(A) study on efficient reader anti-collision protocol for low-cost passive RFID system

Abstract

Low-cost passvie RFID(Radio Frequency IDentification) system which readers verify storage data from tags is one of the auto-identified techniques instead of existing barcode system using wireless freuqnecy. RFID system starts to be spread far and wide after EPCglobal Class 1 Generation 2 is standardization as ISO 18000-6C. However it has problems that are a delaying standardization of other RFID system and low read rate by reader and tag collision problems. Especially reader collision and tag collision are the results of low interrogation efficiency and low read late, so they are the main problems to spread RFID system. Reader collision is the principal problem to be low read rate for RFID system. The frequency interference is the case that neighboring readers use simultaneously same frequency, so the collision originates between commands from readers to tags. The tag interference is the case that many readers want to read a same tag at the same time so the tag could not distinguish between each reader because of using backscattering. Research is focus on avoidance of the frequency interference until now, so it can solve using some methods that neighboring readers use different frequency and transmission frequency between a reader and a tag are divided. These methods are familiar to Dense reader mode and use from each country. However growing up RFID industry, tag interference becomes the most important problem to solve for increasing read rate through approach between readers. In this paper, we analyze specification of a reader and a tag and we propose efficient avoidance of reader-to-tag interference at dense reader mode. Here readers should transmit pre-pulse which readers transmit to occupy channel and post-pulse which readers transmit to idle channel. A reader which transmit pre-pulse should be a master reader of occupied channel and others which receive higher then threshold of pre-pulse should be slave readers of the channel. Using this method, re...