It's 3G, not G3
you are getting mobile broadband, not wireless.
with wireless broadband the broadband is brought into the house via a normal telephone line that is connected to a wireless router, your laptop then connects to that router using wireless. this is the setup your neighbour will have, as they have not got security on the network anyone can connect to it and use their internet.
Mobile broadband uses a small USB dongle that plugs into your computer and receives the internet using the mobile phone network. using this method of getting a internet connection means that only the computer the dongle is physically plugged into can use the connection, there is no way anyone else can use it,