Patent Publication Number: US-2005138178-A1

Title: Wireless mobility manager

Description:
FIELD  
      Embodiments of the invention generally relate to the field of wireless communications. More particularly, one or more embodiments of the invention relate to a wireless mobility manager and its method of operation.  
     GENERAL BACKGROUND  
      Wireless technology provides a mechanism for either replacing or extending traditional wired networks including, but not limited to, local area networks (LANS), personal area networks (PAN) and metropolitan area networks (MAN). Using radio frequency (RF) or non-RF technology, wireless networks transmit and receive data over the air, through walls, ceilings and even cement structures without wired cabling. For example, a wireless LAN (WLAN) is a flexible data communication system that provides all the features and benefits of traditional LAN technology, such as Ethernet and Token Ring, but without the limitations of being tethered together by a cable. This provides increased freedom and flexibility.  
      In other words, a WLAN is a network in which a mobile user can connect to a local area network (LAN) through a wireless (radio) connection according to a wireless protocol. Wireless protocols include, but are not limited to IEEE 802.11 (e.g., IEEE 802.11a, 802.11b, 802.11g), HiperLAN (e.g., HiperLAN1, HiperLAN2, etc.), or any other wireless communication protocol. These wireless protocols are designed to provide high bandwidth allocation at a relatively low cost, without the need for substantial rewiring of various structures.  
      Mobility is a major motivation for deploying a wireless network. This mobility allows devices to move while connected to the network and transit frames while in motion. However, the mobility provided by wireless networks is restricted by several constraints. For example, wireless networks are implemented at the link layer, and therefore, are limited to providing link layer mobility. By way of contrast, the Internet protocol (IP) affords the network designer no such luxury. Although wireless devices can freely move within a network, IP, as it is currently deployed, provides no way to move across subnet boundaries.  
      In other words, one current requirement for mobility of a wireless device is that the IP address of the wireless device can not change when connecting to any of the access points. Accordingly, all wireless devices must remain on the same subnet. As long as the wireless device stays on the same IP subnet, it does not need to re-initialize its network stack and it can keep its transmission control protocol (TCP) connections open. However, if the wireless device leaves the subnet, the device is required to get a new IP address and re-establish any open connection.  
      Accordingly, wireless device mobility is limited to various access points within a single subnet. Furthermore, as the wireless device moves between the various access points of the single IP subnet, the wireless device must perform an authentication and association procedure with a new subnet access point. Therefore, as the wireless device roams within the subnet, the user must know and manually enter a Wired Equivalence Privacy (WEP) key in order to switch between access points of the subnet to maintain communication with the subnet. This increases the amount of user activity required to roam within a subnet.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The various embodiments of the present invention are illustrated by way of example, and not by way of limitation, in the figures of the accompany drawings, and in which:  
       FIG. 1  is a block diagram illustrating a communication system, including one or more wireless stations having a wireless mobility manager, in accordance with one embodiment of the invention.  
       FIG. 2  is a block diagram further illustrating a wireless station of  FIG. 1 , in accordance with the further embodiment of the invention.  
       FIG. 3  is a diagram illustrating a user interface of a wireless station for setting switch and scan thresholds, in accordance with one embodiment of the invention.  
       FIG. 4  is a diagram illustrating a user interface screen of a wireless station for selection of a communications interface, in accordance with one embodiment of the invention.  
       FIG. 5  is a block diagram further illustrating the communication system of  FIG. 1  to show wireless station subnet roaming, in accordance with one embodiment of the invention.  
       FIG. 6  is a flowchart illustrating a method for providing a continuous wireless connection according to a user selected SCAN THRESHOLD and to a user selected SWITCH THRESHOLD, in accordance with one embodiment of the invention.  
       FIG. 7  is a block diagram illustrating a method for downloading an access point list to enable access point scanning, in accordance with one embodiment of the invention.  
       FIG. 8  is a flowchart illustrating a method for establishing a wireless connection with the selected access point, in accordance with one embodiment of the invention.  
