Versatile-Modulation and Megabit-Rate Backscatter System: Design, Implementation, and Experimental Results

Due to its almost zero power consumption and low-hardware costs, backscatter technology has recently gained considerable attention. However, traditional backscatter systems employ basic binary modulations to transmit data at a relatively low rate. In this article, we introduce VITAS, a new backscatter system that enables the tag to communicate with the transceiver using versatile modulations at a megabit rate. First, we present the design of the tag, which supports both binary and higher order modulations. We also develop a series of assembly instructions for the tag controller to generate modulated symbols with minimal clock cycles, thereby enhancing the data rate for a given clock frequency. Then, we design the transceiver to coordinate the backscatter communications with the tag. The transceiver incorporates a specific symbol synchronization algorithm to address the accumulated timing errors resulting from the tag unstable clock during high-rate transmission. Furthermore, we fabricate the tag on a four-layer acrlong PCB and implement the transceiver on a acrlong USRP X310. Finally, we provide experimental results to show that the VITAS system is capable of transmitting acrshort QPSK symbols at a maximum rate of 3 Mbit/s while consuming only $9.63~\mu \text{W}$ (3.21 pJ/bit).