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Method for WLAN NIC location discovering

IP.com Disclosure Number: IPCOM000020733D
Publication Date: 2003-Dec-10
Document File: 3 page(s) / 93K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for wireless local area network (WLAN) network interface card (NIC) location discovering. Benefits include improved functionality.

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Method for WLAN NIC location discovering

Disclosed is a method for wireless local area network (WLAN) network interface card (NIC) location discovering. Benefits include improved functionality.

General description


         The disclosed method is WLAN NIC location discovering. The method includes an algorithm for use in protected mode where some advanced or optimized mathematical functions are not available, such as square root, division, triangular functions.

Advantages

         The disclosed method provides advantages, including:

•         Improved functionality due to providing location discovering using only basic arithmetical instructions

Detailed description

         The disclosed method can be implemented on any processor with three basic arithmetical instructions: addition, subtraction, and multiplication. Most applications use triangular functions to solve distance measurement problems, which is very hard to implement in a low-end computing environment with limited resources.

         In the WLAN environment, if the NIC discovers more than three access points (APs), it can use a geometrical method to figure out its relative location by knowing the distances to the APs and the locations of the APs. For example, the APs can be designated as A1, A2, and A3 (see Figure 1). The user can be designated as U. The disclosed method is used to calculate the location of point U. The distance to the APs, D1, D2, and D3, can be derived from the received signal strength from the APs. The location of the APs are (Xa1, Ya1), (Xa2, Ya2), (Xa3, Ya3), respectively.

         The strategy is to test every point on the smallest circle (such as A2) against another circle (such as A1 or A3) and find two cross points (such as G and U). Then, test the points against the third circle (such as A3) to determine which one is closer the circle (such as point U).

         To implement this strategy, the disclosed method performs the following steps:

1.         Determine the smallest circle by compare the distances (such as A2)

2.         Shift the origin of the coordinate system to the center of the smallest circle

3.         Convert the coordinates of the APs. The equations of the three circles for A1, A2, and A3 in Figure 1 are respectively the following:
         (X-Xa1+Xa2)2+(Y-Ya1+Ya2)2

         X2+Y2
        
(X-Xa3+Xa2)2+(Y-Ya3+Ya2)2

4.         Find the first test point on the circle (such as point S).

         a.         Start from the origin and al...