       FIG. 9  is a flowchart for establishing a wireless connection with a selected access point to provide a pre-allocated bandwidth to a wireless station, in accordance with one embodiment of the invention.  
       FIG. 10  is a flowchart illustrating a method for wireless station roaming from an access point of a first network to a selected access point of a second network, in accordance with one embodiment of the invention.  
       FIG. 11  is a flowchart illustrating a method for scanning for selected access points of a second network, in accordance with one embodiment of the invention.  
       FIG. 12  is a flowchart illustrating a method for detecting one or more access points of a second network, in accordance with one embodiment of the invention.  
       FIG. 13  is a flowchart illustrating a method for establishing a wireless connection with a selected access point of a second network, in accordance with one embodiment of the invention.  
    
    
     DETAILED DESCRIPTION  
      Embodiments of the invention generally relate to a wireless mobility manager and its associated operation as described herein. In one embodiment of the invention, a wireless mobility manager monitors the signal quality of a current wireless connection to a wireless access point. Without user intervention, a scan may be conducted to identify one or more wireless access points within a current communication range when the signal quality of the current wireless connection falls below a SCAN THRESHOLD. The signal quality may be based on signal strength, signal-to-noise ratio (SNR), error rate, connection count or the like. The SCAN THRESHOLD may be either a preset value or a programmable value that is set by the user.  
      Once scanning is complete, the wireless mobility manager determines whether the signal quality of the current wireless connection falls below a SWITCH THRESHOLD, either a preset value or a programmable value that is set by the user and normally less than the SCAN THRESHOLD. If so, the wireless mobility manager allows the wireless station to establish a new wireless connection with another wireless access point selected from the one or more identified access points. This “handoff” is conducted without user intervention as well.  
      According to another embodiment of the invention, the wireless station, having a wireless connection with an access point of a first network, roams into communication range of a second network. Once the wireless station roams into communication range of the second network, the wireless station establishes a wireless connection with a selected access point of the second network. In one embodiment of the invention, the wireless mobility manager of the wireless station determines a signal strength of one or more access points of the second network. In addition, the wireless station may determine various quality of service (QoS) characteristics of the identified access points in order to select an access point based on signal strength and/or QoS characteristics. Hence, the user of the wireless station experiences a quality of service from the selected access point, which is roughly equivalent to the level of service provided by a current wireless connection while experiencing a continuous wireless network connection without requiring user intervention.  
      In the following description, certain terminology is used to describe features of the invention. For example, the term “group” represents one or more. The term “logic” is representative of hardware and/or software configured to perform one or more functions. For instance, examples of “hardware” include, but are not limited or restricted to, an integrated circuit, a finite state machine or even combinatorial logic. The integrated circuit may take the form of a processor such as a microprocessor, application specific integrated circuit, a digital signal processor, a micro-controller, or the like.  
      An example of “software” includes executable code in the form of an application, an applet, a routine or even a series of instructions. The software may be stored in any type of machine readable medium such as a programmable electronic circuit, a semiconductor memory device inclusive of volatile memory (e.g., random access memory, etc.) and/or non-volatile memory (e.g., any type of read-only memory “ROM,” flash memory), a floppy diskette, an optical disk (e.g., compact disk or digital video disk “DVD”), a hard drive disk, tape, or the like.  
      The term “wireless station” or “station” is used to refer to a portable device adapted to receive and/or transmit wireless data. Examples of a wireless station include, but are not limited to a computer, a personal digital assistant (PDA), a wireless appliance, or any other portable device configured to communicate via a wireless communications medium such as, for example, radio frequency (RF) waves.  
      Furthermore, as described herein, the term “access point” or “AP” is an electronic device that provides a connection between one or more wireless stations and a network such as the wired interconnect. According to one embodiment, the connection is bi-directional although this bi-directional connection is not a requirement.  
