Dynamic Framed Slotted ALOHA Algorithm for Fast Object Identification in an RFID System
Dynamic Framed Slotted ALOHA Algorithm for Fast Object Identification in an RFID System
- 주제(키워드) RFID system , Anti-collision algorithm , Slotted ALOHA , Dynmic slot allocation
- 발행기관 아주대학교
- 지도교수 김재현
- 발행년도 2006
- 학위수여년월 2006. 2
- 학위명 석사
- 학과 및 전공 일반대학원 전자공학과
- 본문언어 영어
초록/요약
A Radio Frequency IDentification (RFID) system is a simple form of ubiquitous sensor networks that are used to identify physical objects. It permits remote, non-line-of-sight, and automatic reading. In an RFID system, when two or more tags respond to the reader’s command, the collision occurs and results in interfering the reader from identifying the tags correctly. The reader must avoid this collision by using the anti-collision algorithm. In general, there are two types of anti-collision algorithms; binary-type and ALOHA-type. This thesis will focus on the ALOHA-type anti-collision algorithm, where the Framed Slotted ALOHA (FS-ALOHA) algorithm is generally used. In the conventional FS-ALOHA algorithms, when the number of tags is more than the number of slots, the delay to identify a set of tags increases. On the other hand, in a situation that the number of tags is lower than the number of slots, the wasted slots can occur. Therefore, it needs to appropriately vary the frame size according to the number of tags. In this thesis, we propose Dynamic Framed Slotted ALOHA (DFSA) algorithm using both Tag Estimation (TE) and Dynamic Slot Allocation (DSA) to improve the performance of the conventional FS-ALOHA algorithms. We also compare the performance of the proposed DFSA algorithm with that of the conventional algorithms using OPNET (optimized network engineering simulator) simulation. According to the simulation, the performance of FS-ALOHA algorithms shows a rapid decrease as the number of tags increases because of the fixed frame size. So we have to use the FS-ALOHA algorithms in the specific and restricted applications. However the algorithms using both TE and DSA show the stable performance. Although the performance of the algorithms show the similar performance, the proposed DFSA algorithm is better because it enables faster tag identification and the complexity is lower so that it is easier to be implemented in an RFID system. When considering the parameters defined in ISO 18000-6 Type A, the proposed DFSA algorithm identifies approximately 777 tags per second.
more목차
Contents i
List of figures iii
List of tables iv
Abbreviations v
Chapter 1. Introduction 1
Chapter 2. An RFID system 3
2.1. History of an RFID system 3
2.2. Basics of an RFID system 4
2.2.1. An RFID reader 5
2.2.2. RFID tags 6
2.3. Applications of an RFID system 6
Chapter 3. Anti-collision algorithms 8
3.1. Reader and tag collision problem 8
3.2. Anti-collision algorithms 9
3.2.1. Binary-type anti-collision algorithms 10
3.2.2. ALOHA-type anti-collision algorithms 13
3.3. Anti-collision algorithms in Standards 14
Chapter 4. Related works 17
Chapter 5. Proposed DFSA algorithm 19
5.1. Proposed DFSA algorithm 19
5.1.1. Tag Estimation (TE) 20
5.1.2. Dynamic Slot Allocation (DSA) 22
5.2. Basic operation of DFSA algorithm 26
Chapter 6. Performance evaluation 28
6.1. Simulation environments 28
6.1.1. Frame structure for identification process 28
6.1.2. Network model for simulation 29
6.2. Simulation results 30
6.2.1. Number of slots per round 30
6.2.2. Number of slots per tag vs. number of tags 32
6.2.3. Identification time vs. number of tags 34
Chapter 7. Conclusion 37
Reference 39
