For a new project I need a cheap wireless solution for a master device sending to multiple (<100) battery powered small devices. Size and power consumption of the master device is not an issue.
The master tells the receivers to individually switch their LED on or off, so the communication only needs to be unidirectional.
Range should be within 50m.
Should be as fast as possible (<1ms)
... and of course reliable 
I would be thankful for any hardware suggestions.