Xbox Wire says. This is for a player logged into his own console – if a player logs into his account on a separate console at a friend's house, for example, the Xbox One needs to be connected to the internet at least once every hour.
"With Xbox One you can game offline for up to 24 hours on your primary console, or one hour if you are logged on to a separate console accessing your library," Xbox Wire writes. "Offline gaming is not possible after these prescribed times until you re-establish a connection, but you can still watch live TV and enjoy Blu-ray and DVD movies."
This is the clearest explanation of the Xbox One's internet requirements since Microsoft's reveal on May 21. In a post it removed from Xbox Wire, Microsoft said the console "does not have to be always connected, but Xbox One does require a connection to the Internet."
Microsoft recommends a broadband internet connection of 1.5Mbps for the Xbox One, and suggests mobile broadband for those without access to an Ethernet connection. Xbox One has two wireless antennas, and a gigabit Ethernet port and 802.11n wireless.
"Because every Xbox One owner has a broadband connection, developers can create massive, persistent worlds that evolve even when you're not playing," Xbox Wire says.