GPS on Wireless LAN?

Hi!

I hope that someone would really enlighten me on this aspect.

How can a system pinpoint a handheld user position on a local wireless LAN network?

I understand that through the sending and receiving of signals from the handheld device bythe access points would enable the backend system to determine the user locations. Basically through 3 access points, forming a triangle and lock down on that fellow position.

Would someone please advise me whether this is posibble and how to go about it.

Thanks in advance.

Sagacious