Reader collision occurs in RFID systems when the coverage area of one RFID reader overlaps with that of another reader. This causes two different problems:
- Signal interference
The RF fields of two or more readers may overlap and interfere. This can be solved by having the readers programmed to read at fractionally different times. This technique (called time division multiple access - TDMA) can still result in the same tag being read twice. - Multiple reads of the same tag
The problem here is that the same tag is read one time by each of the overlapping readers. The only solution is to program the RFID system to make sure that a given tag (with its unique ID number) is read only once in a session.