Abstract:
Embodiments of apparatuses, articles, methods, and systems for utilizing a fast transitioning advertisement in wireless networks are generally described herein. Other embodiments may be described and claimed.

Description:
FIELD 
       [0001]    Embodiments of the present invention relate generally to the field of wireless networks, and more particularly to fast transitioning advertisements in said wireless networks. 
       BACKGROUND 
       [0002]    A communication session in a wireless network typically involves a local station communicating with a remote station via a communication link. The communication link may include a wireless connection between the local station and an access point. For various reasons, the quality of the wireless connection between the access point and the local station may deteriorate. This may be due to overloading of the access point, mobility of the station, interference, etc. In order to preserve the established communication link, the local station may reassociate the wireless connection with another access point. When the communication session involves delay intolerant transmissions, e.g., voice or video, various quality of resource (QoS) challenges are presented for a successful and efficient reassociation of the wireless connection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    Embodiments of the invention are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings, in which like references indicate similar elements and in which: 
           [0004]      FIG. 1  illustrates a network providing for fast transitioning in accordance with various embodiments of this invention; 
           [0005]      FIG. 2  illustrates a mobility domain information element in accordance with various embodiments of this invention; 
           [0006]      FIG. 3  illustrates an association policy in accordance with various embodiments of this invention; 
           [0007]      FIG. 4  illustrates a fast transitioning information element in accordance with various embodiments of this invention; 
           [0008]      FIG. 5  illustrates a flowchart depicting a fast transitioning operation in accordance with various embodiments of this invention; 
           [0009]      FIG. 6  illustrates message sequences of a fast transitioning operation in accordance with various embodiments of this invention; 
           [0010]      FIG. 7  illustrates components of a station in accordance with various embodiments of this invention; 
           [0011]      FIG. 8  illustrates components of an access point in accordance with various embodiments of this invention; and 
           [0012]      FIG. 9  illustrates a computing device in accordance with various embodiments of this invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Embodiments of the present invention may provide a method, article of manufacture, apparatus, and system for fast transitioning advertisements in wireless networks. 
         [0014]    Various aspects of the illustrative embodiments 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 alternate embodiments may be practiced with only some of the described aspects. For purposes of explanation, specific devices and configurations are set forth in order to provide a thorough understanding of the illustrative embodiments. However, it will be apparent to one skilled in the art that alternate embodiments may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative embodiments. 
         [0015]    Further, 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 as to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation. 
         [0016]    The phrase “in one embodiment” is used repeatedly. The phrase generally does not refer to the same embodiment; however, it may. The terms “comprising,” “having,” and “including” are synonymous, unless the context dictates otherwise. 
         [0017]    In providing some clarifying context to language that may be used in connection with various embodiments, the phrase “A/B” means (A) or (B); the phrase “A and/or B” means (A), (B), or (A and B); and the phrase “A, B, and/or C” means (A), (B), (C), (A and B), (A and C), (B and C) or (A, B and C). 
         [0018]    As used herein, reference to a “component” may refer to a hardware, a software, and/or a firmware component employed to obtain a desired outcome. Although only a given number of discrete components may be illustrated and/or described, such components may nonetheless be represented by additional components or fewer components without departing from the spirit and scope of embodiments of the invention. 
         [0019]      FIG. 1  illustrates a network  100  supporting fast transitioning (FT) of mobile wireless devices utilizing FT advertisements in accordance with an embodiment of this invention. “Fast transitioning” may also be referred to as “fast roaming.” 
         [0020]    Briefly, the network  100  may include a wireless network node, e.g., station  104 , having a wireless connection  108  with another wireless network node, e.g., access point (AP)  112 . The network  100  may also include other wireless network nodes, e.g., APs  116 ,  120 , and  124 . The APs may be part of a mobility domain (MD)  128  operated by an infrastructure provider. The provider may define the MD  128  as an administrative function. 
