A low delay multiple reader passive RFID system using orthogonal TH-PPM IR-UWB

• Current passive RFID systems face the challenges to locate mobile objects in real time in indoor environments, including the realization of low delay as well as effective cooperation among readers and accurate ranging ability in the physical layer. In order to overcome these challenges, this paper presents a low delay multi-reader passive RFID system using ultra high frequency (UHF) radio as the forward link from readers to tags and orthogonal time hopping pulse-position modulation (TH-PPM) impulse ultra-wideband radio (IR-UWB) over the dynamic framed slotted ALOHA algorithm as the backward link from tags to readers. The asymmetric radio links overlap parts of the forward and backward transmission and avoid reader-tag collisions. Readers cooperate via network synchronization by a server and a contention-based update strategy to acknowledge tags. An optimal system configured with 4 readers using 16 orthogonal TH sequences is suggested and operates 3 times faster than the theoretical potential of EPC Class-1 Generation-2 protocol with the listen-before-talk scheme. 

Nyckelord

IR-UWB

Multi-reader

Orthogonal TH-PPM

Passive RFID

Contention-based

Forward links

Indoor environment

Low delay

Mobile objects

Network synchronization

Physical layers

Real time

Slotted Aloha

Tag collision

Time-hopping

Ultra-high frequency

Ultra-wideband radio

Local area networks

Radio broadcasting

Radio links

Radio transmission

Real time systems

Broadband networks

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