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 involve the host in processing a packet. Thus, the access point can enforce packet filtering rules while the host reduce the station&#39;s power consumption.

Description:
BACKGROUND  
         [0001]    This invention relates generally to wireless computer networks.  
           [0002]    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.  
           [0003]    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.  
           [0004]    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.  
           [0005]    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 host message handling. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0006]    [0006]FIG. 1 is a schematic depiction of a wireless network in accordance with one embodiment of the present invention;  
         [0007]    [0007]FIG. 2 is a depiction of a host in accordance with one embodiment of the present invention;  
         [0008]    [0008]FIG. 3 is a chart that depicts the operation of one embodiment of the present invention;  
         [0009]    [0009]FIG. 4 is a flow chart for software for the host shown in FIG. 2 in accordance with one embodiment of the present invention;  
         [0010]    [0010]FIG. 5 is a flow chart for software for the station shown in FIG. 2 in accordance with one embodiment of the present invention;  
         [0011]    [0011]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; and  
         [0012]    [0012]FIG. 7 is a flow chart for software for the server shown in FIG. 2, in accordance with one embodiment of the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0013]    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.  
         [0014]    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.  
         [0015]    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.  
         [0016]    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.  
         [0017]    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.  
         [0018]    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 .  
         [0019]    The access point  14   b  may be coupled over a wired network to an information services server  15  in one embodiment. The server  15  may store software  90 . The access point  14   b  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.  
         [0020]    In order to reduce the burden on the station  14   a  and thereby to reduce its power consumption, the system may be server driven in that the information services server  15  sends notification messages to a client on a station  14   a  only when new information is available that requires synchronization. The access point  14   b  can then monitor for such notifications, that may be called “alert packets” herein. Thus, when the access point  14   b  recognizes an alert packet, it realizes that this is information which the station  14   a  should be involved in receiving. Other messages that do not include alert packages may then be discarded.  
         [0021]    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.  
         [0022]    The host  18  may be unnecessarily burdened 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  must expend cycles dealing with the message. Such cycles 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.  
         [0023]    As shown in FIG. 3, a packet filtering protocol, implemented on the access point  14   b , filters unnecessary packets that would unnecessarily burden the host  18 , causing the host  18  to unnecessarily consume power.  
         [0024]    Initially, the station  14   a  sends a setup alert 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 alert 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 whether to burden the host  18  with 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 packet filtering function on the access point  14   b  as indicated at  34 , and this enable the message may be acknowledged as indicated at  36 .  
         [0025]    Any “Non-Alert 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 involving the host  18  are simply dropped in one embodiment. When an alert packet arrives (“Alert Packet Comes”) the packet is transferred to the station as indicated at  38 . An alert packet is a packet that meets the criteria provided by the host  18  for involving the host. The station  14   a  acknowledges the packet as indicated at  40 . The host  18  then receives the data packets included with the communication from the server  15  as indicated at  42 .  
         [0026]    Referring to FIG. 4, in one embodiment, the software  34  stored on the host  18  initially determines whether the host desires to implement packet filtering as indicated at diamond  50 . If so, the host  18  notifies the station  14  and provides the appropriate packet filter instructions as indicated in block  52 .  
         [0027]    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 requests packet filtering, as determined in diamond  60 . If so, the station receives the packet filtering instructions as indicated in block  62 . The station then forwards those instructions to the access point as indicated in block  64 .  
         [0028]    Turning to FIG. 6, the access point software  70 , in accordance with one embodiment of the present invention, determines whether it has received 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 .  
         [0029]    A check at diamond  80  determines whether the packet is an alert packet meaning that it is a packet which necessitates involving the host  18 . If not, in some embodiments, the packet may simply be dropped as indicated in block  82 .  
         [0030]    If the packet is an alert packet, the packet is stored in the access point  14   b  temporarily as indicated in block  84  in one embodiment. The stored packet is sent to the station  14   a  which in turn transfers the packet or packets to the host  18 .  
         [0031]    Referring to FIG. 7, the server software  90  begins by determining whether a server driven model has been elected as determined at diamond  92 . If so, the server determines whether new information is available that requires synchronization as indicated at diamond  94 . If received information requires synchronization, then an alert packet is sent over the DS as indicated at block  96 . Otherwise, no such alert message is sent as indicated at block  98 . In this way, only those messages which are important to the station may be originated from the server  15  reducing traffic and reducing the burden on the station  14 . This ultimately may reduce its power consumption.  
         [0032]    In some embodiments of the present invention, a station is made aware of buffered medium access control (MAC) protocol data units by the state of a bit assigned to the station in a traffic indication map and in a directed traffic indication map, both of which are managed by the access point. These maps may be broadcast to the access point in beacon frames. Beacon frames are broadcast in advertised intervals known as beacon intervals. When a station receives a beacon frame and finds that its bit is set in the maps, the station may then be required to transmit a message to an access point to receive buffered MAC protocol data units. Thus, in some embodiments of the present invention, the access point simply fails to indicate in the maps that the MAC protocol data unit is available, allowing the station to simply ignore those protocol data units. However, when the MAC protocol units constitute an alert message which is of importance to the particular station, then the access point sets the appropriate indicators in the maps to cause the station to retrieve the protocol data units.  
         [0033]    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.