`US 20030235170Al
`
`(19) United States
`(12) Patent Application Publication
`Trainin
`
`(10) Pub. No.: US 2003/0235170 Al
`Dec. 25, 2003
`( 43) Pub. Date:
`
`(54) METHOD, APPARATUS, AND SYSTEM FOR
`DISTRIBUTED ACCESS POINTS FOR
`WIRELESS LOCAL AREA NETWORK (LAN)
`
`Publication Classification
`
`Int. Cl.7 ....................................................... H04Q 7/24
`(51)
`(52) U.S. Cl. ............................................ 370/338; 370/349
`
`(76)
`
`Inventor: Solomon B. Trainin, Haifa (IL)
`
`(57)
`
`ABSTRACT
`
`Correspondence Address:
`BLAKELY SOKOLOFF TAYLOR & ZAFMAN
`12400 WILSHIRE BOULEVARD, SEVENTH
`FLOOR
`LOS ANGELES, CA 90025 (US)
`
`(21)
`
`Appl. No.:
`
`10/177,295
`
`(22)
`
`Filed:
`
`Jun.21,2002
`
`According to one embodiment of the invention, an apparatus
`is provided that includes an access point repeater (APR)
`coupled to a wired network. The APR transmits information
`to and receives information from one or more associated
`stations according to a first wireless processing protocol.
`The APR performs the media access functions of the first
`wireless processing protocol. The apparatus further includes
`an access point server (APS) coupled to the APR via the
`wired network to transmit information to and receive infor(cid:173)
`mation from the APR. The APS performs specific point
`control functions of the first wireless processing protocol.
`
`,.-250
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`Petitioners Microsoft Corporation and HP Inc. - Ex. 1038, p. i
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`Petitioners Microsoft Corporation and HP Inc. - Ex. 1038, p. vi
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`processing protocol
`perform specific point control functions of the first wireless
`access point server (APS), the second communication device to
`assign the second communication device to function as an
`
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`media access functions of the first wireless processing protocol
`processing protocol, the first communication device to perform
`with the first communication device, according to a first wireless
`information from one or more mobile units which are associated
`point repeater (APR) to transmit information to and receive
`assign the first communication device to function as an access
`
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`other via the wired local area network
`and second communication devices to communicate with each
`area network to the wired local area network, configure the first
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`connect a first communication device in a wireless local area
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`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1038, p. vii
`
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`US 2003/0235170 Al
`
`Dec. 25, 2003
`
`1
`
`METHOD, APPARATUS, AND SYSTEM FOR
`DISTRIBUTED ACCESS POINTS FOR WIRELESS
`LOCAL AREA NETWORK (LAN)
`
`FIELD
`
`[0001] An embodiment of the invention relates to the field
`of data communications, and more specifically, relates to a
`method, apparatus, and system for distributed access points
`for wireless local area network (LAN).
`
`BACKGROUND
`
`[0002]
`In the past few years, communication systems have
`continued to advance rapidly in light of several technologi(cid:173)
`cal advances and improvements with respect to communi(cid:173)
`cation networks and protocols, in particular wireless com(cid:173)
`munication networks. Wireless local area networks have
`become increasingly used to facilitate effective and efficient
`information communication in various environments and
`improve user mobility and flexibility. A wireless local area
`network (LAN) can be implemented to extend the connec(cid:173)
`tivity of a wired local area network or as an alternative of a
`wired local area network.
`[0003] FIG. 1 illustrates an embodiment of a typical
`wireless network system 100. The wireless network system
`100 includes a link 110 based on a physical medium, which
`is part of a wired network 115 (e.g., a wired local area
`network such as an Ethernet LAN). The wired network 115
`includes network or system resources 120 that can be
`accessed and used by users of the network system 100. For
`example, the system or network resources 120 may include
`network servers, file servers, system databases, application
`programs, etc. As shown in FIG. 1, the network system 100
`further includes multiple access points (APs) 130A-130C
`that communicate via a wireless link with their associated
`mobile units (MUs) 140A-140E. The mobile units are also
`referred to as mobile stations or simply stations herein.
