Bandwidth is important for the host, as the bandwidth required for data transmission scales for every peer that connects - the host has to send and receive from ALL the peers, while each peer only has to send and receive from the host.
3g or 4g, you can have a very large bandwidth on a cellular connection, but generally speaking the latency will ALWAYS be bad. This is why real time synchronous mobile games are very rare. Most mobile games are either asynchronous, or set up in a way where timing and lag don't make little difference on game play. Otherwise, you will need to develop some creative and robust lag compensation techniques, which can be done, just troublesome.