Abstract:
An access point in a wireless network may receive packets over a wired network. The access point may be provided with instructions from the host to determine when to awaken the host from a reduced power consumption state in response to the receipt of a packet. Thus, the access point can enforce wake packet filtering rules while the host is maintained in a reduced power consumption state. This may reduce the power consumption of the host by avoiding the unnecessary awakening of the host every time a packet of little importance arrives over the network.

Description:
BACKGROUND 
     This invention relates generally to wireless computer networks. 
     A host processor-based system may communicate with a variety of other devices to form a wireless network. A variety of peripherals and computer systems may be linked together through a wireless network. One protocol for establishing wireless links of this type is the IEEE Std. 802.11 (1999). In such a system, a host may receive packets over the network. 
     In some cases, the host may be a power consumption sensitive device. One example of such a device is a portable processor-based system that operates from a battery power source. To conserve power, the portable device may power down to a reduced power consumption state. 
     In the course of network operations, a large number of packets may be passed between various devices on the network. Some of these packets may be important and others may be less important. However, each time a packet is transmitted across the network to a given host, that host must receive the packet and determine whether the packet needs handling. If the host is in a reduced power consumption state this means that the host must transition from the reduced power consumption state to an increased power consumption state in order to handle the packet. Such transitions generally increase the power consumption of the host processor-based system. 
     Thus, there is a need for ways to reduce the power consumption of devices on wireless networks and particularly there is a need for ways to reduce the unnecessary interruptions of the host in reduced power consumption states. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic depiction of a wireless network in accordance with one embodiment of the present invention; 
         FIG. 2  is a depiction of a host in accordance with one embodiment of the present invention; 
         FIG. 3  is a chart that depicts the operation of one embodiment of the present invention; 
         FIG. 4  is a flow chart for software for the host shown in  FIG. 2  in accordance with one embodiment of the present invention; 
         FIG. 5  is a flow chart for software for the station shown in  FIG. 2  in accordance with one embodiment of the present invention; and 
         FIG. 6  is a flow chart for software for an access point shown in  FIG. 2 , in accordance with one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a wireless network may include a plurality of basic service sets (BSS)  10  and  12  coupled through a distribution system (DS)  16 . The distribution system  16  interconnects the basic service sets  10 ,  12  in integrated local area networks to create an extended service set. An extended service set is a set of one or more interconnected basic service sets and integrated local area networks that appears as a single basic service set to the logical link control layer at any station associated with one of those basic service sets. 
     Each basic service set  10  or  12  includes a set of stations (STAs)  14  controlled by a single coordination function. A coordination function is a logical function that determines when a station  14 , operating within a basic service set  10  or  12 , is permitted to transmit and may be able to receive protocol data units via a wireless medium. 
     The basic service sets  10  and  12  communicate with the distribution system  16  through access points provided by the stations  14   b  and  14   c . An access point is any entity that has a station functionality while providing access to the distribution services via the wireless medium for associated stations. A station is a device that contains a medium access control (MAC) and a physical layer (PHY) interface to a wireless medium. 
     In accordance with one embodiment of the present invention, the system shown in  FIG. 1  may operate in accordance with the IEEE 802.11 protocol which is set forth in IEEE Std. 802.11, 1999 Edition, available from the IEEE Standards Board, Piscataway, N.J. 08855. 
     Referring to  FIG. 2 , the station  14   a  may communicate with the station  14   b  that acts as an access point (AP). The station  14   a  may be associated with a host  18  that in some embodiments may be a processor-based system including a processor  20 , an interface  22  and a memory  24 . The interface  22 , in some embodiments, may be coupled to a bus  26  that receives the station  14   a . For example, in one embodiment, the station  14   a  may be a network interface card (NIC) that is plugged into the bus  26 . In another embodiment the station  14   a  is an access point as well. 
     The bus  26  may also support an interface  30  that is coupled to a hard disk drive  32 . The drive  32  may in turn store a software program  34 . 
     The access point  14   b  may be coupled over a wired network to a server  15  in one embodiment. The access point may store software  70  and may be a processor-based system in one embodiment. The station  14   a  may be a processor-based system and may store the software  28  in one embodiment of the present invention. 
