QUALITY OF SERVICE DIFFERENTIATION FOR MULTIMEDIA DATA TRANSFER

IN A MULTI-WLAN ENVIRONMENT

TECHNICAL FIELD

[0001] The present invention relates generally to wireless local area network ("WLAN") architectures. More particularly, the present invention relates to the provision of differentiated quality of service ("QoS") for mobile client devices users in a multi- WLAN environment.

BACKGROUND

[0002] WLANs rely on WLAN infrastructure components that establish data communication links with mobile client devices. A mobile client device communicates, via a wireless data communication channel, with an access point or access port device, which in turn communicates with other network components via traditional wired interfaces. A WLAN may also include wireless switches as needed. A WLAN infrastructure may be configured to support a plurality of "virtual" or "logical" WLANs using a single access point device, hi other words, one access point device can support a plurality of logical WLANs, which may be accessed by different groups or categories of client devices. In this regard, administrators of wireless infrastructure systems may want to provide differentiation between virtual WLANs that are supported by the same WLAN infrastructure equipment. For example, it may be desirable to utilize the WLAN infrastructure equipment associated with a particular wireless "hot spot" to provide enhanced service (e.g., for better delivery of multimedia files and/or for higher quality voice over IP sessions) to some wireless client devices, and standard service (e.g., non- prioritized handling of data traffic) to other wireless client devices. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.

BRIEF SUMMARY

[0003] A system as described herein allows WLAN administrators to provide differentiated QoS for "virtual" WLANs supported by a common WLAN infrastructure

through the assignment of different parameters (e.g., Wi-Fi Multimedia ("WMM") QoS parameters, IEEE 802.1 l(e) QoS parameters, or the like) to each virtual WLAN individually. In this way, the mobile users of one logical WLAN can be given better access to the wireless medium than the users of another logical WLAN, at the discretion of the network administrators. For example, this feature can be used to configure one logical WLAN with public "best effort" QoS and another logical WLAN with an enhanced QoS, which may be desirable for voice and/or video data transmission. [0004] The above and other aspects of the invention may be carried out in one form by a method for establishing QoS differentiation in a WLAN environment having a wireless access point configured to support a plurality of logical WLANs. The method involves: identifying an approved logical WLAN for a mobile client device, where the approved logical WLAN is one of the plurality of logical WLANs supported by the wireless access point, and providing the mobile client device with a specified QoS for the approved logical WLAN. The specified QoS influences data type prioritization for data transmission between the mobile client device and the wireless access point.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in conjunction with the following figures, wherein like reference numbers refer to similar elements throughout the figures.

[0006] FIG. 1 is a simplified schematic representation of a typical WLAN infrastructure suitable for use in connection with an example embodiment of the invention;

[0007] FIG. 2 is a schematic representation of an access point device configured in accordance with an example embodiment of the invention;

[0008] FIG. 3 is a schematic representation of a logical structure that may be employed in the access point device shown in FIG. 2;

[0009] FIG. 4 is a schematic representation of a WLAN environment having three access points connected in a common WLAN infrastructure;

[0010] FIG. 5 is a flow chart of a QoS differentiation process that may be performed by an access point device configured in accordance with an example embodiment of the invention; and

[0011] FIG. 6 is a sequence diagram depicting communication, between a client device and an access point device, for establishing differentiated QoS in a WLAN environment.

DETAILED DESCRIPTION

[0012] The following detailed description is merely illustrative in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.

[0013] The invention may be described herein in terms of functional and/or logical block components and various processing steps. It should be appreciated that such block components may be realized by any number of hardware, software, and/or firmware components configured to perform the specified functions. For example, an embodiment of the invention may employ various integrated circuit components, e.g., memory elements, digital signal processing elements, logic elements, look-up tables, or the like, which may carry out a variety of functions under the control of one or more microprocessors or other control devices. In addition, those skilled in the art will appreciate that the present invention may be practiced in conjunction with any number of data transmission protocols and that the system described herein is merely one exemplary application for the invention.

