RFID Tag Acquisition Via Compressed Sensing: Fixed vs. Random Signature Assignment

We introduce a novel scheme to perform radio frequency identification (RFID) with compressed sensing techniques. The proposed scheme allows quick and reliable identification of several RFID tags, even at low signal-to-noise ratio. Contrary to the widely used frame slotted ALOHA (FSA) protocol, the tags activated by a reader deliberately respond simultaneously with their assigned signature during the acquisition phase; collisions are regarded as beneficial rather than destructive. The signatures are drawn from a huge signature pool, and the set of signatures that is assigned to the activated tags is very small compared to the total signature count. This introduces sparsity to the acquisition phase which, in turn, allows formulation of the acquisition as a compressed sensing measurement. Furthermore, our formulation permits the usage of a low-complexity approximate message passing algorithm for compressed sensing recovery. We compare two realizations of the compressed sensing-based approach to the FSA protocol. The first performs fixed signature assignment - this enables very quick identification but sacrifices flexibility. The second performs random signature assignment - this reduces the identification speed but provides flexibility. A comparison via simulation shows that both compressed sensing-based approaches significantly outperform FSA in terms of identification speed and robustness to noise.