Patent Application
20060094476
In a conventional wireless infrastructure network, mobile stations (e.g., a laptop computer with a wireless connection) are associated with a wireless access point (AP) within a basic service set. There may be multiple mobile stations within range of an AP, and the AP generally remains in an active power state while servicing the one or more mobile stations.
Mobile stations may use different power states to conserve power while still providing a high quality user experience. For instance, a mobile station may be in an active power state when the mobile station is in use and generating traffic on a wireless network. Alternately, the mobile station may implement a power saving protocol, such as power save polling (PSP), to enter a standby power state that conserves power when the mobile station is inactive or not generating traffic on a wireless network.
Unlike mobile stations, APs must remain in an active power state at all times. Conventional APs do not use PSP or other power saving protocols to enter a power standby state. This results in an unnecessary waste of power when there is no traffic on a wireless network. For instance, if an AP is servicing mobile stations that have (1) entered a standby power state, or (2) are not generating traffic on the wireless network, then the AP does not have to remain in an active state. If power saving functionality is implemented in an AP, there will be concerns about performance losses and an overall poor user experience if the chosen power saving protocol does not enable fast synchronization with associated mobile stations when the AP wakes up from a standby power state.
The following description, various aspects of the illustrative implementations will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that the present invention may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the illustrative implementations. However, it will be apparent to one skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known circuits, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
References to “one implementation”, “an implementation”, “example implementation”, “various implementations”, etc., indicate that the implementation(s) of the invention so described may include a particular feature, structure, or characteristic, but not every implementation necessarily includes the particular feature, structure, or characteristic. Further, the different implementations described may have some, all, or none of the features described for other implementations.
In the following description and claims, the terms “coupled” and “connected,” along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Rather, in particular implementations, “connected” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupled” may mean that two or more elements co-operate or interact with each other, but they may or may not be in direct physical or electrical contact.
The term “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory. A “computing platform” may comprise one or more processors.
The term “wireless” and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some implementations they might not.
As used herein, unless otherwise specified the use of the ordinal adjectives “first”, “second”, “third”, etc., to describe a common object, merely indicate that different instances of like objects are being referred to, and are not intended to imply that the objects so described must be in a given sequence, either temporally, spatially, in ranking, or in any other manner. Various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the present invention, however, the order of description should not be construed to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.
The mobile stations 102 may be in any one of several power states. Some mobile stations 102 may be in an active power state, therefore these mobile stations 104 may be actively generating data traffic on the WLAN 104. In
When all of the mobile stations 102 that are associated with the AP 100 have been recorded on the station list with their respective power states, the AP 100 may enter a power saving state (212). In some implementations, the power saving state may be a sleep mode, a stand-by mode, a hibernation mode, or any other power saving protocol that is appropriate for the AP 100.
If, however, the station list 250 includes one or more recorded unique identities 252, the AP 100 may attempt to synchronize the mobile stations 102 associated with the recorded unique identities 252. To perform the synchronization, the AP 100 begins by selecting one mobile station 102 that has not been polled (308). Initially, all of the mobile stations 102 recorded on the station list 250 will not have been polled.
The AP 100 may poll the selected mobile station 102 with a null packet based on the last known power state of that mobile station 102 (310). In an implementation, the last known power state of the selected mobile station 102 may be found on the station list 250. Generally, the power state 254 recorded for the selected mobile station 102 when the AP 100 entered the power saving state is the last known power state of that mobile station 102. Accordingly, if the station list 250 discloses that the power state of the selected mobile station 102 is an active power state, the AP 100 may send a null packet to the selected mobile station 102 based on an active power state. Alternately, if the station list 250 discloses that the power state of the selected mobile station 102 is a power saving state, the AP 100 may send a null packet to the selected mobile station 102 based on a power saving state.
The AP 100 may wait for an acknowledgement from the selected mobile station 102 that it has received the null packet (312). In some implementations, the AP 100 may wait a predetermined amount of time for the selected mobile station 102 to acknowledge the null packet. If the mobile station 102 acknowledges the null packet, the AP 100 notes that the selected mobile station is synchronized (314). The AP 100 may then check the station list 250 to determine whether any mobile stations 102 remain that have not been polled by the AP 100 (316). If un-polled mobile stations 102 remain, the AP 100 may select another mobile station 102 to poll (308). If all of the mobile stations 102 recorded on the station list 250 have been polled, the AP 100 may resume normal operation (306).
If the selected mobile station 102 does not acknowledge the null packet from the AP 100, the AP 100 may poll the selected mobile station 102 with a second null packet that is based on an alternate power state (318). For instance, if the first null packet was based on an active power state, the second null packet may be based on a power saving state. Similarly, if the first null packet was based on a power saving state, the second null packet may be based on an active power state.
The AP 100 may wait for an acknowledgement from the selected mobile station 102 that it has received the second null packet (320). In some implementations, the AP 100 may wait a predetermined amount of time for the selected mobile station 102 to acknowledge the second null packet. If the mobile station 102 acknowledges the second null packet, the AP 100 notes that the selected mobile station is synchronized (314). As described previously, the AP 100 may then check the station list 250 to determine whether any un-polled mobile stations 102 remain (316), and if so, the AP 100 may select another mobile station 102 to poll (308). Alternately, if all of the mobile stations 102 recorded on the station list 250 have been polled, the AP 100 may resume normal operation (306).
If the selected mobile station 102 does not acknowledge the second null packet, the AP 100 may determine that the mobile station 102 is unavailable and may disassociate the selected mobile station 102 from the WLAN (322). The mobile station 102 may be unavailable for many reasons. For instance, the mobile station 102 may have moved to a location that is out of range of the AP 100. Alternately, the mobile station 102 may have turned off its wireless functionality or it may have shut down.
After the AP 100 disassociates the selected mobile station 102, the AP 100 may check the station list 250 to determine whether any un-polled mobile stations 102 remain (316), and if so, the AP 100 may select another mobile station 102 to poll (308). Alternately, if all of the mobile stations 102 recorded on the station list 250 have been polled, the AP 100 may resume normal operation (306).
As shown in
In
The AP 100 may wait a predetermined amount of time for an acknowledgement from mobile stations #3 and #4. When no acknowledgement is received during the predetermined time, the AP 100 may transmit a second null packet to mobile stations #3 and #4 based on an alternate power state. Since the first null packets to both mobile stations #3 and #4 were based on an active power state, the second null packets to both may be based on a power saving state. In
Implementations of the invention enable the AP 100 to screen out all mobile stations 102 that have moved out of range or have changed power state during the time when the AP 100 was in a power standby state. Implementations of the invention allow the AP 100 to go into power standby state when there is no active traffic being detected, and allow the AP 100 to wake up as soon as any traffic from mobile stations 102 is detected. The AP 100 may then perform the methods of the invention to synchronize mobile stations 102 with improved performance loss.
The invention may be implemented in one or a combination of hardware, firmware, and software. The invention may also be implemented as instructions stored on a machine-readable medium, which may be read and executed by a processing platform to perform the operations described herein. A machine-readable medium may include any mechanism for storing, transmitting, or receiving information in a form readable by a machine (e.g., a computer). For example, a machine-readable medium may include read only memory (ROM); random access memory (RAM), such as dynamic random access memory (DRAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other form of propagated signals (e.g., carrier waves, infrared signals, digital signals, the interfaces that transmit and/or receive those signals, etc.), and others.
The above description of illustrated implementations of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific implementations of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.
These modifications may be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific implementations disclosed in the specification and the claims. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.