[0014] For the sake of brevity, conventional techniques related to wireless signal processing, wireless data transmission, WLANs, signaling, network control, and other functional aspects of the systems (and the individual operating components of the systems) may not be described in detail herein. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent example functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical embodiment.

[0015] The following description may refer to elements or features being "connected" or "coupled" together. As used herein, unless expressly stated otherwise, "connected" means that one element/feature is directly joined to (or directly communicates with) another element/feature, and not necessarily mechanically. Likewise, unless expressly stated otherwise, "coupled" means that one element/feature is directly or indirectly joined

to (or directly or indirectly communicates with) another element/feature, and not necessarily mechanically. Thus, although the figures may depict example arrangements of elements, additional intervening elements, devices, features, or components may be present in an actual embodiment (assuming that the functionality of the system is not adversely affected).

[0016] As used herein, the term "access point" means any component, device, feature, element, or function that is configured to receive/transmit wireless traffic from a wireless client device in a WLAN environment. Traditionally, an access point or an access point device refers to a hardware component that includes a radio module, memory, processing logic, and a network communication module that enables it to communicate with other network architecture components. Moreover, an access port or an access port device typically refers to a hardware component that includes a radio module, memory, a network communication module that enables it to communicate with other network architecture components, but only a subset of the processing logic needed to provide the wireless infrastructure. In this regard, an access port device is deployed in conjunction with a wireless switch, which includes the additional processing logic and memory that would otherwise be included in an equivalent access point device. For convenience, the term "access point" as used herein contemplates an access point device in the traditional sense, in addition to a subsystem that includes an access port device and a wireless switch. Moreover, the term "access point" contemplates any individual component, device, hardware, or system, and any combination thereof, that is configured to function in the manner described herein. For example, the QoS differentiation features described herein may be implemented in an untraditional architecture that combines the necessary radio module, processing power, memory, and the like with additional features not typically found in conventional stand-alone access point devices.

[0017] The WMM Specification (by Wi-Fi Alliance; www.wi-fi.org) provides for the distribution of WMM Parameters to mobile users in 802.11 beacons, probe responses, and association responses. Any WMM documentation publicly available from Wi-Fi Alliance, either online or otherwise, and IEEE Standard 802.11 (all variants) are incorporated by reference herein. In particular, "Wi-Fi CERTIFIED™ for WMM™ - Support for Multimedia Applications with Quality of Service in Wi-Fi® Networks," Wi- Fi Alliance (September 1, 2004) is incorporated by reference herein. The inclusion of the WMM Parameters in probe responses and association responses is mandatory for WMM enabled networks. The inclusion of the WMM Parameters in beacons, however, is

optional. If WMM Parameters are not included in beacons, then a beacon in a WMM enabled network must include a WMM Info Element, which indicates that WMM is enabled in that network. The WMM Info Element also includes a "parameter set count" which uniquely identifies the current WMM Parameter set.

[0018] In accordance with 802.11, wireless access points are typically associated with a basic service set ("BSS") and an extended service set ("ESS"). The general concept of having multiple ESSs (also known as multi-WLAN or virtual WLAN) is known. In a multi-ESS system, a beacon provides information for a "primary" WLAN only, while probe responses and/or association responses can provide information for the primary WLAN as well as other "secondary" WLANs that are assigned to the same BSS identifier ("BSSID") for the given access point device.

[0019] A network configured in accordance with an example embodiment of the invention extends the multi-ESS feature. In this example, in order to indicate that WMM is enabled on such a network, the WMM Info Element is included in the beacon. This Info Element contains a parameter set count, which is defined to be the same for all logical WLANs assigned to the corresponding BSSID (note that the parameter set count for all of these logical WLANs may change over time). The WMM Parameters, however, are delivered in the probe response and/or association response from the access point device, which allows the delivery of different QoS parameters to clients associated with different ESSs (i.e., different logical WLANs).

