In order to further improve the identification efficiency of the Radio frequency identification (RFID) system

an efficient anti-collision protocol based on on-demand slot assignment is proposed.In this protocol

each identification round is divided into two steps including reservation stage and identification stage.The proposed protocol avoids collision frame slots and empty frame slots by the capture mechanism of reservation collisions and by the reservation mechanism of frame slots

respectively.Furthermore

the optimal bit number of reservation random code and the optimal number of reservation slots are given for obtaining the optimal efficiency.The paper analyses the circuit complexity of tag based on the protocol

and proposes the tag estimation method suitable for the protocol.Performance estimation shows that the average efficiency of the protocol is about 91.28% and it significantly outperforms the existing anti-collision protocols in terms of communication complexity and identification speed.