`Users of the mobile units 140A-140E can access and use the
`system resources 120 via the access points 130A-130C. The
`access points 130A-130C are used as bridges between the
`wired network 115 and a wireless network comprised of
`mobile units 140A-140E. In other words, the access points
`130A-130C provide connectivity between the wired net(cid:173)
`work 115 and the mobile units 140A-140E and also between
`the mobile units themselves. Typically, the mobile units
`140A-140E communicate with the access points 130A-130C
`using a standardized protocol ( e.g., the Institute of Electrical
`and Electronic Engineers (IEEE) 802.11 wireless commu(cid:173)
`nication standard, published Nov. 16, 1998).
`[0004] Generally, an access point is used to for various
`purposes or functions including: (1) providing connection
`between the mobile units or stations and the wireless net(cid:173)
`work; (2) performing the point control functions for the
`associated mobile units, as defined by a standardized pro(cid:173)
`tocol such as the IEEE 802.11 standard; and (3) providing
`the connectivity between the wireless network and the wired
`network (e.g., an Ethernet network). The second function
`performed by an access point requires computation and
`memory resources. However, the first function performed by
`an access point can be considered as the function of a radio
`repeater. Each access point in a typical wireless network
`requires to be equipped and configured to perform all of
`those functions mentioned above. Such a configuration may
`
`result in under-utilization of the resources and capacity of
`some access points and over-utilization of other access
`points in the wireless network. For example, for a given
`period of time, it is assumed that the access point 130A is
`required to perform the point control functions for all of its
`associated mobile units while another access point such as
`130B is only performing the connectivity function for its
`associated mobile units. In this example, it can be seen that
`access point 130A is over-utilized and access point 130B is
`under-utilized with respect to their computation and memory
`resources required to perform their corresponding functions.
`As a result, the conventional configuration of access points
`in a wireless network can be inefficient with respect to cost,
`flexibility, and scalability of resources.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0005] The invention may best be understood by referring
`to the following description and accompanying drawings
`that are used to illustrate embodiments of the invention. In
`the drawings:
`[0006] FIG. 1 shows a block diagram of a wireless net(cid:173)
`work system;
`[0007] FIG. 2 illustrates a block diagram of a wireless
`network configuration according to one embodiment of the
`invention;
`[0008] FIG. 3 shows a block diagram of an access point
`repeater (APR) according to one embodiment of the inven(cid:173)
`tion;
`[0009] FIG. 4 shows a block diagram of an access point
`server (APS) according to one embodiment of the invention;
`[0010] FIG. 5 shows a flow diagram of a process accord(cid:173)
`ing to one embodiment of the invention; and
`[0011] FIG. 6 illustrates a flow diagram of a method
`according to one embodiment of the invention.
`
`DETAILED DESCRIPTION
`
`[0012]
`In the following detailed description numerous
`specific details are set forth. However, it is understood that
`embodiments of the invention may be practiced without
`these specific details.
`[0013] As mentioned above, an access point in a wireless
`network system is used to for various purposes or functions
`including: (1) providing connection between the mobile
`units or stations and the wireless network; (2) performing
`the point control functions for the associated mobile units, as
`defined by a standardized protocol such as the IEEE 802.11
`standard; and (3) providing the connectivity between the
`wireless network and the wired network (e.g., an Ethernet
`network). The second function performed by an access point
`requires computation and memory resources. However, the
`first function performed by an access point can be consid(cid:173)
`ered as the function of a radio repeater.
`[0014]
`In one embodiment of the invention, a distributed
`access point configuration is implemented for a wireless
`local area network system. Instead of having each access
`point configured and equipped to perform both the media
`access functions and the specific point control functions
`according to a wireless communication protocol or standard
`such as the IEEE 802.11 standard, an access point according
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1038, p. 1
`
`
`
`US 2003/0235170 Al
`
`Dec. 25, 2003
`
`2
`
`to one embodiment of the invention is comprised of two
`parts or two components. One component is called an access
`point repeater (APR) and the other component is called an
`access point server (APS). In one embodiment, one APS can
`support multiple access point repeaters (APRs).
`
`[0015]
`In one embodiment of the invention, the functions
`that are performed by a conventional or traditional access
`point in a wireless network system are split between the APR
`and the APS. In one embodiment, the APR can be used to
`perform the media access functions of a standardized access
`control protocol such as the medium access control (MAC)
`protocol as specified in the IEEE 802.11 standard. The APS,
`in one embodiment, can be used to perform the specific point
`control functions that are relatively not real-time functions.
