Weak Wireless Signal on my Macbook

I recently switched to Bright House Network for Internet. My dad has a airport extreme hooked up to the cable modem. He gets a very strong signal at about 15 mbps. I only get about 4 mbps as my room is kind of far from his airport. Sometimes I lose the connection from his airport and have to re-connect which get annoying. Is there any way I can increase the signal in my room, have a faster connection & increase my mbps?

Thanks In Advance