         [0021]    The wireless connection  108  may be initially associated with the AP  112  at the beginning of a communication session. If the station  104  observes deterioration in the quality of the wireless connection  108 , the station  104  may initiate FT operations in order to reassociate the wireless connection  108  with another AP that is capable of providing appropriate quality of service (QoS) levels given the nature of the communication session. In various embodiments, the communication session may include delay and/or jitter sensitive network traffic such as, but not limited to, streaming multimedia, Internet protocol (IP) telephony (e.g., voice-over IP (VoIP)), video teleconferencing, etc. Accordingly, it may be desirable for an FT operation to occur in a manner such that a detectable disruption to the established communication session may be avoided. 
         [0022]    Prior to reassociating the wireless connection  108 , the station  104  may look to discover the policy and capabilities of other neighboring APs to determine if an FT operation is possible. If an FT operation is possible with one or more of the APs, the station  104  may identify those APs as reassociation targets and reassociate with a selected one of the reassociation targets when desired. 
         [0023]    The APs of the MD  128  may transmit management frames, e.g., beacons and/or probe responses, to provide stations with the information to determine acceptable reassociation targets. Beacons may be periodically broadcast (e.g., once every 100 milliseconds) by the APs. Probe responses may be replies from an AP to a station&#39;s probe request. 
         [0024]    Large size beacons and probes may introduce latency and processing delays at all wireless devices, thereby making the operation of the network  100  more power consuming and slow. Undesired elements in a beacon may result in undue processing overhead within and between components of the wireless devices. Accordingly, embodiments of this invention may facilitate FT operations by reducing broadcast overhead. Small broadcast messages may increase packet transmission efficiency over the air (OTA) and may be faster to process and act upon. 
         [0025]    In an embodiment of this invention, the AP  116  may broadcast a low-overhead beacon. In an embodiment, the broadcast beacon may simply include a mobility domain information element (MDIE), which comprises a unique mobility domain identifier (MDID) and an association policy. 
         [0026]    In an embodiment, the station  104  may reassociate the wireless connection  108  with any AP that is operating within the same mobility domain (MD) in which the AP  112  operates, e.g., MD  128 . Accordingly, the MDID may be included in the MDIE so that the station  104  may determine whether the AP  116  resides in the MD  128 . If the MDID of the broadcast beacon matches the MDID of the AP  112 , the station  104  may identify the AP  116  as a reassociation target. 
         [0027]    Prior to reassociating the wireless connection  108  with the AP  116 , the station  104  and the AP  116  may exchange security information. This exchange of security information may be done according to the association policy communicated in the MDIE. Security information may be exchanged through a series of unicast association management messages. 
         [0028]    The communication session may be secured through a number of key holders distributed throughout the MD  128 . Each AP may be associated with a key holder (KH). For example, AP  112  may be associated with KH  132 ; both APs  116  and  120  may be associated with KH  140 ; and AP  124  may be associated with KH  136 . As can be seen, a KH may be uniquely associated with an AP (and may sometimes be implemented in the same device) or a KH may be associated with more than one AP. 
         [0029]    Upon initial association of the wireless connection  108 , the station  104  and an authentication server  144  may mutually authenticate each other using, e.g., an extensible authentication protocol (EAP). Upon mutual authentication, the authentication server  144  may deliver a master secret key (MSK) to the AP  112  and the station  104 . 
         [0030]    The KH associated with the AP  112 , e.g., KH  132 , may use the MSK to compute a pairwise master key (PMK)-R0. In this context, the KH  132  may also be referred to as the R0KH  132 . The R0KH  132  may use the PMK-R0 and an identity of an R1KH, which may be the R0KH  132  for the initial association, to generate a PMK-R1 key. The PMK-R1 key may then be used in deriving a pairwise transient key (PTK) session key. 
         [0031]    The station  104  may use the MSK to derive the PMK-R0, PMK-R1, and PTK keys in a similar manner as the R0KH  132 . The keys derived by the station  104  may match those derived by the R0KH  132  as both use the same ingredients in the same key derivation function. 
