in claim 1, wherein the mini-beacon includes an additional information element that is a vendor-specific information element.

12. A method as recited in claim 11, wherein the additional information element includes a counter field indicative of how many mini-beacon periods before the next parent full beacon frame is to be transmitted.

13. A method as recited in claim 11, wherein the mini-beacon frame has a minimum size of only 58 bytes, including a frame header and the additional mini-beacon information element.

14. An apparatus comprising:

means for transmitting from a first wireless device, full parent beacon frames periodically at the beacon frame rate for a particular network identifier of at least one network identifier active in the first wireless device, the first network device supporting at least one network identifier, each network identifier identifying an infrastructure wireless network for which the first wireless device acts as an access point; and

means for transmitting from the first wireless device at least one mini- beacon frames in between consecutive full parent beacon frames for the particular network identifier, each mini beacon frame including a subset of the information in a full parent beacon frame, and further including timing information indicative of when the next full parent beacon frame will be transmitted for the particular network identifier,

such that a second wireless device for which the first wireless device acts as an access point can determine when the next full parent beacon frame is to be transmitted.

15. An apparatus as recited in claim 14, wherein the full parent frame includes an indication that mini-beacons are to be transmitted.

16. An apparatus as recited in claim 15, wherein the full parent frame includes a measure of the period of the mini beacons.

17. An apparatus as recited in claim 14, wherein the mini-beacon for the particular network identifier includes a measure of the period of the mini beacons.

18. An apparatus as recited in claim 14, wherein the access point of the first wireless device substantially conform to the IEEE 802.11 standard, wherein each of the at least one network identifiers is a BSSID, wherein for the particular BSSID and the first device acting as an AP for the particular BSSID, the full parent beacon frame substantially conforms to an IEEE 802.11 beacon frame, and wherein the infrastructure wireless network for which the first wireless device acts an the access point is a basic service set.

19. An apparatus as recited in claim 18, wherein the full parent frame includes an indication that mini-beacons are to be transmitted.

20. An apparatus as recited in claim 14, wherein the first wireless device supports a plurality of network identifiers at the same time, such that the first wireless device can act as an access point for more than one wireless network at a time.

21. An apparatus as recited in claim 14, wherein the mini-beacon includes an additional information element that is a vendor-specific information element.

22. An apparatus as recited in claim 21, wherein the additional information element includes a counter field indicative of how many mini-beacon periods before the next parent full beacon frame is to be transmitted.

23. A carrier medium, carrying at least one computer readable code segment to instruct one or more processors of a processing system to carry out a method, the method comprising:

for a particular network identifier of at least one network identifier active in a first wireless device that supports at least one network identifier, the first wireless device including a transmitter and modulator for transmitting, and MAC hardware coupled to the transmitter and modulator, each network identifier identifying an infrastructure wireless network for which the first wireless device acts as an access point;

transmitting from the first wireless device full parent beacon frames periodically at the beacon frame rate for the particular network identifier; and

transmitting from the first wireless device at least one mini-beacon frame in between consecutive full parent beacon frames for the particular network identifier, each mini beacon frame including a subset of the information in a full parent beacon frame, and further including timing information indicative of when the next full parent beacon frame will be transmitted for the particular network identifier,

such that a second wireless device for which the first wireless device acts as an access point can determine when the next full parent beacon frame is to be transmitted.