الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Radio frequency identification (RFID) system is a contactless automatic identification 1YItem. RFID was developed very ,early and was widely used in many areas recently. Now, has received much attention in many industries like manufacturing companies, material flow systems, warehouse, location tracking, and mobile remote sensing.
The RFID system consists of three main components, Radio frequency (RF) tags or lr8Dsponders, a reader or transceiver, and RFID middleware.
Simultaneous transmissions in RFID systems lead to collisions because the readers and tags operate on the same channel. The interrogation zone is the area around a reader where • single tag can be successfully read in the absence of any interference from another tag or reader.
When there is more than one transponder within the interrogation zone of a reader, <ill the transponders may send data (or tags) at the same time which lead to mutual interference. This event causes data loss and is referred to as a collision.
An effective RFID must reduce these collisions and identify tags regardless of the occurrence of collisions by using anti-collision protocol. The RFID collision problems are classified into the tags identification problem and reader collision problem. RFID tag collision problems resolved by two methods; the ALOHA-based algorithms (statistical) or the tree-based algorithms (deterministic).
A new algorithm, which is proposed, is a hybrid algorithm of dynamic framed slotted ALOHA (DFSA) and binary query tree search algorithm (BQTS). It starts the same as DFSA in initializing the frame with a number of slots. If a slot has collision of more than two tags, the reader treats it in the same manner as DFSA.
However, the reader uses binary query tree search algorithm to recognize the collision bits between tags in each slot. If a slot has only one collision bit, this means there are only two tags in this slot. If it has more than one collision bit, this means there are multi tags in this slot.