      I. System Architecture  
       FIG. 1  is an exemplary block diagram illustrating a mobility communications system  100  with a wireless station roaming from a first network (or first subnet) to a second network (or a second subnet). According to one embodiment of the invention, mobility communications system  100  comprises a local area network (LAN) backbone  110 . LAN backbone  110  is a wired interconnect (e.g., one or more electrical wires, cable, optical fiber, etc.) that establishes communications with a wide area network (WAN), such as the Internet  102  for example, via a router  106  and a firewall  104 .  
      A virtual private network (VPN) server  160  may be included in the mobility communications system  100  to provide security and encryption/decryption capabilities to the system  100  utilizing, for example, the IP Security (IPSec) protocol. A remote authentication dial-in user service (RADIUS) server  190  may be included in mobility communications system  100  to provide authentication and accounting of users of the system  100 . Other authentication protocols and server systems may be implemented as well, and integration with other authentication protocols, such as the Diameter protocol, for example, may be implemented. Furthermore, a domain server  180  may be included in mobility communications system  100  to facilitate access to and from the Internet  102  via router  106 .  
      Herein, as an example, one or more wireless local area networks (WLAN)  200  are coupled LAN backbone  110 . Such coupling may be accomplished by multiple routers or a single router  170  as shown. In one embodiment of the invention, each WLAN  200  comprises a switch  210  that is coupled to a node server  220 . Although generally referenced as WLAN  200 , switch  210  and node server  220 , each of these elements are separately and specifically represented as WLAN  200 - 1  . . . WLAN  200 -N (N≧1), switch  210 - 1  . . . switch  210 -N, and node server  220 - 1  . . . node server  220 -N, respectively. Each WLAN  200  also comprises one or more access points (AP)  230  (e.g., AP  230 - 1 , . . . , AP  230 -M, where M≧1).  
      More specifically, WLAN  200 - 1  is being accessed by wireless stations  300 - 1  and  300 - 2 . In this illustrated embodiment, for example, wireless station  300 - 1  accesses WLAN  200 - 1  via AP  230 - 1 . Likewise, wireless station  300 - 2  accesses WLAN  200 - 1  via AP  230 - 2 . Herein, both APs  230 - 1  and  230 - 2  are represented as being part of the same subnet. A different WLAN, namely WLAN  200 -N, provides a similar configuration to WLAN  200 - 1 .  
      Prior to communicating data, wireless stations  300  establish an association with their corresponding APs  230 . After an association is established, wireless stations  300  and APs  230  exchange data. In the infrastructure mode, the wireless stations  300  associate with an access point. The association process is a two step process involving three states: (1) “unauthenticated and unassociated”; (2) “authenticated and unassociated”; and (3) “authenticated and associated”. To transition between the states, the communicating parties exchange messages called management frames. In operation, all APs transmit a beacon management frame at a fixed interval.  
      As an example, to associate with an AP  230 - 2  and join a wireless network, a wireless station  300 - 2  listens for beacons to identify APs within its communication range. After identifying AP  230 - 2 , the wireless station  300 - 2  and the AP  230 - 2  may perform a mutual authentication by exchanging several management frames as part of the process. After successful authentication, the wireless station  300 - 2  moves into the second state, authenticated and unassociated. Moving from the second state to the third and final state, authenticated and associated, involves the wireless station  300 - 2  sending an association request frame and the AP responding with an association response frame.  
      In one embodiment of the invention, mobility communications system  100  may be configured as an enterprise network with various APs throughout the floors of the building or different buildings and surroundings forming a corporate campus. APs  230  communicate with wireless stations  300  via radio frequency waves, such as, for example, according to an IEEE 802.11 protocol, a HiperLAN protocol or the like. Unfortunately, as wireless station  300 - 2  roams, association with a detected AP of a WLAN or subnet may be prohibited without wireless station  300 - 2  having some form of authentication information to enable association with a selected AP. In one embodiment, a wireless station  300 - 2  may roam from WLAN  200 - 1  to WLAN  200 -N, while maintaining a continuous wireless connection to mobility communications network  100  without requiring any user intervention.  