[0020] Thus, on the one hand, mobile users can identify that WMM is enabled on the network by observing the beacons and adopting the WMM Parameters from their respective probe responses and/or association responses; while on the other hand, the administrator can deliver different WMM Parameters to clients on different logical WLANs (again, this is because the clients only receive the QoS parameters in their respective probe responses and/or association responses). Since it is through differentiation of the WMM Parameters that the clients gain preferred (or non-preferred) access to the wireless transmission medium, this feature allows the administrator to differentiate between the access granted to the clients without requiring any special implementation on the client side (for example, through 802.1 Ie TSPECS). [0021] Note that it is even possible to disable WMM on one logical WLAN while having it enabled on another logical WLAN provisioned through the same access point device. In the case of the former logical WLAN, the probe response or association response would not contain any WMM Parameters, while in the latter logical WLAN, the

responses would contain the WMM Parameters. In the manner described herein, network administrators can provide differentiated wireless quality of service to different parts of a wireless network without requiring any special implementation on a client (aside from the base WMM certification).

[0022] FIG. 1 is a simplified schematic representation of a typical WLAN infrastructure 100, including mobile client devices 102/104, an access point 106, and a network architecture 108. As explained above, access point 106 may be realized as a subsystem that includes an access port device and a wireless switch coupled between the access port device and network architecture 108. A practical WLAN infrastructure 100 may include any number of mobile client devices and any number of access points dispersed throughout the area of coverage. A mobile client can be any computing device having the wireless transceiver and interface capabilities necessary to communicate with access point 106 via wireless links 110/112. Although not shown in FIG. 1, WLAN infrastructure 100 may include one or more wireless switches coupled between access points and network architecture 108. Access point 106 can communicate with the remaining network architecture 108 via any suitable data communication link 114, such as an Ethernet data cable. Network architecture 108 may include any number of traditional computer network components, including, but not limited to: switches, routers, servers, interfaces, data storage devices, or the like.

[0023] FIG. 2 is a schematic representation of an access point device 200 configured in accordance with an example embodiment of the invention. A practical embodiment of wireless access device 200 will include additional components and elements configured to support known or conventional operating features that need not be described in detail herein. In the example embodiment, wireless access device 200 is a wireless access point that transmits and receives data. An access point connects users to other users within the network and can also serve as the point of interconnection between a WLAN and a fixed wire network. Each access point can serve multiple users within a defined network area. As a wireless client moves beyond the range of one access point, the wireless client can be automatically handed over to another access device, e.g., a different access point or a wireless access port supported by a wireless switch. In practice, the number of wireless access devices in a given network generally increases with the number of network users and the physical size of the network.

[0024] Wireless access device 200 generally includes a physical housing (not shown), a radio module 202, a network communication module 204, a processor architecture 206,

and an appropriate amount of memory 208. A practical wireless access device 200 may of course include any number of radio modules, any number of network communication modules, any number of processor devices, and any number of memory elements; the illustrated device depicts a simple embodiment for ease of description. These and other elements of wireless access device 200 may be interconnected together using a bus 210 or any suitable interconnection arrangement. Such interconnection facilitates communication between the various elements of wireless access device 200. Those of skill in the art will understand that the various illustrative blocks, modules, circuits, and processing logic described in connection with the embodiments disclosed herein may be implemented in hardware, computer-readable software, firmware, or any practical combination thereof. To clearly illustrate this interchangeability and compatibility of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps are described generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software depends upon the particular application and design constraints imposed on the overall system. Those familiar with the concepts described herein may implement such functionality in a suitable manner for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. [0025] Radio module 202, which includes a receiver and a transmitter (or a transceiver), is configured to communicate with wireless clients via a wireless data communication link 212. Radio module 202 may cooperate with a suitably configured RF antenna arrangement (not shown) that supports the particular wireless communication protocol. In the example embodiment, radio module 202 is configured to support WLAN connectivity in compliance with established IEEE Standards, such as 802.11, 802.11a, 802.11b, and 802.1 Ig. Of course, radio module 202 may be configured to support alternate or additional wireless data communication protocols, including future variations of 802.11 such as 802. Hn.

