Power management method of and apparatus for use in a wireless local area network (LAN)

• US 6,564,074 B2
• Filed: 08/23/2001
• Issued: 05/13/2003
• Est. Priority Date: 10/03/1997
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Romans, Christopher Gwyn
• Primary Examiner(s): Le, Thanh Cong
• Assistant Examiner(s): Corsaro, Nick
• Application Number:
  US09/934,568
• Publication Number:
  US 20020019215A1
• Time in Patent Office: 628 Days
• Field of Search: 455/462, 455/465, 455/41, 455/426, 455/574, 455/343, 370/338, 370/318
• US Class Current: 455/574
• CPC Class Codes: H04L 41/00 Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: H04W 52/28 using user profile, e.g. mobile speed, priority or network state, e.g. standby, idle or non transmission
• CPC Class Codes: H04W 52/288 taking into account the usage mode, e.g. hands-free, data transmission, telephone
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In a wireless network containing battery powered stations, one station is designated as a control point (CP). Each of the remaining stations has two operating modes: an active mode in which it receives and transmits messages, and an inactive or sleep mode which incurs reduced power consumption. The Control Point periodically transmits a beacon signal, and each station switches to its active mode to receive at least some of these beacon signals. A beacon signal may indicate that data is available for transmission to a particular station (from another station), in which case that particular station then broadcasts a message to indicate that it is awake and can receive messages. A beacon signal also indicates whether a broadcast period is in progress, and time to elapse until a next possible broadcast period will commence; if the Control Point has previously received and stored any broadcast messages it will re-broadcast them during the next following broadcast period and the remaining stations will react by remaining in active mode for the duration of that period.

Claims

1. A method of operating a wireless network including a plurality of stations, one station being designated as a control station and the remaining stations having an active state and an inactive state which incurs lower power consumption than the active state, the remaining stations being able to transmit and receive data directly to and from each other, wherein:

the control station periodically transmits a beacon signal;

each remaining station periodically enters its active state to receive the beacon signal; and

if there are data for a particular remaining station to receive, that particular remaining station transmits a status signal to indicate to other remaining stations that the particular remaining station is active and able to receive data directly from the other remaining stations.

2. The method of claim 1, wherein the control station incorporates into its beacon signal an indication of the identity of each remaining station for which there are data to be received by that station.

3. The method of claim 1, wherein each remaining station returns to its inactive state if it has not received or transmitted any data during an interval of predetermined duration.

4. The method of claim 1, wherein each remaining station periodically enters its active state to receive every beacon signal.

5. A method of operating a wireless network as claimed in claim 1, further including preventing the remaining stations from sending and receiving messages while in the inactive state.

6. The method of claim 2 further including sending data directly from the sending remaining station to the receiving remaining station when the receiving remaining station is in the active state.

7. A method of operating a wireless network including a plurality of stations, one station being designated as a control station and the remaining stations having an active state and an inactive state which incurs lower power consumption than the active state, wherein:

the control station periodically transmits a beacon signal containing a flag value indicating whether a broadcast period is in progress and a count value indicating time to elapse until commencement of the next possible broadcast period, the broadcast period being longer than the interval between the beacon signals;

each remaining station periodically enters its active state to receive the beacon signal;

each remaining station remains in its active state if the broadcast flag value indicates a broadcast period is in progress, and otherwise returns to its inactive state; and

the control station stores broadcast messages transmitted by any remaining station outside a broadcast period, and broadcasts such stored messages during a subsequent broadcast period.

8. The method of claim 7, wherein each remaining station periodically enters its active state to receive every beacon signal.

9. A method of operating a wireless network as claimed in claim 7, further including activating one of the remaining stations so it communicates directly with another remaining station without routing such communication through the control station while both said remaining stations are in the active state.

10. A method of operating a wireless network as claimed in claim 7, further including preventing the remaining stations from sending and receiving messages while in the inactive state.

11. The method of claim 7 wherein the remaining stations are able to transmit and receive data directly to and from each other if there are data for a particular remaining station to receive, the particular remaining station transmitting a status signal to indicate to other remaining stations that the particular remaining station is active and able to receive data directly from the other remaining stations.

12. A method of operating a wireless network containing a plurality of stations, one station being designated as a control station and the remaining stations having an active state and an inactive state which incurs lower power consumption than the active state, the method comprising:

periodically transmitting a beacon signal from the control station;

causing each remaining station to periodically enter its active state to receive the beacon signal;

if there are data for a particular remaining station to receive, causing that particular remaining station to transmit a status signal to indicate to other remaining stations that the particular remaining station is active and able to receive data, the remaining stations having a first power mode in which they are fully in the active state and a second power mode in which they enter the active state only at predetermined times and remain in the active state under specified conditions and are otherwise in the inactive state;

activating the remaining stations so they enter the active state only to receive the beacon signal while the remaining stations are in the second power mode; and

activating a remaining station to the first power mode to receive a message in response to that remaining station receiving a beacon signal indicating there is a message to receive.