Balanced Golay Complementary Pair-Based Ultrasonic Backscatter Communication for Implantable Sensor Networks

This letter proposes a balanced Golay complementary pair-based ultrasonic backscatter communication (BGCP-UsBC) system for passive implantable sensor networks. The external reader transmits ultrasonic interrogation signals, and the implantable tag modulates and backscatters the incident ultrasonic signal using a BGCP to suppress tag multipath interference through the complementary auto-correlation property of the BGCP, while mitigating environmental multipath interference by the balanced structure. Furthermore, a sliding auto-correlation (S-AC) receiver without channel estimation is designed for the reader to achieve synchronization estimation and reliable reception. The theoretical bit error rate (BER) of the BGCP-UsBC system using the S-AC receiver is derived and validated by Monte Carlo simulations over intra-body fading channels. Both theoretical and simulated results demonstrate that the BER performance of the BGCP-UsBC system is significantly superior to that of systems based on Walsh sequences andm-sequences, as well as traditional UsBC systems, when considering severe multipath interference and timing errors.