         [0032]    When the station  104  targets AP  116  for reassociation, the KH associated with the AP  116 , e.g., KH  140 , and the station  104  may need to derive a new PTK. To do so, the KH  140  may need the identity of the R0KH  132 , which may be responsible for generating and delivering the PMK-R1 keys to the KHs of the MD  128 , in order to request the PMK-R1 key. Upon receiving a PMK-R1 key from the R0KH  132 , the KH  140 , which may be referred to as R1KH  140  in this instance, may derive a PTK. 
         [0033]    The station  104  may receive the identity of the R1KH  140  and derive a PTK session key that should match the PTK session key generated by the R1KH  140 . 
         [0034]    Accordingly, in some embodiments security information exchanged in the series of unicast association messages prior to reassociation may include identities of various key holders, e.g., R0KH-ID and R1KH-ID, to facilitate the derivation and distribution of the PMK-R1 keys. These KH-IDs may be communicated through fast transition information elements (FTIE). 
         [0035]    In various embodiments, an identity of a wireless network node may be a network address such as, but not limited to, a media access control (MAC) address. 
         [0036]    In various embodiments, the network  100  may be a wireless local area network (WLAN), a wireless metropolitan access network (WMAN), etc. In an embodiment, the wireless network  100  may comply with one or more of the Institute of Electrical and Electronics Engineers (IEEE) wireless standards, e.g., the 802.11-2003 and/or 802.16-2004 standards along with any revisions, amendments or updates thereto. 
         [0037]    While the above embodiment discusses an initial association of a wireless connection between a station and an access point and a reassociation of the wireless connection to another access point, other embodiments may include associations among other combinations of wireless network nodes. For example, the association of a wireless connection may be between an AP and another AP, a station and another station, etc. As used herein an “association” may include both an initial association and a reassociation. 
         [0038]    Wireless network nodes may be any type of device capable of performing associations involved in the FT operations described herein. In some embodiments network nodes may be mobile network client devices such as, but not limited to, a personal computing device, a laptop computing device, a phone, etc., or network infrastructure devices, e.g., a server, an access point, etc. 
         [0039]      FIGS. 2-4  illustrate some of the aforementioned information elements and sub-elements thereof in accordance with various embodiments of this invention.  FIG. 2 , in particular, illustrates an MDIE  200  that may be broadcast by the AP  116  in accordance with an embodiment of this invention. The MDIE  200  may have an element ID  204 , a length  208 , an association policy  212 , and an MDID  216 . In an embodiment, the first three parts of the MDIE  200  (e.g., element ID  204 , the length  208 , and the association policy  212 ) may each be one octet; while the MDID  216  may be six octets. In this embodiment, the length  208  may be seven, indicating the size of the remaining parts, e.g., the association policy  212  and the MDID  216 . Accordingly, the total size of the MDIE  200  may be only nine octets. 
         [0040]    The information advertised by the AP  116  by broadcasting the MDIE  200  may be sufficient for the station  104  to determine whether the AP  116  may be targeted for reassociation. The other APs, e.g., APs  116 ,  120 , and  124 , may broadcast similar MDIEs; however, the association policy communicated in the MDIE may be different for each AP. The MDIEs may be advertised by the APs in their beacons and probe responses. 
         [0041]    As used herein, an association policy may provide information on a procedure for a station to use when it is associating or reassociating a wireless connection with an AP.  FIG. 3  illustrates the association policy  212  in accordance with various embodiments of this invention. The association policy  212  may include a first bit b 1  to indicate an AP&#39;s QoS reservation policy. As used herein, a policy allowing pre-reservation of QoS may be referred to as a “pre-reservation policy” while a policy that does not may be referred to as a “base policy.” In an embodiment, if the bit b 1  is set to zero, a station reassociating a wireless connection may adhere to the base policy and if the bit b 1  is set to one, the station may use either the base or the pre-reservation policy. 
         [0042]    The second bit b 2  and the third bit b 3  may provide information on an AP&#39;s management message transmission scheme in accordance with various embodiments of this invention. For example, a second bit b 2  of the association policy  212  may indicate whether the association management messages may be transmitted OTA. A third bit b 3  of the reassociation policy  212  may indicate whether reassociation management messages may be transmitted over the distribution system (ODS), e.g., via the AP  112 . 