     Referring to  FIG. 3 , wireless communications may occur between the access point  14   b  and the station  14   a  in response to information conveyed over a wired network from the server  15 . In some embodiments, the host  18  may be a portable processor-based system or other power sensitive system. Thus, in some cases, the host  18  may enter reduced power consumption modes wherein its processing capabilities may be reduced. However in such modes, the power consumption of the host  18  may also be reduced. 
     When the host  18  is in the reduced power consumption state, it may be unnecessarily awakened from that state by the receipt of relatively unimportant packets sent, for example, by the server  15 . Each time such a packet  15  arrives, absent appropriate filtering, the host  18  may be awakened, causing the host  18  to transition to a higher power consumption state. Such transitions may effectively increase the power consumption of the host  18 . In battery powered applications, this reduces the useful life between battery charges of the host  18 , reducing its desirability and performance. 
     As shown in  FIG. 3 , a wake packet filtering protocol, implemented on the access point  14   b , filters unnecessary packets that would unnecessarily awaken the host  18 , causing the host  18  to transition unnecessarily to an increased power consumption state. 
     Initially, the station  14   a  sends a setup wake packet  30  to the access point  14   b . The access point  14   b  provides an acknowledgment (ACK)  32  to the station  14   a . The setup wake packet  30  provides the information needed by the access point  14   b  to determine which packets are of sufficient importance to involve the host  18 . Thus, a filtering protocol may be provided from the station  14   a  to the access point  14   b  to enable the access point  14   b  to determine, while the host  18  is in a sleep or reduced power consumption mode, whether to awaken the host  18  in order to process an incoming packet. This information may be received by the station  14   a  from the host  18  and particularly the processor  20 . The station  14   a  may then enable the wake packet filtering function on the access point  14   b  as indicated at  34 , and this enable message may be acknowledged as indicated at  36 . 
     Once the host  18  goes into a reduced power consumption mode (“Host Suspended”), any packets (“Non-Wake Packets”) that arrive at the access point  14   b  from the server  15  that do not meet the criteria provided by the host  18  for awakening the host  18  are simply dropped in one embodiment. When a wake packet arrives (“Wake Packet Comes”) the station is awakened as indicated at  38 . A wake packet is a packet that meets the criteria provided by the host  18  for awakening the host when the host is in a reduced power consumption mode. In response to the wake up call from the access point  14   b , a host  18  is awakened by the station  14   a . The station  14   a  acknowledges the wake up call as indicated at  40 . The host  18  then receives the data packets included with the communication from the server  15  as indicated at  42 . 
     Referring to  FIG. 4 , in one embodiment, the software  34  stored on the host  18  initially determines whether the host desires to go into a sleep or reduced power consumption mode as indicated at diamond  50 . If so, the host  18  notifies the station  14  and provides the appropriate wake packet filter instructions as indicated in block  52 . The host  34  then goes to the sleep mode as indicated in block  54 . 
     Referring to  FIG. 5 , in one embodiment, the station software  28  initially determines whether a notice has been received from the host  18  that the host intends to enter a reduced power consumption mode, as determined in diamond  60 . If so, the station receives the wake packet filtering instructions as indicated in block  62 . The station then forwards those instructions to the access point as indicated in block  64 . 
     Turning finally to  FIG. 6 , the access point software  70 , in accordance with one embodiment of the present invention, determines whether it has received wake packet filtering instructions as indicated in diamond  72 . If not, after a time out, the flow ends. If the instructions have been received, those instructions may be stored as indicated in block  74 . When a packet arrives at the access point, for example over the network from the server  15 , the filtering instructions are applied, as indicated in block  78 . 
     A check at diamond  80  determines whether the packet is a wake packet meaning that it is a packet which necessitates reviving the host  18 . If not, in some embodiments, the packet may simply be dropped as indicated in block  82 . 
     If the packet is a wake packet, the packet is stored in the access point  14   b  temporarily as indicated in block  84  in one embodiment. A check at diamond  86  determines whether the station  14   a  has been awakened. If so, the stored packet is sent to the station  14   a  which in turn transfers the packet or packets to the host  18 . If the station cannot be awakened, for example, after a suitable time out period as determined in diamond  86 , communication has apparently been lost between the access point and the station. Therefore, the corresponding link is torn down and the station is removed from the list of active stations with which the access point communicates, as indicated in block  90 . 
     While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.