Automatically transmit file from Bluetooth to device in proximity

Is there any software available for windows laptop/desktop which can send/broadcast a file to the devices in proximity? I am planning to send latest offers to my customers whenever they spend certain time in the shop in certain sections. All the devices will be registered first time. My requirement is, once the registered customer is in store, based on the section he is in, I need to broadcast the offers present in that section of the shop. Please reply if I need to give more information.