         [0043]    Bits b 4 -b 8  may be reserved in this embodiment. In other embodiments, one of the reserved bits, e.g., bit b 4 , may be used to indicate whether the KH  140  associated with the AP  116  is also associated with another AP. In some embodiments selecting a target AP that shares a KH with the current AP may facilitate FT operations by, e.g., reducing key computations. 
         [0044]      FIG. 4  illustrates an FTIE  400  that may be exchanged in unicast association management messages in accordance with various embodiments of the present invention. The FTIE  400  may include an element ID  404 , a length  408 , and an R0KH-ID  412 . In some embodiments, depending on the stage of the exchange, the FTIE  400  may also include an R1KH-ID. In an embodiment, the first two parts of the FTIE  400  (e.g., element ID  404  and the length  408 ) may each be one octet; while the KH-IDs, e.g., the R0KH-ID  412  and R1KH-ID  416 , may be forty-eight octets and six octets, respectively. In this embodiment, the length  408  may be forty-eight if only the R0KH-ID is included, or fifty-four if both the R0KH-ID and the R1KH-IDs are included. Accordingly, the total size of the FTIE  400  may be fifty or fifty-six octets in accordance with this embodiment. 
         [0045]      FIG. 5  illustrates a flowchart depicting an FT operation in accordance with various embodiments of this invention. In this embodiment, the station  104  may initially associate the wireless connection  108  with AP  112  at block  504 . Sometime after the initial association, the station  104  may decide to begin an FT operation. As discussed above, this may be due to a deterioration in the wireless connection  108 ; however, other scenarios may also motivate an FT operation. The station  104  may receive a beacon including an MDIE from the AP  116  at block  508 . The station  104  may determine whether the MDID in the beacon matches the MDID of the current AP, e.g., AP  112 , at block  512 . If the MDIDs are not the same, the station  104  may determine that it may not reassociate the wireless connection  108  with AP  116  at block  516 . If the MDIDs are the same, the station  104  may select AP  116  as a reassociation target at block  520 . 
         [0046]    After selecting the AP  116  as a reassociation target at block  520 , the station  104  may determine the QoS reservation policy of the AP  116  communicated in the association policy of the MDIE at block  524 . If the MDIE indicates that either the base or pre-reservation policy may be used for reassociation, the station  104  may have the liberty to choose which policy to use for reassociation. 
         [0047]    The station  104  may consider a number of factors in choosing between the two policies. For example, the pre-reservation policy may introduce latency into the infrastructure to provide the AP  116  additional time to process QoS calculations by having them done prior to the reassociation request. The base policy, on the other hand, may conserve the resources of the station  104  by providing reduced transmissions and saving power compared to the pre-reservation policy. Additionally, if the station  104  senses wireless congestion, it may wish to pre-reserve QoS resources at a plurality of APs, and reassociate with a selected one of the plurality of APs when desired. 
         [0048]    The station  104  may also reference the MDIE to determine a management message transmission scheme at block  528 . The transmission scheme may be OTA, ODS, or either. 
         [0049]    The station  104  may reassociate the wireless connection  108  with the AP  116  according to the determined policy and transmission scheme at block  532 . 
         [0050]      FIG. 6  illustrates message sequences of an FT (re)association procedure in accordance with various embodiments of the present invention. In this embodiment, the AP  112  may broadcast its beacon  604 . The beacon  604  may include an MDIE, which may be structurally similar to MDIE  200 , having an association policy of the AP  112  and an MDID for the MD  128 . 
         [0051]    The station  104  may decide to perform an initial association with the AP  112  and transmit an association request  608  that includes the received MDIE. The AP  112  may respond with an association response  612  that includes the MDIE and an FTIE, which may be structurally similar to FTIE  400 , having R1KH-ID (in this case, the ID of the KH  132 ), which tells the station  104  on what PMK-R1 to derive. 
         [0052]    The station  104  and the authentication node  144  may conduct an EAP authentication as described above. Following the EAP authentication, EAPOL Key messages used for key management for deriving PTK keys may be exchanged. This exchange may include the station  104  transmitting EAPOL-Key Msg 2  616 , which includes the previously transmitted MDIE and FTIE along with a message integrity check (MIC), and the AP  112  transmitting EAPOL-Key Msg 3  620 , which may also include the MDIE and FTIE along with the MIC. 