`In one embodiment, the APR and the APS are connected via
`a wired network (e.g., an Ethernet wired LAN) to commu(cid:173)
`nicate with each other.
`
`[0016] FIG. 2 illustrates a block diagram of a wireless
`network configuration 200 according to one embodiment of
`the invention. As shown in FIG. 2, the wireless network
`configuration 200 includes an access point server (APS)
`210, one or more access point repeaters (APRs) 220(1)-
`220(N). The APS 210 and the APRs 220 are connected and
`communicate with each other via a link 230, which is part
`of a wired network 240. In one embodiment, the wired
`network 240 is an Ethernet wired local area network (LAN)
`and the link 230 can be an Ethernet hub or switch. The
`network configuration 200 further includes system resources
`250 (e.g., server/router) that are coupled to network link
`230.
`
`[0017]
`In one embodiment, each APR 220 can be associ(cid:173)
`ated with one or more mobile units (not shown). Mobile
`units are also referred to as mobile stations or simply stations
`herein. A "mobile unit" (MU) can be any electronic device
`that includes logic for processing information ( e.g., a pro(cid:173)
`cessor, microcontroller, state machine, etc.) and a wireless
`transceiver for receiving information from and transmitting
`information to another electronic device (e.g., an APR or
`another mobile unit, etc.). Mobile units may include com(cid:173)
`puters (e.g., desktop computers, laptop computers, hand(cid:173)
`held computers such as a personal digital assistant "PDA",
`etc.), communications equipments (e.g., pagers, telephones,
`facsimile machines, etc.), television set-top boxes, PC cards,
`PCI adapters, bar-code scanners, etc. In one embodiment, an
`APS such as the APS 210 can be configured to support
`multiple APRs such as APR 220(1)-220(N).
`
`[0018]
`In one embodiment, the APR 220 is used to per(cid:173)
`form the media access portion of the MAC protocol that
`needs real-time performance and wireless physical layer
`(PHY) functionality. As shown in FIG. 2, each APR 220 is
`connected with the APS 210 through the Ethernet link 230.
`In one embodiment, the APS 210 is a software application
`that can run on any Ethernet-aware platform (e.g., server,
`router, switch, etc.). The APS 210 performs the specific
`point control functions of a wireless communication proto(cid:173)
`col such as the IEEE 802.11 standard. The specific point
`control functions are relatively not real-time functions. For
`example, in one embodiment, the APS 210 is responsible for
`getting and storing frames that cannot be immediately
`delivered or released due to the power state of the receiving
`stations. In one embodiment, the APS 210 can also perform
`the wired equivalent privacy (WEP) and other non-MAC
`
`layer security/authentication algorithms or functions such as
`security key distribution. In one embodiment, the APR 220
`includes 802.11 physical layer (PHY), all or part of the
`802.11 MAC component, Ethernet MAC and PHY, MAC
`address filter, one or more buffers (e.g., FIFO buffers) and
`corresponding buffer control logic. In one embodiment, one
`FIFO buffer is used for wireless to wired network (e.g.,
`wireless to Ethernet) information transfer. One or more
`FIFO buffers are used for wired network to wireless (e.g.,
`Ethernet to wireless) information transfer to allow for flex(cid:173)
`ibility in case of priority and PCF (point coordination
`function) support. For example, one FIFO buffer can be used
`to collect frames sent by DCF ( distributed coordination
`function) and another FIFO buffer can be used to collect
`frames sent by PCF. In one embodiment, multiple FIFO
`buffers may be used to support priority queues and frag(cid:173)
`mentation also.
`[0019] According to one embodiment of the invention,
`MAC multi-addressing mechanism is utilized as follows.
`Each APR 220 is a multi-addressable entity or device on the
`wired network (e.g., Ethernet LAN). Each APR 220 is
`associated in the APS 210 with every MAC address of
`stations supported by the respective APR 220. The APS 210
`is also a multi-addressable entity or device on the wired
`network ( e.g., Ethernet LAN). The APS 210 obtains from the
`Ethernet the basic service set identifier (BSSID) addresses of
`the APRs that are connected to the APS 210. In this
`configuration, no look up is needed to process frames
`transferred between stations, APR, and APS.
