An RFID (radio frequency identification device) tag comprising a processor; a memory configured to store an identification number that distinguishes the tag from other tags; a transponder coupled to the memory and the processor, the tag being configured to arbitrate by selecting a random number, in response to an inventory query from a reader, and to respond to the reader depending on the random number selected, the tag being further configured for multiple concurrent inventory session arbitrations with multiple readers by separately storing random numbers for respective inventory session arbitrations. RFID readers, systems, and methods are also provided.