      In one embodiment of the invention, a continuous wireless connection is enabled by downloading an AP list to which a user of wireless station  300 - 2  has user access privileges. Accordingly, as a user roams throughout mobility communications network  100 , wireless station  300 - 2  maintains a connection with network  100  without requiring user intervention. In one embodiment of the invention, mobile communications (MCS) server  120  is configured to provide a wireless station, upon initial login, with an AP list that contains each AP to which a user of the wireless station has access privileges.  
      According to conventional techniques, wireless AP switching, which may be referred to herein as “AP hand off” is generally not performed by a wireless station until a signal level of the station is unusable. Furthermore, conventional techniques prohibit a wireless station from roaming from a first subnet, such as WLAN  200 - 1 , to a second subnet, such as WLAN  200 -N, since an Internet protocol (IP) address assigned to the wireless station will not allow the wireless station to function within the second subnet without requesting assignment of a new IP address. Furthermore, wireless AP switching does not generally enable voice communication since bandwidth pre-allocation for quality of service (QoS) or load balancing is not provided via conventional techniques.  
      Accordingly, in one embodiment of the invention, wireless stations  300  are configured to include a wireless mobility manager (WMM), which functions in conjunction with MCS server  120 , as well as QoS/load balance server  130 , to enable wireless AP scan and subsequent AP switching. This provides the user with a continuous wireless connection to mobility communications network  100  without user intervention.  
      Moreover, a dynamic host configuration protocol (DHCP) and/or a dynamic rapid configuration protocol (DRCP) server  150 , also connected LAN backbone  110 , are configured to assign IP addresses to the nodes of mobility communications network  100 , as well as an IP address for subnet roaming. Accordingly, in one embodiment, wireless stations  300  are configured, as is depicted with reference to  FIG. 2 .  
      Referring now to  FIG. 2 , an exemplary embodiment of wireless station  300  is shown. Herein, wireless station  300  comprises a processor (MP)  302  in communication with wireless mobility manager (WMM) logic  400  via a chipset  310 . MP  302  and WMM logic  400  collectively operate to perform signal analysis, association, handoff and other operations. The chipset  310  is further coupled to a communications interface  320 , a memory  350  (e.g., persistent memory such as the registry) and user interface logic  360  as described below.  
      As illustrated, wireless station  300  may download an AP list  450 , which includes one or more APs (and perhaps stations) of, for example, each node or subnet of mobility communications system  100  ( FIG. 1 ). In one embodiment, AP handoff logic  410  of WMM logic  400  retries a list of member APs from the MCS server  120  ( FIG. 1 ), via a secure socket (SDL), authenticated simple object access protocol (SOAP) connection. According to one embodiment of the invention, the AP list  450  may be stored in an encrypted format based on the user&#39;s shared secret (e.g., MCS password). The user&#39;s shared secret is never stored on the station  300 .  
      In one embodiment of the invention, AP list  450  may comprise, for example, a data structure, as depicted with reference to Table 1. This differs from conventional wireless AP switching which requires user intervention to provide a name (SSID) and to manually enter a wired equivalence privacy (WEP) key before the user&#39;s wireless station associates with a selected AP. Conversely, AP list  450  provides the necessary information to wireless station  300  to enable automatic association with any member APs, via communications interface  320 , without requiring any user intervention.  
                               TABLE 1                               AP                       Authenti-                   AP   cation   AP   Subnet       AP   MAC   Informa-   IP   IP       SSID   Address   tion   Address   Address                  ITSUM01   00022D38100c   Secret 1   172.24.13.200   172.24.13.201                  
 
      In one embodiment of the invention, the wireless station switching described herein is supported by WMM logic  400 . As illustrated, AP handoff logic  410 , in one embodiment, includes or operates in conjunction with AP scan logic  420 . AP scan logic  420  uses a user selected SCAN THRESHOLD, which is compared to, for example, a signal strength of a current wireless connection to an AP by wireless station  300 . In one embodiment, when the signal strength of the current wireless connection falls below the SCAN THRESHOLD, AP scan logic  420  will utilize AP list  450  to identify one or more APs within the communication range of the station, for example, as illustrated with reference to  FIG. 5 .  
