Recently Microsoft submitted a new application to the American Federal Communications Commission (FCC) about a wireless module and user’s manual of an unknown device. The new device’s FCC ID is ‘C3K-1683’ and the user’s manual showed ‘user’s manual 1525’. Because the FCC ID of the first Xbox One is ‘C3K-1525’, some specialists reckon that no matter what device it will be, it will have the same user’s manual as the Xbox One. Therefore it’s highly possible that this product will be a new version of the Xbox One console – for example, an Xbox One Slim.
It has been two years since the first release of the current-generation games console, we have reason to look forward to a lighter and more effective version this time around. The potential for an upgraded graphics core amongst other things would mean big things for the console’s fans, as the system currently struggles to handle Full HD graphics on the latest titles without substantial sacrifices in smoothness and fidelity. Interestingly, Microsoft also applied for a device with ID is ‘C3K-1682’ and with a different user’s manual from last one. Some people guessed whether this will be an enhanced Xbox One and feature an updated graphics core.
Microsoft however has denied the existence of “Xbox 1.5”. Department Manager Phil Spencer also said they’d prefer a bigger change for the new version and that he is not a fan of the ‘xbox one and a half’.
Sources:  http://m.neogaf.com/showthread.php?t=1206958