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

• US 6,665,520 B2
• Filed: 08/23/2001
• Issued: 12/16/2003
• Est. Priority Date: 10/03/1997
• Status: Expired due to Fees

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Romans, Christopher Gwyn
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Milord, Marceau
• Application Number:
  US09/934,569
• Publication Number:
  US 20020016151A1
• Time in Patent Office: 845 Days
• Field of Search: 455/13.4, 455/343, 455/517, 455/522, 455/574, 455/572, 455/573, 370/311, 370/310
• US Class Current: 455/13.4
• 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 wireless network including

a plurality of stations, one of said stations being a control station for transmitting a permission indication to the remaining stations of the network,

the remaining ones of said stations having an active state and an inactive state during which the remaining stations do not transmit or receive messages, the remaining stations further 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, the remaining stations including a controller arranged for causing the remaining stations to enter the second power mode only in response to the permission indication of the control station;

the control station including a controller for managing communications to the remaining stations dependent on whether the remaining stations are in the first power mode or the second power mode.

2. A wireless network as claimed in claim 1, wherein the remaining station controller is arranged for transmitting a request for a remaining station to enter the second power mode, the remaining station controller being arranged for causing the remaining station to enter the second power mode in response to the remaining station receiving an acceptance of the transmitted request from the control station.

3. A wireless network as claimed in claim 1, wherein the control station controller is arranged for determining if any remaining station is in the second power mode and if so, for buffering and rebroadcasting any broadcast message after requiring such remaining stations to enter the active state in order to receive the rebroadcast message.

4. A wireless network as claimed in claim 1, wherein a remaining station controller is arranged for causing the remaining station to change from the second power mode to the first power mode by submitting a request for such a change to the control station and receiving an acknowledgement of the request.

5. A method of operating a wireless network having a plurality of stations, one of the stations being a control station and the remaining ones of said stations having an active state and an inactive state in which said remaining stations can neither send nor receive messages, the remaining stations further 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, the method comprising:

causing the control station to transmit to the remaining stations permission to enter the second power mode;

causing the remaining stations to enter the second power mode in response to reception of the permission from the control station; and

causing the control station to manage communication to the remaining stations dependent on whether the remaining stations are in the first power mode or the second power mode.

6. A receiver station for use in a wireless network having a control station for deriving a permission signal for transmission to the receiver station, the receiver station having an active state and an inactive state in which said receiver station can neither send nor receive messages, the receiver station further having a first power mode in which it is fully in the active state and a second power mode in which it enters the active state only at predetermined times and remains in the active state under specified conditions and is otherwise in the inactive state, the receiver station including a receiver for the permission signal, and a controller for causing the receiver station to enter the second power mode only in response to receipt of the permission signal of the control station.

7. A wireless network including

a plurality of stations,

one of said stations being a control station,

the remaining ones of said stations having an active state and an inactive state, the remaining stations being arranged so they do not transmit or receive messages while in the inactive state, the remaining stations further 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, the remaining stations including a controller arranged for causing the remaining stations to enter the first power mode from the second power mode only after said remaining stations have made a permission request to the control station;

the control station including a controller for managing communications to the remaining stations dependent on whether the remaining stations are in the first power mode or the second power mode.

8. A wireless network as claimed in claim 7, wherein the controllers of the remaining stations allow the respective remaining stations to enter the first power mode when the remaining station receives an acknowledgement of the permission request from the control station.

9. A wireless network as claimed in claim 7, wherein the controllers of the remaining stations allow the respective remaining station to enter the first power mode when the respective remaining station has sent the permission request to the control station a predetermined number of times.

10. A wireless network as claimed in claim 7, wherein the controllers of the remaining stations are such that when the remaining stations enter the first power mode, they cause the respective remaining station to transmit a broadcast message to the other stations on the wireless network to indicate that it is in the first power mode.

11. A method of operating a wireless network having a plurality of stations, one of the stations being a control station and the remaining ones of said stations having an active state and an inactive state, the inactive state being such that said remaining stations can neither send nor receive messages, the remaining stations further having a first power mode in which they are fully in the active state and a second power mode in which they can enter the active state only at predetermined times and remain in the active state under specified conditions and are otherwise in the inactive state, the method comprising:

activating a remaining station in the second power mode so it asks the control station for permission to enter the first power mode;

causing the remaining station to enter the second power mode when it is permitted to do so; and

causing the control station to manage communication to the remaining stations dependent on whether said remaining stations are in the first power mode or the second power mode.

12. A method of operating a wireless network as claimed in claim 11, further comprising causing the control station to provide an acknowledgement of a permission request to a remaining station between the time said remaining station requests permission and the time said remaining station enters into the second power mode.

13. A wireless network including

a plurality of stations, one of said stations being a control station,

the remaining ones of said stations having an active state and an inactive state during which the remaining stations do not transmit or receive messages, the remaining stations further 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,

the control station being arranged for providing a series of beacon signals for communicating information to the remaining stations that are in the second power mode, and

the remaining stations, while in the second power mode, being arranged to enter the active state only while some of the beacons are transmitted by the control station and not to enter the active state while other beacons are transmitted by the control station.

14. A wireless network as claimed in claim 13, wherein the remaining stations in the second power mode are adapted to enter the active state to receive one in every n beacon signals, where n is a positive integer greater than one.

15. A method of operating a wireless network having a plurality of stations, one of the stations being a control station and the remaining ones of said stations having an active state and an inactive state, said remaining stations being arranged so they can neither send nor receive messages while in the inactive state, the remaining stations further 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, the method comprising:

causing the control station to provide a series of beacon signals to communicate information to the remaining stations that are in the second power mode; and

causing the remaining stations that are in the second power mode to enter the active state to receive only some of the beacon signals,

and preventing said remaining stations that are in the second power mode from entering the active state as frequently as the beacons are transmitted by the location station.

16. A method of operating a wireless network as claimed in claim 15, further comprising causing the remaining stations that are in the second power mode to enter the active state to receive one in every n beacon signals, where n is a positive integer greater that one.