      In one embodiment, scan logic  420  uses a wireless media access control (MAC) address to identify AP membership regarding one or more identified APs. Accordingly, WMM logic  400  operation is possible even if the APs do not broadcast their service set identity (SSID) identifier for security reasons, and it is also possible to have multiple APs with the same SSID operational as well. Therefore, a correct wireless MAC address and SSID for each AP is entered into an AP database (not shown). Usually, the MAC address is found on a label on the back of the wireless AP. Accordingly, AP list  450  comprises at least an SSID and a MAC address for each listed AP.  
      Once AP scan logic  420  identifies one or more available APs, AP switch logic  430  further monitors the current wireless connection of the wireless station to determine whether a signal strength of the current wireless connection falls below a user selected SWITCH THRESHOLD. When such is the case, AP switch logic  430  selects one of the identified APs and performs an authentication and association procedure with the selected AP. In one embodiment, the SCAN THRESHOLD, as well as the SWITCH THRESHOLD, are provided by a user via user interface (UI)  360 , which is further illustrated with reference to  FIGS. 3 and 4 .  
      As illustrated in  FIG. 3 , in one embodiment, MCS station screen  460  allows a user to enable WMM logic  400  ( FIG. 2 ). Once enabled, the user provides a SCAN THRESHOLD value as well as a SWITCH THRESHOLD value. These values may be selected from a group of predetermined values  462  and  464  (e.g., selected by slide bar or pull-down menu) or may be keyed in by the user. According to this illustrated embodiment, the SCAN THRESHOLD is set to −48 dBm, while the SWITCH THRESHOLD is set to −55 dBm.  
      Furthermore, screen  460  comprises a field  466  that indicates the number of currently available APs within the AP list. Also, screen  460  further comprises a user selection button  468 . According to one embodiment, when selected, the user selection button  468  automatically refresh a current AP list from MCS server  120  of  FIG. 1  for example. According to another embodiment, when selected, the user selection button  468  enables the user to update the current AP list and/or select a period of time when the current AP list will be updated automatically. The period of time, along with the SCAN THRESHOLD and SWITCH THRESHOLD values and path information for accessing AP list, may be stored in persistent memory of wireless station  300 , such as the registry of wireless station  300 .  
       FIG. 4  further illustrates another MCS station screen  470 , which allows a user to select between available network access adapter cards once the user logs into, for example, MCS server  120  of  FIG. 1 . For this embodiment, a wireless station may include multiple adapter cards. As such, in the embodiment, AP handoff logic  410  may further analyze identified APs to detect not only APs but other connection points, which may be compared to available wireless station adapter cards. WMM logic  400  switches between available connection points to, for example, reduce costs to a user to maintain continuous wireless/wired connection to, for example, mobility communications network  100  of  FIG. 1 .  
      Referring back to  FIG. 2 , AP handoff logic  410  includes or operates in conjunction with quality of service (QoS)/load balance logic  440 . In such an embodiment, wireless station  300  may request, for example, from a node server  220 , a connection count to each identified AP. This connection count may be used in conjunction with a signal strength of the detected AP. For instance, wireless station  300 - 2  may request a connection count and bandwidth from MCS server  120  ( FIG. 1 ). Alternatively, the connection count may be merely used to compute available bandwidth of each detected AP. Thus, AP handoff is based on how congested the detected AP is or may be in the future.  
      In a further embodiment, wireless station  300 - 2  may request, for example, from node server  220 - 1  and/or QoS/load balance server  130 , pre-allocation of a certain bandwidth from an available AP. QoS/load balance server  130  attempts to pre-allocate the selected bandwidth from an AP. Once server  130  assigns an AP with the requested bandwidth, QoS/load balancing server  130  provides AP handoff logic  410  with the selected AP, in addition to any connection information required to perform association and authentication with the selected AP.  