[0026] Network communication module 204 generally represents the hardware, software, firmware, processing logic, and/or other components of wireless access device 200 that enable bi-directional communication between wireless access device 200 and network components to which wireless access device 200 is connected. For example, network communication module 204 may be configured to support 10/100 Mbps Ethernet LAN traffic. Referring to FIG. 1 as an example, network communication module 204 is suitably configured to transmit data to components in network architecture 108, and to

receive data from components in network architecture 108. In a typical deployment, network communication module 204 provides an Ethernet interface such that wireless access device 200 can communicate with a conventional Ethernet-based computer network. In this regard, network communication module 204 may include a physical interface, such as 10/100/1000 Mbps, for connection to the computer network, and network communication module 204 (and/or processor 206) may handle Ethernet addressing for data packets sent from wireless access device 200.

[0027] Processor architecture 206 may be implemented or realized with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. In this regard, a processor may be realized as a microprocessor, a controller, a microcontroller, a state machine, or the like. A processor may also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration. In practice, processor architecture 206 includes processing logic that is configured to carry out the functions, techniques, and processing tasks associated with the operation of wireless access device 200. In particular, the processing logic is configured to support the QoS differentiation techniques described herein. As mentioned above, in practical embodiments the processing logic may be resident in an access point device that includes radio module 202, or in a wireless switch (which may be considered to be part of network architecture 108) that communicates with an access port device that includes radio module 202.

[0028] Furthermore, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in firmware, in a software module executed by processor architecture 206, or in any practical combination thereof. A software module may reside in memory 208, which may be realized as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In this regard, memory 208 can be coupled to processor architecture 206 such that processor architecture 206 can read information from, and write information to, memory 208. In the alternative, memory 208 may be

integral to processor architecture 206. As an example, processor architecture 206 and memory 208 may reside in an ASIC.

[0029] The concept of a BSS is defined in IEEE Standard 802.11. In practice, a given mobile client is associated with a single BSS. Therefore, from a hardware perspective, a BSS is unique to a given access point, since a mobile client at any given time communicates with one access point. Thus, under 802.11, there is a one-to-one correspondence between an access point and a BSS. For example, a conventional 802.11 WLAN having five access points would utilize five BSSs. A BSS is an abstraction of an access point; the BSS defines or identifies the communication channel for the access point, the access point is configured to utilize certain data rates, the access point provides access to the network architecture, etc. In other words, a BSS defines or indicates operating parameters, characteristics, and qualities of its corresponding access point. The concept of an ESS is also defined in IEEE Standard 802.11. Conceptually, an ESS is a superset of BSSs. An ESS represents those properties that are common to a set of BSSs. The ESS allows a single mobile client to move from one BSS to another BSS within the WLAN environment, while still maintaining connectivity to the network. An ESS has a name or identifier ("ESS ID") and a mobile client is configured for that named ESS, and the ESS will typically include some form of security measure, e.g., authentication, encryption, etc. In accordance with the present invention, the ESS may also have a corresponding set of QoS parameters.

[0030] Under 802.11, a single BSS usually corresponds to a single access point, and a single ESS is configured on multiple access points to constitute a single WLAN. As an extension to this general methodology, some networks provision multiple ESSs for a single BSS. Thus, for a given access point, there can be any number of different ESSs that can be used to create multiple virtual WLANs supported by the same WLAN infrastructure equipment. Thus, the equipment can service different types or categories of clients. For example, one category of clients may be associated with a premium level of service that provides higher quality multimedia transmission, while another category of clients may be associated with a lower level of service that may not provide consistently high quality multimedia transmission. Such an arrangement may be desirable to justify premium access charges for customers in the first category. This allows a single access point to support communication with a plurality of different logical WLAN types. For example, the access point may use one ESS ID to provide restricted access to network data for some users, and another, different ESS ID to provide unrestricted access to the

network data for authorized users. These multiple ESSs can virtualize the WLAN to provide isolation for certain resources and/or data.

