It looks like you are wanting to update to iOS11 over your cellular data network. I'll be happy to provide some information on this. Per the quoted section from the article below, to update the iOS, it needs to either be done on a Wi-Fi network or through iTunes.
Update your iPhone, iPad, or iPod touch
You can update your iPhone, iPad, or iPod touch to the latest version of iOS wirelessly. If you can't see the update on your device, you can update manually using iTunes.
Thanks for using the Apple Support Communities.