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A method of wireless LAN roaming and coexistence with other software Disclosure Number: IPCOM000124548D
Original Publication Date: 2005-Apr-27
Included in the Prior Art Database: 2005-Apr-27
Document File: 4 page(s) / 48K

Publishing Venue



This idea allows to make quick wireless LAN connection to access point when user moves the location from one access point to other access point. For roaming user move from office to home, home to airport, wireless LAN connection will be made very quickly. To achieve this, scan the access point and obtain the MAC address of the access point dynamically and make matching with the predefined connection list. This will allow to detect the access point even the access point is stealth mode (hidden) access point. With this method, pick up the right WLAN profile from the predefined connection list becomes faster and reliable. This method also allows the way to co-exist with other wireless LAN software without affecting the feature of such software. User can switch seamlessly for using the both software without disabling the others.

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Page 1 of 4

A method of wireless LAN roaming and coexistence with other software

Quick roaming:

* Can identify the predefined connection list by matching with scanned access point MAC address.
* Detected the access point/location even stealth mode access point is used
* Minimum search time for screening broadcasted access point

Seamless transition for user experience:

* User can use both software (i.e. Microsoft(*1) Windows(*2) Wireless LAN software) as well as IBM(*3) software without doing any manual switching or disabling others.

Connection List Table

System WLAN access point (

Scan Request

SSID = ??? (Hidden)

Mac Address = b1-b2-b3 Signal strength = 90%
Channel Number = 5

Location SSID MAC address

Office IBMA a1-a2-a3 x1-x2-x3

Meeting Room IBMB b1-b2-b3








1) if scan list shows no SSID (hidden), then by comparing MAC address.
2) If scan list shows SSID (broadcasted), s comparing SSID.

MAC address search only ne SSID (Minimum search overh


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Page 2 of 4

Seamless Transition for two Seamless Transition for two


  Transition (Automatic)

Microsoft WLAN

Software (WZC)

Connection List for IBM

SW Automatic

IBM WLAN Software

Operating System

NDIS Stack

Wireless LAN Driver

1. IBM Software scan the access point and determine which software to control the connec
2. If the MAC address belongs to IBM Software, IBM software takes ownership
3. If the MAC address belongs to Microsoft WLAN software to use, it switches to Microsoft
4. IBM software stays as "listen mode" while Microsoft is taking ownership.

Note: This method does not limit only to Microsoft software but applicable to other commercia software using the same method.


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IBM SW / W ZC m ode transition IBM SW / W ZC m ode transition

IBM SW connection list table   (new)

W ZC settings / roaming

              Mode MAC address SSID

         x,y,z, 111

IB M SW m anaged

             IB M SW m anaged x1,x2,x3 222


          y1,y2 SSID-X

WZC managed

          z1 SSID-Y

WZC managed

          a1,a2 SSID-Z

WZC managed


W ZCSVC Registry Location

Static#001(SSID-X) Static#002(SSID-Y) Static#003(SSID-Z)


1. Scan Access Point and get MAC address (at resume from suspend, or logon/boot time...