[0031] The WMM specification, from Wi-Fi Alliance, is a subset of the IEEE 802.1 Ie specification. WMM relates to the handling of multimedia over a WLAN. WMM generally specifies a technique for prioritizing data depending upon the type of data being transmitted. For example, voice data and video data, which is typically sensitive to transmission delay, may be prioritized higher than other data, such as web browser traffic, that is not as time sensitive. Thus, the transmitter (for either the mobile device or the access point) will use different parameters depending upon the type of data. In the example embodiment, there are four WMM priority levels, and four WMM parameters that control the QoS for each priority level. The WMM priority levels (in increasing order) are: background; best effort; video; and voice. The priority levels are mapped to the eight priority levels set forth in IEEE Standard 802. l(d), the content of which is incorporated by reference herein. Two of the 802. l(d) levels are mapped to each WMM priority level. In the practical embodiment, the WMM parameters are: contention window minimum; contention window maximum; arbitration interframe spacing; and the transmit opportunity time.

[0032] More aggressive parameters can be used for voice and video, thus increasing the likelihood that such data will be transmitted quickly. Two sets of parameters are utilized for WMM: mobile client device parameters and access point parameters. Under the WMM specification, the access point delivers the client parameters to the client device when the client device attaches to the network. The client then assumes those client parameters for communication with the access point. The WMM specification, like 802.11, assumes that only one set of client parameters are used per ESS, and assumes that there is a one-to-one relationship between an ESS and a BSS. In other words, WMM assumes that only one set of parameters will be delivered by any given access point. [0033] The WMM parameters are delivered using 802.11 beacons, probe responses, and association responses, which are management frames. A beacon is broadcast from an access point on a periodic basis. According to 802.11, a beacon is transmitted for a BSS, and a beacon provides parameters for that particular BSS. It includes information about the BSS, and possibly some information about the associated ESS. In a multi-ESS implementation, a primary ESS is identified in the beacon, and other related ESSs are provided elsewhere. When a client is searching for a network, it transmits a probe frame. An access point within range of the client device will respond with a probe response. If

the client device is seeking a network connection, then it sends an association request to the access point. An association response, which is sent by the access point in response to an association request, is utilized to establish the communication channel between the mobile device and the access point.

[0034] In accordance with the example embodiment of the invention, a WMM Info Element is placed into the beacon; the WMM Info Element includes a parameter set count for all of the ESSs that are tied to the particular BSS. The parameter set count is an identifier, such as a number, that identifies the current WMM parameter set. Over time, the parameter set count may change to indicate an updated WMM parameter set for the ESSs for the given BSS. Thus, the parameter set count is initialized to the same value for all of the multiple ESSs. Then, the actual WMM parameters are delivered in the probe responses and association responses. Since the probe responses and association responses are uniquely tied to a given ESS, the administrator can deliver different WMM parameters on an ESS-by-ESS basis.

[0035] In accordance with the invention, a single access point can be configured to deliver a plurality of WMM client parameter sets to client devices, depending upon which ESS the client devices are linked to within a multi-ESS system. This is significant because it allows the network administrator to permit preferred access (i.e., QoS) to certain client devices connected to certain ESSs, and non-preferred access to other client devices connected to other ESSs. If a user of a given client device is a "preferred" customer, then that client device will be able to connect to the particular ESS that is associated with the preferred level of service. The network, via the access point, can grant access to that ESS in response to an authentication/association process. As part of the process of connecting to that ESS, the client receives the WMM client parameters from the access point.

[0036] FIG. 3 is a schematic representation of a logical structure 300 that may be employed in the access point device shown in FIG. 2. In this regard, the access point 302 is suitably configured to support any number of different ESSs (i.e., different virtual WLANs): ESS-I, ESS-2, and so on, up to ESS-JV, within the practical limitations of the network architecture and operating environment. The techniques of the present invention can be implemented to control whether WMM is enabled on a given virtual ESS, and the specific parameters a mobile client device will use to gain access to the medium. For example, the network administrator can configure a given ESS such that WMM is enabled or disabled. In this example, ESS-I and ESS-2 are WMM enabled, while ESS-TV

is WMM disabled. Thus, mobile client devices on ESS-I or ESS-2 would be able to send and receive prioritized data in the manner described herein. Moreover, the network administrator can configure the WMM parameters for the WMM-enabled ESSs to provide differentiated QoS. For example, the WMM Parameter Set 1 (for ESS-I) may be less aggressive than the WMM Parameter Set 2 (for ESS-2). As a result, although mobile client devices on both ESS-I and ESS-2 can send and receive data in a prioritized manner, the user on ESS-2 will obtain a better QoS (QoS_2 in this example) than the user on ESS-I (QoS_l in this example). For example, QoS_2 may correspond to a level of quality needed to support streaming video multimedia applications, while QoS_l may correspond to a level of quality that only supports applications that are less sensitive to transmission latency, such as web browsing. Referring again to FIG. 2, memory 208 may be configured to store the different QoS parameter sets (e.g., the WMM Parameter Sets) and the corresponding ESS IDs depicted in logical structure 300.

