Performance Analysis of RFID Protocols: CDMA Versus the Standard EPC Gen-2

Abstract

Radio frequency identification (RFID) is a ubiquitous wireless technology which allows objects to be identified automatically. An RFID tag is a small electronic device with an antenna and has a unique identification (ID) number. RFID tags can be categorized into passive and active tags. For passive tags, a standard communication protocol known as EPC-global Generation-2, or briefly EPC Gen-2, is currently in use. RFID systems are prone to transmission collisions due to the shared nature of the wireless channel used by tags. The EPC Gen-2 standard recommends using dynamic framed slotted ALOHA technique to solve the collision issue and to read the tag IDs successfully. Recently, some researchers have suggested to replace the dynamic framed slotted ALOHA technique used in the standard EPC Gen-2 protocol with the code division multiple access (CDMA) technique to reduce the number of collisions and to improve the tag identification procedure. In this paper, the standard EPC Gen-2 protocol and the CDMA-based tag identification schemes are modeled as absorbing Markov chain systems. Using the proposed Markov chain systems, the analytical formulae for the average number of queries and the total number of transmitted bits needed to identify all tags in an RFID system are derived for both the EPC Gen-2 protocol and the CDMA-based tag identification schemes. In the next step, the performance of the EPC Gen-2 protocol is compared with the CDMA-based tag identification schemes and it is shown that the standard EPC Gen-2 protocol outperforms the CDMA-based tag identification schemes in terms of the number of transmitted bits and the average time required to identify all tags in the system. Note to Practitioners-In an RFID system, packet collisions can occur when multiple tags transmit a reply message simultaneously in response to a query from the reader. To cope with the collision issue in RFID systems, the EPC Gen-2 standard recommends the dynamic framed slotted ALOHA technique for tag identification purpose. Most of the RFID systems that are currently in use by industry have been designed and implemented based on the EPC Gen-2 standard. Recently, some researchers have suggested to replace the current dynamic framed slotted ALOHA technique used in the EPC Gen-2 protocol with the CDMA technique to allow more tags to be read at each query and to expedite the tag identification procedure. The time needed to identify all tags in the system and the required bandwidth play an important role in designing a commercial or industrial RFID system. Therefore, before adapting the CDMA technique in new RFID systems, it is necessary to know the pros and cons of using this technique for the tag identifica-

Internet of Things: A Survey on Enabling Technologies, Protocols, and Applications

“…A performance evaluation of these techniques has been carried out in [108]. They used the average number of queries and the total number of transmitted bits that are required to identify all tags in the system as their measurement factors.…”

A Review on Internet of Things for Defense and Public Safety

“…In order to decrease the number of collisions in the EPC Gen-2 protocol, and to improve tag identification procedure, researchers have proposed to use Code Division Multiple Access (CDMA) instead of the dynamic framed slotted ALOHA. A performance analysis of the RFID protocols in terms of the average number of queries and the total number of transmitted bits required to identify all tags in the system can be seen in [131]. The expected number of queries for tag identification using the CDMA technique is lower that of the EPC Gen-2 protocol, because CDMA decreases the number of collisions.…”

Performance Analysis of CDMA/ALOHA Networks in Memory Impulse Channels

“…Code division multiple access (CDMA) is popular in wireless networks and power line communication (PLC) networks [1][2][3][4][5][6][7]. ALOHA is a popular media access control (MAC) protocol in wireless and PLC networks [8,9].…”