      Accordingly, referring to  FIG. 5 , mobility communications network  100  is shown to illustrate the communication range of APs  230 - 1 ,  230 - 2 ,  230 - 3  and  230 -M. As wireless station  300  roams within communication range of an AP, this action may or may not cause the signal strength of the wireless station to diminish. However, as the wireless station moves further away from a current wireless connection to an AP, its signal strength will diminish below the SCAN THRESHOLD, which will initiate scanning for additional APs.  
      For example, as illustrated, wireless station  300  will detect AP 2   230 - 2 , as well as AP 3   230 - 3 . As illustrated, wireless station  300  is currently connected to AP 1   230 - 1 . Furthermore, AP 2   230 - 2  is a member of the same subnet as AP 1 . Conversely, AP 3   230 - 3  is a member of second subnet  200 - 2 . As such, in order to perform association and authentication with AP 3   230 - 3 , wireless station may query AP list  450 . However, in order to continue uninterrupted data communications, wireless station  300  is required to use a new IP address for communications within subnet  200 - 2 .  
      According to one embodiment of the invention, MCS server  120  pre-requests a temporary IP address for wireless station  300 , which is included within AP list  450  corresponding to AP 3   230 - 3  and AP 4   230 -M. In an alternative embodiment, wireless station  300  detects that AP 3   230 - 3  is on a different subnet (“new subnet detection”) and requests an IP address to enable communication within the second subnet  200 - 2 . In one embodiment, new subnet detection is performed by evaluating the following conditional expression: 
 
(mask &amp; AP IP)=? (mask &amp; current IP)  (1) 
 
      In one embodiment, if evaluation of the conditional expression (1) returns a true value, the wireless station  300  and AP are on the same subnet. Otherwise, the AP and wireless station  300  are on different subnets. Hence, wireless station  300  requires a new IP address to communicate within the subnet of the AP. Accordingly, in one embodiment, wireless station  300  either utilizes a pre-allocated IP address from MCS server  120  or requests an IP address from, for example, DHCP/DRCP server  150 , for communication within subnet  200 - 2 .  
      In one embodiment, wireless station  300  utilizes session initiation protocol mobile (SIP-M) for voice communications (packet based) and utilize the mobile Internet protocol (mobile IP) for data communications. Representatively, mobile IP permits a wireless station to move from one network link (or subnet) to another without interrupting data communications. Accordingly, as illustrated with reference to  FIG. 5 , wireless station  300  may associate with AP 3   230 - 3  without interrupting communications by utilizing mobile IP. Accordingly, inter-domain roaming is performed, for example, using a pre-allocated subnet IP address, a requested IP address or mobile IP. Procedural methods for implementing embodiments of the invention are now described.  
      II. Operations  
       FIG. 6  is an exemplary flowchart illustrating a method  500  by which the wireless mobility manager of the wireless station initiates wireless access point (AP) handoff, in accordance with one embodiment of the invention. At process block  520 , a wireless station determines whether a signal strength of the current wireless connection to a wireless AP is below a user selected SCAN THRESHOLD. When such a condition is detected, at process block  530 , the wireless station begins scanning a current communication range to identify one or more wireless APs, for example, as illustrated with reference to  FIG. 5 .  
      In one embodiment, in order to reduce the performance impact of the wireless mobility manager (WMM) functionality described herein, the wireless station may discontinue scanning if the current signal strength rises above the user selected SCAN THRESHOLD, which are provided by adjustment via the user interface.  
      At process block  540 , the wireless station determines whether the current signal strength of the current wireless station connection falls below a user selected SWITCH THRESHOLD. In the embodiments illustrated, the SWITCH THRESHOLD represents a weaker or less powerfull signal than the user selected SCAN THRESHOLD. In one embodiment, the SWITCH THRESHOLD is selected to avoid interruption of wireless communication, but below which such communication may be interrupted. Accordingly, at process block  550 , the wireless station establishes a wireless connection with the selected AP from the one or more identified APs.  