[0037] In practice, the quality of service provided by QoS_2 may result in a more consistent video experience and/or clearer voice-over-IP sound for the user on ESS-2. In contrast, the mobile client device on ESS-N would still be able to send and receive voice or video data, but the client device transceiver and the transceiver of access point 302 would not treat this data traffic in any prioritized way relative to other types of traffic. In other words, the QoS for a device on ESS-N (QoS_N in this example) is not controlled by WMM parameters as described above for devices on ESS-I or ESS-2. Thus, access point 302 can be suitably configured and controlled to handle data traffic in a differentiated manner (i.e., whether the data is prioritized and, if so, how the data is prioritized). In the example embodiment, a WLAν architecture configured in accordance with the invention need not limit or restrict the type of data that is handled by a particular virtual ESS; rather, the manner in which the data is handled can be specified for each virtual ESS supported by the WLAν architecture.

[0038] FIG. 4 is a schematic representation of a WLAν environment 400 having three access points 402/404/406, each connected in a common WLAν infrastructure. Each access point can support a plurality of different ESSs, in this example, ESSl, ESS2, and ESS3, where each ESS represents a different logical WLAν having different QoS parameters for data access and transmission. FIG. 4 also depicts a number of mobile devices communicating with the access points. For example, a first mobile device 408 is communicating with access point 402 in the ESSl domain. A second mobile device 410 is communicating with access point 404 in the ESS2 domain. A third mobile device 412

is communicating with access point 406 in the ESS3 domain. A fourth mobile device 414 is communicating with access point 406 in the ESS2 domain. These mobile devices use the QoS or WMM parameters received from the respective access points in the manner described above. Notably, as the mobile devices move around the environment 400, different access points may support communication using the same (or different) ESS domain as needed.

[0039] Assuming that a client device supports the WMM specification such that it could achieve the basic Wi-Fi WMM certification, no modification to the client device is needed to deploy the techniques described herein. The access points (or wireless switches), however, may need to be modified to support the WMM parameter delivery techniques.

[0040] FIG. 5 is a flow chart of a QoS differentiation process 500 that may be performed by an access point device configured in accordance with an example embodiment of the invention. The various tasks performed in connection with process 500 may be performed by software, hardware, firmware, or any combination thereof. For illustrative purposes, the following description of process 500 may refer to elements mentioned above in connection with FIGS. 1-4. hi practical embodiments, portions of process 500 may be performed by different elements of the described system. It should be appreciated that process 500 may include any number of additional or alternative tasks, the tasks shown in FIG. 5 need not be performed in the illustrated order, and process 500 may be incorporated into a more comprehensive procedure or process having additional functionality not described in detail herein.

[0041] QoS differentiation process 500 presumes that the client device and access point support the multiple virtual/logical WLAN arrangement described above. Moreover, process 500 presumes that the client device and access point support a compatible QoS parameter exchange scheme as described above. For example, a practical embodiment of process 500 may be deployed in a WLAN environment that supports 802.1 Ie, the WMM Specification, or any similar standard, protocol, or operating scheme that can provide QoS differentiation in the manner described herein. [0042] In practice, the process of QoS differentiation is initiated when the access point device advertises the available logical WLANs and their different respective QoS settings/parameters in the beacons and probe responses as described above. QoS differentiation process 500 may begin when a mobile client device attempts to establish an association with an identified logical WLAN. In this regard, the access point device

receives the association request from the client device (task 502). In practice, the identified logical WLAN is one of a plurality of logical WLAN configurations supported by the wireless access point under consideration. Briefly, task 502 may include an exchange of packets or frames between the client device and the access point, where the exchange enables the client device to request a connection with a particular logical WLAN.

