PRAM: alleviation of phase cancellation in multiple modulated tag-to-tag communication systems

In this article, we investigate phase cancellation problem in backscatter-based tag-to-tag (BBTT) communication systems. The existing BBTT systems mainly use two-state amplitude shift keying or phase shift keying. The signal received by the receiving tag is a superposition of the reflected signal of the RF source and the transmitting tag. When the receiving tag adopts envelope detection, the transmitting tag transmits different signals, and the received signal may have the same amplitude, resulting in phase cancellation problem and decoding failure. This problem is more common in BBTT systems, reducing communication quality and communication distance. When multiple modulation is used, phase cancellation is more serious. We confirm the existence of phase cancellation problem in this system from theory. Then, we propose an algorithm that uses phase rotation and adaptive modulation to improve the robustness of the system. Finally, through simulation results analysis, we prove that the algorithm can alleviate the phase cancellation problem.