Don't know about worrldwide but here in the UK 2.4 to 2483.5 GHz is licence exempt.
Some uses for this this spectrum already are: Wireless computer networks (WiFi), RF tags (RFID), Bluetooth short-range links, video links, wireless microphones, microwave ovens, movement detectors, industrial control and monitoring.
IMO I would avoid wireless kit in this range as it's just too much of a minefield.
Regards,
Jon.