[0043] In addition, QoS differentiation process 500 may identify the ESS properties corresponding to a logical WLAN (task 504). In practical embodiments, the ESS ID and other parameters corresponding to the ESS may be identified and/or processed during the negotiation described above for task 502. For example, the access point or wireless switch may identify or correlate the ESS corresponding to the received ESS ID so that the access point or wireless switch can obtain or access the appropriate QoS parameter set for that ESS. As mentioned above in connection with FIG. 3, the access point device may maintain a table or other logical structure that links each ESS ID with its respective QoS and/or QoS parameter set. Thus, process 500 can obtain the ESS ID for the approved logical WLAN and identify the QoS parameters corresponding to that ESS ID. Thereafter, process 500 sends the appropriate QoS parameters to the client device (task 506). In practice, the access point transmits the QoS parameters to the client device via the wireless communication link.

[0044] In practical embodiments, process 500 may perform an authentication procedure to authenticate the client device for an approved logical WLAN (task 508). For example, before granting access to a requested logical WLAN, process 500 may require the user of the client device to enter a username and password for processing by the access device and/or by other components in the attached network architecture. In this manner, process 500 can identify an approved logical WLAN for the client device. [0045] In the example embodiment, the delivered QoS parameters are a set of parameters, where each member of the set corresponds to one of the priority levels available. Therefore, each complete set of QoS parameters specifies the parameters for all available priority levels. In the example embodiment, the priority levels include a voice priority level (highest relative priority), a video priority level (next highest relative priority), a best effort priority level (a default priority), and a background priority level (lowest relative priority). The specified QoS parameters for the client device influence data type prioritization for data transmission between the mobile client device and the wireless access point. The relative advantage of one parameter set over another

parameter set is determined by the relationship between the parameters. In the above example, if the QoS parameters for QoS_2 have a contention window minimum of 1 for voice priority, and the QoS parameters for QoS_l have a contention window minimum of 3 for voice priority, then voice traffic in ESS-2 will generally get better access to the wireless medium than voice traffic in ESS-I (all other factors being equal). Assuming the client device has received the parameters from the access point, QoS differentiation process 500 can then provide the client device with the specified QoS for data traffic between that client device and the associated access point (task 510). In practice, task 510 will schedule data traffic between the client device and the access point in accordance with the specified QoS. For the example situation where the client device has the best QoS parameters, task 510 enhances the user's voice and video experience by giving that client device prioritized access to the wireless transmission medium. [0046] FIG. 6 is an example sequence diagram 600 depicting communication between a client device 602 and an access point device 604, where client device 602 and access point device 604 are both configured to support the QoS differentiation techniques described above. Sequence diagram 600 illustrates the establishment of differentiated QoS in a WLAN environment, which may also include various network architecture components 606. Although not a requirement of the invention, the technique described above is particularly suited for use with WMM compliant and 802.11 compliant WLAN environments. In this regard, sequence diagram 600 refers to items, features, and operations found in the 802.11 family of specifications and the WMM specification. For the sake of brevity, known aspects of such items, features, and operations will not be described in detail herein.

[0047] Access point 604 periodically broadcasts beacons, which are associated with a particular BSS. A beacon generally provides operating parameters for the associated BSS. A beacon can be received by all compatible wireless client devices 602 within range of access point 604. The arrow 606 in FIG. 6 represents a beacon transmitted by access point 604 (in reality, access point 604 may transmit more than one beacon within the time period depicted in FIG. 6). In this example embodiment, the WMM parameters are not included in beacon 606. Rather, beacon 606 includes a WMM Info Element that indicates that WMM is enabled for the transmitting access point 604 (in contrast, if WMM is not enabled for the transmitting access point 604, then beacon 606 will not include a WMM Info Element). This Info Element in beacon 606 also includes the current parameter set count, which will be the same for all of the ESSs (and, therefore, for

