Optimized Channel Phase Estimation in Passive RF Tag Network

We present a method for passive wireless channel estimation in RF tag-to-tag link. The technique has a low computational complexity, a small memory footprint and requires only one additional port in the modulator design of RF tag. The performance of the proposed method is evaluated on distance estimation task. The performance in the range of tag-to-tag distance from 28 cm to 228 cm is limited to
$10^{\circ}(9 \text{mm})$
. The demonstrated performance is comparable to performance of distance estimation techniques based on RFID technology which utilize RFID reader and are not scalable as the proposed method. The proposed method is amenable to deployment in near zero power operation RF-powered tags and it enriches RF tags with the ability to passively ‘fingerprint’ their surrounding.