Performance evaluation of multiple access protocols for RFID testbed environment

Multiple access protocols for radio packet communication are classified into contention and contention less protocols. This work presents a performance comparison of contention protocols for example pure ALOHA, slotted ALOHA, non-persistent CSMA, slotted non persistent-ISMA, for the selection of best protocol to be implemented in RFID testbed environment. We evaluate the algorithms in an environment where users are not sure of collision, because other users may transmit (access the channel at same time). We found that the best known method for packet access communication, ALOHA, suffers heavily due to collision among packets. Further, CSMA protocols offer higher capacity but their performance is degraded by hidden terminals. Whereas ISMA, in which receiver controls the flow of packets from the tags, reduces these two problems of collision among data packets and hidden tags behind obstacles. A step by step procedure is presented for implementing all these protocols between receiver and tags. Robustness of protocols is evaluated for throughput and average transmission delay using parameters like power capture ratio, packet length and radius.