all of the logical WLANs) maintained by access point 604. In addition, beacon 606 may include the ESS ID for the primary ESS designated for access point 604. In this example embodiment, beacon 606 does not identify any secondary ESSs supported by access point 604. It should be noted that the use of beacons as described above is not mandatory for purposes of providing QoS differentiation. They are, however, mandatory from the standpoint of compliance with 802.11 and the WMM Specification. [0048] Client device 602 can send probe frames to access point devices in an attempt to discover the available access point devices within range and the respective parameters of the available logical WLANs. The arrow 610 represents a probe frame transmitted by client device 602. Briefly, client device 602 can "search" for a particular logical WLAN by sending a probe frame that contains the ESS ID corresponding to that logical WLAN. In the example embodiment, a probe frame may include the ESS ID for the primary ESS or for any of the secondary ESSs. With respect to the QoS differentiation technique described herein, probe frames aid the user in determining whether WMM is enabled or disabled for a given logical WLAN (insofar as the probe response does or does not contain the WMM parameters). Although probe frames are optional, they provide an efficient mechanism for client device 602 to discover access points within the area (rather than simply waiting and "listening" for beacons). Moreover, unlike beacons, probe frames allow discovery of secondary ESSs in a multi-ESS system.

[0049] A probe response is a frame transmitted by an access point in response to a probe frame. For example, if access point device 604 recognizes the ESS ID contained in probe frame 610, then it will send a probe response frame 612 back to client device 602. If, however, access point device 604 does not recognize the requested ESS ID, then it will simply ignore the probe. This exchange is desirable to enable client devices to discover access points without having to wait for the periodic beacons. This exchange also allows client devices to discover secondary ESSs. In accordance with the example QoS differentiation technique, probe response frame 612 includes the WMM parameters corresponding to the recognized ESS ID (again, the recognized ESS ID may be for the primary ESS or any of the secondary ESSs). In addition, probe response frame 612 may include the current parameter set count for the recognized ESS ID. Since probe responses are associated with a specific ESS ID and, therefore, a specific logical WLAN, the network administrator can provide different QoS parameters for different logical WLANs. Notably, if WMM is not enabled for the recognized ESS ID, then probe response frame 612 will not include any WMM parameters.

[0050] A client device transmits an association request when it wants to establish a connection through an access point. In other words, an association request initiates a connection. In this example, an association request includes the ESS ID for the logical WLAN requested by the client device. The arrow 614 in FIG. 6 represents an association request transmitted by client device 602. In response to association request 614, access point device 604 sends an association response 616 back to the requesting client device 602. Association response 616 may grant (as illustrated) or deny network access to client device 602.

[0051] Assuming that client device 602 is granted network access, then association response 616 may include the appropriate WMM parameters to provide the specified QoS. In accordance with the example QoS differentiation technique, association response 616 includes the WMM parameters corresponding to the requested ESS ID (again, this ESS ID may be for the primary ESS or any of the secondary ESSs). In addition, association response 616 may include the current parameter set count for the recognized ESS ID. Since association responses are associated with a specific ESS ID and, therefore, a specific logical WLAN, the network administrator can provide different QoS parameters for different logical WLANs. Notably, if WMM is not enabled for the requested ESS ID, then association response frame 616 will not include any WMM parameters.

[0052] In practical embodiments, access point device 604 may carry out an authentication procedure 618 to determine whether to grant or deny access to client device 602. As depicted in FIG. 6, authentication procedure 618 may cooperate with one or more network architecture components 606 to determine whether the user of client device 602 is authorized to log in to the identified logical WLAN, and authentication procedure 618 may (but need not) include an identification or transmission of the desired ESS ID for processing by the network architecture components 606. [0053] The negotiation of parameters described above enables the WLAN architecture to provide differentiated QoS for a plurality of logical WLANs supported by access point device 604. The differentiated QoS results in prioritized data traffic handling based not only on data type, but also on logical wireless network segmentation. The arrow 620 in FIG. 6 depicts the ongoing data communication session between client device 602 and access point 604. At this point, data traffic is managed in accordance with the WMM specification.

[0054] While at least one example embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the example embodiment or embodiments described herein are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the described embodiment or embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.