Analog front end design for tags in backscatter-based tag-to-tag communication networks

Backscatter-based tag-to-tag communication (BBTT) is a paradigm wherein radio-less devices communicate with each other by using purely passive backscatter modulation. This allows for highly inexpensive and low power devices. Traditional backscattering devices like RFID tags are designed to communicate directly with an active reader leading to a centralized framework centered on the reader. Under a BBTT network, the tags talk to each other using backscattering in the presence of an external excitation signal, which can come from multiple sources (e.g., dedicated exciters, WiFi access points, TV towers, or cell phone towers). The two main components that determine the range and robustness of a passive tag-to-tag link are the power harvesting and demodulation circuit blocks in the analog front end (AFE). In this paper, we investigate the design constraints, optimization goals, and tradeoffs in the design of the AFE for BBTT tags. We first analyze the BBTT link theoretically and then verify the predicted optimal AFE parameters by simulations.