Multiple-bits-slot reservation aloha protocol for tag identification

The Radio Frequency Identification (RFID) system consists of a reader and many tags. In the mobile RFID environment, consumers can obtain product-related information of tags by using readers which are installed in mobile phones. However, the tag collision problem is serious in this environment. This paper proposes a multiple-bits-slot reservation aloha protocol for handling this problem. In the protocol, the reader assigns reservation slots before allocating frame slots, and each tag generates a random sequence in its own reservation slot randomly selected by this tag to reserve a frame slot, then the reader efficiently captures the reservation collisions in reservation slots by Manchester coding. Accordingly, the protocol significantly reduces collision frame slots, and eliminates empty frame slots. Our performance evaluation shows that the proposed protocol outperforms other aloha-based protocols ¹.