      In the embodiment described in  FIG. 6 , the selection of an AP may be purely based on a signal strength of the identified wireless APs during the wireless station scan. A wireless AP, which provides a highest signal strength, is selected. As an alternative embodiment, however, the wireless mobility manager may request (i) a connection count for each identified AP (e.g., from a node server connected to the AP) and/or (ii) a bandwidth from a QoS/load balance server. As such, the wireless station may make a selection of a new AP based on the connection count, the bandwidth and/or the signal strength of each identified AP.  
      In another embodiment of the invention, the selection of a new AP may be prompted and/or based on a signal-to-noise ratio, which is determined for each identified AP. As such, for voice, as well as certain data communications such as streaming media for example, identified APs may exhibit sufficient signal strength while exhibiting unacceptable signal-to-noise ratios.  
      Likewise, the selection of a new AP may be prompted and/or based on a bit error rate of each identified AP. This measurement would likely be used for wireless stations supporting voice communications, which generally should not be perform by an AP which exhibits a significant bit error rate.  
      In yet another embodiment of the invention, the selection of a new AP may be prompted and/or based on a relative signal strength (RSS) slope computation. The RSS slope computation, which measures the rate of degradation of signal strength between the wireless station and the current AP, is computed as the ratio between the previously measured signal strength and the current measured signal strength.  
      For instance, as one example, when the measured signal strength of the current wireless connection falls below the SCAN THRESHOLD and RSS slope computation is less than a predetermined value, which may be preset or set by the user, the wireless mobility manager prompts the wireless station to scan and identify APs in its communication range. This avoids repeatedly scan operations when the signal strength oscillates around the SCAN THRESHOLD.  
      Alternatively, as a second example, when the RSS slope computation is less than the predetermined value, the wireless mobility manager prompts the wireless station to scan and identify APs in its communication range. This avoids loss of a connection where the signal strength quickly degrades.  
       FIG. 7  is a flowchart illustrating a method  502 , which is performed prior to scanning of the current communication range as set forth by process block  530 . At process block  504 , a wireless station logs into a MCS server as depicted in  FIG. 1 . Once authenticated by the MCS server, the wireless station may download an available AP list, which includes a list of APs to which a user of wireless station is an authorized member. Once downloaded, the wireless station may encrypt the available AP list (process block  508 ) and store the encrypted AP list in internal memory (process block  510 ).  
       FIG. 8  is a flowchart illustrating an exemplary method  532  for selecting an AP once one or more APs are identified at process block  530 . At process block  534 , a channel capacity of each detected AP is computed according to a signal strength and an available bandwidth of each detected AP. At process block  536 , a quality of service (QoS) level is computed for each AP according to the respective channel quality of each detected AP and a connection count of each detected AP. Finally, at process block  538 , an AP is selected according to the QoS level computed for the selected AP. In one embodiment, the QoS level is computed using QoS/load balance logic  440  of  FIG. 2 .  
       FIG. 9  is a flowchart illustrating a method  560  for establishing a wireless connection of process block  550  of  FIG. 6 , in accordance with one embodiment of the invention. At process block  562 , a wireless station requests pre-allocation of a predetermined network bandwidth from an AP of one of the one or more identified AP. In one embodiment, this may be performed by accessing QoS/load balance server  130 , which pre-allocates the bandwidth with an AP within communication network  100 . Alternatively, a node server  220  may perform the pre-allocation via a coupled AP. At process block  564 , the wireless station receives an AP from the one or more identified point wherein the requested bandwidth allocation is pre-allocated. At process block  566 , the wireless station associates with the received AP to establish a wireless connection. Representatively, voice communications may be performed or maintained with the selected AP by utilizing the requested bandwidth allocation to assure a minimum bandwidth of, for example, 64 kilobits per second (kb/s).  
