HK1090999A - System and method for wake on wireless lan - Google Patents

Description

System and method for waking up wireless local area network

RELATED APPLICATIONS

The priority of U.S. provisional patent application No. 60/489,408 entitled "system and method for waking up a wireless Local Area Network (LAN)" filed on 7/22/2003 and U.S. patent application No. 60/489,399 entitled "method and apparatus for automatic configuration of a wireless network" filed on 7/22/2003 are hereby incorporated by reference in their entirety and further to the co-owned and concurrently filed U.S. patent application No. ________, entitled "method and apparatus for automatic configuration of a wireless network", having attorney docket No. 069509 and 0310686 (client-side reference number PCTEL-13200) and being hereby incorporated by reference in its entirety.

Technical Field

The present invention relates to wireless networks, and more particularly, to methods and techniques for conserving power in a wireless environment.

Background

Wireless networks are becoming an attractive solution for local area network access. However, many problems continue to hamper the popularity of wireless networks. Among these problems are power management and energy conservation issues. Direct power down of personal computers to reduce power consumption and conserve energy and extend battery life for mobile devices is well known for monitors, disk drives, and certain other auxiliary functions. However, powering down other devices, including wireless access points and related devices in particular, for the purpose of conserving energy is difficult because the need for the devices to respond can vary unpredictably.

Disclosure of Invention

In a wireless network environment, an access point provides a link between a wired network and a wireless network. In a wireless environment such as that specified by the IEEE 802.11 standard, it is assumed that an access point is "always on" (always on), or always able to respond to an appropriate signal from a transceiver attempting to link to a network through the access point.

Recently, software-based access points (or soft APs) have been developed. For purposes of the present invention, a simple soft AP implementation may include a hardware WiFi adapter and appropriate driver software running on the host to perform the access point functions. More robust soft AP implementations, such as those described in the above-referenced related applications, can provide additional functionality.

To provide a more robust power saving scheme, the present invention provides a method for allowing a soft AP to enter a "standby" mode, in which power consumption may be reduced. In a typical implementation, a "power down time" period is set in the soft AP. If no WiFi activity occurs during this period, the soft AP will enter a power conservation mode (i.e., standby mode), thereby allowing the host PC to also enter a power conservation state. In this typical configuration, no WiFi activity means no connection to any radio, including, for example, no power conservation service and no radio scan detection.

In standby mode, the present invention includes a mechanism for the WiFi hardware adapter to continue to "listen" for the appropriate radio signals. If an appropriate radio signal is received from, for example, a WiFi device seeking a communication link, the present invention causes the WiFi hardware adapter to generate a standard "power management enable" signal to wake up the host PC, and likewise to wake up the soft AP function, which powers up the WiFi hardware for normal functions.

Drawings

FIG. 1 illustrates a typical soft AP configuration, where a PC with integrated soft AP provides access points to PC 1 and PC 2;

FIG. 2 illustrates a power down process according to the present invention;

fig. 3 illustrates a wake-up process according to the present invention.

Detailed Description

A system including a softap such as used in the present invention may be better understood by first referring to fig. 1. In particular, fig. 1 illustrates a soft AP device serving as an access point between wireless and wired devices according to an embodiment of the present invention. As shown in fig. 1, the softap host PC 3(100) acts as a wireless access point for bridging wireless PC stations (120, 130) to wired PC stations (140, 150). This MAC layer bridge (MAC layer bridge)102 of the present invention combines a wireless local area network with a wired local area network by bridging the wired ethernet interface (101) and the soft AP network interface (103). This bridging forms a single logical local area network of all PC stations including the softap host PC 3 (100). Note that the bridging (202) between the PC station's wireless and wired networks is transparent to the layer 3 protocol, so a wireless PC station on one side of the softap host PC 3(100) can talk directly to a wired PC station on the other side of the softap host PC 3(100) without going through a layer 3 proxy or gateway. One example of this embodiment of the invention includes a built-in Windows XP MAC bridge miniport driver that can be used to bridge the ethernet interface (101) and the soft AP network interface (103). It will of course be appreciated that the softap host need not be a personal computer, but may be any device capable of performing the functions of the softap described herein. Thus, instead of a desktop or laptop PC, the soft AP host may be a palm top computer, a tablet computer, a PDA, a cell phone, or other suitable device. For convenience, references hereinafter to a PC or host device refer to any suitably configured device including those specifically described herein.

A typical configuration of the power down process according to the present invention may be better understood by referring next to fig. 2. The process begins at 200 and checks to determine if any WiFi activity has been detected within a predetermined time period at 210. If activity has been detected, the process terminates and the PC continues in normal mode. Optionally, the process restarts at 200 and repeats indefinitely.

