thanks for your answer

1) i have never developed embedded application,so can you please give some links to get started (french or english) ?
2)absolutly, OS take care of protocols and so on but i asked if Qt have some packages for network to manipulate easily wifi?
3)i'm agree with you,i already tried it in a project as just a GUI, but i didn't use embedded or network classes.
4) yes , it's like GPS with cars, but it's for an exiting wifi infrastucture,for exemple to localize my PDA in my university,and find the route to my classroom,it have many advantages.

if you want try to make a little research on www.pdf-search-engine.com with keywords i wrote and you'll find many publications about that topic.