       FIG. 10  is an exemplary flowchart illustrating a method  600  for wireless station roaming from a first network to a second network, in accordance with one embodiment of the invention, for example, as illustrated with reference to  FIG. 5 . At process block  602 , a wireless station having a wireless connection to an AP of a first network detects movement into communication range of a second network. At process block  604 , the wireless station may detect that a signal strength of the wireless connection is below a user selected SCAN THRESHOLD. Hence, at process block  610 , the wireless station scans a current communication range of the wireless station to detect one or more wireless APs of the second network. At process block  650 , the wireless station establishes a wireless connection with a selected AP of the second network. At process block  670 , the wireless station begins communication via the second network using an assigned IP address.  
       FIG. 11  is an exemplary flowchart illustrating a method  620  for performing scanning of process block  610  of  FIG. 10 , in accordance with one embodiment of the invention. At process block  622 , the wireless station selects a downloaded AP list, including one or more available APs of the first network and the second network. At process block  624 , the wireless station compares the identified APs to APs of the downloaded AP list to detect one or more APs of the second network. At process block  640 , the wireless station calculates the signal strength of each detected AP of the second network. At process block  642 , the wireless station calculates an available bandwidth, as well as a connection count, of each AP of the second network. Representatively, the signal strength, available bandwidth and connection count can be utilized by the wireless station to select and establish a wireless connection with an AP of the second network.  
       FIG. 12  is an exemplary flowchart illustrating a method for detecting wireless APs of the second network of process block  624  of  FIG. 11 , in accordance with one embodiment of the invention. At process block  632 , the wireless station determines an IP address of the detected APs according to the downloaded AP lists. At process block  634 , the wireless station compares an IP address of each detected AP to an IP address of the wireless station. At process block  636 , the wireless station identifies each AP having a different subnet address than an IP address of the wireless station as an AP of the second network. Representatively, the wireless station selects between detected APs of the second network to establish a wireless connection thereto.  
       FIG. 13  is a flowchart illustrating a method  652  for establishing a wireless connection to a selected wireless AP of the second network, in accordance with one embodiment of the invention. At process block  654 , the wireless station queries a downloaded AP list to determine authentication information of a selected AP. At process block  656 , the wireless station performs an authentication procedure with the selected AP. At process block  658 , the wireless station determines whether authentication with the selected AP is complete. Once authentication is complete, at process block  660 , the wireless station performs an association procedure with the selected AP. At process block  662 , the wireless station provides a selected AP with an IP address assigned to the wireless station for communication within the second network.  
      In an alternative embodiment, MCS server notifies a node of the second network or subnet of the assigned IP address to enable data communication with the second network. Alternatively, DHCP/DRCP server notifies the second network of an IP address assigned to the wireless station. In one embodiment, the IP address is issued for limited duration of time to avoid excessive issuing of new IP address to enable interdomain roaming. Accordingly, in one embodiment, a wireless station including WMM logic described herein provides a user with a continuous wireless connection as the user roams throughout a communications system without requiring any user intervention.  
      III. Alternate Embodiments  
      Several aspects of the wireless mobility manager for providing wireless AP handoff and a continuous wireless connection have been described. However, various implementations of the wireless mobility manager provide numerous features including, complementing, supplementing, and/or replacing the features described above. Features can be implemented as part of the wireless station or as part of the AP in different embodiment implementations. In addition, the foregoing description, for purposes of explanation, used specific nomenclature to provide a thorough understanding of the embodiments of the invention. However, it will be apparent to one skilled in the art that the specific details are not required in order to practice the embodiments of the invention.  
      In addition, although an embodiment described herein is directed to a wireless mobility manager, it will be appreciated by those skilled in the art that the embodiments of the present invention can be applied to other systems. In fact, systems for wireless communication fall within the embodiments of the present invention, as defined by the appended claims. The embodiments described above were chosen and described in order to best explain the principles of the embodiments of the invention and its practical applications. These embodiments were chosen to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.  
      Having disclosed exemplary embodiments and the best mode, modifications and variations may be made to the disclosed embodiments while remaining within the scope of the embodiments of the invention as defined by the following claims.