Simulation of an anti-collision algorithm for RFID systems using a code division multiple access with adaptive interference cancellation (CDMA/AIC) approach with dynamic processing gain (Gp)
Date
2022-12
Authors
Benitez Gutierrez, Natalia Margarita
Journal Title
Journal ISSN
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Abstract
Radio Frequency Identification (RFID) Systems are modern wireless
communication systems that transmit information from a transponder (tag) to a reader.
RFID systems are well known because of their contactless feature. However, tag
performance is limited by collision problems when multiple tags transmit simultaneously.
Due to the collision problem, much research has been developed using anti-collision
algorithms to enhance the systems' efficiency, save energy, and ensure the correct
transmission of information. Most research has used a Time Division Multiple Access
(TDMA) approach with anti-collision ALOHA-type algorithms. The time slots and
frames of the tags are manipulated to deal with the collision problem. They work with
different ALOHA protocol variants that are always trying to reduce the number of
collisions compared to the previous techniques. The most promising of the ALOHA
protocol variants is Dynamic Frame Slotted ALOHA (DFSA). In addition, research has
been conducted with a Code Division Multiple Access (CDMA) approach, called CDMA
with Adaptive Interference Cancellation (CDMA/AIC). The time slots are not used for
this anti-collision algorithm; instead, Spread Spectrum (SS) technology and Processing
Gain (Gp) were employed. In previous work, the Gp was a fixed value equal to sixty-four
(64). In contrast, this research involved a CDMA/AIC approach with a dynamic Gp
reached by generating different chip rates. This technique depended on the number of
collisions from the previous run to resize the Gp for a subsequent run. CDMA gave the
flexibility to use Spread Spectrum. The modulated signal was spread across the channel using orthogonal pseudorandom (PN) codes (generated for each tag) and was
demodulated at the reader using the same PN code. The more spread the signal was in the
channel, the greater the Gp. The research proved an enhancement in the system's
performance compared to the previous work. The system's efficiency enhancement and
the anti-collision algorithm were proven using MatLab as the simulation software. No
hardware implementation was developed in this research. Both the CDMA and the
modified DFSA code were exposed to the same conditions of noise (12, 9, 6 dB SNR),
number of tags (20, 60, 80, 100, 150, and 200), number of simulations (1000), and
Gp/slots (32, 64, 128, and 256). After the data was collected and processed, the
performance of CDMA in noisy scenarios and with a large number of tags was faster and
more efficient than DFSA. CDMA presented stability and fast information processing
due to its error correction and code spreading features.
Description
Keywords
CDMA/AIC, Dynamic processing gain, Rayleigh distribution, MATLAB, DFSA, Frame size, ALOHA protocol
Citation
Benitez Gutierrez, N. M. (2022). <i>Simulation of an anti-collision algorithm for RFID systems using a code division multiple access with adaptive interference cancellation (CDMA/AIC) approach with dynamic processing gain (Gp)</i> (Unpublished thesis). Texas State University, San Marcos, Texas.