`[0020] FIG. 3 shows a block diagram of an access point
`repeater (APR) 220 according to one embodiment of the
`invention. As shown in FIG. 3, in one embodiment, APR
`220 may include IEEE 802.11 physical layer (PHY) 310,
`IEEE 802.11 MAC Real Time portion 320, one or more
`prioritized transmit buffers 330, one or more non-prioritized
`transmit buffers 335, one or more receive buffers 340,
`buffers control logic 350. The APR 220 further includes
`adaptive multi-addressing filter 360 and Ethernet MAC/
`PHY layer 370 These various components are used by the
`APR 220 to perform its corresponding media access func(cid:173)
`tions of the MAC protocol that need real-time performance
`and wireless PHY functionality.
`[0021]
`In one embodiment, APR 220 is a multi-address(cid:173)
`able entity on the wired network (e.g., the Ethernet LAN).
`The APR 220 is addressable by MAC address of any station
`associated with APR 220. The APR 220 includes a table of
`addresses which is updated each time a station is associated
`with or disassociated from the APR 220. In one embodi(cid:173)
`ment, the APR 220 receives all frames directed to it via the
`wireless medium (e.g., air) according to a wireless commu(cid:173)
`nication standard such as the IEEE 802.11 standard. Control
`frames received by the APR 220 are processed by the APR
`220. Management frames are directed by the APR 220 to the
`APS 210. Data frames can be redirected by the APR 220 to
`the appropriate station provided that certain criteria are
`satisfied. For example, the APR 220 can redirect data frames
`to a station when the respective station is in the same basic
`service set (BSS), in the proper power state to receive data,
`and that the APR 220 is able to properly perform the
`required security functions, if necessary, with respect to the
`data frames to be sent (e.g., decrypt and/or encrypt).
`[0022]
`In one embodiment, the APR 220 will redirect a
`data frame to the APS 210 if the data frame should be stored
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1038, p. 2
`
`
`
`US 2003/0235170 Al
`
`Dec. 25, 2003
`
`3
`
`or needs decryption/encryption processing that the APR 220
`is not able to provide. The APR 220 redirects the received
`data frame to the APS 210 by enveloping the data frame in
`an Ethernet frame and using the corresponding BSSID as the
`destination address.
`
`In one embodiment, the APR 220 gets Ethernet
`[0023]
`frames from APS 210 to be sent to a corresponding station
`via the wireless medium (e.g., air). These frames contain
`valid 802.11 frames under Ethernet envelope. Destination
`address of these frames is the address of the corresponding
`station. There can be various kinds of frames sent from the
`APS 210 to the APR 220. They may include frames for
`immediate transmission and frames that should be sent in a
`particular manner ( e.g., PCF). In this case, the APR 220 can
`recognize and store such frames for later use.
`
`[0024] FIG. 4 shows a block diagram of an access point
`server (APS) (e.g., APS 210) according to one embodiment
`of the invention. As shown in FIG. 4, APS 210 may include
`an Ethernet MAC/PHY layer 410, an adaptive multi-ad(cid:173)
`dressing filter 415, a network driver 420, IEEE 802.11 MAC
`management portion 425, and one or more extended access
`point (AP) applications 430. The APS 210 may further
`include a database 435 for storing information and an
`operating system 440 for controlling the operations of the
`various components included in the APS 210.
`
`In one embodiment, the APS 210 is configured as
`[0025]
`a multi-addressable entity on the wired network (e.g., Eth(cid:173)
`ernet LAN). The APS 210 can be addressable by the
`corresponding BSSID of any APR supported by APS 210. In
`one embodiment, the APS 210 receives redirected frames
`from the APR 220 which are enveloped in Ethernet format.
`The BSSID of the respective APR 220 is used as the
`destination address. In one embodiment, APS 210 gets all
`management frames redirected to APS 210 by APR 220. The
`APS 210 may also get some control frames and data frames.
`The APS 210 is responsible for performing management
`functions of the wireless communication protocol (e.g.,
`IEEE 802.11).
