Fast and accurate detection of unknown tags for rfid systems-hash collisions are desirable

Xiu Long Liu, Sheng Chen, Jia Liu, Wenyu Qu, Fengjun Xiao, Alex X. Liu, Jiannong Cao, Jiangchuan Liu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

25 Citations (Scopus)


Unknown RFID tags appear when tagged items are not scanned before being moved into a warehouse, which can even cause serious security issues. This paper studies the practically important problem of unknown tag detection. Existing solutions either require low-cost tags to perform complex operations or beget a long detection time. To this end, we propose the Collision-Seeking Detection (CSD) protocol, in which the server finds out a collision-seed to make massive known tags hash-collide in the last N slots of a time frame with size f. Thus, all the leading {f-N} pre-empty slots become useful for detection of unknown tags. A challenging issue is that, computation cost for finding the collision-seed is very huge. Hence, we propose a supplementary protocol called Balanced Group Partition (BGP), which divides tag population into n small groups. The group number n is able to trade off between communication cost and computation cost. We also give theoretical analysis to investigate the parameters to ensure the required detection accuracy. The major advantages of our CSD+BGP are two-fold: (i) it only requires tags to perform lightweight operations, which are widely used in classical framed slotted Aloha algorithms. Thus, it is more suitable for low-cost tags; (ii) it is more time-efficient to detect the unknown tags. Simulation results reveal that CSD+BGP can ensure the required detection accuracy, meanwhile achieving 1.7\times speedup in the single-reader scenarios and 3.9\times speedup in the multi-reader scenarios than the state-of-The-Art detection protocol.

Original languageEnglish
Article number8948356
Pages (from-to)126-139
Number of pages14
JournalIEEE/ACM Transactions on Networking
Issue number1
Publication statusPublished - Feb 2020


  • detection
  • hash collision
  • RFID
  • unknown tag

ASJC Scopus subject areas

  • Software
  • Computer Science Applications
  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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