Slot-wise maximum likelihood estimation of the tag population size in FSA protocols

Abstract—Framed Slotted Aloha (FSA) is a popular anticollision technique in state-of-the-art RF-ID systems, as in ISO/IEC CD 18000-6 for 900MHz or the EPCglobal HF Gen 2 draft for 13.56MHz. In many applications the number of tags entering and leaving the detection range of the reader is subject to a strong fluctuation and usually unknown. The current number of tags in the field is a crucial parameter to operate the FSA anti-collision in an optimal manner. Therefore, a lot of effort is spent on the estimation of this parameter and a range of different estimation techniques exist. The contributions of this paper are: 1) a closed formula for the probability of any observed event defined by the number of empty, singleton, and collision slots in the observed frame is developed and empirically verified. 2) This formula is then modified to compute the probability for partly observed frames as well which is of great interest as the referred standards allow for the in-frame adjustment of...

• Type: Journal
• Year: 2010
• Where: TCOM
• Authors: Bastian Knerr, Martin Holzer 0002, Christoph Angerer, Markus Rupp
• Keywords: EPCglobal HF Gen, Observed Frames, Parameter, TCOM 2010