         [0053]    Transmitting the MDIE and FTIE with the MIC may provide some level of assurance to the station  104  and AP  112  that the information elements that the association is based upon, transmitted in previous messages, are genuine and not generated from an impostor. Upon this successful negotiation, the station  104  and the AP  112  may be securely associated. 
         [0054]    The station  104  may decide to fast roam sometime after the initial association. The station  104  may receive a beacon  624 , broadcast by the AP  116 , including an MDIE with the association policy of AP  116  and the MDID of MD  128 . The station  104  may confirm that the MDID of the AP  116  is the same as the MDID of the AP  112 , originally received in the beacon  604 , and identify the AP  116  as a reassociation target. Other embodiments may include pre-reservation policy with an OTD transmission scheme, or a base policy with an OTA or OTD transmission scheme. 
         [0055]    After the station  104  identifies the AP  116  as the reassociation target it may proceed to exchange KH-IDs according to the association policy communicated in the MDIE. In this embodiment, the association policy may be a pre-reservation policy negotiated with an OTA transmission scheme. 
         [0056]    The station  104  may begin the KH-ID exchange by transmitting an FT authentication request  628  repeating the MDIE of the beacon  624  and including an FTIE providing the R0KH-ID. The AP  116  may respond to the FT authentication request  628  with an FT authentication response  632  repeating the MDIE and including an FTIE having the R0KH-ID and an R1KH-ID. The AP  116  may use the R0KH-ID to obtain a PMK-R1 from the R0KH  140 ; while the station  104  may use the R1KH-ID to derive the PMK-R1. This PMK-R1 may then be used to derive the PTK key for securing communications between the AP  116  and the station  104  throughout the communication session. 
         [0057]    With the appropriate keys derived, the station  104  may transmit an FT authentication confirmation  636  repeating the MDIE and FTIE of the FT authentication response  632  along with a MIC to provide assurance to the AP  116  of the integrity and source authentication of the information elements. In an embodiment, the FT authentication confirmation  636  may also include a resource information container (RIC) request having a resource descriptor information element (RDIE) that includes a requested QoS resource. 
         [0058]    The AP  116  may confirm that the MDIE and the FTIE were the same as sent in previous messages, e.g., in the FT authentication response  632 , and may also determine whether it has the requested QoS resource available for allocation to the station  104 . The AP  116  may then prepare and transmit an FT authentication acknowledgement  640  repeating the MDIE and the FTIE along with a MIC to provide assurance to the station  104  of the integrity and source authentication of the information elements. In an embodiment, the FT authentication acknowledgement  640  may also include a RIC response indicating whether the requested QoS resource was allocated to the station  104 . 
         [0059]    If everything is deemed acceptable, the station  104  may execute the reassociation by transmitting a reassociation request  644 , having an MDIE, an FTIE, and a MIC, and the AP  116  may respond by generating and transmitting a reassociation response  648  echoing the elements of the reassociation request  644  with another MIC. At this point, the reassociation of the wireless connection  108  to the AP  116  may be complete. 
         [0060]    As stated above, the procedures shown and discussed in  FIG. 6  are directed towards a pre-allocation policy. In a base policy embodiment, the FT authentication confirmation  636  and/or FT authentication acknowledgement  640  messages, and the functions that they include (e.g., resource allocation and integrity checks) may occur at or after the reassociation management messages, e.g., the reassociation request  644  and/or the reassociation response  648 . 
         [0061]    As also stated above, the procedures shown and discussed in  FIG. 6  may be directed towards an OTA transmission scheme. In an ODS embodiment, the management authentication messages, e.g., FT authentication request  628 , the FT authentication response  632 , the FT authentication confirmation  636 , and the FT authentication acknowledgement  640 , may be referred to as management action messages, e.g., an FT action request, an FT action response, an FT action confirmation, and an FT action acknowledgement. However, the elements contained in these messages may be similar. As used herein an FT request may refer to either an FT authentication request or an FT action request; an FT response may refer to an FT authentication response or an FT action response; and so forth. 
