Wifi extender / repeater for public hotel wifi?

Having a trip come up for several days and I'll be staying in a place that has kind of iffy wifi at times, mostly due to signal. Is there a portable wifi extender or repeater that I can use to boost the signal?

1. There is no ethernet connection in the room.
2. It's public wifi, so no access to the router/settings.

Any ideas? I see talk of using wifi repeaters or extenders in hotels but I've used an extender in the past with a router and I don't know how you can do that without setting it up in a way that would require access to router/other settings.