However, if the check at step 210 is that no wireless activity, such as WiFi activity or 802.11 activity, has occurred within a predetermined period, the soft AP enters a standby mode, as shown at step 220. In this example, no wireless activity means, for example, that there is no current connection to the wireless device, nor is there such a connection for a predetermined period. For example, the predetermined period may be ten minutes, or a longer or shorter period selected by the user for convenience. Furthermore, the lack of wireless activity typically includes the lack of power conservation services and the lack of scan detection of any mobile stations. When the soft AP enters the standby mode, the wireless hardware in the host system is notified to enter the low power standby mode, as shown in step 230. Depending on the power conservation configuration of the host, the host may also enter a sleep or deep sleep mode, as shown in step 240.

Once the soft AP enters the standby mode as shown in step 220, typical implementations remain fully satisfied with the power management protocol of the host system 103. The soft AP implementation is configured to allow the main system to sleep if the power management configuration of the main system is going to sleep or power down.

The operation of the host system in standby mode or during wake-up may be better understood by referring next to fig. 3. The process begins with the host in a standby mode, as shown at 300. In standby mode, the wireless adapter continues to listen for radio signals from stations attempting to communicate with the host by periodically checking whether such signals have been received at step 310. If no such signal is received, the soft AP remains in the standby mode.

However, if the check at step 310 reveals that a signal has been received (such as by a message with a valid preamble, such as typically by the signal characteristics of a preamble defined in the relevant industry standards), then the wireless adapter in the host system generates a standard "power management enable" interrupt signal to wake up the host system, as shown at step 320. For example, the PME signal may be used on a PCI bus, or the "wake-up signal" may be used by USB. When the host system is awakened, the soft AP is also awakened, as shown at step 330, and in turn, the WiFi or other wireless hardware returns to a full power state, as shown at step 340, and all normal functions are restarted.

Various techniques may be used to detect the presence of a client station signal when the host system is in a standby mode. In a first typical configuration using active scanning, the wireless chipset, which may still be a WiFi chipset, may be configured to maintain power only to the radio receiver portion of the chipset. As such, the wireless chipset is configured as a low power "simple" receiver to detect messages with a valid preamble. If such a message is received, a wake-up signal is generated as described above. This approach conserves most of the power and is therefore attractive for at least some portable-based implementations.

Alternatively, if the wireless adapter has its own power supply, such as an external power supply for a USB device, the wireless chipset may be configured to continue to send out beacons to inform the mobile station of the presence of the access point. Alternatively, the apparatus may be configured to provide power only to the receiver as described above. Further, a combination of these configurations may also be selected.

One such configuration includes switching between the two example schemes according to a temporal pattern of wireless activity. For example, an externally powered AP device may be powered to send out a beacon and simultaneously detect signals from in-range radio stations for a predetermined period of time during which the master computing device is in a sleep state. If no radio signal from the radio station has been detected by the end of the period, the AP device may enter a "simple receiver mode" in which only a valid preamble is detected and no radio beacon is emitted, thereby conserving more power.

It will be appreciated from the above description that a new method for power conservation in a host system integrated with a soft AP device has been disclosed. Having thus described the embodiments of the invention in full and various alternative embodiments, it will be appreciated by those skilled in the art that, given the teachings herein, many alternatives and equivalents exist which do not depart from the invention. The invention is therefore not to be limited by the foregoing description but only by the appended claims.

Claims (5)

1. A method of reducing energy consumption in a software-based wireless access point of a computer network, comprising the steps of:

monitoring activity on the access point for a predetermined period;

entering a power conservation mode for the access point when no activity occurs on the access point within the predetermined period; and

restoring the access point to normal functionality when a request to communicate with the access point is detected.

2. The method of claim 1, wherein the request for communication is transmitted by radio signals.

3. The method of claim 1, wherein the restoring step comprises generating a standard power management enable signal to wake up a host computer.

4. A recording medium having recorded thereon a program in a readable manner, wherein the program cooperates with a wireless network access device operatively connected to a host computer to cause the wireless network access device to operate as a software-based access point, the recording medium having instructions for executing on a microprocessor the steps of:

monitoring activity of the wireless network access device;

selectively powering down portions of the network access device while maintaining the ability to detect requests for communication with the network access device in response to no activity for a predetermined period of time; and

the request for communication is responded to by restoring the full functionality.

5. A system for reducing power provided to a wireless network access device, comprising:

a microprocessor;

a memory operatively connected to the microprocessor for storing data;

a timer for determining when a duration of a state in which no activity occurs reaches a predetermined period;

a command stored in the memory for canceling power provided to a portion of the wireless network access devices while still monitoring for a request to communicate with the access device, the command program further restoring power provided to the wireless network access device in response to the request for communication.