Neen help extending a wireless connection

Hi fellas. I have some questions regarding an internet connection at a friends house. My bud lives in the basement apartment, with his brother upstairs. The modem/wireless router, is in the upstairs unit, and the wireless connection doesn't reach his basement unit. This didn't matter before, as he used a desktop, and we ran a hard line to his apartment. Now he's got a laptop, and no desktop, so wireless is a must. My question is, how do I get his basement unit wireless. We have a 50' ethernet cable to his apartment, so could I connect a second router to it? Would that work, or do I need something specific, like a wireless extender? He's got Comcast Cable, so I'm not entirely sure about the range of the router he has from them. I want to avoid replacing his current router, cuz I don't want to disturb his brothers set-up.


Thanks in advance.