Using Analog Network Coding to Improve the RFID Reading Throughput

RFID promises to revolutionize the inventory management in large warehouses, retail stores, hospitals, transportation systems, etc. Periodically reading the IDs of the tags is an important function to guard against administration error, vendor fraud and employee theft. Given the low-speed communication channel in which a RFID system operates, the reading throughput is one of the most important performance metrics. The current protocols have reached the physical throughput limit that can possibly be achieved based on their design methods. To break that limit, we have to apply fundamentally different approaches. This paper investigates how much throughput improvement the analog network coding can bring when it is integrated into the RFID protocols. The idea is to extract useful information from collision slots when multiple tags transmit their IDs simultaneously. Traditionally, those slots are discarded. With analog network coding, we show that a collision slot is almost as useful as a non-collision slot in which exactly one tag transmits. We propose the framed collision-aware tag identification protocol that optimally applies analog network coding to maximize the reading throughput, which is 51.1% ~ 70.6% higher than the best existing protocols.