`
`In one embodiment, the APS 210 is configured to
`[0026]
`store data frames that cannot be immediately sent to stations
`because the stations are in power down state. The APS 210
`also forwards data frames between basic service sets. In one
`embodiment, the APS 210 creates, stores, and distributes
`security keys between stations. The APS 210 allows usage of
`individual key for any station.
`
`In one embodiment, the APS 210 sends IEEE
`[0027]
`802.11 frames to the APR 220 for transmission over the
`wireless medium to the stations. The APS 210 envelops
`these frames in Ethernet format. The destination address of
`these frames is the address of the station. The APS 210 could
`allow roaming between APRs by substitution of the BSSID
`in the registry of stations.
`
`[0028] FIG. 5 shows a flow diagram of a process 500
`according to one embodiment of the invention. As shown in
`FIG. 5, the process 500 includes the association phase or
`sub-process 510, the transmit data phase or sub-process 530,
`and the receive data or sub-process 550. At block 512, a
`station issues an association request with a BSSID. At block
`514, an APR with the corresponding BSSID receives the
`respective association request and forwards the association
`request to anAPS. In one embodiment, the APR appends the
`
`address of this station to its adaptive multi-addressing filter.
`At block 516, the APS processes the association request and
`answers with an association response. The association
`response is then sent from the APS to the APR through a
`wired network (e.g., the Ethernet LAN). The association
`response frame is enveloped in an Ethernet format using the
`station address as the destination address. If the response is
`unsuccessful, the last added MAC address is removed from
`the APR's adaptive multi-addressing filter. At block 518, the
`APR sends the association response to the station via the
`wireless medium (e.g., air).
`
`[0029] Referring again to FIG. 5, at block 532, to transmit
`a data frame from the APS to an APR, the APS envelopes the
`frame to be transmitted in Ethernet format using the station
`address as the destination address and sends the data frame
`to the APR via the wired network (e.g., the Ethernet LAN).
`The APR that receives the data frame is responsible for
`delivering this data frame to the corresponding station so
`that the APS can free the buffer of this data frame (at block
`534). At block 536, the APR transmits the data frame to the
`respective station and waits for an acknowledgement signal
`(ACK) from the respective station. At block 538, the APR
`responds to the APS with the ACK signal so that the APS can
`determine whether the APR frees its buffer for the next
`frame.
`
`[0030] Continuing with the present discussion, at block
`552, a station ( also called a first station) transmits data to
`another station (called a second station). The APR recog(cid:173)
`nizes the BSSID of the frame and receives the frame from
`the first station. At block 554, the APR checks the CRC of
`the frame received to decide whether to respond with ACK.
`At decision block 556, if the CRC fails (CRC not OK), the
`frame is dismissed and ACK is not sent by the APR ( at block
`572). If the CRC is successful (CRC OK), there can be
`different scenarios to process the frame. For example, in one
`embodiment, in one scenario, the APR can be configured to
`send any data frame received from a station to the APS
`(scenario 1, block 558). In this case, the APR forwards the
`data frame to the APS which is enveloped with an Ethernet
`header and using the BSSID as the destination address. The
`APS then decides how to process the data frame (e.g., how
`to decrypt the data frame, to store it or to forward for
`transmission to the targeted station).
`
`[0031] Alternatively, in another embodiment (scenario 2),
`the APR may be configured to decide whether to redirect the
`received data frame to the targeted station or to send the data
`frame to the APS, based on various factors or criteria (at
`block 560). For example, the various factors or criteria used
`by the APR to determine whether to redirect the data frame
`to the targeted station or send the data frame to the APS may
`be based the APR's capabilities to perform certain required
`functions to process and transmit the data frame, the power
`state of the targeted station, whether the targeted station is in
`the same BSS as the transmitting station, etc. For example,
`if each station uses its own key for encryption and the APR
`does not have enough space to store keys for all stations then
`the APR needs to forward the data frame to the APS. As
`another example, if the targeted station is in power down
`mode then the APR needs to send the data frame to the APS
`to be stored for transmission to the targeted station later on.