         [0062]      FIG. 7  illustrates components of the station  104  in accordance with various embodiments of this invention. The station  104  may include a wireless network interface card (WNIC)  704  to facilitate wireless communication with other devices of the network  100 . The WNIC  704  may facilitate processing of messages to and/or from components of a host  708 . The WNIC  704  may cooperate with an antenna structure  712  to provide access to other devices of the network  100 . 
         [0063]    In various embodiments, the antenna structure  712  may include one or more directional antennas, which radiate or receive primarily in one direction (e.g., for 120 degrees), cooperatively coupled to one another to provide substantially omnidirectional coverage; or one or more omnidirectional antennas, which radiate or receive equally well in all directions. 
         [0064]    In various embodiments, the host  708  may include a driver, e.g., wireless local area network (WLAN) driver  716 , to drive the WNIC  704  for other components of the host  708  such as a transitioning manager  720 . The transitioning manager  720  may control FT operations of the station  104  such as those discussed in embodiments of this invention. 
         [0065]    In an embodiment the driver  716  may include a supplicant  724  to act as a security software component, e.g., for performing MIC calculations. 
         [0066]      FIG. 8  illustrates components of the AP  116  in accordance with various embodiments of this invention. The AP  116  may include a WNIC  804  and antenna structure  808  to facilitate wireless communication with wireless devices of the network  100 , similar to like-name components of the station  104 . The AP  116  may include a host  812  having a driver  816  to drive the WNIC  804  for other components of the host  812  such as an association manager  820 . The association manager  160  may control FT operations of the AP  116  such as those discussed in embodiments of this invention. 
         [0067]    In an embodiment the driver  816  may include a supplicant  824  to act as a security software component, e.g., for performing MIC calculations. 
         [0068]      FIG. 9  illustrates a computing device  900  capable of implementing an wireless network device in accordance with various embodiments. As illustrated, for the embodiments, computing device  900  includes processor  904 , memory  908 , and bus  912 , coupled to each other as shown. Additionally, computing device  900  includes storage  916 , and communication interfaces  920 , e.g., a WNIC, coupled to each other, and the earlier described elements as shown. 
         [0069]    Memory  908  and storage  916  may include in particular, temporal and persistent copies of FT logic  924 , respectively. The FT logic  924  may include instructions that when accessed by the processor  904  result in the computing device  900  performing FT operations described in conjunction with various wireless network devices in accordance with embodiments of this invention. 
         [0070]    In various embodiments, the memory  908  may include RAM, dynamic RAM (DRAM), static RAM (SRAM), synchronous DRAM (SDRAM), dual-data rate RAM (DDRRAM), etc. 
         [0071]    In various embodiments, the processor  904  may include one or more single-core processors, multiple-core processors, controllers, application-specific integrated circuits (ASICs), etc. 
         [0072]    In various embodiments, storage  916  may include integrated and/or peripheral storage devices, such as, but not limited to, disks and associated drives (e.g., magnetic, optical), universal serial bus (USB) storage devices and associated ports, flash memory, read-only memory (ROM), non-volatile semiconductor devices, etc. 
         [0073]    In various embodiments, storage  916  may be a storage resource physically part of the computing device  900  or it may be accessible by, but not necessarily a part of, the computing device  900 . For example, the storage  916  may be accessed by the computing device  900  over a network. 
         [0074]    In various embodiments, computing device  900  may have more or less components, and/or different architectures. In various embodiments, computing device  900  may be a station, an access point, or some other wireless network node. 
         [0075]    Although the present invention has been described in terms of the above-illustrated embodiments, it will be appreciated by those of ordinary skill in the art that a wide variety of alternate and/or equivalent implementations calculated to achieve the same purposes may be substituted for the specific embodiments shown and described without departing from the scope of the present invention. Those with skill in the art will readily appreciate that the present invention may be implemented in a very wide variety of embodiments. This description is intended to be regarded as illustrative instead of restrictive on embodiments of the present invention.