RFID Multiple Access Methods

Abstract Due to their limitless possibilities and low cost, RFID systems are powerful object identi cation tools well-suited in everyday applications. When attempting to identify multiple RFID tags from densely populated elds within the shortest timeframe possible, the typical design characteristics of RFID systems lead to a problematic lack of adequate resources to e ciently do so. After a brief introduction to RFID we present several forms of the multipleaccess protocol Aloha known from networking to resolve collisions, with special focus on the variants thereof which make them attractive for deploying in RFID systems. We then review a series of commercially available or standards-de ned RFID systems, and liken the contention resolution protocols used to the presented Aloha variants. The problematic of comparing the systems' performance will be addressed, and several systems brie y put against one-another.