`
`[0032] FIG. 6 illustrates a flow diagram of a method 600
`according to one embodiment of the invention. At block 610,
`
`Petitioners Microsoft Corporation and HP Inc. - Ex. 1038, p. 3
`
`
`
`US 2003/0235170 Al
`
`Dec. 25, 2003
`
`4
`
`a first communication device in a wireless local area net(cid:173)
`work is connected to a wired local area network. At block
`620, a second communication device in the wireless local
`area network is connected to the wired local area network.
`The first and second communication devices communicate
`with each other via the wired local area network. At block
`630, the first communication device is assigned and config(cid:173)
`ured to function as an access point repeater (APR) to
`transmit information to and receive information from one or
`more mobile units (stations) that are associated with the first
`communication device, according to a first wireless process(cid:173)
`ing protocol (e.g., IEEE 802.11 standard). The first commu(cid:173)
`nication device is configured to perform the media access
`functions of the first wireless processing protocol ( e.g., the
`media access portion of IEEE 802.11 MAC protocol). At
`block 640, the second communication device is assigned and
`configured to function as an access point server (APS). The
`second communication device is configured to perform
`specific point control functions of the first wireless process(cid:173)
`ing protocol that are relatively not real-time functions.
`
`[0033] While the invention has been described in terms of
`several embodiments, those of ordinary skill in the art will
`recognize that the invention is not limited to the embodi(cid:173)
`ments described herein. It is evident that numerous alterna(cid:173)
`tives, modifications, variations and uses will be apparent to
`those of ordinary skill in the art in light of the foregoing
`description.
`
`What is claimed is:
`1. An apparatus comprising:
`
`an access point repeater (APR) coupled to a wired net(cid:173)
`work, the APR to transmit information to and receive
`information from one or more associated stations
`according to a first wireless processing protocol, the
`APR to perform media access functions of the first
`wireless processing protocol; and
`
`an access point server (APS) coupled to the APR via the
`wired network to transmit information to and receive
`information from the APR, the APS to perform specific
`point control functions of the first wireless processing
`protocol.
`2. The apparatus of claim 1 wherein the APR is a
`multi-addressable entity on the wired network and is addres(cid:173)
`sable by corresponding media access control (MAC)
`addresses of stations associated with the APR.
`3. The apparatus of claim 2 wherein the APR includes a
`table of MAC addresses of associated stations, the table
`being updated each time a respective station is associated
`with or disassociated from the APR.
`4. The apparatus claim 1 wherein the APS is a multi(cid:173)
`addressable entity on the wired network and is addressable
`by corresponding basic service set identifiers (BSS_ID) of
`access point repeaters that are supported by the APS.
`5. The apparatus of claim 1 wherein the wired network is
`an Ethernet network and wherein the first wireless process(cid:173)
`ing protocol conforms with the Institute of Electrical and
`Electronics Engineers (IEEE) 802.11 wireless standard.
`6. The apparatus of claim 1 wherein, in response to an
`association request issued by a first station, the APR for(cid:173)
`wards the respective association request to the APS which
`processes the respective association request and sends a
`
`corresponding association response to the APR, and wherein
`the APR sends the corresponding association response to the
`first station.
`7. The apparatus of claim 6 wherein, to transmit a data
`frame from the APR to the first station, the APS sends the
`data frame enveloped in Ethernet format with the address of
`the first station used as a destination address (DA) to the
`APR via the wired network, and wherein the APR sends the
`data frame to the first station.
`8. The apparatus of claim 7 wherein, upon receiving a data
`frame from the first station to be transmitted to a second
`station, the APR sends the data frame to the APS for
`transmission to the second station.
`9. The apparatus of claim 7 wherein, upon receiving a data
`frame from the first station to be transmitted to a second
`station, the APR redirects the data frame to the second
`station if one or more criteria are met, the one or more
`criteria including a first criterion indicating whether the
`second station is in the same basic service set (BSS) as the
`first station, a second criterion indicating whether the second
`station is in a proper power state to receive data frames, and
`a third criterion indicating whether the APR is capable of
`performing one or more data security functions required to
`process the data frame before transmitting the data frame to
`the second station.
`10. A system comprising:
`
`a wired local area network;
`
`a wireless local area network including one or more
`mobile units to transmit and receive information via a
`wireless medium;
`
`a first access point coupled to the wired local area
`network, the first access point to function as an access
`point repeater (APR) t