Method for estimating number of tags in slotted aloha-based RFID system

• US 7,675,403 B2
• Filed: 08/02/2006
• Issued: 03/09/2010
• Est. Priority Date: 11/03/2005
• Status: Expired due to Fees

• Current Assignee: Electronics and Telecommunications Research Institute
• Original Assignee: Electronics and Telecommunications Research Institute
• Inventors: Lee, Dong-Han, Quan, ChengHao, Choi, Gil-Young, Chae, Jong-Suk, Pyo, Cheol-Sig, Bae, Ji-Hoon, Mo, Hee-Sook
• Primary Examiner(s): Wu; Daniel
• Assistant Examiner(s): SMALL, NAOMI J
• Application Number:
  US11/497,749
• Publication Number:
  US 20070096877A1
• Time in Patent Office: 1,315 Days
• Field of Search: 340/10.2
• US Class Current: 340/10.2
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: H04W 74/04 Scheduled access hybrid access H04W74/02
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals

Abstract

Provided is a method for estimating the number of tags in a slotted Aloha-based RFID system, which can estimate the number of tags through a new statistical average scheme using the number of slots, the measured number of empty slots, and the measured number of ID slots. The estimating method includes the steps of: a) setting the number (N) of slots, the measured number (c₀) of empty slots, and the measured number (c₁) of ID slots as parameters; and estimating the number (n) of the tags by substituting the set values into n=(N−1)/(c₀/c₁).

Claims

1. A method for estimating the number of tags in a slotted Aloha-based RFID system, the method comprising the steps of:

a) setting the number (N) of slots, the measured number (c₀) of empty slots, and the measured number (c₁) of ID slots as parameters; and

b) estimating the number (n) of the tags by substituting the set values into n=(N−

1)/(c₀/c₁).

2. The method as recited in claim 1, wherein the method for estimating the number of the tags is applied to an anti-collision algorithm of the slotted Aloha-based RFID system using a statistical average method.