Power management system for use with wireless LAN terminal unit

• US 20010004594A1
• Filed: 12/12/2000
• Published: 06/21/2001
• Est. Priority Date: 12/14/1999
• Status: Active Grant

• Current Assignee: NEC Platforms, Ltd.
• Original Assignee: NEC Corporation
• Inventors: Kuroiwa, Ken-ichi
• Granted Patent: US 6,704,561 B2
• Time in Patent Office: Days
• US Class Current: 455/432.1
• CPC Class Codes: H04W 52/0225 using monitoring of external events, e.g. the presence of a signal
• CPC Class Codes: H04W 52/0293 having a sub-controller with a low clock frequency switching on and off a main controller with a high clock frequency
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Provided is a power management system for use with a wireless LAN terminal unit, the system having: a CPU having a suspend/resume function, a RAM; a power supply; a switch for causing the CPU to be placed in the suspend state or a resume state; and a wireless LAN communication LSI; and roaming processor for, when the wireless LAN terminal unit travels, performing a roaming process in which a wireless LAN bridge communication with the wireless LAN terminal unit is switched to another wireless LAN bridge, wherein when the CPU is placed in the suspend state, the wireless LAN communication LSI and the roaming processor are operated by the power supplied by the power supply, and wherein when the CPU is placed is the suspend state, the roaming processor performs the roaming process.

Claims

1. A power management system for use with a wireless LAN terminal unit, the system having:

a CPU having a suspend/resume function,

a RAM;

a power supply;

a switch for causing said CPU to be placed in the suspend state or a resume state; and

a wireless LAN communication LSI; and

roaming processing means for, when the wireless LAN terminal unit travels, performing a roaming process in which a wireless LAN bridge communication with the wireless LAN terminal unit is switched to another wireless LAN bridge,

wherein when said CPU is placed in the suspend state, the wireless LAN communication LSI and the roaming processing means are operated by the power supplied by the power supply, and

wherein when the CPU is placed is the suspend state, the roaming processing means performs the roaming process.

2. The power management system as set forth in

claim 1

, further comprising:

power supply controlling means for controlling the power supplied to said wireless LAN communication LSI and said roaming processing means,

wherein said RAM has an area for storing information representing whether or not the power should be supplied to said wireless LAN communication LSI and said roaming processing means when said CPU is placed in the suspend state, and

wherein said CPU determines whether or not to supply the power to said wireless LAN communication LSI and said roaming processing means through said power supply controlling means corresponding to said information when said CPU is placed in the suspend state.

3. The power management system as set forth in

claim 1

, wherein said roaming processing means is built in said wireless LAN communication LSI.

4. The power management system as set forth in

claim 1

, further comprising:

power supply controlling means for controlling the power supplied to the roaming processing means; and

a timer,

wherein the power supply controlling means uses said timer to supply the power to said roaming processing means in synchronism with the reception time of beacon data periodically transmitted from the wireless LAN bridge so that the roaming processing means performs the roaming process.

5. The power management system as set forth in

claim 4

,

wherein said roaming processing means, said power supply controlling means, and said timer are built in said wireless LAN communication LSI.

6. The power management system as set forth in

claim 1

,

wherein the roaming process is a process for executing a wireless LAN bridge connection switching protocol when the reception intensity of newly received beacon data from a new wireless LAN bridge is stronger than the reception intensity of older beacon data from a previous wireless LAN bridge, said reception intensity of older beacon data being stored in said RAM.