Abstract: The RFID reader collision problem emerges in the large applications; it will decrease the read rate of the whole system A MAC protocol based on the slow frequency hopping spread spectrum (FHSS) was proposed to resolve the reader collision problem.This MAC used reader synchronization mechanism. The reader used the corresponding frequency to communicate with tags if the reader competed with others and reserved the time slot successfully, and informed the neighbor readers to avoid communicating with tag simultaneously, thus prevented the tag interference. This MAC adopted the mechanism that reader transmissions and tag transmissions arc on separate frequency channels and the muti-frenquency hopping, so tags collide with tags but not with readers and readers collide with readers but not with tags, and such separation solves the reader frequency interference. The analysis results of the algorithm show that when the reader load is bigger and the reader average correspondence time is longer, the system throughput is higher.

Key words: RFID, Reader, Anti-collision, MAC