Kenji, I think others are using ethernet to wifi bridges - if I were in the same position, I would too. USB wifi support probably isn't what it could be, for obvious reasons. I was using a DX Chinese wifi bridge until I realised it was beyond hope, it would shut down within five seconds of being powered on, and cycle over and over. I even had a Linux Python script to configure the thing for my old wireless network before I moved... needless to say, it got thrown in a bin. Hopefully you can do better...!