RFID-a RF transceiver?

I want to find a simple RF transceiver which can be interfaced with PIC. Those transceivers are used to make global communication so It is much better if they obtain IDs or multi-channels(to avoid conflict communicating signals). I am developing module using LEGO DUPLO bricks so it should be small to fit inside brick.
If any of you knows any RF chip that satisfies my requirement, please let me know.
Many thanks!