P. Mueller, J.-N. Cao, and C.-L. Wang (Eds.): Infoscale 2009, LNICST 18, pp. 162–174, 2009. © Institute for Computer Science, Social-Informatics and Telecommunications Engineering 2009 Hasten Dynamic Frame Slotted ALOHA Algorithm for Fast Identification in RFID System Siti M. Wasikon and Mustafa M. Deris Faculty of Information Technology and Multimedia, Universiti Tun Hussein Onn Malaysia {mahfuzoh,mmustafa}@uthm.edu.my Abstract. The problems of identifying a set of tagged objects simultaneously in an RFID network have hampered the adoption of RFID universally. When mul- tiple tags transmit their IDs in a single period of time to a single reader over a shared wireless channel, the tag signals may collide. This collision will disturb the reader’s identification process. Hence, we proposed a modified version of Accelerated Frame Slotted ALOHA protocol called Hasten Dynamic Frame Slotted ALOHA (HDFSA) to condense a number of retransmission for one tag, thereby reducing the processing time. In HDFSA, the unread tag will be provided with a new slot in the subsequent reading cycle. The simulation con- ducted revealed that HDFSA outperformed the present Accelerated Frame Slot- ted ALOHA up to 78 percent in terms of processing time with less complexity, while preserving the accuracy of tag identification. Keywords: RFID, Tag Anti-Collision, Unread Tag. 1 Introduction In the early stage of RFID existence, various study have shown that RFID system provides an efficient and inexpensive mechanism for automatically collecting the identity information of an object [1]. This automatic identification (autoID) device operates by transmitting a signal (radio wave) from the reader to the tags. Every command that broadcast by a reader will be processed by all the tags within the range of reader. The reader then will recognize the objects through the ID that given by tags. A simultaneous data transmission by several tags to a single reader will lead to mu- tual interference, and therefore to data loss which also known as tag collision [2] occurred. Tag collision makes RFID loss their usefulness as a quick, flexible, and reliable method to electronically detect [3] a variety of objects in one time. This is especially critical for passive tag due to its limitation to detect collisions or to figure out neighboring tags. Therefore, the need for anti-collision protocol is necessary to enable the recognition of multiple tags in a single time. In general, there are two types of familiar tag anti-collision for passive tags, namely ALOHA based and tree based protocols. Tree-based protocols such as the binary tree protocol [4], [5] and the query tree protocol [6], [7], [8] operate by travers- ing the node sequentially. Every tag that transmits their ID in the same time will form