Rfid Based Shopping Trolley Project Report
756
IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 60, NO. 3, MARCH 2012
Single-Antenna Coherent Detection of Collided FM0 RFID Signals
Aggelos Bletsas, Member, IEEE, John Kimionis, Student Member, IEEE, Antonis G. Dimitriou, Member, IEEE, and George N. Karystinos, Member, IEEE
Abstract—This work derives and evaluates single-antenna detection schemes for collided radio frequency identification (RFID) signals, i.e. simultaneous transmission of two RFID tags, following FM0 (biphase-space) encoding. In sharp contrast to prior art, the proposed detection algorithms take explicitly into account the FM0 encoding characteristics, including its inherent memory. The detection algorithms are derived when error at either or only one out of two tags is considered. It is shown that careful design of one-bit-memory two-tag detection can improve bit-error-rate (BER) performance by 3dB, compared to its memoryless counterpart, on par with existing art for single-tag detection. Furthermore, this work calculates the total tag population inventory delay, i.e. how much time is saved when two-tag detection is utilized, as opposed to conventional, single-tag methods. It is found that two-tag detection could lead to significant inventory time reduction (in some cases on the order of 40%) for basic framed-Aloha access schemes. Analytic calculation of inventory time is confirmed by simulation. This work could augment detection software of existing commercial RFID readers, including single-antenna portable versions, without major modification of their RF front ends. Index Terms—RFID, Gen2, FM0 coding, collision detection.
I. I NTRODUCTION IGNIFICANT progress has been made since the invention and first use of RFID, i.e. transmission of an identification bit string by means of signal reflection rather than active radiation [1]. Today, relevant applications have emerged in various domains, including logistics/inventory management [2], backscatter sensor networks [3]–[5], or even musical
IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 60, NO. 3, MARCH 2012
Single-Antenna Coherent Detection of Collided FM0 RFID Signals
Aggelos Bletsas, Member, IEEE, John Kimionis, Student Member, IEEE, Antonis G. Dimitriou, Member, IEEE, and George N. Karystinos, Member, IEEE
Abstract—This work derives and evaluates single-antenna detection schemes for collided radio frequency identification (RFID) signals, i.e. simultaneous transmission of two RFID tags, following FM0 (biphase-space) encoding. In sharp contrast to prior art, the proposed detection algorithms take explicitly into account the FM0 encoding characteristics, including its inherent memory. The detection algorithms are derived when error at either or only one out of two tags is considered. It is shown that careful design of one-bit-memory two-tag detection can improve bit-error-rate (BER) performance by 3dB, compared to its memoryless counterpart, on par with existing art for single-tag detection. Furthermore, this work calculates the total tag population inventory delay, i.e. how much time is saved when two-tag detection is utilized, as opposed to conventional, single-tag methods. It is found that two-tag detection could lead to significant inventory time reduction (in some cases on the order of 40%) for basic framed-Aloha access schemes. Analytic calculation of inventory time is confirmed by simulation. This work could augment detection software of existing commercial RFID readers, including single-antenna portable versions, without major modification of their RF front ends. Index Terms—RFID, Gen2, FM0 coding, collision detection.
I. I NTRODUCTION IGNIFICANT progress has been made since the invention and first use of RFID, i.e. transmission of an identification bit string by means of signal reflection rather than active radiation [1]. Today, relevant applications have emerged in various domains, including logistics/inventory management [2], backscatter sensor networks [3]–[5], or even musical