Method to put a mobile terminal into sleep when a frame control channel containing a location of slow broadcast channel does not include wakeup information

• US 6,622,251 B1
• Filed: 03/17/2000
• Issued: 09/16/2003
• Est. Priority Date: 04/07/1999
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Ebenhard, Johan, Lindskog, Jan, Wenger, Fabian, Hansson, Ulf, Malmgren, Göran, Almehag, Lorens
• Primary Examiner(s): Lee, Thomas
• Assistant Examiner(s): SURYAWANSHI, SURESH
• Application Number:
  US09/528,101
• Time in Patent Office: 1,278 Days
• Field of Search: 713/300, 713/320, 370/311, 370/328
• US Class Current: 713/300
• CPC Class Codes: H04L 69/324 in the data link layer [OSI layer 2], e.g. HDLC
• CPC Class Codes: H04L 9/40 Network security protocols
• 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

In a WLAN where an AP and MTs use a duplex airlink having a MAC frame structure to communicate with each other, the AP places wakeup PDUs at different locations in a MAC frame to allow the MTs to conserve energy by maximizing sleep time. In other embodiments, the wakeup PDUs are sequenced by MAC-ID so that a MT can conclusively determine whether remaining wakeup PDUs in a sequence can contain its MAC-ID, and go to sleep early if they cannot. In another embodiment, a wakeup PDU type can indicate to a corresponding MT whether the MT can expect downlink data later in the same MAC frame. In addition, the wakeup PDU type can indicate to the MT that the MAC frame that it should awaken and remain awake to receive downlink data in the future.

Claims

1. A method for minimizing power consumption in a mobile terminal in a wireless local area network including an access point, comprising the steps of:

locating wakeup information in a Frame Control Channel (FCCH) of a Medium Access Control (MAC) frame sent by an access point in the network, wherein the wakeup information includes information located at the beginning of the FCCH, the information located at the beginning of the FCCH including an indication of a location of a Slow Broadcast Channel (SBCH) in the MAC frame;

in the mobile terminal, monitoring the FCCH to determine whether the FCCH includes wakeup information having a MAC identification (MAC-ID) that is the same as a MAC-ID of the mobile terminal; and

in the mobile terminal, when the FCCH does not include wakeup information having a MAC identification (MAC-ID) corresponding to the mobile terminal, going to sleep upon conclusion of the monitoring step.

2. The method of claim 1, further comprising the steps of:

determining whether wakeup information in the FCCH is ordered according to MAC-ID;

when the wakeup information in the FCCH is ordered according to MAC-ID, monitoring the wakeup information in the FCCH until either the wakeup information includes a MAC-ID corresponding to the mobile terminal, or until the mobile terminal determines that wakeup information remaining in the FCCH cannot include a MAC-ID corresponding to the mobile terminal, based on the value of the MAC-ID of the mobile terminal and the order of the wakeup information in the FCCH.

3. The method of claim 2, in the event of a decode failure while the mobile terminal is monitoring the wakeup information, further comprising the steps of:

determining whether the MAC-ID of the mobile terminal is excluded from wakeup information remaining in the FCCH based on the value of the MAC-ID and the order of the wakeup information in the FCCH; and

when the MAC-ID of the mobile terminal is excluded from the wakeup information remaining in the FCCH, preventing the mobile terminal from sleeping.

4. The method of claim 1, further comprising the step of:

determining whether the Broadcast Control Channel (BCCH) includes an indication of pending data.

5. The method of claim 4, further comprising the step of:

when the BCCH includes a positive indication of pending data, repeating the step of determining for each successive MAC frame, until the BCCH does not include a positive indication of pending data.

6. The method of claim 4, further comprising the steps of:

when the BCCH is determined to include an indication of pending data, proceeding with the step of locating wakeup information in the FCCH;

when the BCCH is determined to not include an indication of pending data, putting the mobile terminal to sleep.

7. The method of claim 1, wherein the wakeup information in the FCCH includes a MAC-ID and indicates which downlink channel in the MAC frame will contain downlink data for the mobile terminal identified by the MAC-ID.

8. The method of claim 1, wherein the wakeup information in the FCCH instructs the mobile terminal to send a predetermined acknowledge signal back to the access point.

9. The method of claim 8, wherein the wakeup information in the FCCH identifies an allocated uplink channel within the MAC frame via which the mobile terminal is to send the predetermined acknowledge signal.

10. The method of claim 8, wherein the wakeup information in the FCCH instructs the mobile terminal to send the predetermined acknowledge signal via a Random Access Channel (RACH) in the MAC frame.

11. The method of claim 8, wherein the wakeup information in the FCCH instructs the mobile terminal to send the predetermined acknowledge signal via a Random Access Channel (RACH) in a subsequent MAC frame.

12. The method of claim 11, wherein the wakeup information in the FCCH instructs the mobile terminal to send the predetermined acknowledge signal when the RACH first becomes available.

13. The method of claim 1, wherein the wakeup information in the FCCH indicates to the mobile terminal that the MAC frame does not contain downlink data for the mobile terminal, and instructs the mobile terminal to remain awake and decode each FCCH and Broadcast Control Channel (BCCH) that come along, until further notice.

14. The method of claim 1, wherein the local area network includes a plurality of mobile terminals, further comprising the step of:

dividing the mobile terminals into sleep groups based on MAC-IDs of the mobile terminals.

15. The method of claim 14, wherein each of the mobile terminals is assigned to one of two sleep groups based on a least significant bit of the MAC-ID of the mobile terminal.

16. The method of claim 14, further comprising the steps of:

the access point determining which sleep group of mobile terminals will awaken to monitor the FCCH, and

the access point including wakeup information only for those mobile terminals that will awaken to monitor the FCCH.

17. The method of claim 1, further comprising the steps of:

accessing an index at a beginning of the SBCH, indicating locations of wakeup information in the SBCH, to determine when the mobile terminal should awaken to receive wakeup information in the SBCH corresponding to the mobile terminal; and

the mobile terminal sleeping between the index and the wakeup information in the SBCH corresponding to the mobile terminal.

18. The method of claim 17, wherein the index indicates portions of the SBCH that correspond to different ranges of MAC-IDs.

19. The method of claim 1, further comprising the steps of:

during the step of monitoring the FCCH and after evaluating the information at the beginning of the FCCH to determine the location of the SBCH, determining that the FCCH does not include wakeup information having a MAC-ID corresponding to the mobile terminal; and

the mobile terminal awakening at the location of the SBCH.

20. The method of claim 19, further comprising the step of:

when wakeup information in the SBCH is ordered, monitoring the wakeup information beginning at the location of the SBCH at which the mobile terminal awakens, until either the wakeup information includes a MAC-ID corresponding to the MAC-ID of the mobile terminal, or until the mobile terminal determines that wakeup information remaining in the SBCH cannot include a MAC-ID corresponding to the mobile terminal, based on the value of the MAC-ID and the order of the wakeup information in the SBCH.

21. The method of claim 1, wherein:

the wakeup information further includes at least one Wakeup Information Element (IE) located right after the information at the beginning of the FCCH, each at least one Wakeup IE including a MAC-ID; and

in the mobile terminal, when during the step of monitoring it is determined that the at least one Wakeup IE does not contain a MAC-ID corresponding to the mobile terminal, determining that the FCCH does not include wakeup information having a MAC-ID corresponding to the mobile terminal.

22. The method of claim 1, wherein the indication of the location of the SBCH is located at the beginning of the FCCH.